/* Copyright (C) 2018  June McEnroe <june@causal.agency>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <complex.h>
#include <err.h>
#include <math.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <sysexits.h>

#include "gfx/gfx.h"

static double absSq(double complex z) {
    return creal(z) * creal(z) + cimag(z) * cimag(z);
}

static uint32_t depth = 50;

static uint32_t mandelbrot(double complex c) {
    double complex z = 0;
    for (uint32_t i = 0; i < depth; ++i) {
        if (absSq(z) > 4.0) return i;
        z = z * z + c;
    }
    return 0;
}

static uint32_t color(uint32_t n) {
    uint32_t gray = (double)n / (double)depth * 255.0;
    return gray << 16 | gray << 8 | gray;
}

static double complex translate = -0.75;
static double complex rotate = 1.0;
static double scale = 2.5;

void draw(uint32_t *buf, size_t width, size_t height) {
    double yRatio = (height > width) ? (double)height / (double)width : 1.0;
    double xRatio = (width > height) ? (double)width / (double)height : 1.0;
    for (size_t y = 0; y < height; ++y) {
        for (size_t x = 0; x < width; ++x) {
            double zx = ((double)x / (double)width - 0.5) * xRatio;
            double zy = ((double)y / (double)height - 0.5) * yRatio;
            uint32_t n = mandelbrot((zx + zy * I) * scale * rotate + translate);
            buf[y * width + x] = color(n);
        }
    }
}

static uint32_t depthDelta = 1;
static double translateDelta = 0.01;
static double rotateDelta = 0.01;
static double scaleFactor = 1.1;

bool input(char in) {
    const double PI = acos(-1.0);
    switch (in) {
        case 'q': return false;
        case '.': depth += depthDelta; break;
        case ',': if (depth > depthDelta) depth -= depthDelta; break;
        case 'l': translate += translateDelta * scale * rotate; break;
        case 'h': translate -= translateDelta * scale * rotate; break;
        case 'j': translate += translateDelta * I * scale * rotate; break;
        case 'k': translate -= translateDelta * I * scale * rotate; break;
        case 'u': rotate *= cexp(rotateDelta * PI * I); break;
        case 'i': rotate /= cexp(rotateDelta * PI * I); break;
        case '+': scale /= scaleFactor; break;
        case '-': scale *= scaleFactor; break;
    }
    return true;
}

const char *status(void) {
    static char buf[256];
    snprintf(
        buf, sizeof(buf),
        "-d %u -t %g+%gi -r %g+%gi -z %g",
        depth,
        creal(translate), cimag(translate),
        creal(rotate), cimag(rotate),
        scale
    );
    return buf;
}

int init(int argc, char *argv[]) {
    (void)argc;
    (void)argv;
    return EX_OK;
}