#include "animation/AnimationSampling.h"

#include <algorithm>

namespace core {

namespace {

template <typename KeyT, typename FrameGetter>
void sortKeysByFrame(QVector<KeyT>& keys, FrameGetter getFrame) {
    std::sort(keys.begin(), keys.end(), [&](const KeyT& a, const KeyT& b) { return getFrame(a) < getFrame(b); });
}

}  // namespace

QPointF sampleLocation(const QVector<Project::Entity::KeyframeVec2>& keys,
                       int frame,
                       const QPointF& fallbackOrigin,
                       KeyInterpolation mode) {
    QVector<Project::Entity::KeyframeVec2> sorted = keys;
    sortKeysByFrame(sorted, [](const Project::Entity::KeyframeVec2& k) { return k.frame; });

    if (sorted.isEmpty()) {
        return fallbackOrigin;
    }

    if (mode == KeyInterpolation::Hold) {
        QPointF out = fallbackOrigin;
        int best = -1;
        for (const auto& k : sorted) {
            if (k.frame <= frame && k.frame >= best) {
                best = k.frame;
                out = k.value;
            }
        }
        return out;
    }

    // Linear：区间外夹持到端点；中间在相邻关键帧间线性插值（对 x、y 分别 lerp）
    const auto& first = sorted.front();
    const auto& last = sorted.back();
    if (frame <= first.frame) {
        return first.value;
    }
    if (frame >= last.frame) {
        return last.value;
    }

    for (int i = 0; i + 1 < sorted.size(); ++i) {
        const int f0 = sorted[i].frame;
        const int f1 = sorted[i + 1].frame;
        if (frame < f0) {
            continue;
        }
        if (frame <= f1) {
            if (f1 == f0 || frame == f0) {
                return sorted[i].value;
            }
            const double t = static_cast<double>(frame - f0) / static_cast<double>(f1 - f0);
            const QPointF& a = sorted[i].value;
            const QPointF& b = sorted[i + 1].value;
            return QPointF(a.x() + (b.x() - a.x()) * t, a.y() + (b.y() - a.y()) * t);
        }
    }
    return last.value;
}

double sampleDepthScale01(const QVector<Project::Entity::KeyframeFloat01>& keys,
                          int frame,
                          double fallback01,
                          KeyInterpolation mode) {
    QVector<Project::Entity::KeyframeFloat01> sorted = keys;
    sortKeysByFrame(sorted, [](const Project::Entity::KeyframeFloat01& k) { return k.frame; });

    const double fb = std::clamp(fallback01, 0.0, 1.0);

    if (sorted.isEmpty()) {
        return fb;
    }

    if (mode == KeyInterpolation::Hold) {
        double out = fb;
        int best = -1;
        for (const auto& k : sorted) {
            if (k.frame <= frame && k.frame >= best) {
                best = k.frame;
                out = k.value;
            }
        }
        return std::clamp(out, 0.0, 1.0);
    }

    const auto& first = sorted.front();
    const auto& last = sorted.back();
    if (frame <= first.frame) {
        return std::clamp(first.value, 0.0, 1.0);
    }
    if (frame >= last.frame) {
        return std::clamp(last.value, 0.0, 1.0);
    }

    for (int i = 0; i + 1 < sorted.size(); ++i) {
        const int f0 = sorted[i].frame;
        const int f1 = sorted[i + 1].frame;
        if (frame < f0) {
            continue;
        }
        if (frame <= f1) {
            if (f1 == f0 || frame == f0) {
                return std::clamp(sorted[i].value, 0.0, 1.0);
            }
            const double t = static_cast<double>(frame - f0) / static_cast<double>(f1 - f0);
            const double a = sorted[i].value;
            const double b = sorted[i + 1].value;
            return std::clamp(a + (b - a) * t, 0.0, 1.0);
        }
    }
    return std::clamp(last.value, 0.0, 1.0);
}

double sampleUserScale(const QVector<Project::Entity::KeyframeDouble>& keys,
                       int frame,
                       double fallback,
                       KeyInterpolation mode) {
    QVector<Project::Entity::KeyframeDouble> sorted = keys;
    sortKeysByFrame(sorted, [](const Project::Entity::KeyframeDouble& k) { return k.frame; });

    const double fb = std::max(fallback, 1e-6);

    if (sorted.isEmpty()) {
        return fb;
    }

    if (mode == KeyInterpolation::Hold) {
        double out = fb;
        int best = -1;
        for (const auto& k : sorted) {
            if (k.frame <= frame && k.frame >= best) {
                best = k.frame;
                out = k.value;
            }
        }
        return std::max(out, 1e-6);
    }

    const auto& first = sorted.front();
    const auto& last = sorted.back();
    if (frame <= first.frame) {
        return std::max(first.value, 1e-6);
    }
    if (frame >= last.frame) {
        return std::max(last.value, 1e-6);
    }

    for (int i = 0; i + 1 < sorted.size(); ++i) {
        const int f0 = sorted[i].frame;
        const int f1 = sorted[i + 1].frame;
        if (frame < f0) {
            continue;
        }
        if (frame <= f1) {
            if (f1 == f0 || frame == f0) {
                return std::max(sorted[i].value, 1e-6);
            }
            const double t = static_cast<double>(frame - f0) / static_cast<double>(f1 - f0);
            const double a = sorted[i].value;
            const double b = sorted[i + 1].value;
            return std::max(a + (b - a) * t, 1e-6);
        }
    }
    return std::max(last.value, 1e-6);
}

QString sampleImagePath(const QVector<Project::Entity::ImageFrame>& frames,
                        int frame,
                        const QString& fallbackPath) {
    QVector<Project::Entity::ImageFrame> sorted = frames;
    sortKeysByFrame(sorted, [](const Project::Entity::ImageFrame& k) { return k.frame; });

    QString out = fallbackPath;
    int best = -1;
    for (const auto& k : sorted) {
        if (k.frame <= frame && k.frame >= best && !k.imagePath.isEmpty()) {
            best = k.frame;
            out = k.imagePath;
        }
    }
    return out;
}

}  // namespace core