/*

Copyright (c) 2015-2016, Higor Eurípedes
All rights reserved.

Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright notice, this
  list of conditions and the following disclaimer.

* Redistributions in binary form must reproduce the above copyright notice, this
  list of conditions and the following disclaimer in the documentation and/or
  other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "libretro.h"
#include "ttf2c.h"
#include "font24.h"
#include "font16.h"
#include "font10.h"

static retro_environment_t   env_cb   = NULL;
static retro_input_state_t   input_cb = NULL;
static retro_input_poll_t    poll_cb  = NULL;
static retro_video_refresh_t video_cb = NULL;

static bool bool_env(unsigned env, bool value) { return env_cb(env, &value); }
static bool uint_env(unsigned env, unsigned value) { return env_cb(env, &value); }


#define MAX(a,b) ((a) > (b) ? (a) : (b))
#define MIN(a,b) ((a) < (b) ? (a) : (b))

#define SCREEN_WIDTH  640
#define SCREEN_HEIGHT 360
#define SCREEN_MAX_POS MAX(SCREEN_WIDTH, SCREEN_HEIGHT)
#define SCREEN_PITCH  (SCREEN_MAX_POS * sizeof(uint16_t))
#define CELL_SIZE   28
#define GRID_GROUP_SIZE 3
#define GRID_COLS   (GRID_GROUP_SIZE*6)
#define GRID_ROWS   (GRID_GROUP_SIZE*3)
#define GRID_X      100
#define GRID_Y      70

static inline uint16_t rgb565(uint8_t r, uint8_t g, uint8_t b)
{
   return  ((r >> 3U) << 11U)
         | ((g >> 2U) <<  5U)
         | ((b >> 3U) <<  0U);
}

static inline void rgb565_decompose(uint16_t color, uint8_t *r, uint8_t *g, uint8_t *b)
{
   *r = ((color >> 11) << 3) & 0xff;
   *g = ((color >>  5) << 2) & 0xff;
   *b = ((color >>  0) << 3) & 0xff;
}

#define WHITE rgb565(255, 255, 255)
#define BLACK rgb565(255, 255, 255)
#define GREY  rgb565(63, 63, 63)
#define LIGHTGREY  RGB(127, 127, 127)

enum
{
   XALIGN_LEFT   = 0,
   XORIG_RIGHT   = 1 << 0,
   XORIG_CENTER  = 1 << 1,
   YALIGN_TOP    = 0,
   YORIG_BOTTOM  = 1 << 2,
   YORIG_CENTER  = 1 << 3
};

typedef enum
{
   CELL_CLEAR    = 0,
   CELL_SET      = 1,
   CELL_DISABLED = 2,
   CELL_WRONG    = 3,
} cell_state_t;

typedef cell_state_t grid_t[GRID_ROWS][GRID_COLS];

struct {
   struct
   {
      grid_t front; // modifiable by the user
      grid_t back;  // the grid to test against
      int focus_x, focus_y;
   } grid;

   int row_counts[GRID_ROWS][GRID_COLS];
   int col_counts[GRID_COLS][GRID_ROWS];

   bool first_run;

   uint16_t fb[SCREEN_MAX_POS * SCREEN_MAX_POS];


   struct {
      int x, y;
      bool left, right;
      bool prev_left, prev_right;
      bool moved;
   } mouse;

   struct {
      int x, y;
      bool a, b;
      bool moved;
   } joy;

   struct
   {
      unsigned active;
      unsigned hot;
      unsigned last_hot;

      unsigned last_focus;
      unsigned focus;
   } ui;
} g;

static int16_t read_mouse(unsigned id)
{
   return input_cb(0, RETRO_DEVICE_MOUSE, 0, id);
}

static int16_t read_joypad(unsigned id)
{
   return input_cb(0, RETRO_DEVICE_JOYPAD, 0, id);
}

static inline void clip_pos(int *x, int *y)
{
   if (x)
      *x = MAX(MIN(*x, SCREEN_WIDTH), 0);

   if (y)
      *y = MAX(MIN(*y, SCREEN_HEIGHT), 0);
}

static inline void *memset16(void *dst, uint16_t value, size_t count)
{
   if (count > 0)
   {
      uint16_t *dst16 = (uint16_t*)dst;
      int n  = (count + 7) >> 3;

      switch (count & 7)
      {
         case 0: do { *dst16++ = value;
         case 7:      *dst16++ = value;
         case 6:      *dst16++ = value;
         case 5:      *dst16++ = value;
         case 4:      *dst16++ = value;
         case 3:      *dst16++ = value;
         case 2:      *dst16++ = value;
         case 1:      *dst16++ = value; } while (--n);
      }

      return dst16;
   }

   return dst;
}

static void draw_rect(int x1, int y1, int x2, int y2, uint16_t color)
{
   uint16_t *pos = NULL;
   int height, width;

   clip_pos(&x1, &y1);
   clip_pos(&x2, &y2);

   if (x2 - x1 <= 0 || y2 - y1 <= 0)
      return;

   height = y2 - y1;
   width  = x2 - x1;

   pos = &g.fb[y1 * SCREEN_MAX_POS + x1];

   /* use system's memset for black and white */
   if (color == 0xffff || color == 0)
   {
      width <<= 1;
      color >>= 8;

      do
      {
         memset(pos, color, width);

         pos += SCREEN_MAX_POS;
      } while (--height);
   }
   else
   {
      do
      {
         memset16(pos, color, width);

         pos += SCREEN_MAX_POS;
      } while (--height);
   }
}

static void draw_square(int x, int y, int side, uint16_t color)
{
   draw_rect(x, y, x+side, y+side, color);
}

void draw_str(const ttf2c_font *font, int x1, int y1, unsigned orig, uint16_t color, const char *str)
{
   uint8_t sr, sg, sb;

   int line_width  = ttf2c_get_width(font, str);
   int line_height = font->line_height;

   if (orig & XORIG_RIGHT)
      x1 -= line_width;
   else if (orig & XORIG_CENTER)
      x1 -= line_width / 2;

   if (orig & YORIG_BOTTOM)
      y1 -= line_height;
   else if (orig & YORIG_CENTER)
      y1 -= line_height / 2;

   int x2 = x1 + ttf2c_get_width(font, str);
   int y2 = y1 + line_height;

   clip_pos(&x1, &y1);
   clip_pos(&x2, &y2);

   if (x2 - x1 <= 0 || y2 - y1 <= 0 || !*str)
      return;
   rgb565_decompose(color, &sr, &sg, &sb);

   do {
      const ttf2c_glyph *glyph = &font->glyphs[(unsigned)*str++];

      if (glyph->width * glyph->height && glyph->bitmap)
      {
         int x, y;
         int target_y = y1 + font->ascent + glyph->off_y - font->descent;
         int height = MIN(glyph->height, (y2 - y1));
         int width  = glyph->width;

         for (y = 0; y < height; ++y)
         {
            const uint8_t *src = &glyph->bitmap[y * width];
            uint16_t      *dst = &g.fb[target_y * SCREEN_MAX_POS + x1];
            for (x = 0; x < width; ++x)
            {
               uint8_t dr, dg, db;
               rgb565_decompose(*dst, &dr, &dg, &db);
               *dst = rgb565(
                        sr * *src / 255 + dr * (255 - *src) / 255,
                        sg * *src / 255 + dg * (255 - *src) / 255,
                        sb * *src / 255 + db * (255 - *src) / 255);
               ++dst;
               ++src;
            }
            target_y++;
         }
      }

      x1 += glyph->adv_x;

      if (glyph->adv_x <= glyph->width)
         x1++;

   } while (*str);
}

/* UI CODE   ---------------------------------------------------------------- */
static void ui_begin(void)
{
   g.ui.hot = 0;
}

static void ui_end(void)
{
   if (!g.mouse.left && !g.mouse.right)
      g.ui.active = 0;
   else if (g.ui.active == 0)
      g.ui.active = -1;
}

static bool ui_mouse_over(int x1, int y1, int x2, int y2)
{
   unsigned mx = g.mouse.x;
   unsigned my = g.mouse.y;

   return mx >= x1 && mx <= x2 && my >= y1 && my <= y2;
}

static bool ui_mouse_down(bool left, bool right)
{
   return (left && g.mouse.left)
         || (right && g.mouse.right);
}

static bool ui_mouse_up(bool left, bool right)
{
   return (left && !g.mouse.left && g.mouse.prev_left)
         || (right && !g.mouse.right && g.mouse.prev_right);
}

static void ui_check_rect_hotness(unsigned id, int x1, int y1, int x2, int y2)
{
   bool inside = ui_mouse_over(x1, y1, x2, y2);

   if (inside)
   {
      g.ui.last_hot = g.ui.hot;
      g.ui.hot      = id;
   }
}

static void ui_check_focus(unsigned id)
{
   if (g.ui.focus == 0)
      g.ui.focus = id;
}

static bool ui_button_down(unsigned id, bool left, bool right, int x1, int y1, int x2, int y2)
{
   bool result = false;
   ui_check_rect_hotness(id, x1, y1, x2, y2);

   if (g.ui.hot == id && ui_mouse_down(left, right))
   {
      g.ui.last_focus = g.ui.focus;
      g.ui.focus      = id;
      g.ui.active     = id;
      result          = true;
   }

   return result;
}

static bool ui_button_up(unsigned id, bool left, bool right, int x1, int y1, int x2, int y2)
{
   bool result = false;
   ui_check_rect_hotness(id, x1, y1, x2, y2);

   if (g.ui.active == id && ui_mouse_up(left, right))
   {
      if (g.ui.hot == id)
         result = true;

      g.ui.active = 0;
   }

   ui_button_down(id, left, right, x1, y1, x2, y2);

   return result;
}

static int ui_joy_ab(unsigned id)
{
   int result = 0;

   if (!g.ui.focus)
      g.ui.focus = id;

   if (g.ui.focus == id)
      result = g.joy.a - g.joy.b;

   return result;
}

/* GRID CODE ---------------------------------------------------------------- */

static bool grid_valid_cell(int row, int col)
{
   return row >= 0 && row < GRID_ROWS && col >= 0 && col < GRID_COLS;
}

static void grid_clip(int *row, int *col)
{
   if (row)
      *row = (*row < 0) ? 0 : ((*row >= GRID_ROWS) ? GRID_ROWS - 1 : *row);
   if (col)
      *col = (*col < 0) ? 0 : ((*col >= GRID_COLS) ? GRID_COLS - 1 : *col);
}

static void grid_to_screen(int row, int col, int *x, int *y)
{
   if (!grid_valid_cell(row, col))
   {
      if (x)
         *x = INT_MIN;
      if (y)
         *y = INT_MIN;
   }
   if (x)
      *x = GRID_X + col * CELL_SIZE + col + (col / GRID_GROUP_SIZE);
   if (y)
      *y = GRID_Y + row * CELL_SIZE + row + (row / GRID_GROUP_SIZE);
}

static void grid_from_screen(int x, int y, int *row, int *col)
{
   /* many thanks to heez for helping me with the math */
   if (row)
   {
      *row = (GRID_GROUP_SIZE * (y - GRID_Y)) / (GRID_GROUP_SIZE * CELL_SIZE + 4);
      if (*row < 0 || *row >= GRID_COLS)
         *row = INT_MIN;
   }

   if (col)
   {
      *col = (GRID_GROUP_SIZE * (x - GRID_X)) / (GRID_GROUP_SIZE * CELL_SIZE + 4);

      if (*col < 0 || *col >= GRID_COLS)
         *col = INT_MIN;
   }
}

static uint16_t grid_cell_color(grid_t grid, int row, int col)
{
   if (!grid_valid_cell(row, col))
      return rgb565(255, 0, 0);

   cell_state_t val = grid[row][col];
   switch (val)
   {
      case CELL_CLEAR:
      case CELL_SET:
         return !val * ~0;
      case CELL_DISABLED:
         return rgb565(127, 127, 127);
      case CELL_WRONG:
         return rgb565(255, 0, 0);
      default:
         return rgb565(0, 255, 0);
   }
}

static bool ui_grid_cell(grid_t grid, int row, int col, bool *left_down)
{
   unsigned id = (uintptr_t)&grid[row][col];
   bool result;
   int joy = 0;
   int x, y;

   grid_to_screen(row, col, &x, &y);

   result = ui_button_up(id, true, true, x, y, x+CELL_SIZE, y+CELL_SIZE);
   joy    = ui_joy_ab(id);

   if (g.ui.hot == id || g.ui.focus == id)
      draw_square(x-1, y-1, CELL_SIZE+2, rgb565(255, 0, 0));
   else if (g.ui.last_hot == id || g.ui.last_focus == id)
      draw_square(x-1, y-1, CELL_SIZE+2, rgb565(0, 255, 0));

   if (result)
   {
      *left_down = g.mouse.prev_left;
      g.grid.focus_x = col;
      g.grid.focus_y = row;
   }
   else if (joy)
   {
      *left_down = joy > 0;
      result = true;
   }

   draw_square(x, y, CELL_SIZE, grid_cell_color(grid, row, col));

   return result;
}

static void render_labels(void)
{
   draw_rect(0, 0, GRID_X, GRID_Y, ~0);
   draw_str(&font24, 10, 0, 0, rgb565(99, 0, 0), "CRUZES");
   draw_str(&font24, 10, GRID_Y - font24.line_height, 0, rgb565(99, 0, 0), "00:23:04");

   for (int col = 0; col < GRID_COLS; ++col)
   {
      int x, y;
      grid_to_screen(0, col, &x, &y);
      y -= 2;

      for (int index = GRID_ROWS-1; index >= 0; --index)
      {
         char tmp[10];

         if (!g.col_counts[col][index])
            continue;

         snprintf(tmp, sizeof(tmp), "%i", g.col_counts[col][index]);
         draw_str(&font10, x + CELL_SIZE/2, y, YORIG_BOTTOM | XORIG_CENTER, ~0, tmp);
         y -= 12;
      }
   }

   for (int row = 0; row < GRID_ROWS; ++row)
   {
      int x, y;
      grid_to_screen(row, 0, &x, &y);
      x -= 4;

      for (int index = GRID_COLS-1; index >= 0; --index)
      {
         char tmp[10];

         if (!g.row_counts[row][index])
            continue;


         snprintf(tmp, sizeof(tmp), "%i", g.row_counts[row][index]);
         draw_str(&font10, x, y + CELL_SIZE/2, YORIG_CENTER | XORIG_RIGHT, ~0, tmp);

         x -= ttf2c_get_width(&font10, tmp) + 6;
      }
   }
}

static void game_step()
{
   draw_rect(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT, GREY);

   if (g.joy.moved && !g.mouse.moved)
   {
      g.grid.focus_x += g.joy.x;
      g.grid.focus_y += g.joy.y;
      grid_clip(&g.grid.focus_y, &g.grid.focus_x);

      g.ui.last_focus = g.ui.focus;
      g.ui.focus      = (uintptr_t)&g.grid.front[g.grid.focus_y][g.grid.focus_x];
   }

   for (int row = 0; row < GRID_ROWS; ++row)
   {
      for (int col = 0; col < GRID_COLS; ++col)
      {
         bool left_down = false;
         if (ui_grid_cell(g.grid.front, row, col, &left_down))
         {
            cell_state_t *cell = &g.grid.front[row][col];

            if (left_down)
            {
               if (*cell == CELL_CLEAR)
               {
                  *cell = CELL_SET;

                  if (g.grid.back[row][col] != CELL_SET)
                  {
                     *cell = CELL_WRONG;
                  }
               }
            }
            else
               switch (*cell)
               {
                  case CELL_CLEAR: *cell = CELL_DISABLED; break;
                  case CELL_SET:
                  case CELL_DISABLED: *cell = CELL_CLEAR; break;
                  default: break;
               }
         }
      }
   }

   render_labels();

   draw_str(&font16, SCREEN_WIDTH/2, SCREEN_HEIGHT-26, XORIG_CENTER, ~0, "Press START or click here for menu.");

   static uint8_t blinker = 0;
   draw_square(g.mouse.x, g.mouse.y, 4, rgb565(blinker, blinker, blinker));
   blinker += 20;
}


RETRO_API void retro_run(void)
{
   if (g.first_run)
   {
      g.first_run = false;
   }

   poll_cb();

   int delta_x, delta_y;

   delta_x = read_mouse(RETRO_DEVICE_ID_MOUSE_X);
   delta_y = read_mouse(RETRO_DEVICE_ID_MOUSE_Y);

   g.mouse.moved = delta_x || delta_y;
   g.mouse.x    += g.mouse.moved ? delta_x : 0;
   g.mouse.y    += g.mouse.moved ? delta_y : 0;

   g.mouse.left  = read_mouse(RETRO_DEVICE_ID_MOUSE_LEFT);
   g.mouse.right = read_mouse(RETRO_DEVICE_ID_MOUSE_RIGHT);

   delta_x = read_joypad(RETRO_DEVICE_ID_JOYPAD_RIGHT) - read_joypad(RETRO_DEVICE_ID_JOYPAD_LEFT);
   delta_y = read_joypad(RETRO_DEVICE_ID_JOYPAD_DOWN)  - read_joypad(RETRO_DEVICE_ID_JOYPAD_UP);

   g.joy.moved = (delta_x != g.joy.x) || (delta_y != g.joy.y);

   if (g.joy.moved)
   {
      g.joy.x = delta_x;
      g.joy.y = delta_y;
   }

   g.joy.a = read_joypad(RETRO_DEVICE_ID_JOYPAD_A)
         ||  read_joypad(RETRO_DEVICE_ID_JOYPAD_Y);

   g.joy.b = read_joypad(RETRO_DEVICE_ID_JOYPAD_B)
         ||  read_joypad(RETRO_DEVICE_ID_JOYPAD_X);

   clip_pos(&g.mouse.x, &g.mouse.y);

   ui_begin();

   game_step();

   ui_end();

   g.mouse.prev_left  = g.mouse.left;
   g.mouse.prev_right = g.mouse.right;

   video_cb(g.fb, SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_PITCH);
}

static void load_challenge(const char *chal)
{
   if (strlen(chal) != GRID_COLS * GRID_ROWS)
      abort();

   memset(g.row_counts, 0, sizeof(g.row_counts));
   memset(g.col_counts, 0, sizeof(g.col_counts));

   for (int row = 0; row < GRID_ROWS; ++row)
      for (int col = 0; col < GRID_COLS; ++col)
         g.grid.back[row][col] = chal[row*GRID_COLS+col] != ' ' ? CELL_SET : CELL_CLEAR;


   for (int row = 0; row < GRID_ROWS; ++row)
   {
      bool was_set = false;
      int index = 0;
      for (int col = 0; col < GRID_COLS; ++col)
      {
         bool set = g.grid.back[row][col] == CELL_SET;

         if (set != was_set)
         {
            was_set = set;
            ++index;
         }

         if (set)
            ++g.row_counts[row][index];
      }
   }

   for (int col = 0; col < GRID_COLS; ++col)
   {
      bool was_set = false;
      int index = 0;
      for (int row = 0; row < GRID_ROWS; ++row)
      {
         bool set = g.grid.back[row][col] == CELL_SET;

         if (set != was_set)
         {
            was_set = set;
            ++index;
         }

         if (set)
            ++g.col_counts[col][index];
      }
   }
}

RETRO_API void retro_init(void)
{
   memset(&g, 0, sizeof(g));
   g.first_run = true;

   const char *chal =
         "                  "
         "  ##     #        "
         "  ##      #       "
         "       #   #      "
         "      # #  #      "
         "           #      "
         "  ##      #       "
         "  ##     #        "
         "                  ";

   load_challenge(chal);
}

RETRO_API void retro_deinit(void) { }


RETRO_API void retro_reset(void)
{

}

RETRO_API bool retro_load_game(const struct retro_game_info *game)
{
   uint_env(RETRO_ENVIRONMENT_SET_PIXEL_FORMAT, RETRO_PIXEL_FORMAT_RGB565);
   return true;
}

RETRO_API void retro_unload_game(void)
{

}

RETRO_API void retro_set_controller_port_device(unsigned port, unsigned device)
{

}

RETRO_API void retro_get_system_info(struct retro_system_info *info)
{
   info->library_name     = "cruzes";
   info->library_version  = "0.1";
   info->need_fullpath    = false;
   info->valid_extensions = "";
}

RETRO_API void retro_get_system_av_info(struct retro_system_av_info *info)
{
   info->geometry.base_width  = SCREEN_WIDTH;
   info->geometry.base_height = SCREEN_HEIGHT;
   info->geometry.aspect_ratio = (double)info->geometry.base_width / info->geometry.base_height;
   info->geometry.max_width = info->geometry.max_height = MAX(SCREEN_WIDTH, SCREEN_HEIGHT);
   info->timing.fps         = 60;
   info->timing.sample_rate = 0.0;
}

RETRO_API unsigned retro_api_version(void) { return RETRO_API_VERSION; }

RETRO_API void retro_set_video_refresh(retro_video_refresh_t p) { video_cb = p; }
RETRO_API void retro_set_audio_sample(retro_audio_sample_t p) { }
RETRO_API void retro_set_audio_sample_batch(retro_audio_sample_batch_t p) { }
RETRO_API void retro_set_input_poll(retro_input_poll_t p) { poll_cb = p; }
RETRO_API void retro_set_input_state(retro_input_state_t p) { input_cb = p; }
RETRO_API void retro_set_environment(retro_environment_t p)
{
   env_cb = p;
   bool_env(RETRO_ENVIRONMENT_SET_SUPPORT_NO_GAME, true);
}

RETRO_API bool retro_load_game_special(unsigned game_type, const struct retro_game_info *info, size_t num_info)
{
   return false;
}

RETRO_API unsigned retro_get_region(void) { return RETRO_REGION_NTSC; }
RETRO_API size_t retro_serialize_size(void) { return 0; }
RETRO_API bool retro_serialize(void *data, size_t size) { return false; }
RETRO_API bool retro_unserialize(const void *data, size_t size) { return false; }
RETRO_API void retro_cheat_reset(void) { }
RETRO_API void retro_cheat_set(unsigned index, bool enabled, const char *code) { }
RETRO_API void *retro_get_memory_data(unsigned id) { return NULL; }
RETRO_API size_t retro_get_memory_size(unsigned id) { return 0; }