/*
 * Copyright 2022 Rive
 */

#include "rive/math/raw_path.hpp"

#include "rive/command_path.hpp"
#include "rive/math/simd.hpp"
#include <cmath>
#include <cstring>
#include <algorithm>

namespace rive {

RawPath::RawPath(Span<const Vec2D> points, Span<const PathVerb> verbs) :
    m_Points(points.begin(), points.end()), m_Verbs(verbs.begin(), verbs.end()) {}

bool RawPath::operator==(const RawPath& o) const {
    return m_Points == o.m_Points && m_Verbs == o.m_Verbs;
}

AABB RawPath::bounds() const {
    float4 mins, maxes;
    size_t i;
    if (m_Points.size() & 1) {
        mins = maxes = simd::load2f(&m_Points[0].x).xyxy;
        i = 1;
    } else {
        mins = maxes = m_Points.empty() ? float4{0, 0, 0, 0} : simd::load4f(&m_Points[0].x);
        i = 2;
    }
    for (; i < m_Points.size(); i += 2) {
        float4 pts = simd::load4f(&m_Points[i].x);
        mins = simd::min(mins, pts);
        maxes = simd::max(maxes, pts);
    }
    AABB bounds;
    simd::store(&bounds.minX, simd::min(mins.xy, mins.zw));
    simd::store(&bounds.maxX, simd::max(maxes.xy, maxes.zw));
    return bounds;
}

void RawPath::move(Vec2D a) {
    m_Points.push_back(a);
    m_Verbs.push_back(PathVerb::move);
}

void RawPath::line(Vec2D a) {
    m_Points.push_back(a);
    m_Verbs.push_back(PathVerb::line);
}

void RawPath::quad(Vec2D a, Vec2D b) {
    m_Points.push_back(a);
    m_Points.push_back(b);
    m_Verbs.push_back(PathVerb::quad);
}

void RawPath::cubic(Vec2D a, Vec2D b, Vec2D c) {
    m_Points.push_back(a);
    m_Points.push_back(b);
    m_Points.push_back(c);
    m_Verbs.push_back(PathVerb::cubic);
}

void RawPath::close() {
    const auto n = m_Verbs.size();
    if (n > 0 && m_Verbs[n - 1] != PathVerb::close) {
        m_Verbs.push_back(PathVerb::close);
    }
}

RawPath RawPath::transform(const Mat2D& m) const {
    RawPath path;

    path.m_Verbs = m_Verbs;

    path.m_Points.resize(m_Points.size());
    for (size_t i = 0; i < m_Points.size(); ++i) {
        path.m_Points[i] = m * m_Points[i];
    }
    return path;
}

void RawPath::transformInPlace(const Mat2D& m) {
    for (auto& p : m_Points) {
        p = m * p;
    }
}

void RawPath::addRect(const AABB& r, PathDirection dir) {
    // We manually close the rectangle, in case we want to stroke
    // this path. We also call close() so we get proper joins
    // (and not caps).

    m_Points.reserve(5);
    m_Verbs.reserve(6);

    moveTo(r.left(), r.top());
    if (dir == PathDirection::clockwise) {
        lineTo(r.right(), r.top());
        lineTo(r.right(), r.bottom());
        lineTo(r.left(), r.bottom());
    } else {
        lineTo(r.left(), r.bottom());
        lineTo(r.right(), r.bottom());
        lineTo(r.right(), r.top());
    }
    close();
}

void RawPath::addOval(const AABB& r, PathDirection dir) {
    // see https://spencermortensen.com/articles/bezier-circle/
    constexpr float C = 0.5519150244935105707435627f;
    // precompute clockwise unit circle, starting and ending at {1, 0}
    constexpr rive::Vec2D unit[] = {
        {1, 0},
        {1, C},
        {C, 1}, // quadrant 1 ( 4:30)
        {0, 1},
        {-C, 1},
        {-1, C}, // quadrant 2 ( 7:30)
        {-1, 0},
        {-1, -C},
        {-C, -1}, // quadrant 3 (10:30)
        {0, -1},
        {C, -1},
        {1, -C}, // quadrant 4 ( 1:30)
        {1, 0},
    };

    const auto center = r.center();
    const float dx = center.x;
    const float dy = center.y;
    const float sx = r.width() * 0.5f;
    const float sy = r.height() * 0.5f;

    auto map = [dx, dy, sx, sy](rive::Vec2D p) {
        return rive::Vec2D(p.x * sx + dx, p.y * sy + dy);
    };

    m_Points.reserve(13);
    m_Verbs.reserve(6);

    if (dir == PathDirection::clockwise) {
        move(map(unit[0]));
        for (int i = 1; i <= 12; i += 3) {
            cubic(map(unit[i + 0]), map(unit[i + 1]), map(unit[i + 2]));
        }
    } else {
        move(map(unit[12]));
        for (int i = 11; i >= 0; i -= 3) {
            cubic(map(unit[i - 0]), map(unit[i - 1]), map(unit[i - 2]));
        }
    }
    close();
}

void RawPath::addPoly(Span<const Vec2D> span, bool isClosed) {
    if (span.size() == 0) {
        return;
    }

    // should we permit must moveTo() or just moveTo()/close() ?

    m_Points.reserve(span.size() + isClosed);
    m_Verbs.reserve(span.size() + isClosed);

    move(span[0]);
    for (size_t i = 1; i < span.size(); ++i) {
        line(span[i]);
    }
    if (isClosed) {
        close();
    }
}

void RawPath::addPath(const RawPath& src, const Mat2D* mat) {
    m_Verbs.insert(m_Verbs.end(), src.m_Verbs.cbegin(), src.m_Verbs.cend());

    if (mat) {
        const auto oldPointCount = m_Points.size();
        m_Points.resize(oldPointCount + src.m_Points.size());
        Vec2D* dst = m_Points.data() + oldPointCount;
        for (auto i = 0; i < src.m_Points.size(); ++i) {
            dst[i] = *mat * src.m_Points[i];
        }
    } else {
        m_Points.insert(m_Points.end(), src.m_Points.cbegin(), src.m_Points.cend());
    }
}

//////////////////////////////////////////////////////////////////////////

int path_verb_to_point_count(PathVerb v) {
    static uint8_t ptCounts[] = {
        1, // move
        1, // line
        2, // quad
        2, // conic (unused)
        3, // cubic
        0, // close
    };
    size_t index = (size_t)v;
    assert(index < sizeof(ptCounts));
    return ptCounts[index];
}

RawPath::Iter::Rec RawPath::Iter::next() {
    // initialize with "false"
    Rec rec = {nullptr, -1, (PathVerb)-1};

    if (m_currVerb < m_stopVerb) {
        rec.pts = m_currPts;
        rec.verb = *m_currVerb++;
        rec.count = path_verb_to_point_count(rec.verb);

        m_currPts += rec.count;
    }
    return rec;
}

void RawPath::Iter::backUp() {
    --m_currVerb;
    const int n = path_verb_to_point_count(*m_currVerb);
    m_currPts -= n;
}

void RawPath::reset() {
    m_Points.clear();
    m_Points.shrink_to_fit();
    m_Verbs.clear();
    m_Verbs.shrink_to_fit();
}

void RawPath::rewind() {
    m_Points.clear();
    m_Verbs.clear();
}

///////////////////////////////////

void RawPath::addTo(CommandPath* result) const {
    RawPath::Iter iter(*this);
    while (auto rec = iter.next()) {
        switch (rec.verb) {
            case PathVerb::move: result->move(rec.pts[0]); break;
            case PathVerb::line: result->line(rec.pts[0]); break;
            case PathVerb::quad: assert(false); break;
            case PathVerb::cubic: result->cubic(rec.pts[0], rec.pts[1], rec.pts[2]); break;
            case PathVerb::close: result->close(); break;
        }
    }
}

} // namespace rive