#include <stdlib.h>
#include <time.h>
#include <string.h>
#include "world.h"

#define EMPTY ' '
#define BLOCK '#'
#define WIDTH 10
#define HEIGHT 20

typedef struct {
    int x, y;
} Point;

typedef struct {
    Point blocks[4];
    Point position;
} Tetromino;

typedef struct {
    char grid[HEIGHT][WIDTH];
    Tetromino current;
} GameState;

Tetromino tetrominoes[] = {
    {{{0,0}, {1,0}, {0,1}, {1,1}}, {0,0}}, // Square
    {{{0,0}, {1,0}, {2,0}, {3,0}}, {0,0}}, // Line
    {{{0,0}, {1,0}, {1,1}, {2,1}}, {0,0}}, // Z shape
    {{{1,0}, {2,0}, {0,1}, {1,1}}, {0,0}}, // S shape
    {{{0,0}, {1,0}, {2,0}, {1,1}}, {0,0}}, // T shape
    {{{0,0}, {0,1}, {1,1}, {2,1}}, {0,0}}, // L shape
    {{{2,0}, {0,1}, {1,1}, {2,1}}, {0,0}}  // J shape
};

void draw_grid(GameState* game) {
    clear_world();
    for (int y = 0; y < HEIGHT; ++y) {
        for (int x = 0; x < WIDTH; ++x) {
            draw_character(game->grid[y][x], x, y);
        }
    }
    for (int i = 0; i < 4; ++i) {
        draw_character(BLOCK, game->current.position.x + game->current.blocks[i].x,
                               game->current.position.y + game->current.blocks[i].y);
    }
    refresh_world();
}

int is_valid_position(GameState* game, Point new_position) {
    for (int i = 0; i < 4; ++i) {
        int new_x = new_position.x + game->current.blocks[i].x;
        int new_y = new_position.y + game->current.blocks[i].y;
        if (new_x < 0 || new_x >= WIDTH || new_y < 0 || new_y >= HEIGHT || game->grid[new_y][new_x] != EMPTY) {
            return 0;
        }
    }
    return 1;
}

void place_tetromino(GameState* game) {
    for (int i = 0; i < 4; ++i) {
        int x = game->current.position.x + game->current.blocks[i].x;
        int y = game->current.position.y + game->current.blocks[i].y;
        game->grid[y][x] = BLOCK;
    }
}

void clear_lines(GameState* game) {
    for (int y = HEIGHT - 1; y >= 0; --y) {
        int full = 1;
        for (int x = 0; x < WIDTH; ++x) {
            if (game->grid[y][x] == EMPTY) {
                full = 0;
                break;
            }
        }
        if (full) {
            for (int row = y; row > 0; --row) {
                memcpy(game->grid[row], game->grid[row - 1], WIDTH);
            }
            memset(game->grid[0], EMPTY, WIDTH);
            y++;
        }
    }
}

void* init_game() {
    srand(time(NULL));
    GameState* game = malloc(sizeof(GameState));
    memset(game->grid, EMPTY, sizeof(game->grid));
    game->current = tetrominoes[rand() % 7];
    game->current.position.x = WIDTH / 2 - 1;
    game->current.position.y = 0;
    return game;
}

int game_event(struct event* event, void* state) {
    GameState* game = (GameState*)state;
    Point new_position = game->current.position;

    if (event->key) {
        switch (event->key) {
            case 'a': new_position.x -= 1; break;
            case 'd': new_position.x += 1; break;
            case 's': new_position.y += 1; break;
            case 'w': // TODO: Implement rotation
                      break;
            case 27: return 1; // Escape key
        }
        if (is_valid_position(game, new_position)) {
            game->current.position = new_position;
        }
    }

    new_position.y += 1;
    if (!is_valid_position(game, new_position)) {
        place_tetromino(game);
        clear_lines(game);
        game->current = tetrominoes[rand() % 7];
        game->current.position.x = WIDTH / 2 - 1;
        game->current.position.y = 0;
        if (!is_valid_position(game, game->current.position)) {
            return 1; // Game over
        }
    } else {
        game->current.position = new_position;
    }

    draw_grid(game);
    return 0;
}