#include <iostream>
#include <chrono>
#include <thread>

#include "Display.h"
#include "Point.h"
#include "Utility.h"

Display::Display (const std::vector<Point> &pts, int stepSize) : m_stepSize(stepSize)
{
    if (!m_font.loadFromFile("Resources/LiberationSans-Regular.ttf"))
    {
        std::cerr << "font LiberationSans-Regular.ttf could not be loaded!" << std::endl;
    }

    m_textStatus.setPosition(OFFSET, HEIGHT - 2*OFFSET);
    m_textStatus.setFont(m_font);
    m_textStatus.setString("initializing...");
    m_textStatus.setCharacterSize(12);
    m_textStatus.setFillColor(sf::Color::Black);

    size_t points = pts.size();
    for (size_t i = 0; i < points; ++i)
    {
        const Point& pt = pts[i];
        sf::CircleShape shape(OFFSET);
        shape.setOrigin(OFFSET, OFFSET);
        shape.setPosition(pt.x(), pt.y());
        shape.setFillColor(sf::Color::Green);
        shape.setOutlineThickness(1.f);
        shape.setOutlineColor(sf::Color::Black);
        m_points.push_back(shape);

        sf::Text label;
        label.setOrigin(OFFSET / 2 - 1, OFFSET / 2 + 3);
        label.setPosition(pt.x(), pt.y());
        label.setFont(m_font);
        label.setString(std::to_string(i));
        label.setCharacterSize(12);
        label.setFillColor(sf::Color::Black);
        m_labels.push_back(label);
    }
}

// multiple options possible:
// a) draw every frame, using elapsed time for updates
//      --> not really needed because we have no animations... also uses a lot of performance
// b) checking every frame if elapsed time since last tick is larger than a specified offset, then draw the field
//      --> mostly doing nothing but still uses a lot of performance O_o
// c) just start a simple (c++11 <3) non-busy sleep
//      --> may delay user input / events but don't care atm :p
void Display::show()
{
    sf::ContextSettings settings;
    settings.antialiasingLevel = 8;

    sf::RenderWindow window(sf::VideoMode(WIDTH, HEIGHT), "ALGO Prog2: Quickhull - visualization", sf::Style::Default, settings);
    /* b)
    window.setFramerateLimit(0.2);

    sf::Clock clock;
    sf::Time frameTime = sf::seconds(2); //sf::seconds(1.f / 60.f)
    sf::Time timeSinceLastUpdate = frameTime; //sf::Time::Zero;*/
    while (window.isOpen())
    {
        sf::Event event;
        while (window.pollEvent(event))
        {
            if (event.type == sf::Event::Closed)
                window.close();
        }

        // a)
        //update(elapsed);
        //render(window);

        /* b)
        timeSinceLastUpdate += clock.restart();
        // only handle every few seconds because we need no animations
        if (timeSinceLastUpdate >= frameTime)
        {
            std::cout << "entering update and render" << std::endl;

            // start by getting the most left and right point
            timeSinceLastUpdate -= frameTime;

            update();
            render(window);
        }*/

        // c)
        // choose a simple sleep
        update();
        render(window);

        std::this_thread::sleep_for(std::chrono::milliseconds(m_stepSize));
    }
}

void Display::update ()
{
    // TODO: maybe include Akl–Toussaint heuristic first?
    // https://en.wikipedia.org/wiki/Convex_hull_algorithms#Akl%E2%80%93Toussaint_heuristic

    unsigned int curStep = (m_step > 5) ? ((m_step - 2) % 4 + 2) : (m_step % 6); // skip init and first step after first run
    if (m_stepSize == 0 && curStep > 0)
    {
        std::cout << "any key to continue with next step...";
        std::cin.get();
    }

    std::string text = "(" + std::to_string(m_step) + ") step " + std::to_string(curStep) + ": ";
    if (curStep == 1)
    {
        // first step: select min - max x coordinates
        m_textStatus.setString(text + "select min - max x coordinates...");

        // if use Akl–Toussaint heuristic
        bool useAkl = false;
        if (useAkl)
        {
            sf::Vector2f topLeft(WIDTH, HEIGHT);
            sf::Vector2f topRight(0, HEIGHT);
            sf::Vector2f botLeft(WIDTH, 0);
            sf::Vector2f botRight(0, 0);

            for (auto& pt : m_points)
            {
                sf::Vector2f pos = pt.getPosition();
                float x = pos.x;
                float y = pos.y;
                // TODO: only check explicit x and y seperate!
                if (x < topLeft.x && y < topLeft.y) topLeft = pos;
                if (x > topRight.x && y < topLeft.y) topRight = pos;
                if (x < botLeft.x && y > botLeft.y) botLeft = pos;
                if (x > botRight.x && y > botRight.y) botRight = pos;
            }

            m_hull.setPrimitiveType(sf::LineStrip);
            m_hull.append(sf::Vertex(topLeft, sf::Color::Blue));
            m_hull.append(sf::Vertex(topRight, sf::Color::Blue));
            m_hull.append(sf::Vertex(botRight, sf::Color::Blue));
            m_hull.append(sf::Vertex(botLeft, sf::Color::Blue));
            m_hull.append(sf::Vertex(topLeft, sf::Color::Blue));
        }
        else
        {
            sf::Vector2f left(WIDTH, HEIGHT);
            sf::Vector2f right(0, 0);

            int i_left = WIDTH;
            int i_right = 0;

            size_t points = m_points.size();
            for (size_t i = 0; i < points; ++i)
            {
                sf::Vector2f pos = m_points[i].getPosition();
                float x = pos.x;
                if (x < left.x)
                {
                    i_left = i;
                    left = pos;
                }
                if (x > right.x)
                {
                    i_right = i;
                    right = pos;
                }
            }

            // adding starting points from most x to left
            if (i_left < i_right)
            {
                std::swap(i_left, i_right);
            }
            for (int i = 0; i < 2; ++i)
            {
                int pos = (i == 0) ? i_left : i_right;
                m_points[pos].setFillColor(sf::Color::Blue);
                m_hullPoints.push_back(m_points[pos]);
                m_points.erase(m_points.begin() + pos);
            }

            m_lines.push_back(Line(Point(left.x, left.y), Point(right.x, right.y)));
            m_lines.push_back(Line(Point(right.x, right.y), Point(left.x, left.y))); // add first line in both directions to work with "right side"
            m_curLineIdx = 1;
            m_curLine = m_lines[1];

            // TODO: split points and use map
        }
    }
    else if (curStep == 2)
    {
        // second step: split board
        m_textStatus.setString(text + "split board...");

        // get current line with points
        while (m_curLineIdx == -1)
        {
            size_t lines = m_lines.size();
            if (lines < 1) // no more open lines -> fin
            {
                std::cout << "## no more open lines -> fin!" << std::endl;
                m_points.clear();
                if (m_points.size() == 0) m_textStatus.setString(text + "finished calculating convex hull in " + std::to_string((m_step / 4 + 1)) + " cycles");
                return;
            }

            Line cand = m_lines[lines - 1];
            int positives = 0;
            for (auto& pt : m_points)
            {
                positives += (sign(pt.getPosition().x, pt.getPosition().y,
                              cand.from().x(), cand.from().y(),
                              cand.to().x(), cand.to().y()) > 0) ? 1 : 0;
            }

            if (positives > 0)
            {
                m_curLineIdx = lines - 1;
                m_curLine = m_lines[lines - 1];
            }
            else
            {
                m_lines.pop_back();
            }
        }

        for (auto& pt : m_points)
        {
            pt.setFillColor(sign(
                pt.getPosition().x, pt.getPosition().y,
                m_lines[m_curLineIdx].from().x(), m_lines[m_curLineIdx].from().y(),
                m_lines[m_curLineIdx].to().x(), m_lines[m_curLineIdx].to().y()) > 0 ? sf::Color::Red : sf::Color::Green);
        }
    }
    else if (curStep == 3)
    {
        // get line with more than one point -> or use m_curLine
        // calc furthest point
        // create new lines

        // third step: draw triangle, remove inner points
        m_textStatus.setString(text + "find furthest point and draw triangle...");

        sf::Vector2f pos;
        float maxDistance = 0;
        int i_cand = 0;
        size_t points = m_points.size();
        for (size_t i = 0; i < points; ++i)
        {
            if (m_points[i].getFillColor() == sf::Color::Green) continue;

            sf::Vector2f cand = m_points[i].getPosition();
            float distance = pDistance(
                cand.x, cand.y,
                m_lines[m_curLineIdx].from().x(), m_lines[m_curLineIdx].from().y(),
                m_lines[m_curLineIdx].to().x(), m_lines[m_curLineIdx].from().y());

            if (distance > maxDistance)
            {
                i_cand = i;
                pos = cand;
                maxDistance = distance;
            }
        }

        if (maxDistance > 0)
        {
            // move point from all points to hull points
            m_points[i_cand].setFillColor(sf::Color::Blue);
            m_hullPoints.push_back(m_points[i_cand]);
            std::cout << "removing pt " << m_points[i_cand].getPosition().x << ", " << m_points[i_cand].getPosition().y << " at index " << std::to_string(i_cand) << " after inserted to hullpoints" << std::endl;
            m_points.erase(m_points.begin() + i_cand);

            Point to = m_lines[m_curLineIdx].to();
            Point from = m_lines[m_curLineIdx].from();
            m_lines.push_back(Line(Point(pos.x, pos.y),to));
            m_lines[m_lines.size() - 2] = Line(from, Point(pos.x, pos.y)); // updates list entry
        }
        else
        {
            m_lines.pop_back(); // remove last element -> TODO: directly use stack?
        }
    }
    else if (curStep == 4)
    {
        // fourth step: remove inner points
        m_textStatus.setString(text + "remove inner points...");

        size_t lines = m_lines.size() - 1;
        if (lines > 0)
        {
            // assure clockwise order
            Point pt1 = m_lines[lines - 1].from();
            Point pt2 = m_lines[lines - 1].to();
            Point pt3 = m_lines[lines].to();
            if (sign(pt2, pt1, pt3) > 0)
            {
                std::swap(pt1, pt2);
            }

            size_t points = m_points.size();
            for (int i = points - 1; i >= 0; i--)
            {
                Point pt(m_points[i].getPosition().x, m_points[i].getPosition().y);
                if (IsPointInTriangle(pt, pt1, pt2, pt3))
                {
                    std::cout << "remove pt inside triangle -> " << i << " with pos: " << pt.x() << ", " << pt.y() << std::endl;
                    m_points.erase(m_points.begin() + i);
                }
                else
                {
                    m_points[i].setFillColor(sf::Color::Green);
                }
            }
        }
        //m_curLine = nullptr;
        //m_curLineIdx = -1;
    }
    else if (curStep == 5)
    {
        // fifth step: adding new hull point

        m_curLineIdx = -1;
        //m_curLine = m_lines[lines - 1];

        if (m_points.size() == 0) m_textStatus.setString(text + "finished calculating convex hull in " + std::to_string((m_step / 4 + 1)) + " cycles");
        else m_textStatus.setString(text + "adding new hull point...");
    }
    else if (m_step > 0) m_textStatus.setString(text + "invalid status!");

    if (curStep != 5 || m_points.size() > 0) m_step++;
}

bool less (sf::CircleShape a, sf::CircleShape b)
{
    float centerx = WIDTH / 2;
    float centery = HEIGHT / 2;
    float ax = a.getPosition().x;
    float ay = a.getPosition().y;
    float bx = b.getPosition().x;
    float by = b.getPosition().y;
    if (ax - centerx >= 0 && bx - centerx < 0)
        return true;
    if (ax - centerx < 0 && bx - centerx >= 0)
        return false;
    if (ax - centerx == 0 && bx - centerx == 0) {
        if (ay - centery >= 0 || by - centery >= 0)
            return ay > by;
        return by > ay;
    }

    // compute the cross product of vectors (center -> a) x (center -> b)
    int det = (ax - centerx) * (by - centery) - (bx - centerx) * (ay - centery);
    if (det < 0)
        return true;
    if (det > 0)
        return false;

    // points a and b are on the same line from the center
    // check which point is closer to the center
    int d1 = (ax - centerx) * (ax - centerx) + (ay - centery) * (ay - centery);
    int d2 = (bx - centerx) * (bx - centerx) + (by - centery) * (by - centery);
    return d1 > d2;
}

void Display::render (sf::RenderWindow &window)
{
    window.clear(sf::Color::White);

    // draw already calculated hull points
    std::sort(m_hullPoints.begin(), m_hullPoints.end(), less); // sort clockwise

    size_t elements = m_hullPoints.size();
    for (size_t i = 0; i < elements; ++i)
    {
        window.draw(m_hullPoints[i]);

        sf::Vertex ptTo;
        if (i < elements - 1) ptTo = sf::Vertex(m_hullPoints[i + 1].getPosition(), sf::Color::Blue);
        else ptTo = sf::Vertex(m_hullPoints[0].getPosition(), sf::Color::Blue);
        sf::Vertex line[] = { sf::Vertex(sf::Vector2f(m_hullPoints[i].getPosition()), sf::Color::Blue), ptTo };

        window.draw(line, 2, sf::Lines);
    }

    // always print remaining points
    elements = m_points.size();
    for (size_t i = 0; i < elements; ++i)
    {
        window.draw(m_points[i]);
    }

    // seperately print labels for points
    elements = m_labels.size();
    for (size_t i = 0; i < elements; ++i)
    {
        window.draw(m_labels[i]);
    }

    // draw line the algorithm is currently working on
    if (m_curLineIdx != -1)
    {
        sf::Vertex line[] =
        {
            sf::Vertex(sf::Vector2f(m_curLine.from().x(), m_curLine.from().y()), sf::Color::Red),
            sf::Vertex(sf::Vector2f(m_curLine.to().x(), m_curLine.to().y()), sf::Color::Red)
        };
        window.draw(line, 2, sf::Lines);
    }

    // show amount of steps and current status
    window.draw(m_textStatus);

    window.display();
}