#include "formatting.hpp"

#include <charconv>
#include <system_error>

#include <MyGUI_EditBox.h>
#include <MyGUI_EditText.h>
#include <MyGUI_Gui.h>
#include <MyGUI_ImageBox.h>

#include <components/debug/debuglog.hpp>
#include <components/fontloader/fontloader.hpp>
#include <components/interpreter/defines.hpp>
#include <components/misc/resourcehelpers.hpp>
#include <components/misc/strings/algorithm.hpp>
#include <components/resource/resourcesystem.hpp>
#include <components/settings/values.hpp>
#include <components/vfs/manager.hpp>

#include "../mwbase/environment.hpp"
#include "../mwscript/interpretercontext.hpp"

namespace MWGui::Formatting
{
    /* BookTextParser */
    BookTextParser::BookTextParser(const std::string& text, bool shrinkTextAtLastTag)
        : mIndex(0)
        , mText(text)
        , mIgnoreNewlineTags(true)
        , mIgnoreLineEndings(true)
        , mClosingTag(false)
    {
        MWScript::InterpreterContext interpreterContext(
            nullptr, MWWorld::Ptr()); // empty arguments, because there is no locals or actor
        mText = Interpreter::fixDefinesBook(mText, interpreterContext);

        Misc::StringUtils::replaceAll(mText, "\r", {});

        if (shrinkTextAtLastTag)
        {
            // vanilla game does not show any text after the last EOL tag.
            const std::string lowerText = Misc::StringUtils::lowerCase(mText);
            size_t brIndex = lowerText.rfind("<br>");
            size_t pIndex = lowerText.rfind("<p>");
            mPlainTextEnd = 0;
            if (brIndex != pIndex)
            {
                if (brIndex != std::string::npos && pIndex != std::string::npos)
                    mPlainTextEnd = std::max(brIndex, pIndex);
                else if (brIndex != std::string::npos)
                    mPlainTextEnd = brIndex;
                else
                    mPlainTextEnd = pIndex;
            }
        }
        else
            mPlainTextEnd = mText.size();

        registerTag("br", Event_BrTag);
        registerTag("p", Event_PTag);
        registerTag("img", Event_ImgTag);
        registerTag("div", Event_DivTag);
        registerTag("font", Event_FontTag);
    }

    void BookTextParser::registerTag(const std::string& tag, BookTextParser::Events type)
    {
        mTagTypes[tag] = type;
    }

    std::string BookTextParser::getReadyText() const
    {
        return mReadyText;
    }

    BookTextParser::Events BookTextParser::next()
    {
        while (mIndex < mText.size())
        {
            char ch = mText[mIndex];
            if (ch == '[')
            {
                constexpr std::string_view pageBreakTag = "[pagebreak]\n";
                if (std::string_view(mText.data() + mIndex, mText.size() - mIndex).starts_with(pageBreakTag))
                {
                    mIndex += pageBreakTag.size();
                    flushBuffer();
                    mIgnoreNewlineTags = false;
                    return Event_PageBreak;
                }
            }
            if (ch == '<')
            {
                const size_t tagStart = mIndex + 1;
                const size_t tagEnd = mText.find('>', tagStart);
                if (tagEnd == std::string::npos)
                    throw std::runtime_error("BookTextParser Error: Tag is not terminated");
                parseTag(mText.substr(tagStart, tagEnd - tagStart));
                mIndex = tagEnd;

                if (auto it = mTagTypes.find(mTag); it != mTagTypes.end())
                {
                    Events type = it->second;

                    if (type == Event_BrTag || type == Event_PTag)
                    {
                        if (!mIgnoreNewlineTags)
                        {
                            if (type == Event_BrTag)
                                mBuffer.push_back('\n');
                            else
                            {
                                mBuffer.append("\n\n");
                            }
                        }
                        mIgnoreLineEndings = true;
                        if (type == Event_PTag && !mAttributes.empty())
                            flushBuffer();
                    }
                    else
                        flushBuffer();

                    if (type == Event_ImgTag)
                    {
                        mIgnoreNewlineTags = false;
                    }

                    ++mIndex;
                    return type;
                }
            }
            else
            {
                if (!mIgnoreLineEndings || ch != '\n')
                {
                    if (mIndex < mPlainTextEnd)
                        mBuffer.push_back(ch);
                    mIgnoreLineEndings = false;
                    mIgnoreNewlineTags = false;
                }
            }

            ++mIndex;
        }

        flushBuffer();
        return Event_EOF;
    }

    void BookTextParser::flushBuffer()
    {
        mReadyText = mBuffer;
        mBuffer.clear();
    }

    const BookTextParser::Attributes& BookTextParser::getAttributes() const
    {
        return mAttributes;
    }

    bool BookTextParser::isClosingTag() const
    {
        return mClosingTag;
    }

    void BookTextParser::parseTag(std::string tag)
    {
        size_t tagNameEndPos = tag.find(' ');
        mAttributes.clear();
        mTag = tag.substr(0, tagNameEndPos);
        Misc::StringUtils::lowerCaseInPlace(mTag);
        if (mTag.empty())
            return;

        mClosingTag = (mTag[0] == '/');
        if (mClosingTag)
        {
            mTag.erase(mTag.begin());
            return;
        }

        if (tagNameEndPos == std::string::npos)
            return;
        tag.erase(0, tagNameEndPos + 1);

        while (!tag.empty())
        {
            size_t sepPos = tag.find('=');
            if (sepPos == std::string::npos)
                return;

            std::string key = tag.substr(0, sepPos);
            Misc::StringUtils::lowerCaseInPlace(key);
            tag.erase(0, sepPos + 1);

            std::string value;

            if (tag.empty())
                return;

            if (tag[0] == '"' || tag[0] == '\'')
            {
                size_t quoteEndPos = tag.find(tag[0], 1);
                if (quoteEndPos == std::string::npos)
                    throw std::runtime_error("BookTextParser Error: Missing end quote in tag");
                value = tag.substr(1, quoteEndPos - 1);
                tag.erase(0, quoteEndPos + 2);
            }
            else
            {
                size_t valEndPos = tag.find(' ');
                if (valEndPos == std::string::npos)
                {
                    value = tag;
                    tag.erase();
                }
                else
                {
                    value = tag.substr(0, valEndPos);
                    tag.erase(0, valEndPos + 1);
                }
            }

            mAttributes[key] = std::move(value);
        }
    }

    /* BookFormatter */
    Paginator::Pages BookFormatter::markupToWidget(MyGUI::Widget* parent, const std::string& markup,
        const int pageWidth, const int pageHeight, bool shrinkTextAtLastTag)
    {
        Paginator pag(pageWidth, pageHeight);

        while (parent->getChildCount())
        {
            MyGUI::Gui::getInstance().destroyWidget(parent->getChildAt(0));
        }

        mTextStyle = TextStyle();
        mBlockStyle = BlockStyle();

        MyGUI::Widget* paper = parent->createWidget<MyGUI::Widget>("Widget",
            MyGUI::IntCoord(0, 0, pag.getPageWidth(), pag.getPageHeight()), MyGUI::Align::Left | MyGUI::Align::Top);
        paper->setNeedMouseFocus(false);

        BookTextParser parser(markup, shrinkTextAtLastTag);

        bool brBeforeLastTag = false;
        bool isPrevImg = false;
        bool inlineImageInserted = false;
        for (;;)
        {
            BookTextParser::Events event = parser.next();
            if (event == BookTextParser::Event_BrTag
                || (event == BookTextParser::Event_PTag && parser.getAttributes().empty()))
                continue;

            std::string plainText = parser.getReadyText();

            // for cases when linebreaks are used to cause a shift to the next page
            // if the split text block ends in an empty line, proceeding text block(s) should have leading empty lines
            // removed
            if (pag.getIgnoreLeadingEmptyLines())
            {
                while (!plainText.empty())
                {
                    if (plainText[0] == '\n')
                        plainText.erase(plainText.begin());
                    else
                    {
                        pag.setIgnoreLeadingEmptyLines(false);
                        break;
                    }
                }
            }

            if (plainText.empty())
                brBeforeLastTag = true;
            else
            {
                // Each block of text (between two tags / boundary and tag) will be displayed in a separate editbox
                // widget, which means an additional linebreak will be created between them. ^ This is not what vanilla
                // MW assumes, so we must deal with line breaks around tags appropriately.
                bool brAtStart = (plainText[0] == '\n');
                bool brAtEnd = (plainText[plainText.size() - 1] == '\n');

                if (brAtStart && !brBeforeLastTag && !isPrevImg)
                    plainText.erase(plainText.begin());

                if (plainText.size() && brAtEnd)
                    plainText.erase(plainText.end() - 1);

                if (!plainText.empty() || brBeforeLastTag || isPrevImg)
                {
                    if (inlineImageInserted)
                    {
                        pag.setCurrentTop(pag.getCurrentTop() - mTextStyle.mTextSize);
                        plainText = "        " + plainText;
                        inlineImageInserted = false;
                    }
                    TextElement elem(paper, pag, mBlockStyle, mTextStyle, plainText);
                    elem.paginate();
                }

                brBeforeLastTag = brAtEnd;
            }

            if (event == BookTextParser::Event_EOF)
                break;

            isPrevImg = (event == BookTextParser::Event_ImgTag);

            switch (event)
            {
                case BookTextParser::Event_PageBreak:
                    pag << Paginator::Page(pag.getStartTop(), pag.getCurrentTop());
                    pag.setStartTop(pag.getCurrentTop());
                    break;
                case BookTextParser::Event_ImgTag:
                {
                    const BookTextParser::Attributes& attr = parser.getAttributes();

                    auto srcIt = attr.find("src");
                    if (srcIt == attr.end())
                        continue;
                    int width = 0;
                    if (auto widthIt = attr.find("width"); widthIt != attr.end())
                        width = MyGUI::utility::parseInt(widthIt->second);
                    int height = 0;
                    if (auto heightIt = attr.find("height"); heightIt != attr.end())
                        height = MyGUI::utility::parseInt(heightIt->second);

                    const std::string& src = srcIt->second;
                    auto vfs = MWBase::Environment::get().getResourceSystem()->getVFS();

                    std::string correctedSrc;

                    constexpr std::string_view imgPrefix = "img://";
                    if (src.starts_with(imgPrefix))
                    {
                        correctedSrc = src.substr(imgPrefix.size(), src.size() - imgPrefix.size());
                        if (width == 0)
                        {
                            width = 50;
                            inlineImageInserted = true;
                        }
                        if (height == 0)
                            height = 50;
                    }
                    else
                    {
                        if (width == 0 || height == 0)
                            continue;
                        correctedSrc = Misc::ResourceHelpers::correctBookartPath(src, width, height, vfs);
                    }

                    if (!vfs->exists(correctedSrc))
                    {
                        Log(Debug::Warning) << "Warning: Could not find \"" << src << "\" referenced by an <img> tag.";
                        break;
                    }

                    pag.setIgnoreLeadingEmptyLines(false);

                    ImageElement elem(paper, pag, mBlockStyle, correctedSrc, width, height);
                    elem.paginate();
                    break;
                }
                case BookTextParser::Event_FontTag:
                    if (parser.isClosingTag())
                        resetFontProperties();
                    else
                        handleFont(parser.getAttributes());
                    break;
                case BookTextParser::Event_PTag:
                case BookTextParser::Event_DivTag:
                    handleDiv(parser.getAttributes());
                    break;
                default:
                    break;
            }
        }

        // insert last page
        if (pag.getStartTop() != pag.getCurrentTop())
            pag << Paginator::Page(pag.getStartTop(), pag.getStartTop() + pag.getPageHeight());

        paper->setSize(paper->getWidth(), pag.getCurrentTop());

        return pag.getPages();
    }

    Paginator::Pages BookFormatter::markupToWidget(
        MyGUI::Widget* parent, const std::string& markup, bool shrinkTextAtLastTag)
    {
        return markupToWidget(parent, markup, parent->getWidth(), parent->getHeight(), shrinkTextAtLastTag);
    }

    void BookFormatter::resetFontProperties()
    {
        mTextStyle = TextStyle();
    }

    void BookFormatter::handleDiv(const BookTextParser::Attributes& attr)
    {
        auto it = attr.find("align");
        if (it == attr.end())
            return;

        const std::string& align = it->second;

        if (Misc::StringUtils::ciEqual(align, "center"))
            mBlockStyle.mAlign = MyGUI::Align::HCenter;
        else if (Misc::StringUtils::ciEqual(align, "left"))
            mBlockStyle.mAlign = MyGUI::Align::Left;
        else if (Misc::StringUtils::ciEqual(align, "right"))
            mBlockStyle.mAlign = MyGUI::Align::Right;
    }

    void BookFormatter::handleFont(const BookTextParser::Attributes& attr)
    {
        auto it = attr.find("color");
        if (it != attr.end())
        {
            const auto& colorString = it->second;
            unsigned int color = 0;
            std::from_chars(colorString.data(), colorString.data() + colorString.size(), color, 16);

            mTextStyle.mColour
                = MyGUI::Colour((color >> 16 & 0xFF) / 255.f, (color >> 8 & 0xFF) / 255.f, (color & 0xFF) / 255.f);
        }
        it = attr.find("face");
        if (it != attr.end())
        {
            const std::string& face = it->second;
            std::string name{ Gui::FontLoader::getFontForFace(face) };

            mTextStyle.mFont = "Journalbook " + name;
        }
        if (attr.find("size") != attr.end())
        {
            /// \todo
        }
    }

    /* GraphicElement */
    GraphicElement::GraphicElement(MyGUI::Widget* parent, Paginator& pag, const BlockStyle& blockStyle)
        : mParent(parent)
        , mPaginator(pag)
        , mBlockStyle(blockStyle)
    {
    }

    void GraphicElement::paginate()
    {
        int newTop = mPaginator.getCurrentTop() + getHeight();
        while (newTop - mPaginator.getStartTop() > mPaginator.getPageHeight())
        {
            int newStartTop = pageSplit();
            mPaginator << Paginator::Page(mPaginator.getStartTop(), newStartTop);
            mPaginator.setStartTop(newStartTop);
        }

        mPaginator.setCurrentTop(newTop);
    }

    int GraphicElement::pageSplit()
    {
        return mPaginator.getStartTop() + mPaginator.getPageHeight();
    }

    /* TextElement */
    TextElement::TextElement(MyGUI::Widget* parent, Paginator& pag, const BlockStyle& blockStyle,
        const TextStyle& textStyle, const std::string& text)
        : GraphicElement(parent, pag, blockStyle)
        , mTextStyle(textStyle)
    {
        Gui::EditBox* box = parent->createWidget<Gui::EditBox>("NormalText",
            MyGUI::IntCoord(0, pag.getCurrentTop(), pag.getPageWidth(), 0), MyGUI::Align::Left | MyGUI::Align::Top,
            parent->getName() + MyGUI::utility::toString(parent->getChildCount()));
        box->setEditStatic(true);
        box->setEditMultiLine(true);
        box->setEditWordWrap(true);
        box->setNeedMouseFocus(false);
        box->setNeedKeyFocus(false);
        box->setMaxTextLength(text.size());
        box->setTextAlign(mBlockStyle.mAlign);
        box->setTextColour(mTextStyle.mColour);
        box->setFontName(mTextStyle.mFont);
        box->setCaption(MyGUI::TextIterator::toTagsString(text));
        box->setSize(box->getSize().width, box->getTextSize().height);
        mEditBox = box;
    }

    int TextElement::getHeight()
    {
        return mEditBox->getTextSize().height;
    }

    int TextElement::pageSplit()
    {
        // split lines
        const int lineHeight = Settings::gui().mFontSize;
        unsigned int lastLine = (mPaginator.getStartTop() + mPaginator.getPageHeight() - mPaginator.getCurrentTop());
        if (lineHeight > 0)
            lastLine /= lineHeight;
        int ret = mPaginator.getCurrentTop() + lastLine * lineHeight;

        // first empty lines that would go to the next page should be ignored
        mPaginator.setIgnoreLeadingEmptyLines(true);

        const MyGUI::VectorLineInfo& lines = mEditBox->getSubWidgetText()->castType<MyGUI::EditText>()->getLineInfo();
        for (size_t i = lastLine; i < lines.size(); ++i)
        {
            if (lines[i].width == 0)
                ret += lineHeight;
            else
            {
                mPaginator.setIgnoreLeadingEmptyLines(false);
                break;
            }
        }
        return ret;
    }

    /* ImageElement */
    ImageElement::ImageElement(MyGUI::Widget* parent, Paginator& pag, const BlockStyle& blockStyle,
        const std::string& src, int width, int height)
        : GraphicElement(parent, pag, blockStyle)
        , mImageHeight(height)
    {
        int left = 0;
        if (mBlockStyle.mAlign.isHCenter())
            left += (pag.getPageWidth() - width) / 2;
        else if (mBlockStyle.mAlign.isLeft())
            left = 0;
        else if (mBlockStyle.mAlign.isRight())
            left += pag.getPageWidth() - width;

        mImageBox = parent->createWidget<MyGUI::ImageBox>("ImageBox",
            MyGUI::IntCoord(left, pag.getCurrentTop(), width, mImageHeight), MyGUI::Align::Left | MyGUI::Align::Top,
            parent->getName() + MyGUI::utility::toString(parent->getChildCount()));

        mImageBox->setImageTexture(src);
        mImageBox->setProperty("NeedMouse", "false");
    }

    int ImageElement::getHeight()
    {
        return mImageHeight;
    }

    int ImageElement::pageSplit()
    {
        // if the image is larger than the page, fall back to the default pageSplit implementation
        if (mImageHeight > mPaginator.getPageHeight())
            return GraphicElement::pageSplit();
        return mPaginator.getCurrentTop();
    }
}