////////////////////////////////////////////////////////////
//
// SFML - Simple and Fast Multimedia Library
// Copyright (C) 2007-2018 Laurent Gomila (laurent@sfml-dev.org)
//
// This software is provided 'as-is', without any express or implied warranty.
// In no event will the authors be held liable for any damages arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it freely,
// subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented;
//    you must not claim that you wrote the original software.
//    If you use this software in a product, an acknowledgment
//    in the product documentation would be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such,
//    and must not be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source distribution.
//
////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////
// Headers
////////////////////////////////////////////////////////////
#include <SFML/Graphics/Text.hpp>
#include <SFML/Graphics/Texture.hpp>
#include <SFML/Graphics/RenderTarget.hpp>
#include <cmath>


namespace
{
    // Add an underline or strikethrough line to the vertex array
    void addLine(sf::VertexArray& vertices, float lineLength, float lineTop, const sf::Color& color, float offset, float thickness, float outlineThickness = 0)
    {
        float top = std::floor(lineTop + offset - (thickness / 2) + 0.5f);
        float bottom = top + std::floor(thickness + 0.5f);

        vertices.append(sf::Vertex(sf::Vector2f(-outlineThickness,             top    - outlineThickness), color, sf::Vector2f(1, 1)));
        vertices.append(sf::Vertex(sf::Vector2f(lineLength + outlineThickness, top    - outlineThickness), color, sf::Vector2f(1, 1)));
        vertices.append(sf::Vertex(sf::Vector2f(-outlineThickness,             bottom + outlineThickness), color, sf::Vector2f(1, 1)));
        vertices.append(sf::Vertex(sf::Vector2f(-outlineThickness,             bottom + outlineThickness), color, sf::Vector2f(1, 1)));
        vertices.append(sf::Vertex(sf::Vector2f(lineLength + outlineThickness, top    - outlineThickness), color, sf::Vector2f(1, 1)));
        vertices.append(sf::Vertex(sf::Vector2f(lineLength + outlineThickness, bottom + outlineThickness), color, sf::Vector2f(1, 1)));
    }

    // Add a glyph quad to the vertex array
    void addGlyphQuad(sf::VertexArray& vertices, sf::Vector2f position, const sf::Color& color, const sf::Glyph& glyph, float italicShear, float outlineThickness = 0)
    {
        float left   = glyph.bounds.left;
        float top    = glyph.bounds.top;
        float right  = glyph.bounds.left + glyph.bounds.width;
        float bottom = glyph.bounds.top  + glyph.bounds.height;

        float u1 = static_cast<float>(glyph.textureRect.left);
        float v1 = static_cast<float>(glyph.textureRect.top);
        float u2 = static_cast<float>(glyph.textureRect.left + glyph.textureRect.width);
        float v2 = static_cast<float>(glyph.textureRect.top  + glyph.textureRect.height);

        vertices.append(sf::Vertex(sf::Vector2f(position.x + left  - italicShear * top    - outlineThickness, position.y + top    - outlineThickness), color, sf::Vector2f(u1, v1)));
        vertices.append(sf::Vertex(sf::Vector2f(position.x + right - italicShear * top    - outlineThickness, position.y + top    - outlineThickness), color, sf::Vector2f(u2, v1)));
        vertices.append(sf::Vertex(sf::Vector2f(position.x + left  - italicShear * bottom - outlineThickness, position.y + bottom - outlineThickness), color, sf::Vector2f(u1, v2)));
        vertices.append(sf::Vertex(sf::Vector2f(position.x + left  - italicShear * bottom - outlineThickness, position.y + bottom - outlineThickness), color, sf::Vector2f(u1, v2)));
        vertices.append(sf::Vertex(sf::Vector2f(position.x + right - italicShear * top    - outlineThickness, position.y + top    - outlineThickness), color, sf::Vector2f(u2, v1)));
        vertices.append(sf::Vertex(sf::Vector2f(position.x + right - italicShear * bottom - outlineThickness, position.y + bottom - outlineThickness), color, sf::Vector2f(u2, v2)));
    }
}


namespace sf
{
////////////////////////////////////////////////////////////
Text::Text() :
m_string             (),
m_font               (NULL),
m_characterSize      (30),
m_letterSpacingFactor(1.f),
m_lineSpacingFactor  (1.f),
m_style              (Regular),
m_fillColor          (255, 255, 255),
m_outlineColor       (0, 0, 0),
m_outlineThickness   (0),
m_vertices           (Triangles),
m_outlineVertices    (Triangles),
m_bounds             (),
m_geometryNeedUpdate (false),
m_fontTextureId      (0)
{

}


////////////////////////////////////////////////////////////
Text::Text(const String& string, const Font& font, unsigned int characterSize) :
m_string             (string),
m_font               (&font),
m_characterSize      (characterSize),
m_letterSpacingFactor(1.f),
m_lineSpacingFactor  (1.f),
m_style              (Regular),
m_fillColor          (255, 255, 255),
m_outlineColor       (0, 0, 0),
m_outlineThickness   (0),
m_vertices           (Triangles),
m_outlineVertices    (Triangles),
m_bounds             (),
m_geometryNeedUpdate (true),
m_fontTextureId      (0)
{

}


////////////////////////////////////////////////////////////
void Text::setString(const String& string)
{
    if (m_string != string)
    {
        m_string = string;
        m_geometryNeedUpdate = true;
    }
}


////////////////////////////////////////////////////////////
void Text::setFont(const Font& font)
{
    if (m_font != &font)
    {
        m_font = &font;
        m_geometryNeedUpdate = true;
    }
}


////////////////////////////////////////////////////////////
void Text::setCharacterSize(unsigned int size)
{
    if (m_characterSize != size)
    {
        m_characterSize = size;
        m_geometryNeedUpdate = true;
    }
}


////////////////////////////////////////////////////////////
void Text::setLetterSpacing(float spacingFactor)
{
    if (m_letterSpacingFactor != spacingFactor)
    {
        m_letterSpacingFactor = spacingFactor;
        m_geometryNeedUpdate = true;
    }
}


////////////////////////////////////////////////////////////
void Text::setLineSpacing(float spacingFactor)
{
    if (m_lineSpacingFactor != spacingFactor)
    {
        m_lineSpacingFactor = spacingFactor;
        m_geometryNeedUpdate = true;
    }
}


////////////////////////////////////////////////////////////
void Text::setStyle(Uint32 style)
{
    if (m_style != style)
    {
        m_style = style;
        m_geometryNeedUpdate = true;
    }
}


////////////////////////////////////////////////////////////
void Text::setColor(const Color& color)
{
    setFillColor(color);
}


////////////////////////////////////////////////////////////
void Text::setFillColor(const Color& color)
{
    if (color != m_fillColor)
    {
        m_fillColor = color;

        // Change vertex colors directly, no need to update whole geometry
        // (if geometry is updated anyway, we can skip this step)
        if (!m_geometryNeedUpdate)
        {
            for (std::size_t i = 0; i < m_vertices.getVertexCount(); ++i)
                m_vertices[i].color = m_fillColor;
        }
    }
}


////////////////////////////////////////////////////////////
void Text::setOutlineColor(const Color& color)
{
    if (color != m_outlineColor)
    {
        m_outlineColor = color;

        // Change vertex colors directly, no need to update whole geometry
        // (if geometry is updated anyway, we can skip this step)
        if (!m_geometryNeedUpdate)
        {
            for (std::size_t i = 0; i < m_outlineVertices.getVertexCount(); ++i)
                m_outlineVertices[i].color = m_outlineColor;
        }
    }
}


////////////////////////////////////////////////////////////
void Text::setOutlineThickness(float thickness)
{
    if (thickness != m_outlineThickness)
    {
        m_outlineThickness = thickness;
        m_geometryNeedUpdate = true;
    }
}


////////////////////////////////////////////////////////////
const String& Text::getString() const
{
    return m_string;
}


////////////////////////////////////////////////////////////
const Font* Text::getFont() const
{
    return m_font;
}


////////////////////////////////////////////////////////////
unsigned int Text::getCharacterSize() const
{
    return m_characterSize;
}


////////////////////////////////////////////////////////////
float Text::getLetterSpacing() const
{
    return m_letterSpacingFactor;
}


////////////////////////////////////////////////////////////
float Text::getLineSpacing() const
{
    return m_lineSpacingFactor;
}


////////////////////////////////////////////////////////////
Uint32 Text::getStyle() const
{
    return m_style;
}


////////////////////////////////////////////////////////////
const Color& Text::getColor() const
{
    return getFillColor();
}


////////////////////////////////////////////////////////////
const Color& Text::getFillColor() const
{
    return m_fillColor;
}


////////////////////////////////////////////////////////////
const Color& Text::getOutlineColor() const
{
    return m_outlineColor;
}


////////////////////////////////////////////////////////////
float Text::getOutlineThickness() const
{
    return m_outlineThickness;
}


////////////////////////////////////////////////////////////
Vector2f Text::findCharacterPos(std::size_t index) const
{
    // Make sure that we have a valid font
    if (!m_font)
        return Vector2f();

    // Adjust the index if it's out of range
    if (index > m_string.getSize())
        index = m_string.getSize();

    // Precompute the variables needed by the algorithm
    bool  isBold          = m_style & Bold;
    float whitespaceWidth = m_font->getGlyph(L' ', m_characterSize, isBold).advance;
    float letterSpacing   = ( whitespaceWidth / 3.f ) * ( m_letterSpacingFactor - 1.f );
    whitespaceWidth      += letterSpacing;
    float lineSpacing     = m_font->getLineSpacing(m_characterSize) * m_lineSpacingFactor;

    // Compute the position
    Vector2f position;
    Uint32 prevChar = 0;
    for (std::size_t i = 0; i < index; ++i)
    {
        Uint32 curChar = m_string[i];

        // Apply the kerning offset
        position.x += m_font->getKerning(prevChar, curChar, m_characterSize);
        prevChar = curChar;

        // Handle special characters
        switch (curChar)
        {
            case ' ':  position.x += whitespaceWidth;             continue;
            case '\t': position.x += whitespaceWidth * 4;         continue;
            case '\n': position.y += lineSpacing; position.x = 0; continue;
        }

        // For regular characters, add the advance offset of the glyph
        position.x += m_font->getGlyph(curChar, m_characterSize, isBold).advance + letterSpacing;
    }

    // Transform the position to global coordinates
    position = getTransform().transformPoint(position);

    return position;
}


////////////////////////////////////////////////////////////
FloatRect Text::getLocalBounds() const
{
    ensureGeometryUpdate();

    return m_bounds;
}


////////////////////////////////////////////////////////////
FloatRect Text::getGlobalBounds() const
{
    return getTransform().transformRect(getLocalBounds());
}


////////////////////////////////////////////////////////////
void Text::draw(RenderTarget& target, RenderStates states) const
{
    if (m_font)
    {
        ensureGeometryUpdate();

        states.transform *= getTransform();
        states.texture = &m_font->getTexture(m_characterSize);

        // Only draw the outline if there is something to draw
        if (m_outlineThickness != 0)
            target.draw(m_outlineVertices, states);

        target.draw(m_vertices, states);
    }
}


////////////////////////////////////////////////////////////
void Text::ensureGeometryUpdate() const
{
    if (!m_font)
        return;

    // Do nothing, if geometry has not changed and the font texture has not changed
    if (!m_geometryNeedUpdate && m_font->getTexture(m_characterSize).m_cacheId == m_fontTextureId)
        return;

    // Save the current fonts texture id
    m_fontTextureId = m_font->getTexture(m_characterSize).m_cacheId;

    // Mark geometry as updated
    m_geometryNeedUpdate = false;

    // Clear the previous geometry
    m_vertices.clear();
    m_outlineVertices.clear();
    m_bounds = FloatRect();

    // No text: nothing to draw
    if (m_string.isEmpty())
        return;

    // Compute values related to the text style
    bool  isBold             = m_style & Bold;
    bool  isUnderlined       = m_style & Underlined;
    bool  isStrikeThrough    = m_style & StrikeThrough;
    float italicShear        = (m_style & Italic) ? 0.209f : 0.f; // 12 degrees in radians
    float underlineOffset    = m_font->getUnderlinePosition(m_characterSize);
    float underlineThickness = m_font->getUnderlineThickness(m_characterSize);

    // Compute the location of the strike through dynamically
    // We use the center point of the lowercase 'x' glyph as the reference
    // We reuse the underline thickness as the thickness of the strike through as well
    FloatRect xBounds = m_font->getGlyph(L'x', m_characterSize, isBold).bounds;
    float strikeThroughOffset = xBounds.top + xBounds.height / 2.f;

    // Precompute the variables needed by the algorithm
    float whitespaceWidth = m_font->getGlyph(L' ', m_characterSize, isBold).advance;
    float letterSpacing   = ( whitespaceWidth / 3.f ) * ( m_letterSpacingFactor - 1.f );
    whitespaceWidth      += letterSpacing;
    float lineSpacing     = m_font->getLineSpacing(m_characterSize) * m_lineSpacingFactor;
    float x               = 0.f;
    float y               = static_cast<float>(m_characterSize);

    // Create one quad for each character
    float minX = static_cast<float>(m_characterSize);
    float minY = static_cast<float>(m_characterSize);
    float maxX = 0.f;
    float maxY = 0.f;
    Uint32 prevChar = 0;
    for (std::size_t i = 0; i < m_string.getSize(); ++i)
    {
        Uint32 curChar = m_string[i];

        // Apply the kerning offset
        x += m_font->getKerning(prevChar, curChar, m_characterSize);
        prevChar = curChar;

        // If we're using the underlined style and there's a new line, draw a line
        if (isUnderlined && (curChar == L'\n'))
        {
            addLine(m_vertices, x, y, m_fillColor, underlineOffset, underlineThickness);

            if (m_outlineThickness != 0)
                addLine(m_outlineVertices, x, y, m_outlineColor, underlineOffset, underlineThickness, m_outlineThickness);
        }

        // If we're using the strike through style and there's a new line, draw a line across all characters
        if (isStrikeThrough && (curChar == L'\n'))
        {
            addLine(m_vertices, x, y, m_fillColor, strikeThroughOffset, underlineThickness);

            if (m_outlineThickness != 0)
                addLine(m_outlineVertices, x, y, m_outlineColor, strikeThroughOffset, underlineThickness, m_outlineThickness);
        }

        // Handle special characters
        if ((curChar == L' ') || (curChar == L'\n') || (curChar == L'\t'))
        {
            // Update the current bounds (min coordinates)
            minX = std::min(minX, x);
            minY = std::min(minY, y);

            switch (curChar)
            {
                case L' ':  x += whitespaceWidth;     break;
                case L'\t': x += whitespaceWidth * 4; break;
                case L'\n': y += lineSpacing; x = 0;  break;
            }

            // Update the current bounds (max coordinates)
            maxX = std::max(maxX, x);
            maxY = std::max(maxY, y);

            // Next glyph, no need to create a quad for whitespace
            continue;
        }

        // Apply the outline
        if (m_outlineThickness != 0)
        {
            const Glyph& glyph = m_font->getGlyph(curChar, m_characterSize, isBold, m_outlineThickness);

            float left   = glyph.bounds.left;
            float top    = glyph.bounds.top;
            float right  = glyph.bounds.left + glyph.bounds.width;
            float bottom = glyph.bounds.top  + glyph.bounds.height;

            // Add the outline glyph to the vertices
            addGlyphQuad(m_outlineVertices, Vector2f(x, y), m_outlineColor, glyph, italicShear, m_outlineThickness);

            // Update the current bounds with the outlined glyph bounds
            minX = std::min(minX, x + left   - italicShear * bottom - m_outlineThickness);
            maxX = std::max(maxX, x + right  - italicShear * top    - m_outlineThickness);
            minY = std::min(minY, y + top    - m_outlineThickness);
            maxY = std::max(maxY, y + bottom - m_outlineThickness);
        }

        // Extract the current glyph's description
        const Glyph& glyph = m_font->getGlyph(curChar, m_characterSize, isBold);

        // Add the glyph to the vertices
        addGlyphQuad(m_vertices, Vector2f(x, y), m_fillColor, glyph, italicShear);

        // Update the current bounds with the non outlined glyph bounds
        if (m_outlineThickness == 0)
        {
            float left   = glyph.bounds.left;
            float top    = glyph.bounds.top;
            float right  = glyph.bounds.left + glyph.bounds.width;
            float bottom = glyph.bounds.top  + glyph.bounds.height;

            minX = std::min(minX, x + left  - italicShear * bottom);
            maxX = std::max(maxX, x + right - italicShear * top);
            minY = std::min(minY, y + top);
            maxY = std::max(maxY, y + bottom);
        }

        // Advance to the next character
        x += glyph.advance + letterSpacing;
    }

    // If we're using the underlined style, add the last line
    if (isUnderlined && (x > 0))
    {
        addLine(m_vertices, x, y, m_fillColor, underlineOffset, underlineThickness);

        if (m_outlineThickness != 0)
            addLine(m_outlineVertices, x, y, m_outlineColor, underlineOffset, underlineThickness, m_outlineThickness);
    }

    // If we're using the strike through style, add the last line across all characters
    if (isStrikeThrough && (x > 0))
    {
        addLine(m_vertices, x, y, m_fillColor, strikeThroughOffset, underlineThickness);

        if (m_outlineThickness != 0)
            addLine(m_outlineVertices, x, y, m_outlineColor, strikeThroughOffset, underlineThickness, m_outlineThickness);
    }

    // Update the bounding rectangle
    m_bounds.left = minX;
    m_bounds.top = minY;
    m_bounds.width = maxX - minX;
    m_bounds.height = maxY - minY;
}

} // namespace sf
