#include "font.h"
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <limits.h>
#include <SDL3_image/SDL_image.h>

#define FILE_NAME_SIZE 300

void free_sprite_font(sprite_font* font) {
  free(font->characters);
  SDL_DestroyTexture(font->spritesheet);

  memset(font, 0, sizeof(sprite_font));
}

int get_string_parameter(const char* line, const char* parameter, const char** start) {
  *start = strstr(line, parameter);
  if ((*start) == NULL)
    return -1;

  *start += strlen(parameter);
  if ((*start)[0] != '\"') {
    return -1;
  }

  int length = 0;
  while ((*start)[length+1] != '\0' && (*start)[length+1] != '\"') length++;

  (*start)++;
  return length;
}

unsigned char parse_character_tag(const char* character_tag) {
  if (strncmp(character_tag, "space", 5) == 0)
    return ' ';

  return character_tag[0];
}

void extract_dir_name(const char* filename, char dir_name_buffer[FILE_NAME_SIZE]) {
  strcpy(dir_name_buffer, "");

  const char* head = filename;
  const char* next;

  while ((next = strchr(head+1, '/')) != NULL) {
    head=next;
  }

  int dir_name_length = SDL_min(head - filename, FILE_NAME_SIZE-1);
  strncpy(dir_name_buffer, filename, dir_name_length);

  dir_name_buffer[dir_name_length] = '\0';
}

bool get_int_parameter(const char* line, const char* parameter, int* value) {
  const char* start = strstr(line, parameter);
  if (start == NULL) {
    return false;
  }
  start += strlen(parameter);

  int c = 0;
  bool negative = false;

  if (start[0] == '-') {
    negative = true;
    start++;
  }

  for(int i = 0; start[i] >= '0' && start[i] <= '9'; i++) {
    c *= 10; c += start[i] - '0';
  }

  *value = negative ? -c : c;
  return true;
}

bool load_sprite_font(SDL_Renderer* renderer, const char* filename, sprite_font* font) {
  if (font->characters || font->spritesheet) {
    SDL_Log("Trying to reallocate font causing memory leak, exitting!");
    exit(EXIT_FAILURE);
  }

  FILE* f = fopen(filename, "r");
  if (f == NULL) {
    SDL_Log("Failed to open sprite font file %s, error: %s!",
            filename,
            strerror(errno)
            );
    return false;
  }

  char line[PARSER_LINE_SIZE];
  if (fgets(line, sizeof(line), f) == NULL ||
      strncmp(line, "info", 4) != 0) {
    SDL_Log("File %s is not a valid font file!",
            filename);
    fclose(f);
    return false;
  }

  char font_name[FONT_NAME_SIZE];
  const char* font_name_start;
  int font_name_length =
    SDL_min(get_string_parameter(line, "face=", &font_name_start),
            FONT_NAME_SIZE-1
            );

  strncpy(font_name, font_name_start, font_name_length);
  font_name[font_name_length] = '\0';

  int char_size = 0, char_count = 0;
  font_char* characters_unarranged = NULL;

  unsigned char smallest_char = UCHAR_MAX;
  unsigned char largest_char = 0;

  char sprite_file_name[FILE_NAME_SIZE] = "";
  while (fgets(line, PARSER_LINE_SIZE, f) != NULL) {
    font_char* temp;

    if (strncmp(line, "chars", 5) == 0) {
      int total_char_count;

      if(!get_int_parameter(line, "count=", &total_char_count))
        continue;

      char_size = total_char_count;
      temp =
        realloc(characters_unarranged, char_size * sizeof(font_char));

      if (temp == NULL) {
        SDL_Log("Failed to allocate space while loading font %s, error %s",
                filename,
                strerror(errno));

        if (characters_unarranged != NULL) {
          free(characters_unarranged);
        }

        fclose(f);
        return false;
      }

      characters_unarranged = temp;
    }

    //Only one page supported
    else if (strcmp(sprite_file_name, "") == 0 && strncmp(line, "page", 4) == 0) {
      const char* sprite_fname_start;
      int sprite_fname_length =
        SDL_min(get_string_parameter(line, "file=", &sprite_fname_start),
                FONT_NAME_SIZE-1
                );

      if (sprite_fname_length <= 0) {
        SDL_Log("Malformed spritesheet file name in font file %s",
                filename);
        continue;
      }

      strncpy(sprite_file_name, sprite_fname_start, sprite_fname_length);
      font_name[sprite_fname_length] = '\0';
    }

    else if (strncmp(line, "char", 4) == 0) {
      font_char new_font_char;
      new_font_char.active = true;

      int val;

      if (!get_int_parameter(line, "x=", &val))
        continue;
      new_font_char.x = val;

      if (!get_int_parameter(line, "y=", &val))
        continue;
      new_font_char.y = val;

      if (!get_int_parameter(line, "width=", &val))
        continue;
      new_font_char.width = val;

      if (!get_int_parameter(line, "height=", &val))
        continue;
      new_font_char.height = val;

      if (!get_int_parameter(line, "xoffset=", &val))
        continue;
      new_font_char.x_offset = val;

      if (!get_int_parameter(line, "yoffset=", &val))
        continue;
      new_font_char.y_offset = val;

      if (!get_int_parameter(line, "xadvance=", &val))
        continue;
      new_font_char.x_advance = val;

      const char* character_tag;
      if (get_string_parameter(line, "letter=", &character_tag) <= 0)
        continue;
      new_font_char.character = parse_character_tag(character_tag);

      if (new_font_char.character < smallest_char) {
        smallest_char = new_font_char.character;
      }

      if (new_font_char.character > largest_char) {
        largest_char = new_font_char.character;
      }

      if (char_count >= char_size) {
        char_size = char_count+1;
        temp =
          realloc(characters_unarranged, char_size * sizeof(font_char));

        if (temp == NULL) {
          SDL_Log("Failed to allocate space while loading font %s, error %s",
                  filename,
                  strerror(errno));

          if (characters_unarranged != NULL) {
            free(characters_unarranged);
          }

          fclose(f);
          return false;
        }

        characters_unarranged = temp;
      }

      characters_unarranged[char_count] = new_font_char;
      char_count++;
    }
  }

  if (char_count <= 0) {
    SDL_Log("Font %s defines no characters!", filename);

    if (characters_unarranged != NULL) {
      free(characters_unarranged);
    }
    fclose(f);
    return false;
  }

  if (strcmp(sprite_file_name, "") == 0) {
    SDL_Log("Font file %s has no spritesheet defined!",
            filename
            );
    if (characters_unarranged != NULL) {
      free(characters_unarranged);
    }

    fclose(f);
    return false;
  }

  char font_dir_name[FILE_NAME_SIZE];
  extract_dir_name(filename, font_dir_name);

  char font_sprite_fname_full[FILE_NAME_SIZE*2];
  snprintf(font_sprite_fname_full,
           FILE_NAME_SIZE*2,
           "%s/%s",
           strcmp(font_dir_name, "") == 0 ? "." : font_dir_name,
           sprite_file_name
           );

  SDL_Texture* font_spritesheet =
    IMG_LoadTexture(renderer, font_sprite_fname_full);

  if (font_spritesheet == NULL) {
    SDL_Log("Failed to load texture %s as spritesheet for font %s!",
            font_sprite_fname_full,
            filename);

    if (characters_unarranged != NULL) {
      free(characters_unarranged);
    }

    fclose(f);
    return false;
  }

  font_char* characters_arranged =
    malloc((largest_char-smallest_char+1) * sizeof(font_char));
  memset(characters_arranged, 0, (largest_char-smallest_char+1) * sizeof(font_char));

  if (characters_arranged == NULL) {
    SDL_Log("Failed to allocate space while loading font %s, error %s",
            filename,
            strerror(errno));

    if (characters_unarranged != NULL) {
      free(characters_unarranged);
    }

    SDL_DestroyTexture(font_spritesheet);
    fclose(f);
    return false;
  }

  for (int i = 0; i < char_count; i++) {
    font_char* f = &characters_unarranged[i];
    characters_arranged[f->character - smallest_char] = characters_unarranged[i];
  }

  *font = (sprite_font) {
    .smallest_character = smallest_char,
    .largest_character = largest_char,
    .characters = characters_arranged,
    .spritesheet = font_spritesheet
  };

  strncpy(font->name, font_name, FONT_NAME_SIZE-1);
  font_name[FONT_NAME_SIZE-1] = '\0';

  free(characters_unarranged);
  fclose(f);
  return true;
}

void measure_text
(
 sprite_font* font,
 const unsigned char* text,
 float scale,
 float* width, float* height
) {
  *width = 0;
  *height = 0;

  while (*text) {
    const font_char* fc = &font->characters[*text-font->smallest_character];
    if (!fc->active) {
      text++;
      continue;
    }

    *width += fc->x_advance * scale;
    *height = SDL_max(*height, (fc->y_offset+fc->height) * scale);

    text++;
  }
}

void draw_text_with_spritefont_extended
(
 SDL_Renderer* renderer,
 sprite_font* font,
 const unsigned char* text,
 float x_position, float y_position,
 float scale
) {
  float text_column_length, text_column_height;
  measure_text(font, text, scale, &text_column_length, &text_column_height);

  x_position -= text_column_length / 2;
  y_position -= text_column_height / 2;

  while (*text) {
    const font_char* fc = &font->characters[*text-font->smallest_character];
    if (!fc->active) {
      text++;
      continue;
    }

    SDL_RenderTexture(renderer,
                      font->spritesheet,
                      &(SDL_FRect){
                        .x = fc->x,
                        .y = fc->y,
                        .w = fc->width,
                        .h = fc->height
                      },
                      &(SDL_FRect){
                        .x = x_position + fc->x_offset*scale,
                        .y = y_position + fc->y_offset * scale,
                        .w = fc->width * scale,
                        .h = fc->height * scale
                      });
    x_position += fc->x_advance * scale;
    text++;
  }
}


void draw_text_with_spritefont
(
 SDL_Renderer* renderer,
 sprite_font* font,
 const unsigned char* text,
 float x_position, float y_position
) {
  draw_text_with_spritefont_extended(renderer,
                               font,
                               text,
                               x_position,
                               y_position,
                               1.0
                               );
}