#include "../include/Text.hpp"
#include <SFML/Graphics/RectangleShape.hpp>
#include <SFML/Window/Clipboard.hpp>
#include <cmath>
#include <functional>

namespace QuickMedia
{
    const float TAB_WIDTH = 4.0f;
    
    const sf::Color URL_COLOR(15, 192, 252);

    size_t StringViewUtf32::find(const StringViewUtf32 &other, size_t offset) const {
        if(offset >= size)
            return -1;

        auto it = std::search(data + offset, data + size - offset, std::boyer_moore_searcher(other.data, other.data + other.size));
        if(it != data + size)
            return it - data;

        return -1;
    }
    
    Text::Text(const sf::Font *_font) : 
        font(_font),
        characterSize(0),
        vertices(sf::PrimitiveType::Quads),
        maxWidth(0.0f),
        color(sf::Color::White),
        urlColor(URL_COLOR),
        dirty(false),
        dirtyText(false),
        dirtyCaret(false),
        plainText(false),
        editable(false),
        visible(true),
        caretMoveDirection(CaretMoveDirection::NONE),
        lineSpacing(0.0f),
        characterSpacing(0.0f),
        caretIndex(0)
    {
        
    }
    
    Text::Text(const sf::String &_str, const sf::Font *_font, unsigned int _characterSize, float _maxWidth, bool _plainText) : 
        font(_font),
        characterSize(_characterSize),
        vertices(sf::PrimitiveType::Quads),
        maxWidth(_maxWidth),
        color(sf::Color::White),
        urlColor(URL_COLOR),
        dirty(true),
        dirtyText(false),
        dirtyCaret(false),
        plainText(_plainText),
        editable(false),
        visible(true),
        caretMoveDirection(CaretMoveDirection::NONE),
        lineSpacing(0.0f),
        characterSpacing(0.0f),
        caretIndex(0)
    {
        setString(_str);
    }
    
    void Text::setString(const sf::String &str)
    {
        if(str != this->str)
        {
            this->str = str;
            dirty = true;
            dirtyText = true;
            if((int)str.getSize() < caretIndex)
            {
                caretIndex = str.getSize();
                dirtyCaret = true;
            }
        }
    }
    
    const sf::String& Text::getString() const
    {
        return str;
    }
    
    void Text::setPosition(float x, float y)
    {
        position.x = x;
        position.y = y;
    }
    
    void Text::setPosition(const sf::Vector2f &position)
    {
        this->position = position;
    }
    
    sf::Vector2f Text::getPosition() const
    {
        return position;
    }
    
    void Text::setMaxWidth(float maxWidth)
    {
        if(std::abs(maxWidth - this->maxWidth) > 1.0f)
        {
            this->maxWidth = maxWidth;
            dirty = true;
        }
    }
    
    float Text::getMaxWidth() const
    {
        return maxWidth;
    }
    
    void Text::setCharacterSize(unsigned int characterSize)
    {
        if(characterSize != this->characterSize)
        {
            this->characterSize = characterSize;
            dirty = true;
        }
    }
    
    unsigned int Text::getCharacterSize() const
    {
        return characterSize;
    }
    
    const sf::Font* Text::getFont() const
    {
        return font;
    }
    
    void Text::setFillColor(sf::Color color)
    {
        if(color != this->color)
        {
            this->color = color;
            dirty = true;
        }
    }
    
    void Text::setLineSpacing(float lineSpacing)
    {
        if(fabs(lineSpacing - this->lineSpacing) > 0.001f)
        {
            this->lineSpacing = lineSpacing;
            dirty = true;
        }
    }
    
    void Text::setCharacterSpacing(float characterSpacing)
    {
        if(fabs(characterSpacing - this->characterSpacing) > 0.001f)
        {
            this->characterSpacing = characterSpacing;
            dirty = true;
        }
    }
    
    void Text::setEditable(bool editable)
    {
        if(editable != this->editable)
        {
            this->editable = editable;
            if(!plainText)
            {
                dirty = true;
                dirtyText = true;
            }
            dirtyCaret = true;
        }
    }
    
    float Text::getHeight() const
    {
        return boundingBox.height;
    }
    
    // Logic loosely based on https://github.com/SFML/SFML/wiki/Source:-CurvedText
    void Text::updateGeometry(bool update_even_if_not_dirty)
    {
        if(dirtyText)
        {
            textElements.clear();
            StringViewUtf32 wholeStr(this->str.getData(), this->str.getSize());
            textElements.push_back({ wholeStr, TextElement::Type::TEXT });
            dirtyText = false;
        }

        if(!update_even_if_not_dirty && !dirty)
            return;

        vertices.clear();
        float hspace = font->getGlyph(' ', characterSize, false).advance + characterSpacing;
        float vspace = font->getLineSpacing(characterSize);
        
        boundingBox = sf::FloatRect();
        
        sf::Vector2f glyphPos;
        sf::Uint32 prevCodePoint = 0;
        size_t lastSpacingWordWrapIndex = -1;
        float lastSpacingAccumulatedOffset = 0.0f;
        for(usize textElementIndex = 0; textElementIndex < textElements.size(); ++textElementIndex)
        {
            TextElement &textElement = textElements[textElementIndex];
            
            usize vertexOffset = vertices.getVertexCount();
            vertices.resize(vertices.getVertexCount() + 4 * (textElement.text.size + 1));
            textElement.position = glyphPos;
            for(size_t i = 0; i < textElement.text.size; ++i)
            {
                sf::Uint32 codePoint = textElement.text[i];
                float kerning = font->getKerning(prevCodePoint, codePoint, characterSize);
                prevCodePoint = codePoint;
                glyphPos.x += kerning;
                
                usize vertexStart = vertexOffset + i * 4;
                
                switch(codePoint)
                {
                    case ' ':
                    {
                        vertices[vertexStart + 0] = { sf::Vector2f(glyphPos.x, glyphPos.y - vspace), sf::Color::Transparent, sf::Vector2f() };
                        vertices[vertexStart + 1] = { sf::Vector2f(glyphPos.x + hspace, glyphPos.y - vspace), sf::Color::Transparent, sf::Vector2f() };
                        vertices[vertexStart + 2] = { sf::Vector2f(glyphPos.x + hspace, glyphPos.y), sf::Color::Transparent, sf::Vector2f() };
                        vertices[vertexStart + 3] = { sf::Vector2f(glyphPos.x, glyphPos.y), sf::Color::Transparent, sf::Vector2f() };
                        glyphPos.x += hspace;
                        if(glyphPos.x > maxWidth * 0.5f)
                        {
                            lastSpacingWordWrapIndex = i;
                            lastSpacingAccumulatedOffset = glyphPos.x;
                        }
                        continue;
                    }
                    case '\t':
                    {
                        vertices[vertexStart + 0] = { sf::Vector2f(glyphPos.x, glyphPos.y - vspace), sf::Color::Transparent, sf::Vector2f() };
                        vertices[vertexStart + 1] = { sf::Vector2f(glyphPos.x + hspace * TAB_WIDTH, glyphPos.y - vspace), sf::Color::Transparent, sf::Vector2f() };
                        vertices[vertexStart + 2] = { sf::Vector2f(glyphPos.x + hspace * TAB_WIDTH, glyphPos.y), sf::Color::Transparent, sf::Vector2f() };
                        vertices[vertexStart + 3] = { sf::Vector2f(glyphPos.x, glyphPos.y), sf::Color::Transparent, sf::Vector2f() };
                        glyphPos.x += (hspace * TAB_WIDTH);
                        if(glyphPos.x > maxWidth * 0.5f)
                        {
                            lastSpacingWordWrapIndex = i;
                            lastSpacingAccumulatedOffset = glyphPos.x;
                        }
                        continue;
                    }
                    case '\n':
                    {
                        vertices[vertexStart + 0] = { sf::Vector2f(glyphPos.x, glyphPos.y - vspace), sf::Color::Transparent, sf::Vector2f() };
                        vertices[vertexStart + 1] = { sf::Vector2f(0.0f, glyphPos.y), sf::Color::Transparent, sf::Vector2f() };
                        vertices[vertexStart + 2] = { sf::Vector2f(0.0f, glyphPos.y), sf::Color::Transparent, sf::Vector2f() };
                        vertices[vertexStart + 3] = { sf::Vector2f(0.0f, glyphPos.y), sf::Color::Transparent, sf::Vector2f() };
                        glyphPos.x = 0.0f;
                        glyphPos.y += floor(vspace + lineSpacing);
                        continue;
                    }
                }
                
                const sf::Glyph &glyph = font->getGlyph(codePoint, characterSize, false);
                if(glyphPos.x + glyph.advance > maxWidth)
                {
                    // If there was a space in the text and text width is too long, then we need to word wrap at space index instead,
                    // which means we need to change the position of all vertices after the space to the current vertex
                    if(lastSpacingWordWrapIndex != (size_t)-1)
                    {
                        for(size_t j = lastSpacingWordWrapIndex; j < i; ++j)
                        {
                            for(size_t k = 0; k < 4; ++k)
                            {
                                sf::Vector2f &vertexPos = vertices[vertexOffset + j * 4 + k].position;
                                vertexPos.x -= lastSpacingAccumulatedOffset;
                                vertexPos.y += floor(vspace + lineSpacing);
                            }
                        }
                        
                        glyphPos.x -= lastSpacingAccumulatedOffset;
                        lastSpacingWordWrapIndex = -1;
                        lastSpacingAccumulatedOffset = 0.0f;
                    }
                    else
                        glyphPos.x = 0.0f;
                    
                    glyphPos.y += floor(vspace + lineSpacing);
                }
                
                sf::Vector2f vertexTopLeft(glyphPos.x + glyph.bounds.left, glyphPos.y + glyph.bounds.top);
                sf::Vector2f vertexTopRight(glyphPos.x + glyph.bounds.left + glyph.bounds.width, glyphPos.y + glyph.bounds.top);
                sf::Vector2f vertexBottomLeft(glyphPos.x + glyph.bounds.left, glyphPos.y + glyph.bounds.top + glyph.bounds.height);
                sf::Vector2f vertexBottomRight(glyphPos.x + glyph.bounds.left + glyph.bounds.width, glyphPos.y + glyph.bounds.top + glyph.bounds.height);
                
                sf::Vector2f textureTopLeft(glyph.textureRect.left, glyph.textureRect.top);
                sf::Vector2f textureTopRight(glyph.textureRect.left + glyph.textureRect.width, glyph.textureRect.top);
                sf::Vector2f textureBottomLeft(glyph.textureRect.left, glyph.textureRect.top + glyph.textureRect.height);
                sf::Vector2f textureBottomRight(glyph.textureRect.left + glyph.textureRect.width, glyph.textureRect.top + glyph.textureRect.height);
                
                sf::Color fontColor = (textElement.type == TextElement::Type::TEXT ? color : urlColor);
                
                vertices[vertexStart + 0] = { vertexTopLeft, fontColor, textureTopLeft };
                vertices[vertexStart + 1] = { vertexTopRight, fontColor, textureTopRight };
                vertices[vertexStart + 2] = { vertexBottomRight, fontColor, textureBottomRight };
                vertices[vertexStart + 3] = { vertexBottomLeft, fontColor, textureBottomLeft };
                
                glyphPos.x += glyph.advance + characterSpacing;
            }
            
            vertices[vertices.getVertexCount() - 4] = { sf::Vector2f(glyphPos.x, glyphPos.y - vspace), sf::Color::Transparent, sf::Vector2f() };
            vertices[vertices.getVertexCount() - 3] = { sf::Vector2f(glyphPos.x, glyphPos.y - vspace), sf::Color::Transparent, sf::Vector2f() };
            vertices[vertices.getVertexCount() - 2] = { sf::Vector2f(glyphPos.x, glyphPos.y - vspace), sf::Color::Transparent, sf::Vector2f() };
            vertices[vertices.getVertexCount() - 1] = { sf::Vector2f(glyphPos.x, glyphPos.y - vspace), sf::Color::Transparent, sf::Vector2f() };
            
            prevCodePoint = 0;
        }
        
        boundingBox.height = glyphPos.y + lineSpacing;
        boundingBox.height += vspace;

        usize numVertices = vertices.getVertexCount();
        for(usize i = 0; i < numVertices; i += 4)
        {
            const sf::Vertex &bottomRight = vertices[i + 2];
            boundingBox.width = std::max(boundingBox.width, bottomRight.position.x);
        }

        dirty = false;
    }
    
    void Text::updateCaret()
    {
        assert(!dirty && !dirtyText);
        if(textElements.size() == 0)
        {
            float vspace = font->getLineSpacing(characterSize);
            caretIndex = 0;
            caretPosition = sf::Vector2f(0.0f, -vspace);
            return;
        }
        
        switch(caretMoveDirection)
        {
            case CaretMoveDirection::UP:
            {
                caretIndex = getPreviousLineClosestPosition(caretIndex);
                break;
            }
            case CaretMoveDirection::DOWN:
            {
                caretIndex = getNextLineClosestPosition(caretIndex);
                break;
            }
            case CaretMoveDirection::HOME:
            {
                caretIndex = getStartOfLine(caretIndex);
                break;
            }
            case CaretMoveDirection::END:
            {
                caretIndex = getEndOfLine(caretIndex);
                break;
            }
            default:
                // Ignore...
                break;
        }
        
        caretIndex = std::min(std::max(0, caretIndex), (int)textElements[0].text.size);
        
        usize vertexIndex = caretIndex * 4;
        if(vertexIndex == 0)
        {
            float vspace = font->getLineSpacing(characterSize);
            caretPosition = sf::Vector2f(0.0f, -vspace);
        }
        else
        {
            const sf::Vertex &topLeftVertex = vertices[vertexIndex];
            caretPosition = topLeftVertex.position;
        }
    }
    
    bool Text::isCaretAtEnd() const
    {
        assert(!dirty && !dirtyText);
        return textElements[0].text.size == 0 || caretIndex == (int)textElements[0].text.size;
    }
    
    // TODO: This can be optimized by using binary search
    int Text::getStartOfLine(int startIndex) const
    {
        assert(!dirty && !dirtyText);
        int numVertices = vertices.getVertexCount();
        if(numVertices < 4) return 0;
        
        usize vertexIndex = startIndex * 4;
        const sf::Vertex &startTopLeftVertex = vertices[vertexIndex];
        int startRow = getRowByPosition(startTopLeftVertex.position);
        for(int i = startIndex * 4; i > 0; i -= 4)
        {
            const sf::Vertex &topLeftVertex = vertices[i];
            int row = getRowByPosition(topLeftVertex.position);
            if(row != startRow)
            {
                return std::max(0, i / 4 + 1);
            }
        }
        return 0;
    }
    
    // TODO: This can be optimized by using binary search
    int Text::getEndOfLine(int startIndex) const
    {
        assert(!dirty && !dirtyText);
        int numVertices = vertices.getVertexCount();
        if(numVertices < 4) return 0;
        
        usize vertexIndex = startIndex * 4;
        const sf::Vertex &startTopLeftVertex = vertices[vertexIndex];
        int startRow = getRowByPosition(startTopLeftVertex.position);
        for(int i = startIndex * 4; i < numVertices; i += 4)
        {
            const sf::Vertex &topLeftVertex = vertices[i];
            int row = getRowByPosition(topLeftVertex.position);
            if(row != startRow)
            {
                return std::max(0, i / 4 - 1);
            }
        }
        return numVertices / 4;
    }
    
    // TODO: This can be optimized by using binary search
    int Text::getPreviousLineClosestPosition(int startIndex) const
    {
        assert(!dirty && !dirtyText);
        int numVertices = vertices.getVertexCount();
        if(numVertices < 4) return 0;
        
        usize vertexIndex = startIndex * 4;
        const sf::Vertex &startTopLeftVertex = vertices[vertexIndex];
        int startRow = getRowByPosition(startTopLeftVertex.position);
        int closestIndex = -1;
        float closestAbsoluteDiffX = 0.0f;
        for(int i = startIndex * 4; i >= 0; i -= 4)
        {
            const sf::Vertex &topLeftVertex = vertices[i];
            int row = getRowByPosition(topLeftVertex.position);
            float absoluteDiffX = fabs(topLeftVertex.position.x - startTopLeftVertex.position.x);
            int rowDiff = abs(row - startRow);
            if(rowDiff > 1)
                break;
            
            if(rowDiff == 1 && (closestIndex == -1 || absoluteDiffX < closestAbsoluteDiffX))
            {
                closestIndex = i;
                closestAbsoluteDiffX = absoluteDiffX;
            }
        }
        
        if(closestIndex != -1)
            return closestIndex / 4;
        
        return 0;
    }
    
    // TODO: This can be optimized by using binary search
    int Text::getNextLineClosestPosition(int startIndex) const
    {
        assert(!dirty && !dirtyText);
        int numVertices = vertices.getVertexCount();
        if(numVertices < 4) return 0;
        
        usize vertexIndex = startIndex * 4;
        const sf::Vertex &startTopLeftVertex = vertices[vertexIndex];
        int startRow = getRowByPosition(startTopLeftVertex.position);
        int closestIndex = -1;
        float closestAbsoluteDiffX = 0.0f;
        for(int i = startIndex * 4; i < numVertices; i += 4)
        {
            const sf::Vertex &topLeftVertex = vertices[i];
            int row = getRowByPosition(topLeftVertex.position);
            float absoluteDiffX = fabs(topLeftVertex.position.x - startTopLeftVertex.position.x);
            int rowDiff = abs(row - startRow);
            if(rowDiff > 1)
                break;
            
            if(rowDiff == 1 && (closestIndex == -1 || absoluteDiffX < closestAbsoluteDiffX))
            {
                closestIndex = i;
                closestAbsoluteDiffX = absoluteDiffX;
            }
        }
        
        if(closestIndex != -1)
            return closestIndex / 4;
        
        return numVertices / 4;
    }
    
    int Text::getRowByPosition(const sf::Vector2f &position) const
    {
        assert(!dirty && !dirtyText);
        const float vspace = font->getLineSpacing(characterSize);
        return static_cast<int>(1.0f + position.y / (vspace + lineSpacing));
    }
    
    void Text::processEvent(const sf::Event &event)
    {
        if(!editable) return;
        
        bool caretAtEnd = textElements.size() == 0 || textElements[0].text.size == 0 || caretIndex == (int)textElements[0].text.size;
        
        if(event.type == sf::Event::KeyPressed)
        {
            if(event.key.code == sf::Keyboard::Left && caretIndex > 0)
            {
                --caretIndex;
                dirtyCaret = true;
            }
            else if(event.key.code == sf::Keyboard::Right && !caretAtEnd)
            {
                ++caretIndex;
                dirtyCaret = true;
            }
            else if(event.key.code == sf::Keyboard::BackSpace && caretIndex > 0)
            {
                auto strBefore = str.substring(0, caretIndex - 1);
                auto strAfter = str.substring(caretIndex);
                --caretIndex;
                setString(strBefore + strAfter);
                dirtyCaret = true;
            }
            else if(event.key.code == sf::Keyboard::Delete && !caretAtEnd)
            {
                auto strBefore = str.substring(0, caretIndex);
                auto strAfter = str.substring(caretIndex + 1);
                setString(strBefore + strAfter);
            }
            else if(event.key.code == sf::Keyboard::Up)
            {
                caretMoveDirection = CaretMoveDirection::UP;
            }
            else if(event.key.code == sf::Keyboard::Down)
            {
                caretMoveDirection = CaretMoveDirection::DOWN;
            }
            else if(event.key.code == sf::Keyboard::Home)
            {
                caretMoveDirection = CaretMoveDirection::HOME;
            }
            else if(event.key.code == sf::Keyboard::End)
            {
                caretMoveDirection = CaretMoveDirection::END;
            }
            else if(event.key.code == sf::Keyboard::Return)
            {
                if(sf::Keyboard::isKeyPressed(sf::Keyboard::LShift) || sf::Keyboard::isKeyPressed(sf::Keyboard::RShift))
                {
                    if(caretAtEnd)
                        str += '\n';
                    else
                    {
                        auto strBefore = str.substring(0, caretIndex);
                        auto strAfter = str.substring(caretIndex);
                        str = strBefore + '\n' + strAfter;
                    }
                    
                    ++caretIndex;
                    dirty = true;
                    dirtyText = true;
                    dirtyCaret = true;
                }
            }
        }
        else if(event.type == sf::Event::TextEntered)
        {
            if(event.text.unicode == 8 || event.text.unicode == 127) // backspace, del
                return;
            
            sf::String stringToAdd;
            if(event.text.unicode == 22) // ctrl+v
            {
                stringToAdd = sf::Clipboard::getString();
            }
            else if(event.text.unicode >= 32 || event.text.unicode == 9) // 9 == tab
                stringToAdd = event.text.unicode;
            else
                return;
            
            if(caretAtEnd)
                str += stringToAdd;
            else
            {
                auto strBefore = str.substring(0, caretIndex);
                auto strAfter = str.substring(caretIndex);
                str = strBefore + stringToAdd + strAfter;
            }
            
            caretIndex += stringToAdd.getSize();
            dirty = true;
            dirtyText = true;
            dirtyCaret = true;
        }
    }
    
    bool Text::draw(sf::RenderTarget &target)
    {
        updateGeometry();
        
        if(dirtyCaret || caretMoveDirection != CaretMoveDirection::NONE)
        {
            updateCaret();
            dirtyCaret = false;
            caretMoveDirection = CaretMoveDirection::NONE;
        }
        
        float vspace = font->getLineSpacing(characterSize);
        
        sf::RenderStates states;
        sf::Vector2f pos = position;
        pos.y += floor(vspace); // Origin is at bottom left, we want it to be at top left
        
        // TODO: Do not use maxWidth here. Max width might be set to 99999 and actual text width might be 200. Text width should be calculated instead
        //sf::FloatRect targetRect(0.0f, 0.0f, maxWidth, target.getSize().y);
        //sf::FloatRect textRect(pos.x, pos.y, maxWidth, )
        //colRect.contains()
        //if(pos.x + maxWidth <= 0.0f || pos.x >= maxWidth || pos.y + totalHeight <= 0.0f || pos.y >= target.getSize().y) return;
        renderTargetSize = target.getSize();
        if(pos.y + getHeight() <= 0.0f || pos.y >= renderTargetSize.y)
        {
            if(!editable && visible && lastSeenTimer.getElapsedTime().asMilliseconds() > 3000)
            {
                visible = false;
                vertices.resize(0);
            }
            return false;
        }
        
        if(!visible)
            updateGeometry(true);
        
        states.transform.translate(pos);
        states.texture = &font->getTexture(characterSize);
        target.draw(vertices, states);
        lastSeenTimer.restart();
        visible = true;
        
        pos.y -= floor(vspace);
        
        if(!editable) return true;
        
        //float rows = floor(totalHeight / (vspace + lineSpacing));
        const float caretRow = getRowByPosition(caretPosition);
        
        sf::RectangleShape caretRect(sf::Vector2f(2.0f, floor(vspace)));
        caretRect.setFillColor(sf::Color::White);
        caretRect.setPosition(sf::Vector2f(floor(pos.x + caretPosition.x), floor(pos.y + caretRow * (vspace + lineSpacing))));
        target.draw(caretRect);
        return true;
    }
}