#include "text.h"

#include <fcntl.h>
#include <mimalloc.h>
#include <unistd.h>
#include <utils.h>

#include "cglm/types.h"
#include "cglm/vec2.h"
#include "freetype/freetype.h"
#include "hash.h"
#include "rendering.h"
#include "utils.h"

static bool wayc_font_cache_lookup(struct font_s* font, codepoint_t codepoint,
                                   struct glyph_s* out) {
  struct glyph_s glyph;
  bool ok = wayc_hashmap_get(&font->cache, &codepoint, &glyph);
  if (ok) *out = glyph;
  return ok;
}

static void wayc_font_cache_insert(struct font_s* font, codepoint_t codepoint,
                                   struct glyph_s glyph) {
  wayc_notnull(font);
  wayc_hashmap_insert(&font->cache, &codepoint, &glyph);
}

enum font_context_error_e wayc_font_context_init(struct font_context_s* ctx) {
  wayc_notnull(ctx);

  FT_Error err = FT_Init_FreeType(&ctx->library);
  if (err) return FONT_CONTEXT_ERROR_LIBRARY_LOADING;
  return FONT_CONTEXT_ERROR_NONE;
}

void wayc_font_context_deinit(struct font_context_s* ctx) {
  wayc_notnull(ctx);

  FT_Done_FreeType(ctx->library);
}

enum font_error_e wayc_font_init(struct font_s* font,
                                 struct font_context_s* ctx, u32 fsize,
                                 const char* path) {
  wayc_notnull(font);
  wayc_notnull(ctx);
  wayc_notnull(path);

  bool success = false;

  i32 fd = open(path, O_RDONLY);
  if (fd < 0) return FONT_ERROR_FILE_LOAD;
  wayc_defer(close(fd));

  isize size = lseek(fd, 0, SEEK_END);
  if (size < 0) return FONT_ERROR_FILE_LOAD;
  lseek(fd, 0, SEEK_SET);

  u8* data = (u8*)mi_malloc(size);
  wayc_defer_cond({ mi_free(data); }, success, true);

  isize _read = read(fd, data, size);
  if (_read < 0 || _read != size) return FONT_ERROR_FILE_LOAD;

  FT_Error err = FT_New_Memory_Face(ctx->library, data, size, 0, &font->face);
  if (err) return FONT_ERROR_FONT_LOAD;
  wayc_defer_cond(FT_Done_Face(font->face);, success, true);

  err = FT_Set_Pixel_Sizes(font->face, 0, fsize);
  if (err) return FONT_ERROR_FONT_LOAD;

  font->data = data;
  wayc_hashmap_init(&font->cache);

  success = true;
  return FONT_ERROR_NONE;
}

enum font_error_e wayc_font_lookup(struct font_s* font, struct atlas_s* atlas,
                                   struct atlas_packer_s* packer,
                                   codepoint_t codepoint, struct glyph_s* out) {
  wayc_notnull(font);
  wayc_notnull(atlas);
  wayc_notnull(out);

  FT_Face face = font->face;

  bool found = wayc_font_cache_lookup(font, codepoint, out);
  if (found) return FONT_ERROR_NONE;

  FT_UInt glyph_index = FT_Get_Char_Index(face, codepoint);
  if (glyph_index == 0) return FONT_ERROR_NOT_MATCH;

  FT_Load_Glyph(face, glyph_index, FT_LOAD_DEFAULT);
  FT_GlyphSlot slot = face->glyph;
  FT_Render_Glyph(slot, FT_RENDER_MODE_NORMAL);

  FT_Bitmap bitmap = slot->bitmap;
  if (bitmap.pitch != (i32)bitmap.width) wayc_panic("unsupported pitch");

  ivec2 size = {(i32)bitmap.width, (i32)bitmap.rows};
  ivec2 uv0;

  bool ok = wayc_atlas_packer_allocate(packer, WAYC_X(size), WAYC_Y(size), uv0);
  if (!ok) return FONT_ERROR_ATLAS_FULL;

  ok = wayc_atlas_set(atlas, IMAGE_DATA_TYPE_UNSIGNED_BYTE, uv0, WAYC_X(size),
                      WAYC_Y(size), IMAGE_FORMAT_RED_ALIGNMENT, bitmap.buffer);
  if (!ok) return FONT_ERROR_ATLAS_FULL;

  struct glyph_s glyph = {};
  glyph.bearing_x = slot->bitmap_left;
  glyph.bearing_y = slot->bitmap_top;
  glyph.advance = (f32)slot->advance.x / WAYC_SCALE;

  wayc_font_cache_insert(font, codepoint, glyph);

  *out = glyph;
  return FONT_ERROR_NONE;
}

void wayc_font_deinit(struct font_s* font) {
  wayc_notnull(font);

  wayc_hashmap_deinit(&font->cache);
  FT_Done_Face(font->face);
  mi_free(font->data);
}

enum text_error_e wayc_text_vertices(struct text_s* text,
                                     struct text_vertex_s** out) {
  wayc_notnull(text);
  wayc_notnull(out);

  bool success = false;

  usize nverts = WAYC_LETTER_NVERTICES * wayc_string_length(&text->string);
  usize verts_bytes = nverts * sizeof(struct text_vertex_s);

  struct text_vertex_s* verts = (struct text_vertex_s*)mi_malloc(verts_bytes);
  wayc_defer_cond(mi_free(verts), success, true);

  vec2 pen = GLM_VEC2_ZERO_INIT;
  usize idx = 0;
  for (usize i = 0; i < wayc_string_length(&text->string); i++) {
    codepoint_t codep =
        wayc_string_data(&text->string)[i];  // TODO: do proper UTF-8 decoding

    struct glyph_s glyph;
    enum font_error_e err =
        wayc_font_lookup(text->font, text->atlas, text->packer, codep, &glyph);
    if (err != FONT_ERROR_NONE) return TEXT_ERROR_ATLAS;

    f32 x0 = WAYC_X(pen) + glyph.bearing_x;
    f32 y0 = WAYC_Y(pen) - glyph.bearing_y;
    f32 x1 = x0 + WAYC_X(glyph.uv1) - WAYC_X(glyph.uv0);
    f32 y1 = y0 + WAYC_Y(glyph.uv1) - WAYC_Y(glyph.uv0);

    f32 u0 = (f32)WAYC_X(glyph.uv0) / text->atlas->width;
    f32 v0 = (f32)WAYC_Y(glyph.uv0) / text->atlas->height;
    f32 u1 = (f32)WAYC_X(glyph.uv1) / text->atlas->width;
    f32 v1 = (f32)WAYC_Y(glyph.uv1) / text->atlas->height;

    struct text_vertex_s ps0 = {{x0, y0}, {u0, v0}};
    struct text_vertex_s ps1 = {{x0, y1}, {u0, v1}};
    struct text_vertex_s ps2 = {{x1, y1}, {u1, v1}};
    struct text_vertex_s ps3 = {{x1, y0}, {u1, v0}};

    verts[idx++] = ps0;
    verts[idx++] = ps1;
    verts[idx++] = ps2;
    verts[idx++] = ps0;
    verts[idx++] = ps2;
    verts[idx++] = ps3;
  }

  success = true;
  *out = verts;
  return TEXT_ERROR_NONE;
}