//
// Created by bruno on 1.6.2025.
//

#include "atlas.h"
#include "util.h"

SDL_Texture *atlasTexture;

int atlasX = 0, atlasY = 0;

int tileIndex = 0;        // Which 32x32 tile we're on
int quadrantIndex = 0;    // Which 16x16 slot inside that tile



SDL_Rect allocate_16x16(SDL_Texture *srcTexture, SDL_Renderer *renderer) {
    SDL_Texture * oldTarget = SDL_GetRenderTarget(renderer);
    SDL_SetRenderTarget(renderer, atlasTexture);
    int tileX = tileIndex % ATLAS_TILES_PER_ROW;
    int tileY = tileIndex / ATLAS_TILES_PER_ROW;

    int dx = (quadrantIndex % 2) * QUADRANT_SIZE;
    int dy = (quadrantIndex / 2) * QUADRANT_SIZE;

    SDL_Rect destRect = {
            tileX * TILE_SIZE + dx,
            tileY * TILE_SIZE + dy,
            QUADRANT_SIZE,
            QUADRANT_SIZE
    };
    SDL_RenderCopy(renderer, srcTexture, NULL, &destRect);

    quadrantIndex++;
    if (quadrantIndex >= 4) {
        tileIndex++;
        quadrantIndex = 0;
    }
    SDL_SetRenderTarget(renderer, oldTarget);
    return destRect;
}

SDL_Rect allocate_32x32(SDL_Texture *srcTexture, SDL_Renderer *renderer) {
    SDL_Texture * oldTarget = SDL_GetRenderTarget(renderer);
    SDL_SetRenderTarget(renderer, atlasTexture);
    // If we’re not at the start of a tile, skip to the next clean one
    if (quadrantIndex != 0) {
        tileIndex++;
        quadrantIndex = 0;
    }

    int tileX = tileIndex % ATLAS_TILES_PER_ROW;
    int tileY = tileIndex / ATLAS_TILES_PER_ROW;

    SDL_Rect destRect = {
            tileX * TILE_SIZE,
            tileY * TILE_SIZE,
            TILE_SIZE,
            TILE_SIZE
    };
    SDL_RenderCopy(renderer, srcTexture, NULL, &destRect);

    tileIndex++; // Move to next tile
    // quadrantIndex stays 0 — new tile is fresh
    SDL_SetRenderTarget(renderer, oldTarget);
    return destRect;
}

void initAtlas(SDL_Renderer *renderer) {

// Clear atlas with transparent
    SDL_SetRenderTarget(renderer, atlasTexture);
    SDL_SetRenderDrawColor(renderer, 0, 0, 0, 0);
    SDL_RenderClear(renderer);


    atlasTexture = SDL_CreateTexture(renderer,
                                     SDL_PIXELFORMAT_RGBA8888, SDL_TEXTUREACCESS_TARGET,
                                     ATLAS_SIZE, ATLAS_SIZE);
}