// slang-doc.cpp
#include "slang-doc.h"

#include "../core/slang-string-util.h"

namespace Slang {

/* TODO(JS):

* If Decls hand SourceRange, then we could use the range to simplify getting the Post markup, as will be trivial to get to the 'end'
* Need to handle preceeding * in some markup styles
* If we want to be able to disable markup we need a mechanism to do this. Probably define source ranges.

* Need a way to take the extracted markup and produce suitable markdown
** This will need to display the decoration appropriately
*/

/* Extracts 'markup' from comments in Slang source core. The comments are extracted and associated in declarations. The association
is held in DocMarkup type. The comment style follows the doxygen style */
class DocMarkupExtractor 
{
public:

    typedef uint32_t MarkupFlags;
    struct MarkupFlag
    {
        enum Enum : MarkupFlags
        {
            Before          = 0x1,
            After           = 0x2,
            IsMultiToken    = 0x4,          ///< Can use more than one token
            IsBlock         = 0x8,          ///< 
        };
    };

    enum class MarkupType
    {
        None,
        BlockBefore,        /// /**  */ or /*!  */.
        BlockAfter,         /// /*!< */ or /**< */

        LineBangBefore,      /// //! Can be multiple lines
        LineSlashBefore,     /// /// Can be multiple lines

        LineBangAfter,       /// //!< Can be multiple lines
        LineSlashAfter,      /// ///< Can be multiple lines
    };

    struct IndexRange
    {
        SLANG_FORCE_INLINE Index getCount() const { return end - start; }

        Index start;
        Index end;
    };

    enum class Location
    {
        None,                           ///< No defined location
        Before,
        AfterParam,                     ///< Can have trailing , or )
        AfterSemicolon,                 ///< Can have a trailing ;
    };

    struct FoundMarkup
    {
        void reset()
        {
            location = Location::None;
            type = MarkupType::None;
            range = IndexRange { 0, 0 };
        }

        Location location = Location::None;
        MarkupType type = MarkupType::None;
        IndexRange range;
    };

    struct FindInfo
    {

        SourceView* sourceView;         ///< The source view the tokens were generated from
        TokenList* tokenList;           ///< The token list
        Index declTokenIndex;           ///< The token index location (where searches start from)
        Index declLineIndex;            ///< The line number for the decl
    };

    SlangResult extract(DocMarkup* doc, ModuleDecl* moduleDecl, SourceManager* sourceManager, DiagnosticSink* sink);

    static MarkupFlags getFlags(MarkupType type);
    static MarkupType findMarkupType(const Token& tok);
    static UnownedStringSlice removeStart(MarkupType type, const UnownedStringSlice& comment);

protected:
        /// returns SLANG_E_NOT_FOUND if not found, SLANG_OK on success else an error
    SlangResult _findMarkup(const FindInfo& info, Location location, FoundMarkup& out);

        /// Locations are processed in order, and the first successful used. If found in another location will issue a warning.
        /// returns SLANG_E_NOT_FOUND if not found, SLANG_OK on success else an error
    SlangResult _findFirstMarkup(const FindInfo& info, const Location* locs, Index locCount, FoundMarkup& out, Index& outIndex);

    SlangResult _findMarkup(const FindInfo& info, const Location* locs, Index locCount, FoundMarkup& out);

        /// Given the decl, the token stream, and the decls tokenIndex, try to find some associated markup
    SlangResult _findMarkup(const FindInfo& info, Decl* decl, FoundMarkup& out);

        /// Given a found markup location extracts the contents of the tokens into out
    SlangResult _extractMarkup(const FindInfo& info, const FoundMarkup& foundMarkup, StringBuilder& out);

        /// Given a location, try to find the first token index that could potentially be markup
        /// Will return -1 if not found
    Index _findStartIndex(const FindInfo& info, Location location);

        /// True if the tok is 'on' lineIndex. Interpretation of 'on' depends on the markup type.
    static bool _isTokenOnLineIndex(SourceView* sourceView, MarkupType type, const Token& tok, Index lineIndex);

    void _addDecl(Decl* decl);
    void _addDeclRec(Decl* decl);
    void _findDecls(ModuleDecl* moduleDecl);
    
    List<Decl*> m_decls;

    DocMarkup* m_doc;
    ModuleDecl* m_moduleDecl;
    SourceManager* m_sourceManager;
    DiagnosticSink* m_sink;
};

/* static */UnownedStringSlice DocMarkupExtractor::removeStart(MarkupType type, const UnownedStringSlice& comment)
{
    switch (type)
    {
        case MarkupType::BlockBefore:
        {
            if (comment.startsWith(UnownedStringSlice::fromLiteral("/**")) ||
                comment.startsWith(UnownedStringSlice::fromLiteral("/*!")))
            {
                /// /**  */ or /*!  */.
                return comment.tail(3);
            }
            return comment;
        }   
        case MarkupType::BlockAfter:
        {
            
            if (comment.startsWith(UnownedStringSlice::fromLiteral("/**<")) ||
                comment.startsWith(UnownedStringSlice::fromLiteral("/*!<")))
            {
                /// /*!< */ or /**< */
                return comment.tail(4);
            }
            return comment;
        }

        case MarkupType::LineBangBefore:
        {
            return comment.startsWith(UnownedStringSlice::fromLiteral("//!")) ? comment.tail(3) : comment;
        }
        case MarkupType::LineSlashBefore:
        {
            return comment.startsWith(UnownedStringSlice::fromLiteral("///")) ? comment.tail(3) : comment;
        }

        case MarkupType::LineBangAfter:
        {
            /// //!< Can be multiple lines
            return comment.startsWith(UnownedStringSlice::fromLiteral("//!<")) ? comment.tail(4) : comment;
        }
        case MarkupType::LineSlashAfter:
        {
            return comment.startsWith(UnownedStringSlice::fromLiteral("///<")) ? comment.tail(4) : comment;
        }
        default: break;
    }
    return comment;
}

void DocMarkupExtractor::_addDecl(Decl* decl)
{
    if (!decl->loc.isValid())
    {
        return;
    }
    m_decls.add(decl);
}

void DocMarkupExtractor::_addDeclRec(Decl* decl)
{
    // Just add.
    // There may be things we don't want to add, but just add them all of now
    _addDecl(decl);

#if 0
    if (CallableDecl* callableDecl = as<CallableDecl>(decl))
    {
        // For callables (like functions),

        m_decls.add(callableDecl);
    }
    else
#endif
    if (ContainerDecl* containerDecl = as<ContainerDecl>(decl))
    {
        // Add the container - which could be a class, struct, enum, namespace, extension, generic etc.
        // Now add what the container contains
        for (Decl* childDecl : containerDecl->members)
        {
            _addDeclRec(childDecl);
        }
    }
}

void DocMarkupExtractor::_findDecls(ModuleDecl* moduleDecl)
{
    for (Decl* decl : moduleDecl->members)
    {
        _addDeclRec(decl);
    }
}

static Index _findTokenIndex(SourceLoc loc, const Token* toks, Index numToks)
{
    // Use a binary search to find the token
    Index lo = 0;
    Index hi = numToks;

    while (lo + 1 < hi)
    {
        const Index mid = (hi + lo) >> 1;
        const Token& midToken = toks[mid];

        if (midToken.loc == loc)
        {
            return mid;
        }

        if (midToken.loc.getRaw() <= loc.getRaw())
        {
            lo = mid;
        }
        else
        {
            hi = mid;
        }
    }

    // Not found
    return -1;
}

/* static */DocMarkupExtractor::MarkupFlags DocMarkupExtractor::getFlags(MarkupType type)
{
    switch (type)
    {
        default:
        case MarkupType::None:              return 0;
        case MarkupType::BlockBefore:      return MarkupFlag::Before | MarkupFlag::IsBlock; 
        case MarkupType::BlockAfter:       return MarkupFlag::After  | MarkupFlag::IsBlock;

        case MarkupType::LineBangBefore:     return MarkupFlag::Before | MarkupFlag::IsMultiToken; 
        case MarkupType::LineSlashBefore:    return MarkupFlag::Before | MarkupFlag::IsMultiToken; 

        case MarkupType::LineBangAfter:      return MarkupFlag::After | MarkupFlag::IsMultiToken; 
        case MarkupType::LineSlashAfter:     return MarkupFlag::After | MarkupFlag::IsMultiToken;
    }
}

/* static */DocMarkupExtractor::MarkupType DocMarkupExtractor::findMarkupType(const Token& tok)
{
    switch (tok.type)
    {
        case TokenType::BlockComment:
        {
            UnownedStringSlice slice = tok.getContent();
            if (slice.getLength() >= 3 && (slice[2] == '!' || slice[2] == '*'))
            {
                return (slice.getLength() >= 4 && slice[3] == '<') ? MarkupType::BlockAfter : MarkupType::BlockBefore;
            }
            break;
        }
        case TokenType::LineComment:
        {
            UnownedStringSlice slice = tok.getContent();
            if (slice.getLength() >= 3)
            {
                if (slice[2] == '!')
                {
                    return (slice.getLength() >= 4 && slice[3] == '<') ? MarkupType::LineBangAfter : MarkupType::LineBangBefore;
                }
                else if (slice[2] == '/')
                {
                    return (slice.getLength() >= 4 && slice[3] == '<') ? MarkupType::LineSlashAfter : MarkupType::LineSlashBefore;
                }
            }
            break;
        }
        default: break;
    }
    return MarkupType::None;
}

static Index _calcWhitespaceIndent(const UnownedStringSlice& line)
{
    // TODO(JS): For now we ignore tabs and just work out indentation based on spaces/assume ASCII
    Index indent = 0;
    const Index count = line.getLength();
    for (; indent < count && line[indent] == ' '; indent++);
    return indent;
}

static Index _calcIndent(const UnownedStringSlice& line)
{
    // TODO(JS): For now we just assume no tabs, and that every char is ASCII
    return line.getLength();
}

static void _appendUnindenttedLine(const UnownedStringSlice& line, Index maxIndent, StringBuilder& out)
{
    Index indent = _calcWhitespaceIndent(line);

    // We want to remove indenting remove no more than maxIndent
    if (maxIndent >= 0)
    {
        indent = (indent > maxIndent) ? maxIndent : indent;
    }

    // Remove the indenting, and append to out
    out.append(line.tail(indent));
}

SlangResult DocMarkupExtractor::_extractMarkup(const FindInfo& info, const FoundMarkup& foundMarkup, StringBuilder& out)
{
    SourceView* sourceView = info.sourceView;
    SourceFile* sourceFile = sourceView->getSourceFile();

    // Here we want to produce the text that is implied by the markup tokens.
    // We want to removing surrounding markup, and to also keep appropriate indentation
    
    switch (foundMarkup.type)
    {
        case MarkupType::BlockBefore:
        case MarkupType::BlockAfter:
        {
            // We should only have a single line
            SLANG_ASSERT(foundMarkup.range.getCount() == 1);

            const auto& tok = info.tokenList->m_tokens[foundMarkup.range.start];
            uint32_t offset = sourceView->getRange().getOffset(tok.loc);

            const UnownedStringSlice startLine = sourceFile->getLineContainingOffset(offset);

            UnownedStringSlice content = tok.getContent();

            // Split into lines
            List<UnownedStringSlice> lines;

            StringUtil::calcLines(content, lines);

            Index maxIndent = -1;

            StringBuilder unindentedLine;

            const Index linesCount = lines.getCount();
            for (Index i = 0; i < linesCount; ++i)
            {
                UnownedStringSlice line = lines[i];
                unindentedLine.Clear();

                if (i == 0)
                {
                    if (startLine.isMemoryContained(line.begin()))
                    {
                        // For now we'll ignore tabs, and that the indent amount is, the amount of *byte*
                        // NOTE! This is only appropriate for ASCII without tabs.
                        maxIndent = _calcIndent(UnownedStringSlice(startLine.begin(), line.begin()));

                        // Let's strip the start stuff
                        line = removeStart(foundMarkup.type, line);
                    }
                }

                if (i == linesCount - 1)
                {
                    SLANG_ASSERT(line.tail(line.getLength() - 2) == UnownedStringSlice::fromLiteral("*/"));
                    // Remove the */ at the end of the line
                    line = line.head(line.getLength() - 2);
                }

                if (i > 0)
                {
                    _appendUnindenttedLine(line, maxIndent, unindentedLine);
                }
                else
                {
                    unindentedLine.append(line);
                }
                
                // If the first or last line are all white space, just ignore them
                if ((i == linesCount - 1 || i == 0) && unindentedLine.getUnownedSlice().trim().getLength() == 0)
                {
                    continue;
                }

                out.append(unindentedLine);
                out.appendChar('\n');
            }

            break;
        }
        case MarkupType::LineBangBefore:      
        case MarkupType::LineSlashBefore:
        case MarkupType::LineBangAfter:
        case MarkupType::LineSlashAfter:
        {
            // Holds the lines extracted, they may have some white space indenting (like the space at the start of //) 
            List<UnownedStringSlice> lines;

            const auto& range = foundMarkup.range;
            for (Index i = range.start; i < range.end; ++ i)
            {
                const auto& tok = info.tokenList->m_tokens[i];
                UnownedStringSlice line = tok.getContent();
                line = removeStart(foundMarkup.type, line);

                // If the first or last line are all white space, just ignore them
                if ((i == range.start || i == range.end - 1) && line.trim().getLength() == 0)
                {
                    continue;
                }
                lines.add(line);
            }

            if (lines.getCount() == 0)
            {
                // If there are no lines, theres no content
                return SLANG_OK;
            }

            Index minIndent = 0x7fffffff;
            for (const auto& line : lines)
            {
                const Index indent = _calcWhitespaceIndent(line);
                minIndent = (indent < minIndent) ? indent : minIndent;
            }

            for (const auto& line : lines)
            {
                _appendUnindenttedLine(line, minIndent, out);
                out.appendChar('\n');
            }

            break;
        }
        default:    return SLANG_FAIL;
    }

    return SLANG_OK;
}

Index DocMarkupExtractor::_findStartIndex(const FindInfo& info, Location location)
{
    Index openParensCount = 0;
    Index openBracketCount = 0;

    const TokenList& toks = *info.tokenList;
    const Index tokIndex = info.declTokenIndex;

    Index direction = (location == Location::Before) ? -1 : 1;

    const Index count = toks.m_tokens.getCount();
    for (Index i = tokIndex; i >= 0 && i < count; i += direction)
    {
        const Token& tok = toks.m_tokens[i];

        switch (tok.type)
        {
            case TokenType::LParent:
            {
                ++openParensCount;
                break;
            }
            case TokenType::RBracket:
            {
                openBracketCount += Index(location == Location::Before);
                break;
            }
            case TokenType::LBracket:
            {
                openBracketCount -= Index(location == Location::Before);
                break;
            }
            case TokenType::RParent:
            {
                if (openParensCount == 0 &&
                    location == Location::AfterParam)
                {
                    return i + 1;
                }

                --openParensCount;
                if (openParensCount < 0)
                {
                    // Not found - or weird parens at least 
                    return -1;
                }
                break;
            }
            case TokenType::Comma:
            {
                if (location == Location::AfterParam)
                {
                    return i + 1;
                }
                break;
            }
            case TokenType::RBrace:
            {
                // If we haven't hit a candidate yet before hitting } it's not going to work
                if (location == Location::Before)
                {
                    return -1;
                }
                break;
            }
            case TokenType::Semicolon:
            {
                // If we haven't hit a candidate yet it's not going to work
                if (location == Location::Before)
                {
                    return -1;
                }

                if (openParensCount == 0 && location == Location::AfterSemicolon)
                {
                    return i + 1;
                }
                break;
            }
            case TokenType::LineComment:
            case TokenType::BlockComment:
            {
                // We hit a comment this could be the markup
                if (location == Location::Before && openParensCount == 0 && openBracketCount == 0)
                {
                    return i;
                }
                break;
            }
            default: break;
        }
    }

    return -1;
}

/* static */bool DocMarkupExtractor::_isTokenOnLineIndex(SourceView* sourceView, MarkupType type, const Token& tok, Index lineIndex)
{
    SourceFile* sourceFile = sourceView->getSourceFile();
    const int offset = sourceView->getRange().getOffset(tok.loc);

    auto const flags = getFlags(type);

    if (flags & MarkupFlag::IsBlock)
    {
        // Either the start or the end of the block have to be on the specified line
        return sourceFile->isOffsetOnLine(offset, lineIndex) || sourceFile->isOffsetOnLine(offset + tok.charsCount, lineIndex);
    }
    else
    {
        // Has to be exactly on the specified line
        return sourceFile->isOffsetOnLine(offset, lineIndex);
    }
}


SlangResult DocMarkupExtractor::_findMarkup(const FindInfo& info, Location location, FoundMarkup& out)
{
    out.reset();

    const auto& toks = info.tokenList->m_tokens;
    const Index tokIndex = info.declTokenIndex;

    // The starting token index
    Index startIndex = _findStartIndex(info, location);
    if (startIndex <= 0)
    {
        return SLANG_E_NOT_FOUND;
    }

    SourceView* sourceView = info.sourceView;
    SourceFile* sourceFile = sourceView->getSourceFile();

    // Let's lookup the line index where this occurred
    const int startOffset = sourceView->getRange().getOffset(toks[startIndex - 1].loc);

    // The line index that the markoff starts from 
    Index lineIndex = sourceFile->calcLineIndexFromOffset(startOffset);
    if (lineIndex < 0)
    {
        return SLANG_E_NOT_FOUND;
    }

    const Index searchDirection = (location == Location::Before) ? -1 : 1;
    
    // Get the type and flags
    const MarkupType type = findMarkupType(toks[startIndex]);
    const MarkupFlags flags = getFlags(type);

    const MarkupFlag::Enum requiredFlag = (location == Location::Before) ? MarkupFlag::Before : MarkupFlag::After;
    if ((flags & requiredFlag) == 0)
    {
        return SLANG_E_NOT_FOUND;
    }

#if 0
    // The token still isn't accepted, unless it's on the expected line
    if (_isTokenOnLineIndex(info.sourceView, type, toks[startIndex], expectedLineIndex))
    {
        return SLANG_E_NOT_FOUND;
    }
#endif

    Index endIndex = startIndex;

    // If it's multiline, so look for the end index
    if (flags & MarkupFlag::IsMultiToken)
    {
        Index expectedLineIndex = lineIndex;

        // TODO(JS):
        // We should probably do the work here to confirm  indentation - but that
        // requires knowing something about tabs, so for now we leave.

        while (true)
        {
            endIndex += searchDirection;
            expectedLineIndex += searchDirection;

            if (endIndex < 0 || endIndex >= toks.getCount())
            {
                break;
            }

            // Do we find a token of the right type?
            if (findMarkupType(toks[endIndex]) != type)
            {
                break;
            }

            // Is it on the right line?
            if (_isTokenOnLineIndex(info.sourceView, type, toks[startIndex], expectedLineIndex))
            {
                break;
            }
        }

        // Fix the end index (it's the last one that worked)
        endIndex -= searchDirection;
    }

    // Put start < end order
    if (endIndex < startIndex)
    {
        Swap(endIndex, startIndex);
    }
    // The range excludes end so increase
    endIndex++;

    // Okay we've found the markup
    out.type = type;
    out.location = location;
    out.range = IndexRange{ startIndex, endIndex };

    SLANG_ASSERT(out.range.getCount() > 0);

    return SLANG_OK;
}

SlangResult DocMarkupExtractor::_findFirstMarkup(const FindInfo& info, const Location* locs, Index locCount, FoundMarkup& out, Index& outIndex)
{
    Index i = 0;
    for (; i < locCount; ++i)
    {
        SlangResult res = _findMarkup(info, locs[i], out);
        if (SLANG_SUCCEEDED(res) || (SLANG_FAILED(res) && res != SLANG_E_NOT_FOUND))
        {
            outIndex = i;
            return res;
        }
    }
    return SLANG_E_NOT_FOUND;
}

SlangResult DocMarkupExtractor::_findMarkup(const FindInfo& info, const Location* locs, Index locCount, FoundMarkup& out)
{
    Index foundIndex;
    SLANG_RETURN_ON_FAIL(_findFirstMarkup(info, locs, locCount, out, foundIndex));

    // Lets see if the remaining ones match
    {
        FoundMarkup otherMarkup;
        for (Index i = foundIndex + 1; i < locCount; ++i)
        {
            SlangResult res = _findMarkup(info, locs[i], otherMarkup);
            if (SLANG_SUCCEEDED(res))
            {
                // TODO(JS): Warning found markup in another location
            }
        }
    }

    return SLANG_OK;
}

SlangResult DocMarkupExtractor::_findMarkup(const FindInfo& info, Decl* decl, FoundMarkup& out)
{
    if (auto paramDecl = as<ParamDecl>(decl))
    {
        Location locs[] = { Location::Before, Location::AfterParam };
        return _findMarkup(info, locs, SLANG_COUNT_OF(locs), out);
    }
    else if (auto callableDecl = as<CallableDecl>(decl))
    {
        // We allow it defined before
        return _findMarkup(info, Location::Before, out);
    }
    else if (as<VarDecl>(decl) || as<TypeDefDecl>(decl) || as<AssocTypeDecl>(decl))
    {
        Location locs[] = { Location::Before, Location::AfterSemicolon };
        return _findMarkup(info, locs, SLANG_COUNT_OF(locs), out);
    }
    else
    {
        // We'll only allow before
        return _findMarkup(info, Location::Before, out);
    }
}

SlangResult DocMarkupExtractor::extract(DocMarkup* doc, ModuleDecl* moduleDecl, SourceManager* sourceManager, DiagnosticSink* sink)
{
    m_doc = doc;
    m_moduleDecl = moduleDecl;
    m_sourceManager = sourceManager;
    m_sink = sink;

    _findDecls(moduleDecl);

    struct Entry
    {
        typedef Entry ThisType;

        bool operator<(const ThisType& rhs) const { return locOrOffset < rhs.locOrOffset; }

        Index viewIndex;                    ///< The view/file index this loc is found in
        SourceLoc::RawValue locOrOffset;    ///< Can be a loc or an offset into the file

        Decl* decl;                         ///< The decl
    };

    List<Entry> entries;

    {
        const Index count = m_decls.getCount();
        entries.setCount(count);

        for (Index i = 0; i < count; ++i)
        {
            Entry& entry = entries[i];
            auto decl = m_decls[i];
            entry.decl = decl;
            entry.viewIndex = -1;            //< We don't know what file/view it's in
            entry.locOrOffset = decl->loc.getRaw();
        }
    }

    // We hold one view per *SourceFile*
    List<SourceView*> views;

    // Sort them into loc order
    entries.sort([](Entry& a, Entry& b) { return a.locOrOffset < b.locOrOffset; });

    {
        SourceView* sourceView = nullptr;
        Index viewIndex = -1;

        for (auto& entry : entries)
        {
            const SourceLoc loc = SourceLoc::fromRaw(entry.locOrOffset);

            if (sourceView == nullptr || !sourceView->getRange().contains(loc))
            {
                // Find the new view
                sourceView = m_sourceManager->findSourceView(loc);
                SLANG_ASSERT(sourceView);

                // We want only one view per SourceFile
                SourceFile* sourceFile = sourceView->getSourceFile();

                // NOTE! The view found might be different than sourceView. 
                viewIndex = views.findFirstIndex([&](SourceView* currentView) -> bool { return currentView->getSourceFile() == sourceFile; });

                if (viewIndex < 0)
                {
                    viewIndex = views.getCount();
                    views.add(sourceView);
                }
            }

            SLANG_ASSERT(viewIndex >= 0);
            SLANG_ASSERT(sourceView && sourceView->getRange().contains(loc));

            // Set the file index
            entry.viewIndex = viewIndex;
            // Set as the offset within the file 
            entry.locOrOffset = sourceView->getRange().getOffset(loc);
        }

        // Sort into view/file and then offset order
        entries.sort([](Entry& a, Entry& b) { return (a.viewIndex < b.viewIndex) || ((a.viewIndex == b.viewIndex) && a.locOrOffset < b.locOrOffset); });
    }

    {
        TokenList tokens;

        MemoryArena memoryArena;
        RootNamePool rootNamePool;
        NamePool namePool;
        namePool.setRootNamePool(&rootNamePool);

        Index viewIndex = -1;
        SourceView* sourceView = nullptr;

        for (auto& entry : entries)
        {
            if (viewIndex != entry.viewIndex)
            {
                viewIndex = entry.viewIndex;
                sourceView = views[viewIndex];

                // Make all memory free again
                memoryArena.reset();

                // Run the lexer
                Lexer lexer;
                lexer.initialize(sourceView, sink, &namePool, &memoryArena, Lexer::OptionFlag::TokenizeComments);

                // Lex everything
                tokens = lexer.lexAllTokens();
            }

            // Get the offset within the source file
            const uint32_t offset = entry.locOrOffset;

            // We need to get the loc in the source views space, so we look up appropriately in the list of tokens (which uses the views loc range)
            const SourceLoc loc = sourceView->getRange().getSourceLocFromOffset(offset);

            // Work out the line number
            SourceFile* sourceFile = sourceView->getSourceFile();
            const Index lineIndex = sourceFile->calcLineIndexFromOffset(int(offset));

            // Okay, lets find the token index with a binary chop
            Index tokenIndex = _findTokenIndex(loc, tokens.m_tokens.getBuffer(), tokens.m_tokens.getCount());
            if (tokenIndex >= 0 && lineIndex >= 0)
            {
                FindInfo findInfo;
                findInfo.declTokenIndex = tokenIndex;
                findInfo.declLineIndex = lineIndex;
                findInfo.tokenList = &tokens;
                findInfo.sourceView = sourceView;

                // Okay let's see if we extract some documentation then for this.
                FoundMarkup foundMarkup;
                SlangResult res = _findMarkup(findInfo, entry.decl, foundMarkup);

                if (SLANG_SUCCEEDED(res))
                {
                    // We need to extract
                    StringBuilder buf;
                    SLANG_RETURN_ON_FAIL(_extractMarkup(findInfo, foundMarkup, buf));

                    // Add to the documentation
                    DocMarkup::Entry& docEntry = m_doc->addEntry(entry.decl);
                    docEntry.m_markup = buf;
                }
                else if (res != SLANG_E_NOT_FOUND)
                {
                    return res;
                }
            }
        }
    }
   
    return SLANG_OK;
}

SlangResult DocMarkup::extract(ModuleDecl* moduleDecl, SourceManager* sourceManager, DiagnosticSink* sink)
{
    m_moduleDecl = moduleDecl;

    DocMarkupExtractor context;
    return context.extract(this, moduleDecl, sourceManager, sink);
}

/* static */SlangResult DocumentationUtil::writeMarkdown(DocMarkup* markup, StringBuilder& out)
{
    for (const auto& entry : markup->getEntries())
    {
        NodeBase* node = entry.m_node;
        Decl* decl = as<Decl>(node);
        if (!decl)
        {
            continue;
        }

        // Skip these they will be output as part of their respective 'containers'
        if (as<ParamDecl>(decl) || as<EnumCaseDecl>(decl))
        {
            continue;
        }

        if (CallableDecl* callableDecl = as<CallableDecl>(decl))
        {
            out << entry.m_markup;

            // There's code to output sigs in the SemanticsVisitor - we probably need to extract that functionality
            // out so can be used here

            //   String declString = getDeclSignatureString(item);

            auto params = callableDecl->getParameters();
            //const auto& returnType = callableDecl->returnType;

            // Let's see if we can get markup on the parameters            
            for (auto param : params)
            {
                DocMarkup::Entry* paramEntry = markup->getEntry(param);

                if (paramEntry)
                {
                    out << paramEntry->m_markup;

                    auto type = param->getType();

                    if (type)
                    {
                        out << type->toString();
                    }

                    Name* name = param->getName();
                    if (name)
                    {
                        out << " ";
                        out << name->text;
                    }
                    out << "\n\n";
                }
            }
        }
        else if (EnumDecl* enumDecl = as<EnumDecl>(decl))
        {

        }
        else if (StructDecl* structDecl = as<StructDecl>(decl))
        {
        }
        else if (ClassDecl* classDecl = as<ClassDecl>(decl))
        {
        }
    }

    return SLANG_OK;
}

} // namespace Slang