/**
 * Copyright (c) 2017 rxi
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the MIT license. See LICENSE for details.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "lib/dmt/dmt.h"
#include "lib/stb/stb_truetype.h"
#include "filesystem.h"
#include "font.h"


static const char *initFont(font_t *self, const void *data, int ptsize) {
  int i;

  /* Init font */
  stbtt_fontinfo font;
  if ( !stbtt_InitFont(&font, data, 0) ) {
    return "could not load font";
  }

  /* Get height and scale */
  int ascent, descent, lineGap;
  stbtt_GetFontVMetrics(&font, &ascent, &descent, &lineGap);
  float scale = stbtt_ScaleForMappingEmToPixels(&font, ptsize);
  self->height = (ascent - descent + lineGap) * scale + 0.5;

  /* Init image */
  int w = 128, h = 128;
retry:
  image_initBlank(&self->image, w, h);

  /* Load glyphs */
  float s = stbtt_ScaleForMappingEmToPixels(&font, 1) /
            stbtt_ScaleForPixelHeight(&font, 1);
  int res = stbtt_BakeFontBitmap(
    data, 0, ptsize * s, self->image.data, w, h, 0, 128, self->glyphs);

  /* Retry with a larger image buffer if the buffer wasn't large enough */
  if (res < 0) {
    w <<= 1;
    h <<= 1;
    image_deinit(&self->image);
    goto retry;
  }

  /* Adjust glyph yoffsets */
  int scaledAscent = ascent * scale + 0.5;
  for (i = 0; i < 128; i++) {
    self->glyphs[i].yoff += scaledAscent;
  }

  /* Init image data and mask */
  for (i = 0; i < w * h; i++) {
    self->image.data[i] = (self->image.data[i] > 127) ? 1 : 0;
    self->image.mask[i] = (self->image.data[i] == 0) ? 0xff : 0;
  }

  /* Return NULL for no error */
  return NULL;
}


const char *font_init(font_t *self, const char *filename, int ptsize) {
  const char *errmsg = NULL;
  void *data = NULL;
  FILE *fp = NULL;
  memset(self, 0, sizeof(*self));

  /* Load font file */
  int size;
  data = filesystem_read(filename, &size);
  if (!data) {
    errmsg = "could not open font file";
    goto fail;
  }

  /* Init font */
  errmsg = initFont(self, data, ptsize);
  if (errmsg) {
    goto fail;
  }

  /* Free font data */
  filesystem_free(data);
  data = NULL;

  return NULL;

fail:
  if (fp) fclose(fp);
  filesystem_free(data);
  return errmsg;
}


const char *font_initEmbedded(font_t *self, int ptsize) {
  #include "font_ttf.h"
  return initFont(self, font_ttf, 8);
}


void font_deinit(font_t *self) {
  image_deinit(&self->image);
}


extern int image_blendMode;
extern int image_flip;

void font_blit(font_t *self, pixel_t *buf, int bufw, int bufh,
               const char *str, int dx, int dy
) {
  const char *p = str;
  int x = dx;
  int y = dy;

  int oldBlendMode = image_blendMode;
  int oldFlip = image_flip;
  image_blendMode = IMAGE_COLOR;
  image_flip = 0;

  while (*p) {
    if (*p == '\n') {
      x = dx;
      y += self->height;
    } else {
      stbtt_bakedchar *g = &self->glyphs[(int) (*p & 127)];
      int w = g->x1 - g->x0;
      int h = g->y1 - g->y0;
      image_blit(&self->image, buf, bufw, bufh,
                 x + g->xoff, y + g->yoff, g->x0, g->y0, w, h);
      x += g->xadvance;
    }
    p++;
  }

  image_blendMode = oldBlendMode;
  image_flip = oldFlip;
}