#include "MarkdownParser.h"

#include "MarkdownDocument.h"
#include "MarkdownComponents.h"

#include "Lexer.h"
#include "StringUtils.h"

#include <sstream>

static constexpr char MULTILINE_QUOTE_DELIMITER[]{"```"};
static constexpr char HEADING_DELIMITER{'#'};

MarkdownParser::MarkdownParser()
{
    mCustomMultilineDelimiters = {{"$$"}};
    mCustomInlineDelimiters = {{"$"}};
}

MarkdownParser::~MarkdownParser()
{

}

bool MarkdownParser::isInMultilineBlock() const
{
    if (!mWorkingElement)
    {
        return false;
    }
    auto working_type = mWorkingElement->getType();
    return working_type == MarkdownElement::Type::MULTILINE_QUOTE || working_type == MarkdownElement::Type::CUSTOM_MULTILINE ;
}

unsigned MarkdownParser::checkForLink(const std::string& lineSection)
{
    if (lineSection.empty())
    {
        return 0;
    }

    std::vector<std::string> hits;
    unsigned hit_size{0};
    if (Lexer::matchPattern("[@](@)", lineSection, '@', hits))
    {
        if (hits.size() == 2)
        {
            auto tag = hits[0];
            auto target = hits[1];

            onTextSpanFinished();

            auto element = std::make_unique<MarkdownLink>(target);
            element->appendTextContent(tag);
            addChildToWorkingElement(std::move(element));
            hit_size = 4 + tag.size() + target.size();
        }
    }
    return hit_size;
}

unsigned MarkdownParser::checkForImage(const std::string& lineSection)
{
    if (lineSection.empty())
    {
        return 0;
    }

    std::vector<std::string> hits;
    unsigned hit_size{0};
    if (Lexer::matchPattern("![@](@)", lineSection, '@', hits))
    {
        if (hits.size() == 2)
        {
            auto alt = hits[0];
            auto source = hits[1];

            onTextSpanFinished();

            auto element = std::make_unique<MarkdownImage>(source, alt);
            addChildToWorkingElement(std::move(element));
            hit_size = 5 + alt.size() + source.size();
        }
    }
    return hit_size;
}

unsigned MarkdownParser::checkForInlineQuote(const std::string& lineSection)
{
    if (lineSection.empty())
    {
        return 0;
    }

    std::vector<std::string> hits;
    unsigned hit_size{0};
    if (Lexer::matchPattern("`@`", lineSection, '@', hits))
    {
        if (hits.size() == 1)
        {
            auto content = hits[0];

            onTextSpanFinished();

            auto element = std::make_unique<MarkdownInlineQuote>();
            element->appendTextContent(content);

            addChildToWorkingElement(std::move(element));
            hit_size = 2 + content.size();
        }
    }
    return hit_size;
}
unsigned MarkdownParser::checkForCustomInline(const std::string& lineSection)
{
    if (lineSection.empty())
    {
        return 0;
    }

    std::vector<std::string> hits;
    unsigned hit_size{0};

    for(unsigned idx=0; idx<mCustomInlineDelimiters.size(); idx++)
    {
        const auto delimiter = mCustomInlineDelimiters[idx];
        if (Lexer::matchPattern(delimiter + "@" + delimiter, lineSection, '@', hits))
        {
            if (hits.size() == 1)
            {
                auto content = hits[0];

                onTextSpanFinished();

                auto element = std::make_unique<MarkdownCustomInline>(delimiter);
                element->appendTextContent(content);

                addChildToWorkingElement(std::move(element));
                hit_size = 2*delimiter.size() + content.size();
                break;
            }
        }
    }
    return hit_size;
}

void MarkdownParser::onTextSpanFinished()
{
    if (!mWorkingLine.empty())
    {
        if (mWorkingTextSpan)
        {
            mWorkingTextSpan->appendTextContent(mWorkingLine);
        }
        else
        {
            auto text_span = std::make_unique<MarkdownTextSpan>();
            text_span->addLine(mWorkingLine);
            mWorkingTextSpan = text_span.get();

            addChildToWorkingElement(std::move(text_span));
        }
        mWorkingLine.clear();
        mWorkingTextSpan = nullptr;
    }
}

void MarkdownParser::addChildToWorkingElement(std::unique_ptr<MarkdownInlineElement> child)
{
    dynamic_cast<MarkdownElementWithChildren*>(mWorkingElement)->addChild(std::move(child));
}

void MarkdownParser::processLine(const std::string& line)
{
    if (isInMultilineBlock())
    {
        mWorkingElement->addLine(line);
        return;
    }

    if (!mWorkingElement)
    {
        auto paragraph = std::make_unique<MarkdownParagraph>();
        mWorkingElement = paragraph.get();
        mMarkdownDocument->addElement(std::move(paragraph));
    }

    if (mWorkingElement && mWorkingElement->getType() == MarkdownElement::Type::PARAGRAPH)
    {
        if (auto last_text_span = dynamic_cast<MarkdownParagraph*>(mWorkingElement)->getLastChild())
        {
            mWorkingTextSpan = last_text_span;
        }
    }

    unsigned line_position = 0;
    mWorkingLine.clear();
    while(line_position < line.size())
    {
        const auto remaining = line.substr(line_position, line.size() - line_position);
        if(auto length = checkForImage(remaining))
        {
            line_position += length;
        }
        else if(auto length = checkForLink(remaining))
        {
            line_position += length;
        }
        else if(auto length = checkForInlineQuote(remaining))
        {
            line_position += length;
        }
        else if(auto length = checkForCustomInline(remaining))
        {
            line_position += length;
        }
        else
        {
            mWorkingLine += line[line_position];
            line_position++;
        }
    }
    onTextSpanFinished();
}

void MarkdownParser::onEmptyLine()
{
    if (!isInMultilineBlock())
    {
        onSectionFinished();
    }
}

bool MarkdownParser::startsWithMultiLineQuote(const std::string& line) const
{
    const bool ignore_whitespace{true};
    return StringUtils::startsWith(line, MULTILINE_QUOTE_DELIMITER, ignore_whitespace);
}

int MarkdownParser::startsWithCustomMultilineBlock(const std::string& line) const
{
    for(unsigned idx=0; idx<mCustomMultilineDelimiters.size(); idx++)
    {
        if (StringUtils::startsWith(line, mCustomMultilineDelimiters[idx], true))
        {
            return idx;
        }
    }
    return -1;
}

bool MarkdownParser::startsWithHeading(const std::string& line) const
{
    return StringUtils::startsWith(line, "#", true);
}

bool MarkdownParser::startsWithBulletItem(const std::string& line) const
{
    return StringUtils::startsWith(line, "*", true);
}

void MarkdownParser::onFoundMultiLineQuote(const std::string& line)
{
    if (mWorkingElement && mWorkingElement->getType() == MarkdownElement::Type::MULTILINE_QUOTE)
    {
        onSectionFinished();
    }
    else if(isInMultilineBlock())
    {
        processLine(line);
    }
    else
    {
        const auto tag = StringUtils::removeUpTo(line, MULTILINE_QUOTE_DELIMITER);
        auto quote = std::make_unique<MarkdownMultilineQuote>(tag);
        mWorkingElement = quote.get();
        mMarkdownDocument->addElement(std::move(quote));
    }
}

void MarkdownParser::onFoundCustomMultiLineBlock(const std::string& line, unsigned blockSlot)
{
    if (mWorkingElement && mWorkingElement->getType() == MarkdownElement::Type::CUSTOM_MULTILINE && blockSlot == mCustomDelimiterIndex)
    {
        onSectionFinished();
    }
    else if(isInMultilineBlock())
    {
        processLine(line);
    }
    else
    {
        const auto delimiter = mCustomMultilineDelimiters[blockSlot];
        const auto tag = StringUtils::removeUpTo(line, delimiter);
        auto quote = std::make_unique<MarkdownCustomMultiLine>(tag, delimiter);
        mWorkingElement = quote.get();
        mMarkdownDocument->addElement(std::move(quote));
    }
}

void MarkdownParser::onFoundHeading(const std::string& line)
{
    if(isInMultilineBlock())
    {
        processLine(line);
    }
    else
    {
        onSectionFinished();

        unsigned level = StringUtils::countFirstConsecutiveHits(line, HEADING_DELIMITER);
        auto heading = std::make_unique<MarkdownHeading>(level);

        std::string prefix;
        for(unsigned idx=0; idx<level; idx++)
        {
            prefix += HEADING_DELIMITER;
        }
        heading->appendTextContent(StringUtils::stripSurroundingWhitepsace(StringUtils::removeUpTo(line, prefix)));
        mMarkdownDocument->addElement(std::move(heading));
    }
}

void MarkdownParser::onFoundBulletItem(const std::string& line)
{
    if(isInMultilineBlock())
    {
        processLine(line);
    }
    else
    {
        if (mWorkingBulletList)
        {
            auto item = std::make_unique<MarkdownBulletItem>();
            mWorkingElement = item.get();
            mWorkingBulletList->addChild(std::move(item));
        }
        else
        {
            auto bullet_list = std::make_unique<MarkdownBulletList>();
            mWorkingBulletList = bullet_list.get();

            mMarkdownDocument->addElement(std::move(bullet_list));

            auto bullet_item = std::make_unique<MarkdownBulletItem>();
            mWorkingElement = bullet_item.get();
            mWorkingBulletList->addChild(std::move(bullet_item));
        }
        processLine(StringUtils::removeUpTo(line, "*"));
    }
}

void MarkdownParser::onSectionFinished()
{
    mWorkingElement = nullptr;
    mWorkingBulletList = nullptr;
    mWorkingTextSpan = nullptr;
}

std::unique_ptr<MarkdownDocument> MarkdownParser::run(const std::string& content)
{
    mMarkdownDocument = std::make_unique<MarkdownDocument>();

    std::stringstream ss(content);
    std::string line;

    while (std::getline(ss, line, '\n'))
    {
        if (StringUtils::isWhitespaceOnly(line))
        {
            onEmptyLine();
            continue;
        }
        else if (startsWithMultiLineQuote(line))
        {
            onFoundMultiLineQuote(line);
        }
        else if (auto result = startsWithCustomMultilineBlock(line); result >= 0)
        {
            onFoundCustomMultiLineBlock(line, result);
        }
        else if (startsWithHeading(line))
        {
            onFoundHeading(line);
        }
        else if(startsWithBulletItem(line))
        {
            onFoundBulletItem(line);
        }
        else
        {
            processLine(line);
        }
    }

    return std::move(mMarkdownDocument);
}