#include "catch.hpp"

// mapnik
#include <mapnik/global.hpp>
#include <mapnik/coord.hpp>
#include <mapnik/vertex.hpp>
#include <mapnik/offset_converter.hpp>

// stl
#include <stdexcept>
#include <iostream>
#include <fstream>
#include <vector>
#include <tuple>
#include <algorithm>

namespace offset_test {

struct fake_path
{
    using coord_type = std::tuple<double, double, unsigned>;
    using cont_type = std::vector<coord_type>;
    cont_type vertices_;
    cont_type::iterator itr_;

    fake_path(std::initializer_list<double> l)
        : fake_path(l.begin(), l.size()) {
    }

    fake_path(std::vector<double> const &v)
        : fake_path(v.begin(), v.size()) {
    }

    template <typename Itr>
    fake_path(Itr itr, size_t sz) {
        size_t num_coords = sz >> 1;
        vertices_.reserve(num_coords);

        for (size_t i = 0; i < num_coords; ++i) {
            double x = *itr++;
            double y = *itr++;
            unsigned cmd = (i == 0) ? mapnik::SEG_MOVETO : mapnik::SEG_LINETO;
            vertices_.push_back(std::make_tuple(x, y, cmd));
        }
        itr_ = vertices_.begin();
    }

    unsigned vertex(double *x, double *y) {
        if (itr_ == vertices_.end()) {
            return mapnik::SEG_END;
        }
        *x = std::get<0>(*itr_);
        *y = std::get<1>(*itr_);
        unsigned cmd = std::get<2>(*itr_);
        ++itr_;
        return cmd;
    }

    void rewind(unsigned) {
        itr_ = vertices_.begin();
    }
};

static double DELTA_BUFF = 0.5;

double dist(double x0, double y0, double x1, double y1)
{
    double dx = x0 - x1;
    double dy = y0 - y1;
    return std::sqrt(dx*dx + dy*dy);
}

void test_simple_segment(double const &offset)
{
    fake_path path = {0, 0, 1, 0}, off_path = {0, offset, 1, offset};
    mapnik::offset_converter<fake_path> off_path_new(path);
    off_path_new.set_offset(-offset);

    double x0, y0, x1, y1;
    unsigned cmd0 = off_path_new.vertex(&x0, &y0);
    unsigned cmd1 = off_path.vertex(&x1,&y1);
    double d = dist(x0, y0, x1, y1);
    while (true) {
        if (d > (std::abs(offset) + DELTA_BUFF))
        {
            cmd0 = off_path_new.vertex(&x0,&y0);
            REQUIRE(cmd0 != mapnik::SEG_END);
            d = dist(x0, y0, x1, y1);
            REQUIRE(d <= (std::abs(offset) + DELTA_BUFF));
        }
        else
        {
            REQUIRE(d <= (std::abs(offset) + DELTA_BUFF));
            
        }
        
        cmd1 = off_path.vertex(&x1,&y1);
        if (cmd1 == mapnik::SEG_END) break;
        d = dist(x0, y0, x1, y1);
        bool done = false;
        while (d <= (std::abs(offset) + DELTA_BUFF))
        {
            CHECK(true);
            cmd0 = off_path_new.vertex(&x0,&y0);
            if (cmd0 == mapnik::SEG_END)
            {
                done = true;
                break;
            }
        }
        if (done) break;
    }
}

void test_straight_line(double const &offset) {
    fake_path path = {0, 0, 1, 0, 9, 0, 10, 0},
        off_path = {0, offset, 1, offset, 9, offset, 10, offset};
    mapnik::offset_converter<fake_path> off_path_new(path);
    off_path_new.set_offset(-offset);

    double x0, y0, x1, y1;
    unsigned cmd0 = off_path_new.vertex(&x0, &y0);
    unsigned cmd1 = off_path.vertex(&x1,&y1);
    double d = dist(x0, y0, x1, y1);
    while (true) {
        if (d > (std::abs(offset) + DELTA_BUFF))
        {
            cmd0 = off_path_new.vertex(&x0,&y0);
            REQUIRE(cmd0 != mapnik::SEG_END);
            d = dist(x0, y0, x1, y1);
            REQUIRE(d <= (std::abs(offset) + DELTA_BUFF));
        }
        else
        {
            REQUIRE(d <= (std::abs(offset) + DELTA_BUFF));
            
        }
        
        cmd1 = off_path.vertex(&x1,&y1);
        d = dist(x0, y0, x1, y1);
        bool done = false;
        while (d <= (std::abs(offset) + DELTA_BUFF))
        {
            CHECK(true);
            cmd0 = off_path_new.vertex(&x0,&y0);
            if (cmd0 == mapnik::SEG_END)
            {
                done = true;
                break;
            }
        }
        if (done) break;
    }
}

void test_offset_curve(double const &offset) {
    const double r = (1.0 + offset);

    std::vector<double> pos, off_pos;
    const size_t max_i = 1000;
    for (size_t i = 0; i <= max_i; ++i) {
        double x = M_PI * double(i) / max_i;
        pos.push_back(-std::cos(x)); pos.push_back(std::sin(x));
        off_pos.push_back(-r * std::cos(x)); off_pos.push_back(r * std::sin(x));
    }

    fake_path path(pos), off_path(off_pos);
    mapnik::offset_converter<fake_path> off_path_new(path);
    off_path_new.set_offset(-offset);

    double x0, y0, x1, y1;
    unsigned cmd0 = off_path_new.vertex(&x0, &y0);
    unsigned cmd1 = off_path.vertex(&x1,&y1);
    double d = dist(x0, y0, x1, y1);
    while (true) {
        if (d > (std::abs(offset) + DELTA_BUFF))
        {
            cmd0 = off_path_new.vertex(&x0,&y0);
            REQUIRE(cmd0 != mapnik::SEG_END);
            d = dist(x0, y0, x1, y1);
            REQUIRE(d <= (std::abs(offset) + DELTA_BUFF));
        }
        else
        {
            REQUIRE(d <= (std::abs(offset) + DELTA_BUFF));
            
        }
        
        cmd1 = off_path.vertex(&x1,&y1);
        d = dist(x0, y0, x1, y1);
        bool done = false;
        while (d <= (std::abs(offset) + DELTA_BUFF))
        {
            CHECK(true);
            cmd0 = off_path_new.vertex(&x0,&y0);
            if (cmd0 == mapnik::SEG_END)
            {
                done = true;
                break;
            }
        }
        if (done) break;
    }
}

void test_s_shaped_curve(double const &offset) {
    const double r = (1.0 + offset);
    const double r2 = (1.0 - offset);

    std::vector<double> pos, off_pos;
    const size_t max_i = 1000;
    for (size_t i = 0; i <= max_i; ++i) {
        double x = M_PI * double(i) / max_i;
        pos.push_back(-std::cos(x) - 1); pos.push_back(std::sin(x));
        off_pos.push_back(-r * std::cos(x) - 1); off_pos.push_back(r * std::sin(x));
    }
    for (size_t i = 0; i <= max_i; ++i) {
        double x = M_PI * double(i) / max_i;
        pos.push_back(-std::cos(x) + 1); pos.push_back(-std::sin(x));
        off_pos.push_back(-r2 * std::cos(x) + 1); off_pos.push_back(-r2 * std::sin(x));
    }

    fake_path path(pos), off_path(off_pos);
    mapnik::offset_converter<fake_path> off_path_new(path);
    off_path_new.set_offset(-offset);

    double x0, y0, x1, y1;
    unsigned cmd0 = off_path_new.vertex(&x0, &y0);
    unsigned cmd1 = off_path.vertex(&x1,&y1);
    double d = dist(x0, y0, x1, y1);
    while (true) {
        if (d > (std::abs(offset) + DELTA_BUFF))
        {
            cmd0 = off_path_new.vertex(&x0,&y0);
            REQUIRE(cmd0 != mapnik::SEG_END);
            d = dist(x0, y0, x1, y1);
            REQUIRE(d <= (std::abs(offset) + DELTA_BUFF));
        }
        else
        {
            REQUIRE(d <= (std::abs(offset) + DELTA_BUFF));
            
        }
        
        cmd1 = off_path.vertex(&x1,&y1);
        d = dist(x0, y0, x1, y1);
        bool done = false;
        while (d <= (std::abs(offset) + DELTA_BUFF))
        {
            CHECK(true);
            cmd0 = off_path_new.vertex(&x0,&y0);
            if (cmd0 == mapnik::SEG_END)
            {
                done = true;
                break;
            }
        }
        if (done) break;
    }
}

} // END NS

TEST_CASE("offset converter") {

SECTION("simple segment") {
    try {

        std::vector<double> offsets = { 1, -1 };
        for (double offset : offsets) {
            // test simple straight line segment - should be easy to
            // find the correspondance here.
            offset_test::test_simple_segment(offset);
        }
    }
    catch (std::exception const& ex)
    {
        std::cerr << ex.what() << "\n";
        REQUIRE(false);
    }
}

SECTION("straight line") {
    try {

        std::vector<double> offsets = { 1, -1 };
        for (double offset : offsets) {
            // test straight line consisting of more than one segment.
            offset_test::test_straight_line(offset);
        }
    }
    catch (std::exception const& ex)
    {
        std::cerr << ex.what() << "\n";
        REQUIRE(false);
    }
}

SECTION("curve") {
    try {

        std::vector<double> offsets = { 1, -1 };
        for (double offset : offsets) {
            offset_test::test_offset_curve(offset);
        }
    }
    catch (std::exception const& ex)
    {
        std::cerr << ex.what() << "\n";
        REQUIRE(false);
    }
}

SECTION("s curve") {
    try {

        std::vector<double> offsets = { 1, -1 };
        for (double offset : offsets) {
            offset_test::test_s_shaped_curve(offset);
        }
    }
    catch (std::exception const& ex)
    {
        std::cerr << ex.what() << "\n";
        REQUIRE(false);
    }
}

}