/* Copyright (c) Mark J. Kilgard, 1997. */

/* This program is freely distributable without licensing fees  and is
   provided without guarantee or warrantee expressed or  implied. This
   program is -not- in the public domain. */

#include <assert.h>
#include <ctype.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <GL/glu.h>
#include "TexFont.h"

#if 0
/* Uncomment to debug various scenarios. */
#undef GL_VERSION_1_1
#undef GL_EXT_texture_object
#undef GL_EXT_texture
#endif

#ifndef GL_VERSION_1_1
#if defined(GL_EXT_texture_object) && defined(GL_EXT_texture)
#define glGenTextures glGenTexturesEXT
#define glBindTexture glBindTextureEXT
#ifndef GL_INTENSITY4
#define GL_INTENSITY4 GL_INTENSITY4_EXT
#endif
int useLuminanceAlpha = 0;
#else
#define USE_DISPLAY_LISTS
/* Intensity texture format not in OpenGL 1.0; added by the EXT_texture
   extension and now part of OpenGL 1.1. */
int useLuminanceAlpha = 1;
#endif
#else
int useLuminanceAlpha = 0;
#endif

/* byte swap a 32-bit value */
#define SWAPL(x, n) { \
                 n = ((char *) (x))[0];\
                 ((char *) (x))[0] = ((char *) (x))[3];\
                 ((char *) (x))[3] = n;\
                 n = ((char *) (x))[1];\
                 ((char *) (x))[1] = ((char *) (x))[2];\
                 ((char *) (x))[2] = n; }

/* byte swap a short */
#define SWAPS(x, n) { \
                 n = ((char *) (x))[0];\
                 ((char *) (x))[0] = ((char *) (x))[1];\
                 ((char *) (x))[1] = n; }

static TexGlyphVertexInfo *
getTCVI(TexFont * txf, int c)
{
  TexGlyphVertexInfo *tgvi;

  /* Automatically substitute uppercase letters with lowercase if not
     uppercase available (and vice versa). */
  if ((c >= txf->min_glyph) && (c < txf->min_glyph + txf->range)) {
    tgvi = txf->lut[c - txf->min_glyph];
    if (tgvi) {
      return tgvi;
    }
    if (islower(c)) {
      c = toupper(c);
      if ((c >= txf->min_glyph) && (c < txf->min_glyph + txf->range)) {
        return txf->lut[c - txf->min_glyph];
      }
    }
    if (isupper(c)) {
      c = tolower(c);
      if ((c >= txf->min_glyph) && (c < txf->min_glyph + txf->range)) {
        return txf->lut[c - txf->min_glyph];
      }
    }
  }
  fprintf(stderr, "texfont: tried to access unavailable font character \"%c\" (%d)\n",
    isprint(c) ? c : ' ', c);
  abort();
  /* NOTREACHED */
}

static char *lastError;

char *
txfErrorString(void)
{
  return lastError;
}

TexFont *
txfLoadFont(char *filename)
{
  TexFont *txf;
  FILE *file;
  GLfloat w, h, xstep, ystep;
  char fileid[4], tmp;
  unsigned char *texbitmap;
  int min_glyph, max_glyph;
  int endianness, swap, format, stride, width, height;
  int i, j, got;

  txf = NULL;
  file = fopen(filename, "rb");
  if (file == NULL) {
    lastError = "file open failed.";
    goto error;
  }
  txf = (TexFont *) malloc(sizeof(TexFont));
  if (txf == NULL) {
    lastError = "out of memory.";
    goto error;
  }
  /* For easy cleanup in error case. */
  txf->tgi = NULL;
  txf->tgvi = NULL;
  txf->lut = NULL;
  txf->teximage = NULL;

  got = fread(fileid, 1, 4, file);
  if (got != 4 || strncmp(fileid, "\377txf", 4)) {
    lastError = "not a texture font file.";
    goto error;
  }
  assert(sizeof(int) == 4);  /* Ensure external file format size. */
  got = fread(&endianness, sizeof(int), 1, file);
  if (got == 1 && endianness == 0x12345678) {
    swap = 0;
  } else if (got == 1 && endianness == 0x78563412) {
    swap = 1;
  } else {
    lastError = "not a texture font file.";
    goto error;
  }
#define EXPECT(n) if (got != n) { lastError = "premature end of file."; goto error; }
  got = fread(&format, sizeof(int), 1, file);
  EXPECT(1);
  got = fread(&txf->tex_width, sizeof(int), 1, file);
  EXPECT(1);
  got = fread(&txf->tex_height, sizeof(int), 1, file);
  EXPECT(1);
  got = fread(&txf->max_ascent, sizeof(int), 1, file);
  EXPECT(1);
  got = fread(&txf->max_descent, sizeof(int), 1, file);
  EXPECT(1);
  got = fread(&txf->num_glyphs, sizeof(int), 1, file);
  EXPECT(1);

  if (swap) {
    SWAPL(&format, tmp);
    SWAPL(&txf->tex_width, tmp);
    SWAPL(&txf->tex_height, tmp);
    SWAPL(&txf->max_ascent, tmp);
    SWAPL(&txf->max_descent, tmp);
    SWAPL(&txf->num_glyphs, tmp);
  }
  txf->tgi = (TexGlyphInfo *) malloc(txf->num_glyphs * sizeof(TexGlyphInfo));
  if (txf->tgi == NULL) {
    lastError = "out of memory.";
    goto error;
  }
  assert(sizeof(TexGlyphInfo) == 12);  /* Ensure external file format size. */
  got = fread(txf->tgi, sizeof(TexGlyphInfo), txf->num_glyphs, file);
  EXPECT(txf->num_glyphs);

  if (swap) {
    for (i = 0; i < txf->num_glyphs; i++) {
      SWAPS(&txf->tgi[i].c, tmp);
      SWAPS(&txf->tgi[i].x, tmp);
      SWAPS(&txf->tgi[i].y, tmp);
    }
  }
  txf->tgvi = (TexGlyphVertexInfo *)
    malloc(txf->num_glyphs * sizeof(TexGlyphVertexInfo));
  if (txf->tgvi == NULL) {
    lastError = "out of memory.";
    goto error;
  }
  w = txf->tex_width;
  h = txf->tex_height;
  xstep = 0.5 / w;
  ystep = 0.5 / h;
  for (i = 0; i < txf->num_glyphs; i++) {
    TexGlyphInfo *tgi;

    tgi = &txf->tgi[i];
    txf->tgvi[i].t0[0] = tgi->x / w + xstep;
    txf->tgvi[i].t0[1] = tgi->y / h + ystep;
    txf->tgvi[i].v0[0] = tgi->xoffset;
    txf->tgvi[i].v0[1] = tgi->yoffset;
    txf->tgvi[i].t1[0] = (tgi->x + tgi->width) / w + xstep;
    txf->tgvi[i].t1[1] = tgi->y / h + ystep;
    txf->tgvi[i].v1[0] = tgi->xoffset + tgi->width;
    txf->tgvi[i].v1[1] = tgi->yoffset;
    txf->tgvi[i].t2[0] = (tgi->x + tgi->width) / w + xstep;
    txf->tgvi[i].t2[1] = (tgi->y + tgi->height) / h + ystep;
    txf->tgvi[i].v2[0] = tgi->xoffset + tgi->width;
    txf->tgvi[i].v2[1] = tgi->yoffset + tgi->height;
    txf->tgvi[i].t3[0] = tgi->x / w + xstep;
    txf->tgvi[i].t3[1] = (tgi->y + tgi->height) / h + ystep;
    txf->tgvi[i].v3[0] = tgi->xoffset;
    txf->tgvi[i].v3[1] = tgi->yoffset + tgi->height;
    txf->tgvi[i].advance = tgi->advance;
  }

  min_glyph = txf->tgi[0].c;
  max_glyph = txf->tgi[0].c;
  for (i = 1; i < txf->num_glyphs; i++) {
    if (txf->tgi[i].c < min_glyph) {
      min_glyph = txf->tgi[i].c;
    }
    if (txf->tgi[i].c > max_glyph) {
      max_glyph = txf->tgi[i].c;
    }
  }
  txf->min_glyph = min_glyph;
  txf->range = max_glyph - min_glyph + 1;

  txf->lut = (TexGlyphVertexInfo **)
    calloc(txf->range, sizeof(TexGlyphVertexInfo *));
  if (txf->lut == NULL) {
    lastError = "out of memory.";
    goto error;
  }
  for (i = 0; i < txf->num_glyphs; i++) {
    txf->lut[txf->tgi[i].c - txf->min_glyph] = &txf->tgvi[i];
  }

  switch (format) {
  case TXF_FORMAT_BYTE:
    if (useLuminanceAlpha) {
      unsigned char *orig;

      orig = (unsigned char *) malloc(txf->tex_width * txf->tex_height);
      if (orig == NULL) {
        lastError = "out of memory.";
        goto error;
      }
      got = fread(orig, 1, txf->tex_width * txf->tex_height, file);
      EXPECT(txf->tex_width * txf->tex_height);
      txf->teximage = (unsigned char *)
        malloc(2 * txf->tex_width * txf->tex_height);
      if (txf->teximage == NULL) {
        lastError = "out of memory.";
        goto error;
      }
      for (i = 0; i < txf->tex_width * txf->tex_height; i++) {
        txf->teximage[i * 2] = orig[i];
        txf->teximage[i * 2 + 1] = orig[i];
      }
      free(orig);
    } else {
      txf->teximage = (unsigned char *)
        malloc(txf->tex_width * txf->tex_height);
      if (txf->teximage == NULL) {
        lastError = "out of memory.";
        goto error;
      }
      got = fread(txf->teximage, 1, txf->tex_width * txf->tex_height, file);
      EXPECT(txf->tex_width * txf->tex_height);
    }
    break;
  case TXF_FORMAT_BITMAP:
    width = txf->tex_width;
    height = txf->tex_height;
    stride = (width + 7) >> 3;
    texbitmap = (unsigned char *) malloc(stride * height);
    if (texbitmap == NULL) {
      lastError = "out of memory.";
      goto error;
    }
    got = fread(texbitmap, 1, stride * height, file);
    EXPECT(stride * height);
    if (useLuminanceAlpha) {
      txf->teximage = (unsigned char *) calloc(width * height * 2, 1);
      if (txf->teximage == NULL) {
        lastError = "out of memory.";
        goto error;
      }
      for (i = 0; i < height; i++) {
        for (j = 0; j < width; j++) {
          if (texbitmap[i * stride + (j >> 3)] & (1 << (j & 7))) {
            txf->teximage[(i * width + j) * 2] = 255;
            txf->teximage[(i * width + j) * 2 + 1] = 255;
          }
        }
      }
    } else {
      txf->teximage = (unsigned char *) calloc(width * height, 1);
      if (txf->teximage == NULL) {
        lastError = "out of memory.";
        goto error;
      }
      for (i = 0; i < height; i++) {
        for (j = 0; j < width; j++) {
          if (texbitmap[i * stride + (j >> 3)] & (1 << (j & 7))) {
            txf->teximage[i * width + j] = 255;
          }
        }
      }
    }
    free(texbitmap);
    break;
  }

  fclose(file);
  return txf;

error:

  if (txf) {
    if (txf->tgi)
      free(txf->tgi);
    if (txf->tgvi)
      free(txf->tgvi);
    if (txf->lut)
      free(txf->lut);
    if (txf->teximage)
      free(txf->teximage);
    free(txf);
  }
  if (file)
    fclose(file);
  return NULL;
}

GLuint
txfEstablishTexture(
  TexFont * txf,
  GLuint texobj,
  GLboolean setupMipmaps)
{
  if (txf->texobj == 0) {
    if (texobj == 0) {
#if !defined(USE_DISPLAY_LISTS)
      glGenTextures(1, &txf->texobj);
#else
      txf->texobj = glGenLists(1);
#endif
    } else {
      txf->texobj = texobj;
    }
  }
#if !defined(USE_DISPLAY_LISTS)
  glBindTexture(GL_TEXTURE_2D, txf->texobj);
#else
  glNewList(txf->texobj, GL_COMPILE);
#endif

#if 1
  /* XXX Indigo2 IMPACT in IRIX 5.3 and 6.2 does not support the GL_INTENSITY
     internal texture format. Sigh. Win32 non-GLX users should disable this
     code. */
  if (useLuminanceAlpha == 0) {
    char *vendor, *renderer, *version;

    renderer = (char *) glGetString(GL_RENDERER);
    vendor = (char *) glGetString(GL_VENDOR);
    if (!strcmp(vendor, "SGI") && !strncmp(renderer, "IMPACT", 6)) {
      version = (char *) glGetString(GL_VERSION);
      if (!strcmp(version, "1.0 Irix 6.2") ||
        !strcmp(version, "1.0 Irix 5.3")) {
        unsigned char *latex;
        int width = txf->tex_width;
        int height = txf->tex_height;
        int i;

        useLuminanceAlpha = 1;
        latex = (unsigned char *) calloc(width * height * 2, 1);
        /* XXX unprotected alloc. */
        for (i = 0; i < height * width; i++) {
          latex[i * 2] = txf->teximage[i];
          latex[i * 2 + 1] = txf->teximage[i];
        }
        free(txf->teximage);
        txf->teximage = latex;
      }
    }
  }
#endif

  if (useLuminanceAlpha) {
    if (setupMipmaps) {
      gluBuild2DMipmaps(GL_TEXTURE_2D, GL_LUMINANCE_ALPHA,
        txf->tex_width, txf->tex_height,
        GL_LUMINANCE_ALPHA, GL_UNSIGNED_BYTE, txf->teximage);
    } else {
      glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE_ALPHA,
        txf->tex_width, txf->tex_height, 0,
        GL_LUMINANCE_ALPHA, GL_UNSIGNED_BYTE, txf->teximage);
    }
  } else {
#if defined(GL_VERSION_1_1) || defined(GL_EXT_texture)
    /* Use GL_INTENSITY4 as internal texture format since we want to use as
       little texture memory as possible. */
    if (setupMipmaps) {
      gluBuild2DMipmaps(GL_TEXTURE_2D, GL_INTENSITY4,
        txf->tex_width, txf->tex_height,
        GL_LUMINANCE, GL_UNSIGNED_BYTE, txf->teximage);
    } else {
      glTexImage2D(GL_TEXTURE_2D, 0, GL_INTENSITY4,
        txf->tex_width, txf->tex_height, 0,
        GL_LUMINANCE, GL_UNSIGNED_BYTE, txf->teximage);
    }
#else
    abort();            /* Should not get here without EXT_texture or OpenGL
                           1.1. */
#endif
  }

#if defined(USE_DISPLAY_LISTS)
  glEndList();
  glCallList(txf->texobj);
#endif
  return txf->texobj;
}

void
txfBindFontTexture(
  TexFont * txf)
{
#if !defined(USE_DISPLAY_LISTS)
  glBindTexture(GL_TEXTURE_2D, txf->texobj);
#else
  glCallList(txf->texobj);
#endif
}

void
txfUnloadFont(
  TexFont * txf)
{
  if (txf->teximage) {
    free(txf->teximage);
  }
  free(txf->tgi);
  free(txf->tgvi);
  free(txf->lut);
  free(txf);
}

void
txfGetStringMetrics(
  TexFont * txf,
  char *string,
  int len,
  int *width,
  int *max_ascent,
  int *max_descent)
{
  TexGlyphVertexInfo *tgvi;
  int w, i;

  w = 0;
  for (i = 0; i < len; i++) {
    if (string[i] == 27) {
      switch (string[i + 1]) {
      case 'M':
        i += 4;
        break;
      case 'T':
        i += 7;
        break;
      case 'L':
        i += 7;
        break;
      case 'F':
        i += 13;
        break;
      }
    } else {
      tgvi = getTCVI(txf, string[i]);
      w += tgvi->advance;
    }
  }
  *width = w;
  *max_ascent = txf->max_ascent;
  *max_descent = txf->max_descent;
}

void
txfRenderGlyph(TexFont * txf, int c)
{
  TexGlyphVertexInfo *tgvi;

  tgvi = getTCVI(txf, c);
  glBegin(GL_QUADS);
  glTexCoord2fv(tgvi->t0);
  glVertex2sv(tgvi->v0);
  glTexCoord2fv(tgvi->t1);
  glVertex2sv(tgvi->v1);
  glTexCoord2fv(tgvi->t2);
  glVertex2sv(tgvi->v2);
  glTexCoord2fv(tgvi->t3);
  glVertex2sv(tgvi->v3);
  glEnd();
  glTranslatef(tgvi->advance, 0.0, 0.0);
}

void
txfRenderString(
  TexFont * txf,
  char *string,
  int len)
{
  int i;

  for (i = 0; i < len; i++) {
    txfRenderGlyph(txf, string[i]);
  }
}

enum {
  MONO, TOP_BOTTOM, LEFT_RIGHT, FOUR
};

void
txfRenderFancyString(
  TexFont * txf,
  char *string,
  int len)
{
  TexGlyphVertexInfo *tgvi;
  GLubyte c[4][3];
  int mode = MONO;
  int i;

  for (i = 0; i < len; i++) {
    if (string[i] == 27) {
      switch (string[i + 1]) {
      case 'M':
        mode = MONO;
        glColor3ubv((GLubyte *) & string[i + 2]);
        i += 4;
        break;
      case 'T':
        mode = TOP_BOTTOM;
        memcpy(c, &string[i + 2], 6);
        i += 7;
        break;
      case 'L':
        mode = LEFT_RIGHT;
        memcpy(c, &string[i + 2], 6);
        i += 7;
        break;
      case 'F':
        mode = FOUR;
        memcpy(c, &string[i + 2], 12);
        i += 13;
        break;
      }
    } else {
      switch (mode) {
      case MONO:
        txfRenderGlyph(txf, string[i]);
        break;
      case TOP_BOTTOM:
        tgvi = getTCVI(txf, string[i]);
        glBegin(GL_QUADS);
        glColor3ubv(c[0]);
        glTexCoord2fv(tgvi->t0);
        glVertex2sv(tgvi->v0);
        glTexCoord2fv(tgvi->t1);
        glVertex2sv(tgvi->v1);
        glColor3ubv(c[1]);
        glTexCoord2fv(tgvi->t2);
        glVertex2sv(tgvi->v2);
        glTexCoord2fv(tgvi->t3);
        glVertex2sv(tgvi->v3);
        glEnd();
        glTranslatef(tgvi->advance, 0.0, 0.0);
        break;
      case LEFT_RIGHT:
        tgvi = getTCVI(txf, string[i]);
        glBegin(GL_QUADS);
        glColor3ubv(c[0]);
        glTexCoord2fv(tgvi->t0);
        glVertex2sv(tgvi->v0);
        glColor3ubv(c[1]);
        glTexCoord2fv(tgvi->t1);
        glVertex2sv(tgvi->v1);
        glColor3ubv(c[1]);
        glTexCoord2fv(tgvi->t2);
        glVertex2sv(tgvi->v2);
        glColor3ubv(c[0]);
        glTexCoord2fv(tgvi->t3);
        glVertex2sv(tgvi->v3);
        glEnd();
        glTranslatef(tgvi->advance, 0.0, 0.0);
        break;
      case FOUR:
        tgvi = getTCVI(txf, string[i]);
        glBegin(GL_QUADS);
        glColor3ubv(c[0]);
        glTexCoord2fv(tgvi->t0);
        glVertex2sv(tgvi->v0);
        glColor3ubv(c[1]);
        glTexCoord2fv(tgvi->t1);
        glVertex2sv(tgvi->v1);
        glColor3ubv(c[2]);
        glTexCoord2fv(tgvi->t2);
        glVertex2sv(tgvi->v2);
        glColor3ubv(c[3]);
        glTexCoord2fv(tgvi->t3);
        glVertex2sv(tgvi->v3);
        glEnd();
        glTranslatef(tgvi->advance, 0.0, 0.0);
        break;
      }
    }
  }
}

int
txfInFont(TexFont * txf, int c)
{
  TexGlyphVertexInfo *tgvi;

  /* NOTE: No uppercase/lowercase substituion. */
  if ((c >= txf->min_glyph) && (c < txf->min_glyph + txf->range)) {
    if (txf->lut[c - txf->min_glyph]) {
      return 1;
    }
  }
  return 0;
}