/*
  ==============================================================================

   This file is part of the JUCE 6 technical preview.
   Copyright (c) 2020 - Raw Material Software Limited

   You may use this code under the terms of the GPL v3
   (see www.gnu.org/licenses).

   For this technical preview, this file is not subject to commercial licensing.

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

  ==============================================================================
*/

namespace juce
{

static String substring (const String& text, Range<int> range)
{
    return text.substring (range.getStart(), range.getEnd());
}

TextLayout::Glyph::Glyph (int glyph, Point<float> anch, float w) noexcept
    : glyphCode (glyph), anchor (anch), width (w)
{
}

TextLayout::Glyph::Glyph (const Glyph& other) noexcept
    : glyphCode (other.glyphCode), anchor (other.anchor), width (other.width)
{
}

TextLayout::Glyph& TextLayout::Glyph::operator= (const Glyph& other) noexcept
{
    glyphCode = other.glyphCode;
    anchor = other.anchor;
    width = other.width;
    return *this;
}

TextLayout::Glyph::~Glyph() noexcept {}

//==============================================================================
TextLayout::Run::Run() noexcept
    : colour (0xff000000)
{
}

TextLayout::Run::Run (Range<int> range, int numGlyphsToPreallocate)
    : colour (0xff000000), stringRange (range)
{
    glyphs.ensureStorageAllocated (numGlyphsToPreallocate);
}

TextLayout::Run::Run (const Run& other)
    : font (other.font),
      colour (other.colour),
      glyphs (other.glyphs),
      stringRange (other.stringRange)
{
}

TextLayout::Run::~Run() noexcept {}

Range<float> TextLayout::Run::getRunBoundsX() const noexcept
{
    Range<float> range;
    bool isFirst = true;

    for (auto& glyph : glyphs)
    {
        Range<float> r (glyph.anchor.x, glyph.anchor.x + glyph.width);

        if (isFirst)
        {
            isFirst = false;
            range = r;
        }
        else
        {
            range = range.getUnionWith (r);
        }
    }

    return range;
}

//==============================================================================
TextLayout::Line::Line() noexcept
    : ascent (0.0f), descent (0.0f), leading (0.0f)
{
}

TextLayout::Line::Line (Range<int> range, Point<float> o, float asc, float desc,
                        float lead, int numRunsToPreallocate)
    : stringRange (range), lineOrigin (o),
      ascent (asc), descent (desc), leading (lead)
{
    runs.ensureStorageAllocated (numRunsToPreallocate);
}

TextLayout::Line::Line (const Line& other)
    : stringRange (other.stringRange), lineOrigin (other.lineOrigin),
      ascent (other.ascent), descent (other.descent), leading (other.leading)
{
    runs.addCopiesOf (other.runs);
}

TextLayout::Line::~Line() noexcept
{
}

Range<float> TextLayout::Line::getLineBoundsX() const noexcept
{
    Range<float> range;
    bool isFirst = true;

    for (auto* run : runs)
    {
        auto runRange = run->getRunBoundsX();

        if (isFirst)
        {
            isFirst = false;
            range = runRange;
        }
        else
        {
            range = range.getUnionWith (runRange);
        }
    }

    return range + lineOrigin.x;
}

Range<float> TextLayout::Line::getLineBoundsY() const noexcept
{
    return { lineOrigin.y - ascent,
             lineOrigin.y + descent };
}

Rectangle<float> TextLayout::Line::getLineBounds() const noexcept
{
    auto x = getLineBoundsX();
    auto y = getLineBoundsY();

    return { x.getStart(), y.getStart(), x.getLength(), y.getLength() };
}

//==============================================================================
TextLayout::TextLayout()
    : width (0), height (0), justification (Justification::topLeft)
{
}

TextLayout::TextLayout (const TextLayout& other)
    : width (other.width), height (other.height),
      justification (other.justification)
{
    lines.addCopiesOf (other.lines);
}

TextLayout::TextLayout (TextLayout&& other) noexcept
    : lines (std::move (other.lines)),
      width (other.width), height (other.height),
      justification (other.justification)
{
}

TextLayout& TextLayout::operator= (TextLayout&& other) noexcept
{
    lines = std::move (other.lines);
    width = other.width;
    height = other.height;
    justification = other.justification;
    return *this;
}

TextLayout& TextLayout::operator= (const TextLayout& other)
{
    width = other.width;
    height = other.height;
    justification = other.justification;
    lines.clear();
    lines.addCopiesOf (other.lines);
    return *this;
}

TextLayout::~TextLayout()
{
}

TextLayout::Line& TextLayout::getLine (int index) const noexcept
{
    return *lines.getUnchecked (index);
}

void TextLayout::ensureStorageAllocated (int numLinesNeeded)
{
    lines.ensureStorageAllocated (numLinesNeeded);
}

void TextLayout::addLine (std::unique_ptr<Line> line)
{
    lines.add (line.release());
}

void TextLayout::draw (Graphics& g, Rectangle<float> area) const
{
    auto origin = justification.appliedToRectangle (Rectangle<float> (width, getHeight()), area).getPosition();

    auto& context   = g.getInternalContext();
    context.saveState();

    auto clip       = context.getClipBounds();
    auto clipTop    = clip.getY()      - origin.y;
    auto clipBottom = clip.getBottom() - origin.y;

    for (auto& line : *this)
    {
        auto lineRangeY = line.getLineBoundsY();

        if (lineRangeY.getEnd() < clipTop)
            continue;

        if (lineRangeY.getStart() > clipBottom)
            break;

        auto lineOrigin = origin + line.lineOrigin;

        for (auto* run : line.runs)
        {
            context.setFont (run->font);
            context.setFill (run->colour);

            for (auto& glyph : run->glyphs)
                context.drawGlyph (glyph.glyphCode, AffineTransform::translation (lineOrigin.x + glyph.anchor.x,
                                                                                  lineOrigin.y + glyph.anchor.y));

            if (run->font.isUnderlined())
            {
                auto runExtent = run->getRunBoundsX();
                auto lineThickness = run->font.getDescent() * 0.3f;

                context.fillRect ({ runExtent.getStart() + lineOrigin.x, lineOrigin.y + lineThickness * 2.0f,
                                    runExtent.getLength(), lineThickness });
            }
        }
    }

    context.restoreState();
}

void TextLayout::createLayout (const AttributedString& text, float maxWidth)
{
    createLayout (text, maxWidth, 1.0e7f);
}

void TextLayout::createLayout (const AttributedString& text, float maxWidth, float maxHeight)
{
    lines.clear();
    width = maxWidth;
    height = maxHeight;
    justification = text.getJustification();

    if (! createNativeLayout (text))
        createStandardLayout (text);

    recalculateSize();
}

void TextLayout::createLayoutWithBalancedLineLengths (const AttributedString& text, float maxWidth)
{
    createLayoutWithBalancedLineLengths (text, maxWidth, 1.0e7f);
}

void TextLayout::createLayoutWithBalancedLineLengths (const AttributedString& text, float maxWidth, float maxHeight)
{
    auto minimumWidth = maxWidth / 2.0f;
    auto bestWidth = maxWidth;
    float bestLineProportion = 0.0f;

    while (maxWidth > minimumWidth)
    {
        createLayout (text, maxWidth, maxHeight);

        if (getNumLines() < 2)
            return;

        auto line1 = lines.getUnchecked (lines.size() - 1)->getLineBoundsX().getLength();
        auto line2 = lines.getUnchecked (lines.size() - 2)->getLineBoundsX().getLength();
        auto shortest = jmin (line1, line2);
        auto longest  = jmax (line1, line2);
        auto prop = shortest > 0 ? longest / shortest : 1.0f;

        if (prop > 0.9f && prop < 1.1f)
            return;

        if (prop > bestLineProportion)
        {
            bestLineProportion = prop;
            bestWidth = maxWidth;
        }

        maxWidth -= 10.0f;
    }

    if (bestWidth != maxWidth)
        createLayout (text, bestWidth, maxHeight);
}

//==============================================================================
namespace TextLayoutHelpers
{
    struct Token
    {
        Token (const String& t, const Font& f, Colour c, bool whitespace)
            : text (t), font (f), colour (c),
              area (font.getStringWidthFloat (t), f.getHeight()),
              isWhitespace (whitespace),
              isNewLine (t.containsChar ('\n') || t.containsChar ('\r'))
        {}

        const String text;
        const Font font;
        const Colour colour;
        Rectangle<float> area;
        int line;
        float lineHeight;
        const bool isWhitespace, isNewLine;

        Token& operator= (const Token&) = delete;
    };

    struct TokenList
    {
        TokenList() noexcept {}

        void createLayout (const AttributedString& text, TextLayout& layout)
        {
            layout.ensureStorageAllocated (totalLines);

            addTextRuns (text);
            layoutRuns (layout.getWidth(), text.getLineSpacing(), text.getWordWrap());

            int charPosition = 0;
            int lineStartPosition = 0;
            int runStartPosition = 0;

            std::unique_ptr<TextLayout::Line> currentLine;
            std::unique_ptr<TextLayout::Run> currentRun;

            bool needToSetLineOrigin = true;

            for (int i = 0; i < tokens.size(); ++i)
            {
                auto& t = *tokens.getUnchecked (i);

                Array<int> newGlyphs;
                Array<float> xOffsets;
                t.font.getGlyphPositions (getTrimmedEndIfNotAllWhitespace (t.text), newGlyphs, xOffsets);

                if (currentRun == nullptr)  currentRun  = std::make_unique<TextLayout::Run>();
                if (currentLine == nullptr) currentLine = std::make_unique<TextLayout::Line>();

                if (newGlyphs.size() > 0)
                {
                    currentRun->glyphs.ensureStorageAllocated (currentRun->glyphs.size() + newGlyphs.size());
                    auto tokenOrigin = t.area.getPosition().translated (0, t.font.getAscent());

                    if (needToSetLineOrigin)
                    {
                        needToSetLineOrigin = false;
                        currentLine->lineOrigin = tokenOrigin;
                    }

                    auto glyphOffset = tokenOrigin - currentLine->lineOrigin;

                    for (int j = 0; j < newGlyphs.size(); ++j)
                    {
                        auto x = xOffsets.getUnchecked (j);
                        currentRun->glyphs.add (TextLayout::Glyph (newGlyphs.getUnchecked(j),
                                                                   glyphOffset.translated (x, 0),
                                                                   xOffsets.getUnchecked (j + 1) - x));
                    }

                    charPosition += newGlyphs.size();
                }
                else if (t.isWhitespace || t.isNewLine)
                {
                    ++charPosition;
                }

                if (auto* nextToken = tokens[i + 1])
                {
                    if (t.font != nextToken->font || t.colour != nextToken->colour)
                    {
                        addRun (*currentLine, currentRun.release(), t, runStartPosition, charPosition);
                        runStartPosition = charPosition;
                    }

                    if (t.line != nextToken->line)
                    {
                        if (currentRun == nullptr)
                            currentRun = std::make_unique<TextLayout::Run>();

                        addRun (*currentLine, currentRun.release(), t, runStartPosition, charPosition);
                        currentLine->stringRange = { lineStartPosition, charPosition };

                        if (! needToSetLineOrigin)
                            layout.addLine (std::move (currentLine));

                        runStartPosition = charPosition;
                        lineStartPosition = charPosition;
                        needToSetLineOrigin = true;
                    }
                }
                else
                {
                    addRun (*currentLine, currentRun.release(), t, runStartPosition, charPosition);
                    currentLine->stringRange = { lineStartPosition, charPosition };

                    if (! needToSetLineOrigin)
                        layout.addLine (std::move (currentLine));

                    needToSetLineOrigin = true;
                }
            }

            if ((text.getJustification().getFlags() & (Justification::right | Justification::horizontallyCentred)) != 0)
            {
                auto totalW = layout.getWidth();
                bool isCentred = (text.getJustification().getFlags() & Justification::horizontallyCentred) != 0;

                for (auto& line : layout)
                {
                    auto dx = totalW - line.getLineBoundsX().getLength();

                    if (isCentred)
                        dx /= 2.0f;

                    line.lineOrigin.x += dx;
                }
            }
        }

    private:
        static void addRun (TextLayout::Line& glyphLine, TextLayout::Run* glyphRun,
                            const Token& t, int start, int end)
        {
            glyphRun->stringRange = { start, end };
            glyphRun->font = t.font;
            glyphRun->colour = t.colour;
            glyphLine.ascent  = jmax (glyphLine.ascent,  t.font.getAscent());
            glyphLine.descent = jmax (glyphLine.descent, t.font.getDescent());
            glyphLine.runs.add (glyphRun);
        }

        static int getCharacterType (juce_wchar c) noexcept
        {
            if (c == '\r' || c == '\n')
                return 0;

            return CharacterFunctions::isWhitespace (c) ? 2 : 1;
        }

        void appendText (const String& stringText, const Font& font, Colour colour)
        {
            auto t = stringText.getCharPointer();
            String currentString;
            int lastCharType = 0;

            for (;;)
            {
                auto c = t.getAndAdvance();

                if (c == 0)
                    break;

                auto charType = getCharacterType (c);

                if (charType == 0 || charType != lastCharType)
                {
                    if (currentString.isNotEmpty())
                        tokens.add (new Token (currentString, font, colour,
                                               lastCharType == 2 || lastCharType == 0));

                    currentString = String::charToString (c);

                    if (c == '\r' && *t == '\n')
                        currentString += t.getAndAdvance();
                }
                else
                {
                    currentString += c;
                }

                lastCharType = charType;
            }

            if (currentString.isNotEmpty())
                tokens.add (new Token (currentString, font, colour, lastCharType == 2));
        }

        void layoutRuns (float maxWidth, float extraLineSpacing, AttributedString::WordWrap wordWrap)
        {
            float x = 0, y = 0, h = 0;
            int i;

            for (i = 0; i < tokens.size(); ++i)
            {
                auto& t = *tokens.getUnchecked(i);
                t.area.setPosition (x, y);
                t.line = totalLines;
                x += t.area.getWidth();
                h = jmax (h, t.area.getHeight() + extraLineSpacing);

                auto* nextTok = tokens[i + 1];

                if (nextTok == nullptr)
                    break;

                bool tokenTooLarge = (x + nextTok->area.getWidth() > maxWidth);

                if (t.isNewLine || ((! nextTok->isWhitespace) && (tokenTooLarge && wordWrap != AttributedString::none)))
                {
                    setLastLineHeight (i + 1, h);
                    x = 0;
                    y += h;
                    h = 0;
                    ++totalLines;
                }
            }

            setLastLineHeight (jmin (i + 1, tokens.size()), h);
            ++totalLines;
        }

        void setLastLineHeight (int i, float height) noexcept
        {
            while (--i >= 0)
            {
                auto& tok = *tokens.getUnchecked (i);

                if (tok.line == totalLines)
                    tok.lineHeight = height;
                else
                    break;
            }
        }

        void addTextRuns (const AttributedString& text)
        {
            auto numAttributes = text.getNumAttributes();
            tokens.ensureStorageAllocated (jmax (64, numAttributes));

            for (int i = 0; i < numAttributes; ++i)
            {
                auto& attr = text.getAttribute (i);

                appendText (substring (text.getText(), attr.range),
                            attr.font, attr.colour);
            }
        }

        static String getTrimmedEndIfNotAllWhitespace (const String& s)
        {
            auto trimmed = s.trimEnd();

            if (trimmed.isEmpty() && s.isNotEmpty())
                trimmed = s.replaceCharacters ("\r\n\t", "   ");

            return trimmed;
        }

        OwnedArray<Token> tokens;
        int totalLines = 0;

        JUCE_DECLARE_NON_COPYABLE (TokenList)
    };
}

//==============================================================================
void TextLayout::createStandardLayout (const AttributedString& text)
{
    TextLayoutHelpers::TokenList l;
    l.createLayout (text, *this);
}

void TextLayout::recalculateSize()
{
    if (! lines.isEmpty())
    {
        auto bounds = lines.getFirst()->getLineBounds();

        for (auto* line : lines)
            bounds = bounds.getUnion (line->getLineBounds());

        for (auto* line : lines)
            line->lineOrigin.x -= bounds.getX();

        width  = bounds.getWidth();
        height = bounds.getHeight();
    }
    else
    {
        width = 0;
        height = 0;
    }
}

} // namespace juce