// Unit tests for the geometric/numeric helpers in types.hpp and face_utils.hpp:
// cosine_similarity and the ArcFace 5-point alignment transform. GPU-free,
// model-free.
#include <catch2/catch_test_macros.hpp>
#include <catch2/matchers/catch_matchers_floating_point.hpp>

#include "face_utils.hpp"
#include "types.hpp"

#include <array>
#include <cmath>

using Catch::Matchers::WithinAbs;

TEST_CASE("cosine_similarity of a unit vector with itself is 1", "[types]") {
    std::array<float, 512> raw{};
    raw[3] = 2.f; raw[7] = -1.f;
    Embedding e = l2_normalise(raw.data());
    CHECK_THAT(cosine_similarity(e, e), WithinAbs(1.0f, 1e-6f));
}

TEST_CASE("cosine_similarity of orthogonal vectors is 0", "[types]") {
    Embedding a{}, b{};
    a[0] = 1.f;
    b[1] = 1.f;
    CHECK_THAT(cosine_similarity(a, b), WithinAbs(0.0f, 1e-6f));
}

TEST_CASE("cosine_similarity of opposite vectors is -1", "[types]") {
    Embedding a{}, b{};
    a[5] = 1.f;
    b[5] = -1.f;
    CHECK_THAT(cosine_similarity(a, b), WithinAbs(-1.0f, 1e-6f));
}

TEST_CASE("align_face maps the reference landmarks onto the 112x112 canvas", "[face_utils]") {
    // Build a synthetic image where the five landmarks sit at known positions.
    // Feeding align_face the *reference* positions themselves should yield an
    // (near-)identity similarity transform, so the output is 112x112.
    cv::Mat img(200, 200, CV_8UC3, cv::Scalar(0, 0, 0));
    std::array<cv::Point2f, 5> lm;
    for (int i = 0; i < 5; ++i) {
        lm[i] = {kArcFaceRef[i][0], kArcFaceRef[i][1]};
        cv::circle(img, lm[i], 2, cv::Scalar(255, 255, 255), -1);
    }

    cv::Mat crop = align_face(img, lm);
    REQUIRE_FALSE(crop.empty());
    CHECK(crop.cols == 112);
    CHECK(crop.rows == 112);
}

TEST_CASE("align_face is translation-equivariant", "[face_utils]") {
    // Shifting all landmarks by a constant offset must still produce a valid
    // 112x112 crop (the similarity transform absorbs the translation).
    cv::Mat img(300, 300, CV_8UC3, cv::Scalar(30, 30, 30));
    std::array<cv::Point2f, 5> lm;
    const float dx = 100.f, dy = 80.f;
    for (int i = 0; i < 5; ++i)
        lm[i] = {kArcFaceRef[i][0] + dx, kArcFaceRef[i][1] + dy};

    cv::Mat crop = align_face(img, lm);
    REQUIRE_FALSE(crop.empty());
    CHECK(crop.cols == 112);
    CHECK(crop.rows == 112);
}

TEST_CASE("align_face returns empty on degenerate (collinear) landmarks", "[face_utils]") {
    // All five landmarks identical → the affine fit is degenerate.
    cv::Mat img(200, 200, CV_8UC3, cv::Scalar(0, 0, 0));
    std::array<cv::Point2f, 5> lm;
    for (auto& p : lm) p = {50.f, 50.f};

    cv::Mat crop = align_face(img, lm);
    CHECK(crop.empty());
}