//
// Created by Keuin on 2022/4/11.
//

#ifndef RT_BITMAP_H
#define RT_BITMAP_H

#include <vector>
#include <cstdint>
#include <ostream>
#include <cassert>

#define COLORMIX_OVERFLOW_CHECK

//// T is some unsigned integer
//template<typename T>
//T saturate_add(T a, T b) {
//    T c = a + b;
//    if (a > c || b > c) {
//        c = (1ULL << (sizeof(T) * 8U)) - 1ULL;
//    }
//    return c;
//}

// T is some unsigned integer, do not use float point types!
template<typename T>
struct pixel {
    T r, g, b;

    /**
     * Create a pixel with given depth, from normalized color values.
     * For example: for 8bit pixel, with (1, 0.5, 0.25), we get: (255, 127, 63).
     */
    static inline pixel<T> from_normalized(double r, double g, double b) {
        const auto mod = (1ULL << (sizeof(T) * 8U)) - 1ULL;
        return pixel<T>{.r = (T) (mod * r), .g = (T) (mod * g), .b = (T) (mod * b)};
    }

    // v3d must be a normalized vector
    static inline pixel<T> from_normalized(const vec3d &v3d) {
        return from_normalized(v3d.x / 2.0 + 0.5, v3d.y / 2.0 + 0.5, v3d.z / 2.0 + 0.5);
    }
};

// Mix two colors a and b. Returns a*u + b*v
template<typename T>
inline pixel<T> mix(const pixel<T> &a, const pixel<T> &b, double u, double v) {
    assert(u >= 0);
    assert(v >= 0);
    assert(u <= 1);
    assert(v <= 1);
    assert(u + v <= 1);
    pixel<T> c{0, 0, 0};
    c.r = (T) (u * a.r + v * b.r);
    c.g = (T) (u * a.g + v * b.g);
    c.b = (T) (u * a.b + v * b.b);
    return c;
}

// 8 bit pixel
using pixel8b = pixel<uint8_t>;

template<typename T>
class bitmap {
    const unsigned width, height;
    std::vector<pixel<T>> content; // pixels scanned by rows, from top to bottom

    pixel<T> &image(unsigned x, unsigned y) {
        assert(x < width);
        assert(y < height);
        return content[x + y * width];
    }

    pixel<T> &image(unsigned x, unsigned y) const {
        assert(x < width);
        assert(y < height);
        return content[x + y * width];
    }

public:
    bitmap() = delete;

    bitmap(unsigned int width, unsigned int height) : width(width), height(height) {
        content.resize(width * height, pixel<T>{});
    }

    void set(unsigned x, unsigned y, const pixel<T> &pixel) {
        image(x, y) = pixel;
    }

    pixel<T> get(unsigned x, unsigned y) const {
        return image(x, y);
    }

    // Do not use float-point pixels, or this routine will break.
    void write_plain_ppm(std::ostream &out) const;
};

template<typename T>
void bitmap<T>::write_plain_ppm(std::ostream &out) const {
    const auto depth = (1ULL << (sizeof(T) * 8)) - 1ULL; // color depth of pixels
    out << "P3\n" // file header
        << width << ' ' << height << '\n' // image width and height
        << depth << '\n'; // normalized max color depth (e.g. 255 for 8bit image)

    for (const auto &pixel: content) {
        out << (unsigned long long) pixel.r << ' '
            << (unsigned long long) pixel.g << ' '
            << (unsigned long long) pixel.b << '\n';
    }
}

using bitmap8b = bitmap<uint8_t>;


#endif //RT_BITMAP_H