Module:MarkdownToWikitext

Documentation for this module may be created at Module:MarkdownToWikitext/doc

local p = {}

-- Escape special wikitext characters
local function escapeWikitext(text)
    if not text then return "" end
    -- Escape wikitext special characters
    text = text:gsub("([%[%]{}|=])", "\\%1")
    return text
end

-- Convert headers
local function convertHeaders(text)
    -- Convert ATX headers (# Header)
    text = text:gsub("^(#+)%s*(.-)%s*#*$", function(hashes, content)
        local level = #hashes
        if level > 6 then level = 6 end
        local equals = string.rep("=", level + 1)
        return equals .. " " .. content .. " " .. equals
    end)
    
    return text
end

-- Convert emphasis and strong
local function convertEmphasis(text)
    -- Convert **bold** and __bold__
    text = text:gsub("%*%*(.-)%*%*", "'''%1'''")
    text = text:gsub("__(.-)__", "'''%1'''")
    
    -- Convert *italic* and _italic_
    text = text:gsub("([^%*])%*([^%*].-[^%*])%*([^%*])", "%1''%2''%3")
    text = text:gsub("^%*([^%*].-[^%*])%*([^%*])", "''%1''%2")
    text = text:gsub("([^%*])%*([^%*].-[^%*])%*$", "%1''%2''")
    text = text:gsub("^%*([^%*].-[^%*])%*$", "''%1''")
    
    text = text:gsub("([^_])_([^_].-[^_])_([^_])", "%1''%2''%3")
    text = text:gsub("^_([^_].-[^_])_([^_])", "''%1''%2")
    text = text:gsub("([^_])_([^_].-[^_])_$", "%1''%2''")
    text = text:gsub("^_([^_].-[^_])_$", "''%1''")
    
    return text
end

-- Convert links
local function convertLinks(text)
    -- Convert [text](url) links
    text = text:gsub("%[(.-)%]%((.-)%)", "[%2 %1]")
    
    -- Convert <url> autolinks
    text = text:gsub("<(https?://[^>]+)>", "[%1]")
    
    return text
end

-- Convert images
local function convertImages(text)
    -- Convert ![alt](url) images
    text = text:gsub("!%[(.-)%]%((.-)%)", "[[File:%2|thumb|%1]]")
    
    return text
end

-- Convert code blocks and inline code
local function convertCode(text)
    -- Convert fenced code blocks (```lang\ncode\n```) - must be on their own lines
    text = text:gsub("\n```([^\n]*)\n(.-)\n```\n", function(lang, code)
        if lang and lang ~= "" then
            return "\n<syntaxhighlight lang=\"" .. lang .. "\">\n" .. code .. "\n</syntaxhighlight>\n"
        else
            return "\n<pre>\n" .. code .. "\n</pre>\n"
        end
    end)
    
    -- Handle fenced code blocks at start/end of text
    text = text:gsub("^```([^\n]*)\n(.-)\n```\n", function(lang, code)
        if lang and lang ~= "" then
            return "<syntaxhighlight lang=\"" .. lang .. "\">\n" .. code .. "\n</syntaxhighlight>\n"
        else
            return "<pre>\n" .. code .. "\n</pre>\n"
        end
    end)
    
    text = text:gsub("\n```([^\n]*)\n(.-)\n```$", function(lang, code)
        if lang and lang ~= "" then
            return "\n<syntaxhighlight lang=\"" .. lang .. "\">\n" .. code .. "\n</syntaxhighlight>"
        else
            return "\n<pre>\n" .. code .. "\n</pre>"
        end
    end)
    
    -- Convert indented code blocks (4+ spaces at start of line, multiple consecutive lines)
    local lines = {}
    for line in text:gmatch("[^\n]*") do
        table.insert(lines, line)
    end
    
    local result = {}
    local codeBlock = {}
    local inCodeBlock = false
    
    for i, line in ipairs(lines) do
        local hasLeadingSpaces = line:match("^    ")
        local isEmpty = line:match("^%s*$")
        
        if hasLeadingSpaces then
            -- This line starts with 4+ spaces
            if not inCodeBlock then
                inCodeBlock = true
            end
            table.insert(codeBlock, line:gsub("^    ", ""))
        elseif isEmpty and inCodeBlock then
            -- Empty line in code block - include it
            table.insert(codeBlock, "")
        else
            -- Non-code line
            if inCodeBlock then
                -- End the code block
                if #codeBlock > 0 then
                    table.insert(result, "<pre>")
                    for _, codeLine in ipairs(codeBlock) do
                        table.insert(result, codeLine)
                    end
                    table.insert(result, "</pre>")
                end
                codeBlock = {}
                inCodeBlock = false
            end
            table.insert(result, line)
        end
    end
    
    -- Handle code block at end
    if inCodeBlock and #codeBlock > 0 then
        table.insert(result, "<pre>")
        for _, codeLine in ipairs(codeBlock) do
            table.insert(result, codeLine)
        end
        table.insert(result, "</pre>")
    end
    
    text = table.concat(result, "\n")
    
    -- Convert inline code (`code`) - but not if it spans multiple lines
    text = text:gsub("`([^`\n]+)`", "<code>%1</code>")
    
    return text
end

-- Convert lists
local function convertLists(text)
    local lines = {}
    for line in text:gmatch("[^\n]*") do
        table.insert(lines, line)
    end
    
    local result = {}
    local inList = false
    local listType = nil
    
    for i, line in ipairs(lines) do
        local trimmed = line:match("^%s*(.-)%s*$")
        
        -- Unordered list
        local bulletMatch = line:match("^(%s*)[-*+]%s+(.+)$")
        if bulletMatch then
            local indent, content = line:match("^(%s*)[-*+]%s+(.+)$")
            local level = math.floor(#indent / 2) + 1
            local bullets = string.rep("*", level)
            table.insert(result, bullets .. " " .. content)
            inList = true
            listType = "unordered"
        -- Ordered list
        elseif line:match("^%s*%d+%.%s+") then
            local indent, content = line:match("^(%s*)%d+%.%s+(.+)$")
            local level = math.floor(#indent / 2) + 1
            local bullets = string.rep("#", level)
            table.insert(result, bullets .. " " .. content)
            inList = true
            listType = "ordered"
        else
            if inList and trimmed == "" then
                -- Empty line in list - continue list
                table.insert(result, "")
            else
                inList = false
                listType = nil
                table.insert(result, line)
            end
        end
    end
    
    return table.concat(result, "\n")
end

-- Convert blockquotes
local function convertBlockquotes(text)
    local lines = {}
    for line in text:gmatch("[^\n]*") do
        table.insert(lines, line)
    end
    
    local result = {}
    local inQuote = false
    local quoteLines = {}
    
    for i, line in ipairs(lines) do
        if line:match("^>%s*") then
            local content = line:gsub("^>%s*", "")
            table.insert(quoteLines, content)
            inQuote = true
        else
            if inQuote then
                -- End of blockquote
                table.insert(result, "<blockquote>")
                for _, quoteLine in ipairs(quoteLines) do
                    table.insert(result, quoteLine)
                end
                table.insert(result, "</blockquote>")
                quoteLines = {}
                inQuote = false
            end
            table.insert(result, line)
        end
    end
    
    -- Handle blockquote at end of text
    if inQuote then
        table.insert(result, "<blockquote>")
        for _, quoteLine in ipairs(quoteLines) do
            table.insert(result, quoteLine)
        end
        table.insert(result, "</blockquote>")
    end
    
    return table.concat(result, "\n")
end

-- Strip HTML tags
local function stripHTML(text)
    if not text then return "" end
    
    -- Remove HTML comments
    text = text:gsub("<!%-%-.-%-%-?>", "")
    
    -- Remove script and style tags and their content
    text = text:gsub("<[Ss][Cc][Rr][Ii][Pp][Tt][^>]*>.-</[Ss][Cc][Rr][Ii][Pp][Tt]>", "")
    text = text:gsub("<[Ss][Tt][Yy][Ll][Ee][^>]*>.-</[Ss][Tt][Yy][Ll][Ee]>", "")
    
    -- Remove iframe tags and content
    text = text:gsub("<[Ii][Ff][Rr][Aa][Mm][Ee][^>]*>.-</[Ii][Ff][Rr][Aa][Mm][Ee]>", "")
    
    -- Handle paragraph tags specially - convert to line breaks
    text = text:gsub("<[Pp]>", "")
    text = text:gsub("</[Pp]>", "\n\n")
    
    -- Handle line breaks
    text = text:gsub("<[Bb][Rr][^>]*>", "\n")
    
    -- Remove self-closing HTML tags (like <img/>, etc.)
    text = text:gsub("<[^>]+/>", "")
    
    -- Remove remaining opening and closing HTML tags
    text = text:gsub("<[^>]+>", "")
    
    return text
end

-- Handle escape sequences
local function handleEscapeSequences(text)
    if not text then return "" end
    
    -- Convert common escape sequences
    text = text:gsub("\\n", "\n")
    text = text:gsub("\\r", "\r")
    text = text:gsub("\\t", "\t")
    text = text:gsub("\\\"", "\"")
    text = text:gsub("\\'", "'")
    text = text:gsub("\\\\", "\\")
    
    -- Handle unicode escape sequences (\u0000)
    text = text:gsub("\\u(%x%x%x%x)", function(hex)
        local num = tonumber(hex, 16)
        if num then
            return string.char(num)
        else
            return "\\u" .. hex
        end
    end)
    
    return text
end

-- Clean up extra whitespace and normalize line breaks
local function normalizeWhitespace(text)
    if not text then return "" end
    
    -- Convert different line break styles to consistent \n
    text = text:gsub("\r\n", "\n")
    text = text:gsub("\r", "\n")
    
    -- Remove excessive blank lines (more than 2 consecutive)
    text = text:gsub("\n\n\n+", "\n\n")
    
    -- Trim leading and trailing whitespace
    text = text:match("^%s*(.-)%s*$")
    
    return text
end

-- Convert horizontal rules
local function convertHorizontalRules(text)
    -- Convert --- or *** or ___ to ----
    text = text:gsub("\n%s*[-*_][-*_%s]*[-*_]%s*\n", "\n----\n")
    text = text:gsub("^%s*[-*_][-*_%s]*[-*_]%s*\n", "----\n")
    text = text:gsub("\n%s*[-*_][-*_%s]*[-*_]%s*$", "\n----")
    
    return text
end

-- Convert tables
local function convertTables(text)
    local lines = {}
    for line in text:gmatch("[^\n]*") do
        table.insert(lines, line)
    end
    
    local result = {}
    local inTable = false
    local tableLines = {}
    
    for i, line in ipairs(lines) do
        if line:match("|") and not line:match("^%s*$") then
            table.insert(tableLines, line)
            inTable = true
        else
            if inTable then
                -- Process the table
                local wikiTable = convertMarkdownTable(tableLines)
                for _, tableLine in ipairs(wikiTable) do
                    table.insert(result, tableLine)
                end
                tableLines = {}
                inTable = false
            end
            table.insert(result, line)
        end
    end
    
    -- Handle table at end
    if inTable then
        local wikiTable = convertMarkdownTable(tableLines)
        for _, tableLine in ipairs(wikiTable) do
            table.insert(result, tableLine)
        end
    end
    
    return table.concat(result, "\n")
end

-- Helper function to convert markdown table to wikitable
function convertMarkdownTable(lines)
    local result = {"{| class=\"wikitable\""}
    local headerProcessed = false
    
    for i, line in ipairs(lines) do
        local trimmed = line:match("^%s*(.-)%s*$")
        
        -- Skip separator lines (|---|---|)
        if not trimmed:match("^|?[-:%s|]+|?$") then
            local cells = {}
            for cell in trimmed:gmatch("|([^|]*)") do
                local cleanCell = cell:match("^%s*(.-)%s*$")
                table.insert(cells, cleanCell)
            end
            
            if not headerProcessed then
                -- First row is header
                table.insert(result, "|-")
                for j, cell in ipairs(cells) do
                    table.insert(result, "! " .. cell)
                end
                headerProcessed = true
            else
                -- Data row
                table.insert(result, "|-")
                for j, cell in ipairs(cells) do
                    table.insert(result, "| " .. cell)
                end
            end
        end
    end
    
    table.insert(result, "|}")
    return result
end

-- Main conversion function
function p.convert(frame)
    local markdown = frame.args[1] or frame:getParent().args[1] or ""
    local stripHtml = frame.args.striphtml or frame:getParent().args.striphtml or "true"
    local handleEscapes = frame.args.escapes or frame:getParent().args.escapes or "true"
    
    -- Apply pre-processing
    local wikitext = markdown
    
    -- Strip HTML if requested (default: true)
    if stripHtml ~= "false" then
        wikitext = stripHTML(wikitext)
    end
    
    -- Handle escape sequences if requested (default: true)
    if handleEscapes ~= "false" then
        wikitext = handleEscapeSequences(wikitext)
    end
    
    -- Normalize whitespace
    wikitext = normalizeWhitespace(wikitext)
    
    -- Apply conversions in order
    
    -- Code blocks first (to protect code from other conversions)
    wikitext = convertCode(wikitext)
    
    -- Headers
    wikitext = convertHeaders(wikitext)
    
    -- Emphasis and strong
    wikitext = convertEmphasis(wikitext)
    
    -- Links and images
    wikitext = convertLinks(wikitext)
    wikitext = convertImages(wikitext)
    
    -- Lists
    wikitext = convertLists(wikitext)
    
    -- Blockquotes
    wikitext = convertBlockquotes(wikitext)
    
    -- Tables
    wikitext = convertTables(wikitext)
    
    -- Horizontal rules
    wikitext = convertHorizontalRules(wikitext)
    
    return wikitext
end

-- Function to just clean/strip content without markdown conversion
function p.clean(frame)
    local text = frame.args[1] or frame:getParent().args[1] or ""
    local stripHtml = frame.args.striphtml or frame:getParent().args.striphtml or "true"
    local handleEscapes = frame.args.escapes or frame:getParent().args.escapes or "true"
    
    local cleaned = text
    
    -- Strip HTML if requested (default: true)
    if stripHtml ~= "false" then
        cleaned = stripHTML(cleaned)
    end
    
    -- Handle escape sequences if requested (default: true)
    if handleEscapes ~= "false" then
        cleaned = handleEscapeSequences(cleaned)
    end
    
    -- Normalize whitespace
    cleaned = normalizeWhitespace(cleaned)
    
    return cleaned
end

-- Function to strip only HTML
function p.stripHTML(frame)
    local text = frame.args[1] or frame:getParent().args[1] or ""
    return stripHTML(text)
end

-- Function to handle only escape sequences
function p.handleEscapes(frame)
    local text = frame.args[1] or frame:getParent().args[1] or ""
    return handleEscapeSequences(text)
end

-- Function to convert just specific elements
function p.convertHeaders(frame)
    local text = frame.args[1] or frame:getParent().args[1] or ""
    return convertHeaders(text)
end

function p.convertEmphasis(frame)
    local text = frame.args[1] or frame:getParent().args[1] or ""
    return convertEmphasis(text)
end

function p.convertLinks(frame)
    local text = frame.args[1] or frame:getParent().args[1] or ""
    return convertLinks(text)
end

function p.convertLists(frame)
    local text = frame.args[1] or frame:getParent().args[1] or ""
    return convertLists(text)
end

return p