/**
 * Copyright (c) 2025 Dominic Masters
 * 
 * This software is released under the MIT License.
 * https://opensource.org/licenses/MIT
 */

#include "display/render.h"
#include "assert/assert.h"
#include "util/memory.h"

uint8_t RENDER_BACKGROUND_X = 0;
uint8_t RENDER_BACKGROUND_Y = 0;
uint8_t RENDER_STATUS = 0;
bool_t RENDER_DISPLAY_ON = false;
uint8_t RENDER_TILES[RENDER_TILE_COUNT] = { 0 };
uint8_t RENDER_BACKGROUND_TILEMAP[RENDER_BACKGROUND_TILE_COUNT] = { 0 };
Color RENDER_PALETTE[RENDER_PALETTE_COLOR_COUNT] = {
  { 102, 191, 47, 255 },
  { 78, 146, 35, 255 },
  { 48, 89, 22, 255 },
  { 18, 33, 8, 255 }
};

RenderTexture2D RENDER_BACKBUFFER;
RenderTexture2D RENDER_TILES_TEXTURE;

void renderInit(void) {
  InitWindow(RENDER_WIDTH_PIXELS * 4, RENDER_HEIGHT_PIXELS * 4, "Dusk");
  SetTargetFPS(60);
  SetWindowState(
    FLAG_WINDOW_RESIZABLE |
    FLAG_WINDOW_HIGHDPI |
    FLAG_VSYNC_HINT
  );

  // Create back buffer for rendering.
  RENDER_BACKBUFFER = LoadRenderTexture(
    RENDER_WIDTH_PIXELS,
    RENDER_HEIGHT_PIXELS
  );

  // Create texture to hold the tile data.
  RENDER_TILES_TEXTURE = LoadRenderTexture(
    RENDER_TILE_COUNT * RENDER_TILE_WIDTH,
    RENDER_TILE_HEIGHT
  );
}

void renderVsync() {
  int32_t x, y, i;
  BeginDrawing();

  if(RENDER_DISPLAY_ON) {
    // Update the texture with the new tile data
    BeginTextureMode(RENDER_TILES_TEXTURE);
    i = 0;
    for(i = 0; i < RENDER_TILE_COUNT; i++) {
      uint8_t *tile = RENDER_TILES + (i * RENDER_TILE_BYTES_PER_TILE);

      // For each pixel in the tile...
      for(y = 0; y < RENDER_TILE_HEIGHT; y++) {
        uint8_t low = tile[y * RENDER_TILE_BYTES_PER_ROW];
        uint8_t high = tile[y * RENDER_TILE_BYTES_PER_ROW + 1];

        for(x = 0; x < RENDER_TILE_WIDTH; x++) {
          uint8_t loBit = (low >> (7 - x)) & 1;
          uint8_t hiBit = (high >> (7 - x)) & 1;
          uint8_t paletteIndex = (hiBit << 1) | loBit;

          // Draw the pixel to the texture
          DrawPixel(
            (i * RENDER_TILE_WIDTH) + x,
            y,
            RENDER_PALETTE[paletteIndex]
          );
        }
      }
    }
    EndTextureMode();

    // Clear the back buffer
    BeginTextureMode(RENDER_BACKBUFFER);
    ClearBackground(RENDER_PALETTE[0]);

    // Render background tiles
    i = 0;
    for(y = 0; y < RENDER_BACKGROUND_ROWS; y++) {
      for(x = 0; x < RENDER_BACKGROUND_COLUMNS; x++) {
        // Get the tile index from the tilemap
        uint8_t tileIndex = RENDER_BACKGROUND_TILEMAP[i++];

        DrawTexturePro(
          RENDER_TILES_TEXTURE.texture,
          (Rectangle){
            .x = ((int32_t)tileIndex) * RENDER_TILE_WIDTH,
            .y = 0,
            .width = RENDER_TILE_WIDTH,
            .height = -RENDER_TILE_HEIGHT
          },
          (Rectangle){
            ((int32_t)x * RENDER_TILE_WIDTH) - RENDER_BACKGROUND_X,
            ((int32_t)y * RENDER_TILE_HEIGHT) - RENDER_BACKGROUND_Y,
            RENDER_TILE_WIDTH,
            RENDER_TILE_HEIGHT
          },
          (Vector2){ 0, 0 },
          0.0f,
          WHITE
        );
      }
    }
    
    // Render the back buffer to the screen
    EndTextureMode();
    ClearBackground(WHITE);
    
    // Keep aspect and center the render
    int32_t renderWidth, renderHeight, renderX, renderY;
    const int32_t width = GetScreenWidth();
    const int32_t height = GetScreenHeight();
    if (RENDER_WIDTH_PIXELS * height > RENDER_HEIGHT_PIXELS * width) {
      renderWidth = width;
      renderHeight = (RENDER_HEIGHT_PIXELS * width) / RENDER_WIDTH_PIXELS;
      renderX = 0;
      renderY = (height - renderHeight) / 2;
    } else {
      renderWidth = (RENDER_WIDTH_PIXELS * height) / RENDER_HEIGHT_PIXELS;
      renderHeight = height;
      renderX = (width - renderWidth) / 2;
      renderY = 0;
    }
    DrawTexturePro(
      RENDER_BACKBUFFER.texture,
      (Rectangle) { 0, 0, RENDER_WIDTH_PIXELS, -RENDER_HEIGHT_PIXELS },
      (Rectangle) { renderX, renderY, renderWidth, renderHeight },
      (Vector2) { 0, 0 },
      0.0f,
      WHITE
    );
  }

  EndDrawing();
  if(WindowShouldClose()) RENDER_STATUS |= RENDER_SHOULD_EXIT;
}

void renderDispose() {
  UnloadRenderTexture(RENDER_TILES_TEXTURE);
  CloseWindow();
}

void renderDisplayOn(void) {
  RENDER_DISPLAY_ON = true;
}

void renderDisplayOff(void) {
  RENDER_DISPLAY_ON = false;
}

void renderTilesBuffer(
  const uint8_t index,
  const uint8_t count,
  const uint8_t *tiles
) {
  assertTrue(count > 0, "Count must be greater than zero");
  assertNotNull(tiles, "Tiles pointer must not be null");

  // Copy data to fake vram
  memoryCopy(
    &RENDER_TILES[index * RENDER_TILE_BYTES_PER_TILE],
    tiles,
    count  * RENDER_TILE_BYTES_PER_TILE
  );
}

void renderBackgroundTilesBufferRectangle(
  const uint8_t xPos,
  const uint8_t yPos,
  const uint8_t width,
  const uint8_t height,
  const uint8_t *tiles
) {
  uint8_t w = width, h = height, x = xPos, y = yPos;
  assertNotNull(tiles, "Tiles pointer must not be null");

  // Clamp x and y to tilemap bounds
  if (x >= RENDER_BACKGROUND_COLUMNS) x = RENDER_BACKGROUND_COLUMNS - 1;
  if (y >= RENDER_BACKGROUND_ROWS) y = RENDER_BACKGROUND_ROWS - 1;

  // Clamp width and height so we don't overflow past edges
  if (x + w > RENDER_BACKGROUND_COLUMNS) {
    w = RENDER_BACKGROUND_COLUMNS - x;
  }
  if (y + h > RENDER_BACKGROUND_ROWS) {
    h = RENDER_BACKGROUND_ROWS - y;
  }

  if (w == 0 || h == 0) return;

  for (uint8_t row = 0; row < h; row++) {
    memoryCopy(
      &RENDER_BACKGROUND_TILEMAP[(y + row) * RENDER_BACKGROUND_COLUMNS + x],
      &tiles[row * width],
      w
    );
  }
}