#include "pattern.h"

#include <limits.h>
#include <stddef.h>

static const cell_offset_t glider_cells[] = {
    {1,0},{2,1},{0,2},{1,2},{2,2}
};
static const cell_offset_t blinker_cells[] = {
    {0,0},{1,0},{2,0}
};
static const cell_offset_t block_cells[] = {
    {0,0},{1,0},{0,1},{1,1}
};
static const cell_offset_t toad_cells[] = {
    {1,0},{2,0},{3,0},{0,1},{1,1},{2,1}
};

static const pattern_t patterns[] = {
    {"glider", 5, glider_cells},
    {"blinker", 3, blinker_cells},
    {"block", 4, block_cells},
    {"toad", 6, toad_cells},
};

int pattern_count(void) { return 4; }

const pattern_t *pattern_get(int index) {
    if (index < 0 || index >= pattern_count()) return NULL;
    return &patterns[index];
}

int pattern_rotated_offsets(int index, int rotation, int *out_dx, int *out_dy) {
    const pattern_t *p = pattern_get(index);
    if (!p) return 0;
    rotation = ((rotation % 4) + 4) % 4;
    int minx = INT_MAX, miny = INT_MAX;
    int tx[16], ty[16];
    for (int i = 0; i < p->count; i++) {
        int x = p->cells[i].dx;
        int y = p->cells[i].dy;
        for (int r = 0; r < rotation; r++) {
            int nx = y;
            int ny = -x;
            x = nx; y = ny;
        }
        tx[i] = x; ty[i] = y;
        if (x < minx) minx = x;
        if (y < miny) miny = y;
    }
    for (int i = 0; i < p->count; i++) {
        out_dx[i] = tx[i] - minx;
        out_dy[i] = ty[i] - miny;
    }
    return p->count;
}

void pattern_bounds(int index, int rotation, int *w, int *h) {
    int dx[16], dy[16];
    int n = pattern_rotated_offsets(index, rotation, dx, dy);
    int maxx = 0, maxy = 0;
    for (int i = 0; i < n; i++) {
        if (dx[i] > maxx) maxx = dx[i];
        if (dy[i] > maxy) maxy = dy[i];
    }
    if (w) *w = maxx + 1;
    if (h) *h = maxy + 1;
}