#pragma once

// Optional OpenCV integration (link alvin::vision).

#include <filesystem>
#include <optional>
#include <vector>

#include <opencv2/core.hpp>

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

namespace alvin::vision {

// Zero-copy CV_8UC4 (BGRA) view. The Frame must outlive the Mat.
cv::Mat view(const Frame& frame);
// Deep copy converted to CV_8UC3 (BGR), the layout most OpenCV code expects.
cv::Mat toBgr(const Frame& frame);

Result<Frame> fromMat(const cv::Mat& mat);
Result<cv::Mat> loadImage(const std::filesystem::path& path);  // BGR
Status saveImage(const Frame& frame, const std::filesystem::path& path);  // png/jpg/...

struct Match {
    Rect rect;          // in frame pixels
    double score = 0;   // 0..1, higher is better
};

struct MatchOptions {
    double threshold = 0.9;
    bool grayscale = false;  // faster, ignores colour differences
    int maxResults = 16;     // findAll only
};

// Normalised cross-correlation template matching.
Result<std::optional<Match>> find(const Frame& haystack, const cv::Mat& needle, const MatchOptions& opts = {});
Result<std::vector<Match>> findAll(const Frame& haystack, const cv::Mat& needle, const MatchOptions& opts = {});

}  // namespace alvin::vision