/* GIMP plug-in to load and save Paint Shop Pro files (.PSP and .TUB)
 *
 * Copyright (C) 1999 Tor Lillqvist
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 *
 * Work in progress! Doesn't handle saving yet.
 *
 * For a copy of the PSP file format documentation, surf to
 * http://www.jasc.com.
 *
 */

#define LOAD_PROC      "file-psp-load"
#define SAVE_PROC      "file-psp-save"
#define PLUG_IN_BINARY "file-psp"

/* set to the level of debugging output you want, 0 for none */
#define PSP_DEBUG 0

#define IFDBG(level) if (PSP_DEBUG >= level)

#include "config.h"

#include <errno.h>
#include <string.h>
#include <zlib.h>

#include <glib/gstdio.h>

#include <libgimp/gimp.h>
#include <libgimp/gimpui.h>
#include <libgimpbase/gimpparasiteio.h>

#include "libgimp/stdplugins-intl.h"


/* Note that the upcoming PSP version 6 writes PSP file format version
 * 4.0, but the documentation for that apparently isn't publicly
 * available (yet). The format is luckily designed to be somwehat
 * downward compatible, however. The semantics of many of the
 * additional fields and block types can be relatively easily reverse
 * engineered.
 */

/* The following was cut and pasted from the PSP file format
 * documentation version 3.0.(Minor stylistic changes done.)
 *
 *
 * To be on the safe side, here is the whole copyright notice from the
 * specification:
 *
 * The Paint Shop Pro File Format Specification (the Specification) is
 * copyright 1998 by Jasc Software, Inc. Jasc grants you a
 * nonexclusive license to use the Specification for the sole purposes
 * of developing software products(s) incorporating the
 * Specification. You are also granted the right to identify your
 * software product(s) as incorporating the Paint Shop Pro Format
 * (PSP) provided that your software in incorporating the
 * Specification complies with the terms, definitions, constraints and
 * specifications contained in the Specification and subject to the
 * following: DISCLAIMER OF WARRANTIES. THE SPECIFICATION IS PROVIDED
 * AS IS. JASC DISCLAIMS ALL OTHER WARRANTIES, EXPRESS OR IMPLIED,
 * INCLUDING, BUT NOT LIMITED TO, ANY IMPLIED WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT.
 *
 * You are solely responsible for the selection, use, efficiency and
 * suitability of the Specification for your software products.  OTHER
 * WARRANTIES EXCLUDED. JASC SHALL NOT BE LIABLE FOR ANY DIRECT,
 * INDIRECT, CONSEQUENTIAL, EXEMPLARY, PUNITIVE OR INCIDENTAL DAMAGES
 * ARISING FROM ANY CAUSE EVEN IF JASC HAS BEEN ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGES. CERTAIN JURISDICTIONS DO NOT PERMIT
 * THE LIMITATION OR EXCLUSION OF INCIDENTAL DAMAGES, SO THIS
 * LIMITATION MAY NOT APPLY TO YOU.  IN NO EVENT WILL JASC BE LIABLE
 * FOR ANY AMOUNT GREATER THAN WHAT YOU ACTUALLY PAID FOR THE
 * SPECIFICATION. Should any warranties be found to exist, such
 * warranties shall be limited in duration to ninety (90) days
 * following the date you receive the Specification.
 *
 * Indemnification. By your inclusion of the Paint Shop Pro File
 * Format in your software product(s) you agree to indemnify and hold
 * Jasc Software, Inc. harmless from any and all claims of any kind or
 * nature made by any of your customers with respect to your software
 * product(s).
 *
 * Export Laws. You agree that you and your customers will not export
 * your software or Specification except in compliance with the laws
 * and regulations of the United States.
 *
 * US Government Restricted Rights. The Specification and any
 * accompanying materials are provided with Restricted Rights. Use,
 * duplication or disclosure by the Government is subject to
 * restrictions as set forth in subparagraph (c)(1)(ii) of The Rights
 * in Technical Data and Computer Software clause at DFARS
 * 252.227-7013, or subparagraphs (c)(1) and (2) of the Commercial
 * Computer Software - Restricted Rights at 48 CFR 52.227-19, as
 * applicable. Contractor/manufacturer is Jasc Software, Inc., PO Box
 * 44997, Eden Prairie MN 55344.
 *
 * Jasc reserves the right to amend, modify, change, revoke or
 * withdraw the Specification at any time and from time to time. Jasc
 * shall have no obligation to support or maintain the Specification.
 */

/* Block identifiers.
 */
typedef enum {
  PSP_IMAGE_BLOCK = 0,                  /* General Image Attributes Block (main) */
  PSP_CREATOR_BLOCK,                    /* Creator Data Block (main) */
  PSP_COLOR_BLOCK,                      /* Color Palette Block (main and sub) */
  PSP_LAYER_START_BLOCK,                /* Layer Bank Block (main) */
  PSP_LAYER_BLOCK,                      /* Layer Block (sub) */
  PSP_CHANNEL_BLOCK,                    /* Channel Block (sub) */
  PSP_SELECTION_BLOCK,                  /* Selection Block (main) */
  PSP_ALPHA_BANK_BLOCK,                 /* Alpha Bank Block (main) */
  PSP_ALPHA_CHANNEL_BLOCK,              /* Alpha Channel Block (sub) */
  PSP_THUMBNAIL_BLOCK,                  /* Thumbnail Block (main) */
  PSP_EXTENDED_DATA_BLOCK,              /* Extended Data Block (main) */
  PSP_TUBE_BLOCK,                       /* Picture Tube Data Block (main) */
  PSP_ADJUSTMENT_EXTENSION_BLOCK,       /* Adjustment Layer Extension Block (sub) (since PSP6)*/
  PSP_VECTOR_EXTENSION_BLOCK,           /* Vector Layer Extension Block (sub) (since PSP6) */
  PSP_SHAPE_BLOCK,                      /* Vector Shape Block (sub) (since PSP6) */
  PSP_PAINTSTYLE_BLOCK,                 /* Paint Style Block (sub) (since PSP6) */
  PSP_COMPOSITE_IMAGE_BANK_BLOCK,       /* Composite Image Bank (main) (since PSP6) */
  PSP_COMPOSITE_ATTRIBUTES_BLOCK,       /* Composite Image Attributes (sub) (since PSP6) */
  PSP_JPEG_BLOCK,                       /* JPEG Image Block (sub) (since PSP6) */
  PSP_LINESTYLE_BLOCK,                  /* Line Style Block (sub) (since PSP7) */
  PSP_TABLE_BANK_BLOCK,                 /* Table Bank Block (main) (since PSP7) */
  PSP_TABLE_BLOCK,                      /* Table Block (sub) (since PSP7) */
  PSP_PAPER_BLOCK,                      /* Vector Table Paper Block (sub) (since PSP7) */
  PSP_PATTERN_BLOCK,                    /* Vector Table Pattern Block (sub) (since PSP7) */
  PSP_GRADIENT_BLOCK,                   /* Vector Table Gradient Block (not used) (since PSP8) */
  PSP_GROUP_EXTENSION_BLOCK,            /* Group Layer Block (sub) (since PSP8) */
  PSP_MASK_EXTENSION_BLOCK,             /* Mask Layer Block (sub) (since PSP8) */
  PSP_BRUSH_BLOCK,                      /* Brush Data Block (main) (since PSP8) */
} PSPBlockID;

/* Bitmap type.
 */
typedef enum {
  PSP_DIB_IMAGE = 0,            /* Layer color bitmap */
  PSP_DIB_TRANS_MASK,           /* Layer transparency mask bitmap */
  PSP_DIB_USER_MASK,            /* Layer user mask bitmap */
  PSP_DIB_SELECTION,            /* Selection mask bitmap */
  PSP_DIB_ALPHA_MASK,           /* Alpha channel mask bitmap */
  PSP_DIB_THUMBNAIL,            /* Thumbnail bitmap */
  PSP_DIB_THUMBNAIL_TRANS_MASK, /* Thumbnail transparency mask (since PSP6) */
  PSP_DIB_ADJUSTMENT_LAYER,     /* Adjustment layer bitmap (since PSP6) */
  PSP_DIB_COMPOSITE,            /* Composite image bitmap (since PSP6) */
  PSP_DIB_COMPOSITE_TRANS_MASK, /* Composite image transparency (since PSP6) */
  PSP_DIB_PAPER,                /* Paper bitmap (since PSP7) */
  PSP_DIB_PATTERN,              /* Pattern bitmap (since PSP7) */
  PSP_DIB_PATTERN_TRANS_MASK,   /* Pattern transparency mask (since PSP7) */
} PSPDIBType;

/* Type of image in the composite image bank block. (since PSP6)
 */
typedef enum {
  PSP_IMAGE_COMPOSITE = 0,      /* Composite Image */
  PSP_IMAGE_THUMBNAIL,          /* Thumbnail Image */
} PSPCompositeImageType;

/* Graphic contents flags. (since PSP6)
 */
typedef enum {
  /* Layer types */
  keGCRasterLayers     = 0x00000001,    /* At least one raster layer */
  keGCVectorLayers     = 0x00000002,    /* At least one vector layer */
  keGCAdjustmentLayers = 0x00000004,    /* At least one adjustment layer */

  /* Additional attributes */
  keGCThumbnail              = 0x01000000,      /* Has a thumbnail */
  keGCThumbnailTransparency  = 0x02000000,      /* Thumbnail transp. */
  keGCComposite              = 0x04000000,      /* Has a composite image */
  keGCCompositeTransparency  = 0x08000000,      /* Composite transp. */
  keGCFlatImage              = 0x10000000,      /* Just a background */
  keGCSelection              = 0x20000000,      /* Has a selection */
  keGCFloatingSelectionLayer = 0x40000000,      /* Has float. selection */
  keGCAlphaChannels          = 0x80000000,      /* Has alpha channel(s) */
} PSPGraphicContents;

/* Character style flags. (since PSP6)
 */
typedef enum {
  keStyleItalic      = 0x00000001,      /* Italic property bit */
  keStyleStruck      = 0x00000002,      /* Strike­out property bit */
  keStyleUnderlined  = 0x00000004,      /* Underlined property bit */
  keStyleWarped      = 0x00000008,      /* Warped property bit (since PSP8) */
  keStyleAntiAliased = 0x00000010,      /* Anti­aliased property bit (since PSP8) */
} PSPCharacterProperties;

/* Table type. (since PSP7)
 */
typedef enum {
  keTTUndefined = 0,     /* Undefined table type */
  keTTGradientTable,     /* Gradient table type */
  keTTPaperTable,        /* Paper table type */
  keTTPatternTable       /* Pattern table type */
} PSPTableType;

/* Layer flags. (since PSP6)
 */
typedef enum {
  keVisibleFlag      = 0x00000001,      /* Layer is visible */
  keMaskPresenceFlag = 0x00000002,      /* Layer has a mask */
} PSPLayerProperties;

/* Shape property flags. (since PSP6)
 */
typedef enum {
  keShapeAntiAliased = 0x00000001,      /* Shape is anti­aliased */
  keShapeSelected    = 0x00000002,      /* Shape is selected */
  keShapeVisible     = 0x00000004,      /* Shape is visible */
} PSPShapeProperties;

/* Polyline node type flags. (since PSP7)
 */
typedef enum {
  keNodeUnconstrained     = 0x0000,     /* Default node type */
  keNodeSmooth            = 0x0001,     /* Node is smooth */
  keNodeSymmetric         = 0x0002,     /* Node is symmetric */
  keNodeAligned           = 0x0004,     /* Node is aligned */
  keNodeActive            = 0x0008,     /* Node is active */
  keNodeLocked            = 0x0010,     /* Node is locked */
  keNodeSelected          = 0x0020,     /* Node is selected */
  keNodeVisible           = 0x0040,     /* Node is visible */
  keNodeClosed            = 0x0080,     /* Node is closed */

  /* TODO: This might be a thinko in the spec document only or in the image
   *       format itself. Need to investigate that later
   */
  keNodeLockedPSP6        = 0x0016,     /* Node is locked */
  keNodeSelectedPSP6      = 0x0032,     /* Node is selected */
  keNodeVisiblePSP6       = 0x0064,     /* Node is visible */
  keNodeClosedPSP6        = 0x0128,     /* Node is closed */

} PSPPolylineNodeTypes;

/* Blend modes. (since PSP6)
 */
typedef enum {
  PSP_BLEND_NORMAL,
  PSP_BLEND_DARKEN,
  PSP_BLEND_LIGHTEN,
  PSP_BLEND_HUE,
  PSP_BLEND_SATURATION,
  PSP_BLEND_COLOR,
  PSP_BLEND_LUMINOSITY,
  PSP_BLEND_MULTIPLY,
  PSP_BLEND_SCREEN,
  PSP_BLEND_DISSOLVE,
  PSP_BLEND_OVERLAY,
  PSP_BLEND_HARD_LIGHT,
  PSP_BLEND_SOFT_LIGHT,
  PSP_BLEND_DIFFERENCE,
  PSP_BLEND_DODGE,
  PSP_BLEND_BURN,
  PSP_BLEND_EXCLUSION,
  PSP_BLEND_TRUE_HUE, /* since PSP8 */
  PSP_BLEND_TRUE_SATURATION, /* since PSP8 */
  PSP_BLEND_TRUE_COLOR, /* since PSP8 */
  PSP_BLEND_TRUE_LIGHTNESS, /* since PSP8 */
  PSP_BLEND_ADJUST = 255,
} PSPBlendModes;

/* Adjustment layer types. (since PSP6)
 */
typedef enum {
  keAdjNone = 0,        /* Undefined adjustment layer type */
  keAdjLevel,           /* Level adjustment */
  keAdjCurve,           /* Curve adjustment */
  keAdjBrightContrast,  /* Brightness­contrast adjustment */
  keAdjColorBal,        /* Color balance adjustment */
  keAdjHSL,             /* HSL adjustment */
  keAdjChannelMixer,    /* Channel mixer adjustment */
  keAdjInvert,          /* Invert adjustment */
  keAdjThreshold,       /* Threshold adjustment */
  keAdjPoster           /* Posterize adjustment */
} PSPAdjustmentLayerType;

/* Vector shape types. (since PSP6)
 */
typedef enum {
  keVSTUnknown = 0,     /* Undefined vector type */
  keVSTText,            /* Shape represents lines of text */
  keVSTPolyline,        /* Shape represents a multiple segment line */
  keVSTEllipse,         /* Shape represents an ellipse (or circle) */
  keVSTPolygon,         /* Shape represents a closed polygon */
  keVSTGroup,           /* Shape represents a group shape (since PSP7) */
} PSPVectorShapeType;

/* Text element types. (since PSP6)
 */
typedef enum {
  keTextElemUnknown = 0,        /* Undefined text element type */
  keTextElemChar,               /* A single character code */
  keTextElemCharStyle,          /* A character style change */
  keTextElemLineStyle           /* A line style change */
} PSPTextElementType;

/* Text alignment types. (since PSP6)
 */
typedef enum {
  keTextAlignmentLeft = 0,      /* Left text alignment */
  keTextAlignmentCenter,        /* Center text alignment */
  keTextAlignmentRight          /* Right text alignment */
} PSPTextAlignment;

/* Paint style types. (since PSP6)
 */
typedef enum {
  keStyleNone     = 0x0000,     /* No paint style info applies */
  keStyleColor    = 0x0001,     /* Color paint style info */
  keStyleGradient = 0x0002,     /* Gradient paint style info */
  keStylePattern  = 0x0004,     /* Pattern paint style info (since PSP7) */
  keStylePaper    = 0x0008,     /* Paper paint style info (since PSP7) */
  keStylePen      = 0x0010,     /* Organic pen paint style info (since PSP7) */
} PSPPaintStyleType;

/* Gradient type. (since PSP7)
 */
typedef enum {
  keSGTLinear = 0,      /* Linera gradient type */
  keSGTRadial,          /* Radial gradient type */
  keSGTRectangular,     /* Rectangulat gradient type */
  keSGTSunburst         /* Sunburst gradient type */
} PSPStyleGradientType;

/* Paint Style Cap Type (Start & End). (since PSP7)
 */
typedef enum {
  keSCTCapFlat = 0,             /* Flat cap type (was round in psp6) */
  keSCTCapRound,                /* Round cap type (was square in psp6) */
  keSCTCapSquare,               /* Square cap type (was flat in psp6) */
  keSCTCapArrow,                /* Arrow cap type */
  keSCTCapCadArrow,             /* Cad arrow cap type */
  keSCTCapCurvedTipArrow,       /* Curved tip arrow cap type */
  keSCTCapRingBaseArrow,        /* Ring base arrow cap type */
  keSCTCapFluerDelis,           /* Fluer deLis cap type */
  keSCTCapFootball,             /* Football cap type */
  keSCTCapXr71Arrow,            /* Xr71 arrow cap type */
  keSCTCapLilly,                /* Lilly cap type */
  keSCTCapPinapple,             /* Pinapple cap type */
  keSCTCapBall,                 /* Ball cap type */
  keSCTCapTulip                 /* Tulip cap type */
} PSPStyleCapType;

/* Paint Style Join Type. (since PSP7)
 */
typedef enum {
  keSJTJoinMiter = 0,
  keSJTJoinRound,
  keSJTJoinBevel
} PSPStyleJoinType;

/* Organic pen type. (since PSP7)
 */
typedef enum {
  keSPTOrganicPenNone = 0,      /* Undefined pen type */
  keSPTOrganicPenMesh,          /* Mesh pen type */
  keSPTOrganicPenSand,          /* Sand pen type */
  keSPTOrganicPenCurlicues,     /* Curlicues pen type */
  keSPTOrganicPenRays,          /* Rays pen type */
  keSPTOrganicPenRipple,        /* Ripple pen type */
  keSPTOrganicPenWave,          /* Wave pen type */
  keSPTOrganicPen               /* Generic pen type */
} PSPStylePenType;


/* Channel types.
 */
typedef enum {
  PSP_CHANNEL_COMPOSITE = 0,    /* Channel of single channel bitmap */
  PSP_CHANNEL_RED,              /* Red channel of 24 bit bitmap */
  PSP_CHANNEL_GREEN,            /* Green channel of 24 bit bitmap */
  PSP_CHANNEL_BLUE              /* Blue channel of 24 bit bitmap */
} PSPChannelType;

/* Possible metrics used to measure resolution.
 */
typedef enum {
  PSP_METRIC_UNDEFINED = 0,     /* Metric unknown */
  PSP_METRIC_INCH,              /* Resolution is in inches */
  PSP_METRIC_CM                 /* Resolution is in centimeters */
} PSP_METRIC;

/* Possible types of compression.
 */
typedef enum {
  PSP_COMP_NONE = 0,            /* No compression */
  PSP_COMP_RLE,                 /* RLE compression */
  PSP_COMP_LZ77,                /* LZ77 compression */
  PSP_COMP_JPEG                 /* JPEG compression (only used by thumbnail and composite image) (since PSP6) */
} PSPCompression;

/* Picture tube placement mode.
 */
typedef enum {
  tpmRandom,                    /* Place tube images in random intervals */
  tpmConstant                   /* Place tube images in constant intervals */
} TubePlacementMode;

/* Picture tube selection mode.
 */
typedef enum {
  tsmRandom,                    /* Randomly select the next image in  */
                                /* tube to display */
  tsmIncremental,               /* Select each tube image in turn */
  tsmAngular,                   /* Select image based on cursor direction */
  tsmPressure,                  /* Select image based on pressure  */
                                /* (from pressure-sensitive pad) */
  tsmVelocity                   /* Select image based on cursor speed */
} TubeSelectionMode;

/* Extended data field types.
 */
typedef enum {
  PSP_XDATA_TRNS_INDEX = 0,     /* Transparency index field */
  PSP_XDATA_GRID,               /* Image grid information (since PSP7) */
  PSP_XDATA_GUIDE,              /* Image guide information (since PSP7) */
  PSP_XDATA_EXIF,               /* Image EXIF information (since PSP8) */
} PSPExtendedDataID;

/* Creator field types.
 */
typedef enum {
  PSP_CRTR_FLD_TITLE = 0,       /* Image document title field */
  PSP_CRTR_FLD_CRT_DATE,        /* Creation date field */
  PSP_CRTR_FLD_MOD_DATE,        /* Modification date field */
  PSP_CRTR_FLD_ARTIST,          /* Artist name field */
  PSP_CRTR_FLD_CPYRGHT,         /* Copyright holder name field */
  PSP_CRTR_FLD_DESC,            /* Image document description field */
  PSP_CRTR_FLD_APP_ID,          /* Creating app id field */
  PSP_CRTR_FLD_APP_VER          /* Creating app version field */
} PSPCreatorFieldID;

/* Grid units type. (since PSP7)
 */
typedef enum {
  keGridUnitsPixels = 0,        /* Grid units is pixels */
  keGridUnitsInches,            /* Grid units is inches */
  keGridUnitsCentimeters        /* Grid units is centimeters */
} PSPGridUnitsType;

/* Guide orientation type. (since PSP7)
 */
typedef enum  {
  keHorizontalGuide = 0,
  keVerticalGuide
} PSPGuideOrientationType;

/* Creator application identifiers.
 */
typedef enum {
  PSP_CREATOR_APP_UNKNOWN = 0,  /* Creator application unknown */
  PSP_CREATOR_APP_PAINT_SHOP_PRO /* Creator is Paint Shop Pro */
} PSPCreatorAppID;

/* Layer types.
 */
typedef enum {
  PSP_LAYER_NORMAL = 0,         /* Normal layer */
  PSP_LAYER_FLOATING_SELECTION  /* Floating selection layer */
} PSPLayerTypePSP5;

/* Layer types. (since PSP6)
 */
typedef enum {
  keGLTUndefined = 0,           /* Undefined layer type */
  keGLTRaster,                  /* Standard raster layer */
  keGLTFloatingRasterSelection, /* Floating selection (raster layer) */
  keGLTVector,                  /* Vector layer */
  keGLTAdjustment,              /* Adjustment layer */
  keGLTMask                     /* Mask layer (since PSP8) */
} PSPLayerTypePSP6;


/* Truth values.
 */
#if 0                           /* FALSE and TRUE taken by GLib */
typedef enum {
  FALSE = 0,
  TRUE
} PSP_BOOLEAN;
#else
typedef gboolean PSP_BOOLEAN;
#endif

/* End of cut&paste from psp spec */

/* We store the various PSP data in own structures.
 * We cannot use structs intended to be direct copies of the file block
 * headers because of struct alignment issues.
 */
typedef struct
{
  guint32 width, height;
  gdouble resolution;
  guchar metric;
  guint16 compression;
  guint16 depth;
  guchar greyscale;
  guint32 active_layer;
  guint16 layer_count;
} PSPimage;

/* Declare some local functions.
 */
static void   query      (void);
static void   run        (const gchar      *name,
                          gint              nparams,
                          const GimpParam  *param,
                          gint             *nreturn_vals,
                          GimpParam       **return_vals);
static gint32 load_image (const gchar      *filename,
                          GError          **error);
static gint   save_image (const gchar      *filename,
                          gint32            image_ID,
                          gint32            drawable_ID,
                          GError          **error);

/* Various local variables...
 */
const GimpPlugInInfo PLUG_IN_INFO =
{
  NULL,  /* init_proc  */
  NULL,  /* quit_proc  */
  query, /* query_proc */
  run,   /* run_proc   */
};

/* Save info  */
typedef struct
{
  PSPCompression compression;
} PSPSaveVals;

static PSPSaveVals psvals =
{
  PSP_COMP_LZ77
};

static guint16 psp_ver_major, psp_ver_minor;


MAIN ()

static void
query (void)
{
  static const GimpParamDef load_args[] =
  {
    { GIMP_PDB_INT32,  "run-mode",     "The run mode { RUN-INTERACTIVE (0), RUN-NONINTERACTIVE (1) }" },
    { GIMP_PDB_STRING, "filename",     "The name of the file to load" },
    { GIMP_PDB_STRING, "raw-filename", "The name of the file to load" }
  };
  static const GimpParamDef load_return_vals[] =
  {
    { GIMP_PDB_IMAGE, "image", "Output image" }
  };

#if 0
  static const GimpParamDef save_args[] =
  {
    { GIMP_PDB_INT32,    "run-mode",     "The run mode { RUN-INTERACTIVE (0), RUN-NONINTERACTIVE (1) }" },
    { GIMP_PDB_IMAGE,    "image",        "Input image" },
    { GIMP_PDB_DRAWABLE, "drawable",     "Drawable to save" },
    { GIMP_PDB_STRING,   "filename",     "The name of the file to save the image in" },
    { GIMP_PDB_STRING,   "raw-filename", "The name of the file to save the image in" },
    { GIMP_PDB_INT32,    "compression",  "Specify 0 for no compression, 1 for RLE, and 2 for LZ77" }
  };
#endif

  gimp_install_procedure (LOAD_PROC,
                          "loads images from the Paint Shop Pro PSP file format",
                          "This plug-in loads and saves images in "
                          "Paint Shop Pro's native PSP format. "
                          "Vector layers aren't handled. Saving isn't "
                          "yet implemented.",
                          "Tor Lillqvist",
                          "Tor Lillqvist",
                          "1999",
                          N_("Paint Shop Pro image"),
                          NULL,
                          GIMP_PLUGIN,
                          G_N_ELEMENTS (load_args),
                          G_N_ELEMENTS (load_return_vals),
                          load_args, load_return_vals);

  gimp_register_file_handler_mime (LOAD_PROC, "image/x-psp");
  gimp_register_magic_load_handler (LOAD_PROC,
                                    "psp,tub,pspimage",
                                    "",
                                    "0,string,Paint\\040Shop\\040Pro\\040Image\\040File\n\032");

  /* commented out until saving is implemented */
#if 0
  gimp_install_procedure (SAVE_PROC,
                          "saves images in the Paint Shop Pro PSP file format",
                          "This plug-in loads and saves images in "
                          "Paint Shop Pro's native PSP format. "
                          "Vector layers aren't handled. Saving isn't "
                          "yet implemented.",
                          "Tor Lillqvist",
                          "Tor Lillqvist",
                          "1999",
                          N_("Paint Shop Pro image"),
                          "RGB*, GRAY*, INDEXED*",
                          GIMP_PLUGIN,
                          G_N_ELEMENTS (save_args), 0,
                          save_args, NULL);

  gimp_register_save_handler (SAVE_PROC, "psp,tub", "");
#endif
}

static gboolean
save_dialog (void)
{
  GtkWidget *dialog;
  GtkWidget *frame;
  gint       run;

  dialog = gimp_export_dialog_new (_("PSP"), PLUG_IN_BINARY, SAVE_PROC);

  /*  file save type  */
  frame = gimp_int_radio_group_new (TRUE, _("Data Compression"),
                                    G_CALLBACK (gimp_radio_button_update),
                                    &psvals.compression, psvals.compression,

                                    _("None"), PSP_COMP_NONE, NULL,
                                    _("RLE"),  PSP_COMP_RLE,  NULL,
                                    _("LZ77"), PSP_COMP_LZ77, NULL,

                                    NULL);

  gtk_container_set_border_width (GTK_CONTAINER (frame), 12);
  gtk_box_pack_start (GTK_BOX (gimp_export_dialog_get_content_area (dialog)),
                      frame, FALSE, TRUE, 0);
  gtk_widget_show (frame);

  gtk_widget_show (dialog);

  run = (gimp_dialog_run (GIMP_DIALOG (dialog)) == GTK_RESPONSE_OK);

  gtk_widget_destroy (dialog);

  return run;
}

/* This helper method is used to get the name of the block for the known block
 * types. The enum PSPBlockID must cover the input values.
 */
static const gchar *
block_name (gint id)
{
  static const gchar *block_names[] =
  {
    "IMAGE",
    "CREATOR",
    "COLOR",
    "LAYER_START",
    "LAYER",
    "CHANNEL",
    "SELECTION",
    "ALPHA_BANK",
    "ALPHA_CHANNEL",
    "THUMBNAIL",
    "EXTENDED_DATA",
    "TUBE",
    "ADJUSTMENT_EXTENSION",
    "VECTOR_EXTENSION_BLOCK",
    "SHAPE_BLOCK",
    "PAINTSTYLE_BLOCK",
    "COMPOSITE_IMAGE_BANK_BLOCK",
    "COMPOSITE_ATTRIBUTES_BLOCK",
    "JPEG_BLOCK",
  };
  static gchar *err_name = NULL;

  if (id >= 0 && id <= PSP_JPEG_BLOCK)
    return block_names[id];

  g_free (err_name);
  err_name = g_strdup_printf ("id=%d", id);

  return err_name;
}

/* This helper method is used during loading. It verifies the block we are
 * reading has a valid header. Fills the variables init_len and total_len
 */
static gint
read_block_header (FILE    *f,
                   guint32 *init_len,
                   guint32 *total_len)
{
  guchar buf[4];
  guint16 id;
  long header_start;
  guint32 len;

  IFDBG(3) header_start = ftell (f);

  if (fread (buf, 4, 1, f) < 1
      || fread (&id, 2, 1, f) < 1
      || fread (&len, 4, 1, f) < 1
      || (psp_ver_major < 4 && fread (total_len, 4, 1, f) < 1))
    {
      g_message ("Error reading block header");
      return -1;
    }
  if (memcmp (buf, "~BK\0", 4) != 0)
    {
      IFDBG(3)
        g_message ("Invalid block header at %ld", header_start);
      else
        g_message ("Invalid block header");
      return -1;
    }

  IFDBG(3) g_message ("%s at %ld", block_name (id), header_start);

  if (psp_ver_major < 4)
    {
      *init_len = GUINT32_FROM_LE (len);
      *total_len = GUINT32_FROM_LE (*total_len);
    }
  else
    {
      /* Version 4.0 seems to have dropped the initial data chunk length
       * field.
       */
      *init_len = 0xDEADBEEF;   /* Intentionally bogus, should not be used */
      *total_len = GUINT32_FROM_LE (len);
    }

  return GUINT16_FROM_LE (id);
}

/* Read the PSP_IMAGE_BLOCK */
static gint
read_general_image_attribute_block (FILE     *f,
                                    guint     init_len,
                                    guint     total_len,
                                    PSPimage *ia)
{
  gchar buf[6];
  guint64 res;
  gchar graphics_content[4];

  if (init_len < 38 || total_len < 38)
    {
      g_message ("Invalid general image attribute chunk size");
      return -1;
    }

  if (psp_ver_major >= 4)
    {
      /* TODO: This causes the chunk size to be ignored. Better verify if it is
       *       valid since it might create read offset problems with the
       *       "expansion field" (which follows after the "graphics content" and
       *       is of unkown size).
       */
      fseek (f, 4, SEEK_CUR);
    }

  if (fread (&ia->width, 4, 1, f) < 1
      || fread (&ia->height, 4, 1, f) < 1
      || fread (&res, 8, 1, f) < 1
      || fread (&ia->metric, 1, 1, f) < 1
      || fread (&ia->compression, 2, 1, f) < 1
      || fread (&ia->depth, 2, 1, f) < 1
      || fread (buf, 2+4, 1, f) < 1 /* Skip plane and colour count */
      || fread (&ia->greyscale, 1, 1, f) < 1
      || fread (buf, 4, 1, f) < 1 /* Skip total image size */
      || fread (&ia->active_layer, 4, 1, f) < 1
      || fread (&ia->layer_count, 2, 1, f) < 1
      || (psp_ver_major >= 4 && fread (graphics_content, 4, 1, f) < 1))
    {
      g_message ("Error reading general image attribute block");
      return -1;
    }
  ia->width = GUINT32_FROM_LE (ia->width);
  ia->height = GUINT32_FROM_LE (ia->height);

  res = GUINT64_FROM_LE (res);
  memcpy (&ia->resolution, &res, 8);
  if (ia->metric == PSP_METRIC_CM)
    ia->resolution /= 2.54;

  ia->compression = GUINT16_FROM_LE (ia->compression);
  if (ia->compression > PSP_COMP_LZ77)
    {
      g_message ("Unknown compression type %d", ia->compression);
      return -1;
    }

  ia->depth = GUINT16_FROM_LE (ia->depth);
  if (ia->depth != 24)
    {
      g_message ("Unsupported bit depth %d", ia->depth);
      return -1;
    }

  ia->active_layer = GUINT32_FROM_LE (ia->active_layer);
  ia->layer_count = GUINT16_FROM_LE (ia->layer_count);

  return 0;
}

static gint
try_fseek (FILE  *f,
           glong  pos,
           gint   whence)
{
  if (fseek (f, pos, whence) < 0)
    {
      g_message ("Seek error: %s", g_strerror (errno));
      fclose (f);
      return -1;
    }
  return 0;
}



static gint
read_creator_block (FILE     *f,
                    gint      image_ID,
                    guint     total_len,
                    PSPimage *ia)
{
  long          data_start;
  guchar        buf[4];
  guint16       keyword;
  guint32       length;
  gchar        *string;
  gchar        *title = NULL, *artist = NULL, *copyright = NULL, *description = NULL;
  guint32       dword;
  guint32       cdate = 0, mdate = 0, appid, appver;
  GString      *comment;
  GimpParasite *comment_parasite;

  data_start = ftell (f);
  comment = g_string_new (NULL);

  while (ftell (f) < data_start + total_len)
    {
      if (fread (buf, 4, 1, f) < 1
          || fread (&keyword, 2, 1, f) < 1
          || fread (&length, 4, 1, f) < 1)
        {
          g_message ("Error reading creator keyword chunk");
          return -1;
        }
      if (memcmp (buf, "~FL\0", 4) != 0)
        {
          g_message ("Invalid keyword chunk header");
          return -1;
        }
      keyword = GUINT16_FROM_LE (keyword);
      length = GUINT32_FROM_LE (length);
      switch (keyword)
        {
        case PSP_CRTR_FLD_TITLE:
        case PSP_CRTR_FLD_ARTIST:
        case PSP_CRTR_FLD_CPYRGHT:
        case PSP_CRTR_FLD_DESC:
          string = g_malloc (length + 1);
          if (fread (string, length, 1, f) < 1)
            {
              g_message ("Error reading creator keyword data");
              g_free (string);
              return -1;
            }
          switch (keyword)
            {
            case PSP_CRTR_FLD_TITLE:
              g_free (title); title = string; break;
            case PSP_CRTR_FLD_ARTIST:
              g_free (artist); artist = string; break;
            case PSP_CRTR_FLD_CPYRGHT:
              g_free (copyright); copyright = string; break;
            case PSP_CRTR_FLD_DESC:
              g_free (description); description = string; break;
            default:
              g_free (string);
            }
          break;
        case PSP_CRTR_FLD_CRT_DATE:
        case PSP_CRTR_FLD_MOD_DATE:
        case PSP_CRTR_FLD_APP_ID:
        case PSP_CRTR_FLD_APP_VER:
          if (fread (&dword, 4, 1, f) < 1)
            {
              g_message ("Error reading creator keyword data");
              return -1;
            }
          switch (keyword)
            {
            case PSP_CRTR_FLD_CRT_DATE:
              cdate = dword; break;
            case PSP_CRTR_FLD_MOD_DATE:
              mdate = dword; break;
            case PSP_CRTR_FLD_APP_ID:
              appid = dword; break;
            case PSP_CRTR_FLD_APP_VER:
              appver = dword; break;
            }
          break;
        default:
          if (try_fseek (f, length, SEEK_CUR) < 0)
            {
              return -1;
            }
          break;
        }
    }

  if (title)
    {
      g_string_append (comment, title);
      g_free (title);
      g_string_append (comment, "\n");
    }
  if (artist)
    {
      g_string_append (comment, artist);
      g_free (artist);
      g_string_append (comment, "\n");
    }
  if (copyright)
    {
      g_string_append (comment, "Copyright ");
      g_string_append (comment, copyright);
      g_free (copyright);
      g_string_append (comment, "\n");
    }
  if (description)
    {
      g_string_append (comment, description);
      g_free (description);
      g_string_append (comment, "\n");
    }
  if (comment->len > 0)
    {
      comment_parasite = gimp_parasite_new ("gimp-comment",
                                            GIMP_PARASITE_PERSISTENT,
                                            strlen (comment->str) + 1,
                                            comment->str);
      gimp_image_parasite_attach(image_ID, comment_parasite);
      gimp_parasite_free (comment_parasite);
    }

  g_string_free (comment, FALSE);

  return 0;
}

static void inline
swab_rect (guint32 *rect)
{
  rect[0] = GUINT32_FROM_LE (rect[0]);
  rect[1] = GUINT32_FROM_LE (rect[1]);
  rect[2] = GUINT32_FROM_LE (rect[2]);
  rect[3] = GUINT32_FROM_LE (rect[3]);
}

static GimpLayerModeEffects
gimp_layer_mode_from_psp_blend_mode (PSPBlendModes mode)
{
  switch (mode)
    {
    case PSP_BLEND_NORMAL:
      return GIMP_NORMAL_MODE;
    case PSP_BLEND_DARKEN:
      return GIMP_DARKEN_ONLY_MODE;
    case PSP_BLEND_LIGHTEN:
      return GIMP_LIGHTEN_ONLY_MODE;
    case PSP_BLEND_HUE:
      return GIMP_HUE_MODE;
    case PSP_BLEND_SATURATION:
      return GIMP_SATURATION_MODE;
    case PSP_BLEND_COLOR:
      return GIMP_COLOR_MODE;
    case PSP_BLEND_LUMINOSITY:
      return GIMP_VALUE_MODE;   /* ??? */
    case PSP_BLEND_MULTIPLY:
      return GIMP_MULTIPLY_MODE;
    case PSP_BLEND_SCREEN:
      return GIMP_SCREEN_MODE;
    case PSP_BLEND_DISSOLVE:
      return GIMP_DISSOLVE_MODE;
    case PSP_BLEND_OVERLAY:
      return GIMP_OVERLAY_MODE;
    case PSP_BLEND_HARD_LIGHT:
      return GIMP_HARDLIGHT_MODE;
    case PSP_BLEND_SOFT_LIGHT:
      return GIMP_SOFTLIGHT_MODE;
    case PSP_BLEND_DIFFERENCE:
      return GIMP_DIFFERENCE_MODE;
    case PSP_BLEND_DODGE:
      return GIMP_DODGE_MODE;
    case PSP_BLEND_BURN:
      return GIMP_BURN_MODE;
    case PSP_BLEND_EXCLUSION:
      return -1;                /* ??? */
    case PSP_BLEND_ADJUST:
      return -1;                /* ??? */
    case PSP_BLEND_TRUE_HUE:
      return -1;                /* ??? */
    case PSP_BLEND_TRUE_SATURATION:
      return -1;                /* ??? */
    case PSP_BLEND_TRUE_COLOR:
      return -1;                /* ??? */
    case PSP_BLEND_TRUE_LIGHTNESS:
      return -1;                /* ??? */
    }
  return -1;
}

static const gchar *
blend_mode_name (PSPBlendModes mode)
{
  static const gchar *blend_mode_names[] =
  {
    "NORMAL",
    "DARKEN",
    "LIGHTEN",
    "HUE",
    "SATURATION",
    "COLOR",
    "LUMINOSITY",
    "MULTIPLY",
    "SCREEN",
    "DISSOLVE",
    "OVERLAY",
    "HARD_LIGHT",
    "SOFT_LIGHT",
    "DIFFERENCE",
    "DODGE",
    "BURN",
    "EXCLUSION"
  };
  static gchar *err_name = NULL;

  /* TODO: what about PSP_BLEND_ADJUST? */
  if (mode >= 0 && mode <= PSP_BLEND_EXCLUSION)
    return blend_mode_names[mode];

  g_free (err_name);
  err_name = g_strdup_printf ("unknown layer blend mode %d", mode);

  return err_name;
}

static const gchar *
bitmap_type_name (gint type)
{
  static const gchar *bitmap_type_names[] =
  {
    "IMAGE",
    "TRANS_MASK",
    "USER_MASK",
    "SELECTION",
    "ALPHA_MASK",
    "THUMBNAIL"
  };
  static gchar *err_name = NULL;

  if (type >= 0 && type <= PSP_DIB_THUMBNAIL)
    return bitmap_type_names[type];

  g_free (err_name);
  err_name = g_strdup_printf ("unknown bitmap type %d", type);

  return err_name;
}

static const gchar *
channel_type_name (gint type)
{
  static const gchar *channel_type_names[] =
  {
    "COMPOSITE",
    "RED",
    "GREEN",
    "BLUE"
  };
  static gchar *err_name = NULL;

  if (type >= 0 && type <= PSP_CHANNEL_BLUE)
    return channel_type_names[type];

  g_free (err_name);
  err_name = g_strdup_printf ("unknown channel type %d", type);

  return err_name;
}

static void *
psp_zalloc (void  *opaque,
            guint  items,
            guint  size)
{
  return g_malloc (items*size);
}

static void
psp_zfree (void *opaque,
           void *ptr)
{
  g_free (ptr);
}

static int
read_channel_data (FILE       *f,
                   PSPimage   *ia,
                   guchar    **pixels,
                   guint       bytespp,
                   guint       offset,
                   GimpDrawable  *drawable,
                   guint32     compressed_len)
{
  gint i, y, width = drawable->width, height = drawable->height;
  gint npixels = width * height;
  guchar *buf, *p, *q, *endq;
  guchar *buf2 = NULL;  /* please the compiler */
  guchar runcount, byte;
  z_stream zstream;

  switch (ia->compression)
    {
    case PSP_COMP_NONE:
      if (bytespp == 1)
        {
          if ((width % 4) == 0)
            fread (pixels[0], height * width, 1, f);
          else
            {
              for (y = 0; y < height; y++)
                {
                  fread (pixels[y], width, 1, f);
                  fseek (f, 4 - (width % 4), SEEK_CUR);
                }
            }
        }
      else
        {
          buf = g_malloc (width);
          for (y = 0; y < height; y++)
            {
              fread (buf, width, 1, f);
              if (width % 4)
                fseek (f, 4 - (width % 4), SEEK_CUR);
              p = buf;
              q = pixels[y] + offset;
              for (i = 0; i < width; i++)
                {
                  *q = *p++;
                  q += bytespp;
                }
            }
          g_free (buf);
        }
      break;

    case PSP_COMP_RLE:
      q = pixels[0] + offset;
      endq = q + npixels * bytespp;
      buf = g_malloc (127);
      while (q < endq)
        {
          p = buf;
          fread (&runcount, 1, 1, f);
          if (runcount > 128)
            {
              runcount -= 128;
              fread (&byte, 1, 1, f);
              memset (buf, byte, runcount);
            }
          else
            fread (buf, runcount, 1, f);
          if (bytespp == 1)
            {
              memmove (q, buf, runcount);
              q += runcount;
            }
          else
            {
              p = buf;
              for (i = 0; i < runcount; i++)
                {
                  *q = *p++;
                  q += bytespp;
                }
            }
        }
      g_free (buf);
      break;

    case PSP_COMP_LZ77:
      buf = g_malloc (compressed_len);
      fread (buf, compressed_len, 1, f);
      zstream.next_in = buf;
      zstream.avail_in = compressed_len;
      zstream.zalloc = psp_zalloc;
      zstream.zfree = psp_zfree;
      zstream.opaque = f;
      if (inflateInit (&zstream) != Z_OK)
        {
          g_message ("zlib error");
          return -1;
        }
      if (bytespp == 1)
        zstream.next_out = pixels[0];
      else
        {
          buf2 = g_malloc (npixels);
          zstream.next_out = buf2;
        }
      zstream.avail_out = npixels;
      if (inflate (&zstream, Z_FINISH) != Z_STREAM_END)
        {
          g_message ("zlib error");
          inflateEnd (&zstream);
          return -1;
        }
      inflateEnd (&zstream);
      g_free (buf);

      if (bytespp > 1)
        {
          p = buf2;
          q = pixels[0] + offset;
          for (i = 0; i < npixels; i++)
            {
              *q = *p++;
              q += bytespp;
            }
          g_free (buf2);
        }
      break;
    }

  return 0;
}

static gint
read_layer_block (FILE     *f,
                  gint      image_ID,
                  guint     total_len,
                  PSPimage *ia)
{
  gint i;
  long block_start, sub_block_start, channel_start;
  gint sub_id;
  guint32 sub_init_len, sub_total_len;
  gchar *name = NULL;
  guint16 namelen;
  guchar type, opacity, blend_mode, visibility, transparency_protected;
  guchar link_group_id, mask_linked, mask_disabled;
  guint32 image_rect[4], saved_image_rect[4], mask_rect[4], saved_mask_rect[4];
  gboolean null_layer = FALSE;
  guint16 bitmap_count, channel_count;
  GimpImageType drawable_type;
  guint32 layer_ID = 0;
  GimpLayerModeEffects layer_mode;
  guint32 channel_init_len, channel_total_len;
  guint32 compressed_len, uncompressed_len;
  guint16 bitmap_type, channel_type;
  gint width, height, bytespp, offset;
  guchar **pixels, *pixel;
  GimpDrawable *drawable;
  GimpPixelRgn pixel_rgn;

  block_start = ftell (f);

  while (ftell (f) < block_start + total_len)
    {
      /* Read the layer sub-block header */
      sub_id = read_block_header (f, &sub_init_len, &sub_total_len);
      if (sub_id == -1)
        return -1;

      if (sub_id != PSP_LAYER_BLOCK)
        {
          g_message ("Invalid layer sub-block %s, should be LAYER",
                     block_name (sub_id));
          return -1;
        }

      sub_block_start = ftell (f);

      /* Read layer information chunk */
      if (psp_ver_major >= 4)
        {
          if (fseek (f, 4, SEEK_CUR) < 0
              || fread (&namelen, 2, 1, f) < 1
              || ((namelen = GUINT16_FROM_LE (namelen)) && FALSE)
              || (name = g_malloc (namelen + 1)) == NULL
              || fread (name, namelen, 1, f) < 1
              || fread (&type, 1, 1, f) < 1
              || fread (&image_rect, 16, 1, f) < 1
              || fread (&saved_image_rect, 16, 1, f) < 1
              || fread (&opacity, 1, 1, f) < 1
              || fread (&blend_mode, 1, 1, f) < 1
              || fread (&visibility, 1, 1, f) < 1
              || fread (&transparency_protected, 1, 1, f) < 1
              || fread (&link_group_id, 1, 1, f) < 1
              || fread (&mask_rect, 16, 1, f) < 1
              || fread (&saved_mask_rect, 16, 1, f) < 1
              || fread (&mask_linked, 1, 1, f) < 1
              || fread (&mask_disabled, 1, 1, f) < 1
              || fseek (f, 47, SEEK_CUR) < 0
              || fread (&bitmap_count, 2, 1, f) < 1
              || fread (&channel_count, 2, 1, f) < 1)
            {
              g_message ("Error reading layer information chunk");
              g_free (name);
              return -1;
            }

          name[namelen] = 0;
          type = PSP_LAYER_NORMAL; /* ??? */
        }
      else
        {
          name = g_malloc (257);
          name[256] = 0;

          if (fread (name, 256, 1, f) < 1
              || fread (&type, 1, 1, f) < 1
              || fread (&image_rect, 16, 1, f) < 1
              || fread (&saved_image_rect, 16, 1, f) < 1
              || fread (&opacity, 1, 1, f) < 1
              || fread (&blend_mode, 1, 1, f) < 1
              || fread (&visibility, 1, 1, f) < 1
              || fread (&transparency_protected, 1, 1, f) < 1
              || fread (&link_group_id, 1, 1, f) < 1
              || fread (&mask_rect, 16, 1, f) < 1
              || fread (&saved_mask_rect, 16, 1, f) < 1
              || fread (&mask_linked, 1, 1, f) < 1
              || fread (&mask_disabled, 1, 1, f) < 1
              || fseek (f, 43, SEEK_CUR) < 0
              || fread (&bitmap_count, 2, 1, f) < 1
              || fread (&channel_count, 2, 1, f) < 1)
            {
              g_message ("Error reading layer information chunk");
              g_free (name);
              return -1;
            }
        }

      if (type == PSP_LAYER_FLOATING_SELECTION)
        g_message ("Floating selection restored as normal layer");

      swab_rect (image_rect);
      swab_rect (saved_image_rect);
      swab_rect (mask_rect);
      swab_rect (saved_mask_rect);
      bitmap_count = GUINT16_FROM_LE (bitmap_count);
      channel_count = GUINT16_FROM_LE (channel_count);

      layer_mode = gimp_layer_mode_from_psp_blend_mode (blend_mode);
      if ((int) layer_mode == -1)
        {
          g_message ("Unsupported PSP layer blend mode %s "
                     "for layer %s, setting layer invisible",
                     blend_mode_name (blend_mode), name);
          layer_mode = GIMP_NORMAL_MODE;
          visibility = FALSE;
        }

      width = saved_image_rect[2] - saved_image_rect[0];
      height = saved_image_rect[3] - saved_image_rect[1];

      if ((width < 0) || (width > GIMP_MAX_IMAGE_SIZE)       /* w <= 2^18 */
          || (height < 0) || (height > GIMP_MAX_IMAGE_SIZE)  /* h <= 2^18 */
          || ((width / 256) * (height / 256) >= 8192))       /* w * h < 2^29 */
        {
          g_message ("Invalid layer dimensions: %dx%d", width, height);
          return -1;
        }

      IFDBG(2) g_message
        ("layer: %s %dx%d (%dx%d) @%d,%d opacity %d blend_mode %s "
         "%d bitmaps %d channels",
         name,
         image_rect[2] - image_rect[0], image_rect[3] - image_rect[1],
         width, height,
         saved_image_rect[0], saved_image_rect[1],
         opacity, blend_mode_name (blend_mode),
         bitmap_count, channel_count);

      IFDBG(2) g_message
        ("mask %dx%d (%dx%d) @%d,%d",
         mask_rect[2] - mask_rect[0],
         mask_rect[3] - mask_rect[1],
         saved_mask_rect[2] - saved_mask_rect[0],
         saved_mask_rect[3] - saved_mask_rect[1],
         saved_mask_rect[0], saved_mask_rect[1]);

      if (width == 0)
        {
          width++;
          null_layer = TRUE;
        }
      if (height == 0)
        {
          height++;
          null_layer = TRUE;
        }

      if (ia->greyscale)
        if (!null_layer && bitmap_count == 1)
          drawable_type = GIMP_GRAY_IMAGE, bytespp = 1;
        else
          drawable_type = GIMP_GRAYA_IMAGE, bytespp = 1;
      else
        if (!null_layer && bitmap_count == 1)
          drawable_type = GIMP_RGB_IMAGE, bytespp = 3;
        else
          drawable_type = GIMP_RGBA_IMAGE, bytespp = 4;

      layer_ID = gimp_layer_new (image_ID, name,
                                 width, height,
                                 drawable_type,
                                 100.0 * opacity / 255.0,
                                 layer_mode);
      if (layer_ID == -1)
        {
          g_message ("Error creating layer");
          return -1;
        }

      g_free (name);

      gimp_image_insert_layer (image_ID, layer_ID, -1, -1);

      if (saved_image_rect[0] != 0 || saved_image_rect[1] != 0)
        gimp_layer_set_offsets (layer_ID,
                                saved_image_rect[0], saved_image_rect[1]);

      if (!visibility)
        gimp_item_set_visible (layer_ID, FALSE);

      gimp_layer_set_lock_alpha (layer_ID, transparency_protected);

      if (psp_ver_major < 4)
        if (try_fseek (f, sub_block_start + sub_init_len, SEEK_SET) < 0)
          {
            return -1;
          }

      pixel = g_malloc0 (height * width * bytespp);
      if (null_layer)
        {
          pixels = NULL;
        }
      else
        {
          pixels = g_new (guchar *, height);
          for (i = 0; i < height; i++)
            pixels[i] = pixel + width * bytespp * i;
        }

      drawable = gimp_drawable_get (layer_ID);
      gimp_pixel_rgn_init (&pixel_rgn, drawable, 0, 0,
                           width, height, TRUE, FALSE);

      gimp_tile_cache_size (gimp_tile_height () * width * bytespp);

      /* Read the layer channel sub-blocks */
      while (ftell (f) < sub_block_start + sub_total_len)
        {
          sub_id = read_block_header (f, &channel_init_len,
                                      &channel_total_len);
          if (sub_id == -1)
            {
              gimp_image_delete (image_ID);
              return -1;
            }

          if (sub_id != PSP_CHANNEL_BLOCK)
            {
              g_message ("Invalid layer sub-block %s, should be CHANNEL",
                         block_name (sub_id));
              return -1;
            }

          channel_start = ftell (f);

          if (psp_ver_major == 4)
            fseek (f, 4, SEEK_CUR); /* Unknown field */

          if (fread (&compressed_len, 4, 1, f) < 1
              || fread (&uncompressed_len, 4, 1, f) < 1
              || fread (&bitmap_type, 2, 1, f) < 1
              || fread (&channel_type, 2, 1, f) < 1)
            {
              g_message ("Error reading channel information chunk");
              return -1;
            }

          compressed_len = GUINT32_FROM_LE (compressed_len);
          uncompressed_len = GUINT32_FROM_LE (uncompressed_len);
          bitmap_type = GUINT16_FROM_LE (bitmap_type);
          channel_type = GUINT16_FROM_LE (channel_type);

          if (bitmap_type > PSP_DIB_USER_MASK)
            {
              g_message ("Invalid bitmap type %d in channel information chunk",
                         bitmap_type);
              return -1;
            }

          if (channel_type > PSP_CHANNEL_BLUE)
            {
              g_message ("Invalid channel type %d in channel information chunk",
                         channel_type);
              return -1;
            }

          IFDBG(2) g_message ("channel: %s %s %d (%d) bytes %d bytespp",
                              bitmap_type_name (bitmap_type),
                              channel_type_name (channel_type),
                              uncompressed_len, compressed_len,
                              bytespp);

          if (bitmap_type == PSP_DIB_TRANS_MASK)
            offset = 3;
          else
            offset = channel_type - PSP_CHANNEL_RED;

          if (psp_ver_major < 4)
            if (try_fseek (f, channel_start + channel_init_len, SEEK_SET) < 0)
              {
                return -1;
              }

          if (!null_layer)
            if (read_channel_data (f, ia, pixels, bytespp,
                                   offset, drawable, compressed_len) == -1)
              {
                return -1;
              }

          if (try_fseek (f, channel_start + channel_total_len, SEEK_SET) < 0)
            {
              return -1;
            }
        }

      gimp_pixel_rgn_set_rect (&pixel_rgn, pixel, 0, 0, width, height);

      gimp_drawable_flush (drawable);
      gimp_drawable_detach (drawable);

      g_free (pixels);
      g_free (pixel);
    }

  if (try_fseek (f, block_start + total_len, SEEK_SET) < 0)
    {
      return -1;
    }

  return layer_ID;
}

static gint
read_tube_block (FILE     *f,
                 gint      image_ID,
                 guint     total_len,
                 PSPimage *ia)
{
  guint16            version;
  guchar             name[514];
  guint32            step_size, column_count, row_count, cell_count;
  guint32            placement_mode, selection_mode;
  gint               i;
  GimpPixPipeParams  params;
  GimpParasite      *pipe_parasite;
  gchar             *parasite_text;

  gimp_pixpipe_params_init (&params);

  if (fread (&version, 2, 1, f) < 1
      || fread (name, 513, 1, f) < 1
      || fread (&step_size, 4, 1, f) < 1
      || fread (&column_count, 4, 1, f) < 1
      || fread (&row_count, 4, 1, f) < 1
      || fread (&cell_count, 4, 1, f) < 1
      || fread (&placement_mode, 4, 1, f) < 1
      || fread (&selection_mode, 4, 1, f) < 1)
    {
      g_message ("Error reading tube data chunk");
      return -1;
    }

  name[513] = 0;
  version = GUINT16_FROM_LE (version);
  params.step = GUINT32_FROM_LE (step_size);
  params.cols = GUINT32_FROM_LE (column_count);
  params.rows = GUINT32_FROM_LE (row_count);
  params.ncells = GUINT32_FROM_LE (cell_count);
  placement_mode = GUINT32_FROM_LE (placement_mode);
  selection_mode = GUINT32_FROM_LE (selection_mode);

  for (i = 1; i < params.cols; i++)
    gimp_image_add_vguide (image_ID, (ia->width * i)/params.cols);
  for (i = 1; i < params.rows; i++)
    gimp_image_add_hguide (image_ID, (ia->height * i)/params.rows);

  /* We use a parasite to pass in the tube (pipe) parameters in
   * case we will have any use of those, for instance in the gpb
   * plug-in that saves a GIMP image pipe.
   */
  params.dim = 1;
  params.cellwidth = ia->width / params.cols;
  params.cellheight = ia->height / params.rows;
  params.placement = (placement_mode == tpmRandom ? "random" :
                      (placement_mode == tpmConstant ? "constant" :
                       "default"));
  params.rank[0] = params.ncells;
  params.selection[0] = (selection_mode == tsmRandom ? "random" :
                         (selection_mode == tsmIncremental ? "incremental" :
                          (selection_mode == tsmAngular ? "angular" :
                           (selection_mode == tsmPressure ? "pressure" :
                            (selection_mode == tsmVelocity ? "velocity" :
                             "default")))));
  parasite_text = gimp_pixpipe_params_build (&params);

  IFDBG(2) g_message ("parasite: %s", parasite_text);

  pipe_parasite = gimp_parasite_new ("gimp-brush-pipe-parameters",
                                     GIMP_PARASITE_PERSISTENT,
                                     strlen (parasite_text) + 1, parasite_text);
  gimp_image_parasite_attach (image_ID, pipe_parasite);
  gimp_parasite_free (pipe_parasite);
  g_free (parasite_text);

  return 0;
}

static const gchar *
compression_name (gint compression)
{
  switch (compression)
    {
    case PSP_COMP_NONE:
      return "no compression";
    case PSP_COMP_RLE:
      return "RLE";
    case PSP_COMP_LZ77:
      return "LZ77";
    }
  g_assert_not_reached ();

  return NULL;
}

/* The main function for loading PSP-images
 */
static gint32
load_image (const gchar  *filename,
            GError      **error)
{
  FILE *f;
  struct stat st;
  char buf[32];
  PSPimage ia;
  guint32 block_init_len, block_total_len;
  long block_start;
  PSPBlockID id = -1;
  gint block_number;

  gint32 image_ID = -1;

  if (g_stat (filename, &st) == -1)
    return -1;

  f = g_fopen (filename, "rb");
  if (f == NULL)
    {
      g_set_error (error, G_FILE_ERROR, g_file_error_from_errno (errno),
                   _("Could not open '%s' for reading: %s"),
                   gimp_filename_to_utf8 (filename), g_strerror (errno));
      return -1;
    }

  /* Read the PSP File Header and determine file version */
  if (fread (buf, 32, 1, f) < 1
      || fread (&psp_ver_major, 2, 1, f) < 1
      || fread (&psp_ver_minor, 2, 1, f) < 1)
    {
      g_message ("Error reading file header");
      goto error;
    }

  if (memcmp (buf, "Paint Shop Pro Image File\n\032\0\0\0\0\0", 32) != 0)
    {
      g_message ("Incorrect file signature");
      goto error;
    }

  psp_ver_major = GUINT16_FROM_LE (psp_ver_major);
  psp_ver_minor = GUINT16_FROM_LE (psp_ver_minor);

  /* I only have the documentation for file format version 3.0,
   * but PSP 6 writes version 4.0. Let's hope it's backwards compatible.
   * Earlier versions probably don't have all the fields I expect
   * so don't accept those.
   */
  if (psp_ver_major < 3)
    {
      g_message ("Unsupported PSP file format version "
                 "%d.%d, only knows 3.0 (and later?)",
                 psp_ver_major, psp_ver_minor);
      goto error;
    }
  else if ((psp_ver_major == 3)
        || (psp_ver_major == 4)
        || (psp_ver_major == 5)
        || (psp_ver_major == 6))
    ; /* OK */
  else
    {
      g_message ("Unsupported PSP file format version %d.%d",
                 psp_ver_major, psp_ver_minor);
      goto error;
    }

  /* Read all the blocks */
  block_number = 0;

  IFDBG(3) g_message ("size = %d", (int)st.st_size);
  while (ftell (f) != st.st_size
         && (id = read_block_header (f, &block_init_len,
                                     &block_total_len)) != -1)
    {
      block_start = ftell (f);

      if (id == PSP_IMAGE_BLOCK)
        {
          if (block_number != 0)
            {
              g_message ("Duplicate General Image Attributes block");
              goto error;
            }
          if (read_general_image_attribute_block (f, block_init_len,
                                                  block_total_len, &ia) == -1)
            {
              goto error;
            }

          IFDBG(2) g_message ("%d dpi %dx%d %s",
                              (int) ia.resolution,
                              ia.width, ia.height,
                              compression_name (ia.compression));

          image_ID = gimp_image_new (ia.width, ia.height,
                                     ia.greyscale ? GIMP_GRAY : GIMP_RGB);
          if (image_ID == -1)
            {
              goto error;
            }

          gimp_image_set_filename (image_ID, filename);

          gimp_image_set_resolution (image_ID, ia.resolution, ia.resolution);
        }
      else
        {
          if (block_number == 0)
            {
              g_message ("Missing General Image Attributes block");
              goto error;
            }

          switch (id)
            {
            case PSP_CREATOR_BLOCK:
              if (read_creator_block (f, image_ID, block_total_len, &ia) == -1)
                goto error;
              break;

            case PSP_COLOR_BLOCK:
              break;            /* Not yet implemented */

            case PSP_LAYER_START_BLOCK:
              if (read_layer_block (f, image_ID, block_total_len, &ia) == -1)
                goto error;
              break;

            case PSP_SELECTION_BLOCK:
              break;            /* Not yet implemented */

            case PSP_ALPHA_BANK_BLOCK:
              break;            /* Not yet implemented */

            case PSP_THUMBNAIL_BLOCK:
              break;            /* No use for it */

            case PSP_EXTENDED_DATA_BLOCK:
              break;            /* Not yet implemented */

            case PSP_TUBE_BLOCK:
              if (read_tube_block (f, image_ID, block_total_len, &ia) == -1)
                goto error;
              break;

            case PSP_COMPOSITE_IMAGE_BANK_BLOCK:
              break;            /* Not yet implemented */

            case PSP_LAYER_BLOCK:
            case PSP_CHANNEL_BLOCK:
            case PSP_ALPHA_CHANNEL_BLOCK:
            case PSP_ADJUSTMENT_EXTENSION_BLOCK:
            case PSP_VECTOR_EXTENSION_BLOCK:
            case PSP_SHAPE_BLOCK:
            case PSP_PAINTSTYLE_BLOCK:
            case PSP_COMPOSITE_ATTRIBUTES_BLOCK:
            case PSP_JPEG_BLOCK:
              g_message ("Sub-block %s should not occur "
                         "at main level of file",
                         block_name (id));
              break;

            default:
              g_message ("Unrecognized block id %d", id);
              break;
            }
        }

      if (block_start + block_total_len >= st.st_size)
        break;

      if (try_fseek (f, block_start + block_total_len, SEEK_SET) < 0)
        goto error;

      block_number++;
    }

  if (id == -1)
    {
    error:
      fclose (f);
      if (image_ID != -1)
        gimp_image_delete (image_ID);
      return -1;
    }

  fclose (f);

  return image_ID;
}

static gint
save_image (const gchar  *filename,
            gint32        image_ID,
            gint32        drawable_ID,
            GError      **error)
{
  g_message ("Saving not implemented yet");

  return FALSE;
}

static void
run (const gchar      *name,
     gint              nparams,
     const GimpParam  *param,
     gint             *nreturn_vals,
     GimpParam       **return_vals)
{
  static GimpParam   values[2];
  GimpRunMode        run_mode;
  GimpPDBStatusType  status = GIMP_PDB_SUCCESS;
  gint32             image_ID;
  gint32             drawable_ID;
  GimpExportReturn   export = GIMP_EXPORT_CANCEL;
  GError            *error  = NULL;

  INIT_I18N ();

  run_mode = param[0].data.d_int32;

  *nreturn_vals = 1;
  *return_vals  = values;

  values[0].type          = GIMP_PDB_STATUS;
  values[0].data.d_status = GIMP_PDB_EXECUTION_ERROR;

  if (strcmp (name, LOAD_PROC) == 0)
    {
      image_ID = load_image (param[1].data.d_string, &error);

      if (image_ID != -1)
        {
          *nreturn_vals = 2;
          values[1].type         = GIMP_PDB_IMAGE;
          values[1].data.d_image = image_ID;
        }
      else
        {
          status = GIMP_PDB_EXECUTION_ERROR;
        }
    }
  else if (strcmp (name, SAVE_PROC) == 0)
    {
      image_ID = param[1].data.d_int32;
      drawable_ID = param[2].data.d_int32;

      /*  eventually export the image */
      switch (run_mode)
        {
        case GIMP_RUN_INTERACTIVE:
        case GIMP_RUN_WITH_LAST_VALS:
          gimp_ui_init (PLUG_IN_BINARY, FALSE);
          export = gimp_export_image (&image_ID, &drawable_ID, NULL,
                                      GIMP_EXPORT_CAN_HANDLE_RGB     |
                                      GIMP_EXPORT_CAN_HANDLE_GRAY    |
                                      GIMP_EXPORT_CAN_HANDLE_INDEXED |
                                      GIMP_EXPORT_CAN_HANDLE_ALPHA   |
                                      GIMP_EXPORT_CAN_HANDLE_LAYERS);
          if (export == GIMP_EXPORT_CANCEL)
            {
              values[0].data.d_status = GIMP_PDB_CANCEL;
              return;
            }
          break;
        default:
          break;
        }

      switch (run_mode)
        {
        case GIMP_RUN_INTERACTIVE:
          /*  Possibly retrieve data  */
          gimp_get_data (SAVE_PROC, &psvals);

          /*  First acquire information with a dialog  */
          if (! save_dialog ())
            status = GIMP_PDB_CANCEL;
          break;

        case GIMP_RUN_NONINTERACTIVE:
          /*  Make sure all the arguments are there!  */
          if (nparams != 6)
            {
              status = GIMP_PDB_CALLING_ERROR;
            }
          else
            {
              psvals.compression = (param[5].data.d_int32) ? TRUE : FALSE;

              if (param[5].data.d_int32 < 0 ||
                  param[5].data.d_int32 > PSP_COMP_LZ77)
                status = GIMP_PDB_CALLING_ERROR;
            }

        case GIMP_RUN_WITH_LAST_VALS:
          gimp_get_data (SAVE_PROC, &psvals);
          break;

        default:
          break;
        }

      if (status == GIMP_PDB_SUCCESS)
        {
          if (save_image (param[3].data.d_string, image_ID, drawable_ID,
                          &error))
            {
              gimp_set_data (SAVE_PROC, &psvals, sizeof (PSPSaveVals));
            }
          else
            {
              status = GIMP_PDB_EXECUTION_ERROR;
            }
        }

      if (export == GIMP_EXPORT_EXPORT)
        gimp_image_delete (image_ID);
    }
  else
    {
      status = GIMP_PDB_CALLING_ERROR;
    }

  if (status != GIMP_PDB_SUCCESS && error)
    {
      *nreturn_vals = 2;
      values[1].type          = GIMP_PDB_STRING;
      values[1].data.d_string = error->message;
    }

  values[0].data.d_status = status;
}
