#pragma once

#include <cstddef>
#include <cstdint>
#include <filesystem>
#include <span>
#include <vector>

#include "alvin/error.hpp"
#include "alvin/types.hpp"

namespace alvin {

// Byte order in memory. Every capture backend normalises to BGRA8, which is
// what OpenCV (CV_8UC4) and Win32 DIBs use natively.
enum class PixelFormat : std::uint8_t {
    BGRA8,
};

struct Color {
    std::uint8_t r = 0, g = 0, b = 0, a = 255;
    friend bool operator==(const Color&, const Color&) = default;
};

class Frame {
public:
    Frame() = default;
    Frame(int width, int height);  // zero-filled BGRA8

    int width() const { return width_; }
    int height() const { return height_; }
    Size size() const { return {width_, height_}; }
    std::size_t stride() const { return static_cast<std::size_t>(width_) * 4; }
    PixelFormat format() const { return PixelFormat::BGRA8; }
    bool empty() const { return data_.empty(); }

    std::uint8_t* data() { return data_.data(); }
    const std::uint8_t* data() const { return data_.data(); }
    std::span<const std::uint8_t> bytes() const { return data_; }
    std::uint8_t* row(int y) { return data_.data() + y * stride(); }
    const std::uint8_t* row(int y) const { return data_.data() + y * stride(); }

    Color pixel(int x, int y) const;

    // Where this frame sits on the desktop, in logical pixels. Frames from a
    // HiDPI monitor have more pixels than their logical size; use
    // toDesktop()/fromDesktop() to convert instead of assuming 1:1.
    Rect desktopRect() const { return desktopRect_; }
    void setDesktopRect(Rect r) { desktopRect_ = r; }
    Point toDesktop(Point framePixel) const;
    Point fromDesktop(Point desktopPoint) const;

    std::int64_t timestampNs() const { return timestampNs_; }
    void setTimestampNs(std::int64_t t) { timestampNs_ = t; }

    Frame crop(Rect r) const;  // r in frame pixels; clipped to bounds

    // Binary PPM (P6), dependency-free. Alpha is dropped.
    Status savePpm(const std::filesystem::path& path) const;

private:
    int width_ = 0;
    int height_ = 0;
    std::vector<std::uint8_t> data_;
    Rect desktopRect_;
    std::int64_t timestampNs_ = 0;
};

}  // namespace alvin