-- Documentation and master version: https://en.wikipedia.org/wiki/Module:Excerpt
-- Authors: User:Sophivorus, User:Certes, User:Aidan9382 & others
-- License: CC-BY-SA-3.0

local Transcluder = require( 'Module:Transcluder' )

local yesno = require( 'Module:Yesno' )

local ok, config = pcall
if not ok then config = {} end

local p = {}

-- Helper function to get arguments
local args
local function getArg
	local value = args[ key ]
	if value and mw.text.trim( value ) ~= '' then
		return value
	end
	return default
end

-- Helper function to handle errors
local function getError
	if type( message ) == 'string' then
		message = Transcluder.getError
	end
	if config.categories and config.categories.errors and mw.title.getCurrentTitle.isContentPage then
		message:node( 'Category:' .. config.categories.errors .. '' )
	end
	return message
end

-- Helper function to get localized messages
local function getMessage( key )
	local ok, TNT = pcall
	if not ok then return key end
	return TNT.format
end

-- Main entry point for templates
function p.main( frame )
	args = Transcluder.parseArgs( frame )

	-- Make sure the requested page exists
	local page = getArg( 1 )
	if not page or page == '}' then return getError( 'no-page' ) end
	local title = mw.title.new(page)
	if not title then return getError end
	if title.isRedirect then title = title.redirectTarget end
	if not title.exists then return getError end
	page = title.prefixedText

	-- Set variables from the template parameters
	local section = getArg( 2, mw.ustring.match( getArg( 1 ), '[^#]+#(.+)' ) )
	local hat = yesno( getArg )
	local edit = yesno( getArg )
	local this = getArg( 'this' )
	local only = getArg( 'only' )
	local files = getArg( 'files', getArg( 'file', ( only == 'file' and 1 ) ) )
	local lists = getArg( 'lists', getArg( 'list', ( only == 'list' and 1 ) ) )
	local tables = getArg( 'tables', getArg( 'table', ( only == 'table' and 1 ) ) )
	local templates = getArg( 'templates', getArg( 'template', ( only == 'template' and 1 ) ) )
	local paragraphs = getArg( 'paragraphs', getArg( 'paragraph', ( only == 'paragraph' and 1 ) ) )
	local references = getArg( 'references' )
	local subsections = not yesno( getArg( 'subsections' ) )
	local noLinks = not yesno( getArg )
	local noBold = not yesno( getArg( 'bold' ) )
	local onlyFreeFiles = yesno( getArg )
	local briefDates = yesno( getArg )
	local inline = yesno( getArg( 'inline' ) )
	local quote = yesno( getArg( 'quote' ) )
	local more = yesno( getArg( 'more' ) )
	local class = getArg( 'class' )
	local displaytitle = getArg( 'displaytitle' ) or page

	-- Build the hatnote
	if hat and not inline then
		if this then
			hat = this
		elseif quote then
			hat = getMessage( 'this' )
		elseif only then
			hat = getMessage( only )
		else
			hat = getMessage( 'section' )
		end
		hat = hat .. ' ' .. getMessage( 'excerpt' ) .. ' '
		if section then
			hat = hat .. '[[:' .. page .. '#' .. mw.uri.anchorEncode( section ) .. '|' .. displaytitle
				.. ' § ' .. mw.ustring.gsub( section, '%[%[([^]|]+)|?[^]]*%]%]', '%1' ) .. ']].' -- remove nested links
		else
			hat = hat .. '' .. displaytitle .. '.'
		end
		if edit then
			hat = hat .. '['
			hat = hat .. title:fullUrl( 'action=edit' ) .. ' ' .. mw.message.new( 'editsection' ):plain
			hat = hat .. ']'
		end
		if config.hat then
			hat = config.hat .. hat .. '}}'
			hat = frame:preprocess( hat )
		else
			hat = mw.html.create( 'div' ):addClass( 'dablink excerpt-hat' ):wikitext( hat )
		end
	else
		hat = nil
	end

	-- Build the "Read more" link
	if more and not inline then
		more = "**" .. getMessage( 'more' ) .. "**"
		more = mw.html.create( 'div' ):addClass( 'noprint excerpt-more' ):wikitext( more )
	else
		more = nil
	end

	-- Build the options for Module:Transcluder out of the template parameters and the desired defaults
	local options = {
		files = files,
		lists = lists,
		tables = tables,
		paragraphs = paragraphs,
		sections = subsections,
		categories = 0,
		references = references,
		only = only and mw.text.trim .. 's',
		noLinks = noLinks,
		noBold = noBold,
		noSelfLinks = true,
		noNonFreeFiles = onlyFreeFiles,
		noBehaviorSwitches = true,
		fixReferences = true,
		linkBold = true,

	-- Get the excerpt itself
	local title = page .. '#' .. ( section or '' )
	local ok, excerpt = pcall
	if not ok then return getError( excerpt ) end
	if mw.text.trim( excerpt ) == '' and not only then
		if section then return getError else return getError( 'lead-empty' ) end
	end

	-- Fix birth and death dates, but only in the first paragraph
	if briefDates then
		local startpos = 1 -- skip initial templates
		local s
		local e = 0
		repeat
			startpos = e + 1
			s, e = mw.ustring.find
		until not s or s > startpos
		s, e = mw.ustring.find -- get (...), which may be (year–year)
		if s and s < startpos + 100 then -- look only near the start
			local year1, conjunction, year2 = mw.ustring.match( mw.ustring.sub, '(%d%d%d+)(.-)(%d%d%d+)' )
			if year1 and year2 and (mw.ustring.match or mw.ustring.match) then
				local y1 = tonumber(year1)
				local y2 = tonumber(year2)
				if y2 > y1 and y2 < y1 + 125 and y1 <= tonumber( os.date( "%Y" )) then
					excerpt = mw.ustring.sub .. year1 .. "–" .. year2 .. mw.ustring.sub
				end
			end
		end
	end

	-- If no file was found, try to get one from the infobox
	local fileNamespaces = Transcluder.getNamespaces( 'File' )
	if ( ( only == 'file' or only == 'files' ) or ( not only and ( files ~= '0' or not files ) ) ) and -- caller asked for files
		not Transcluder.matchAny and -- and there are no files in Transcluder's output
		config.captions -- and we have the config option required to try finding files in templates
	then
		-- We cannot distinguish the infobox from the other templates so we search them all
		local infobox = Transcluder.getTemplates( excerpt );
		infobox = table.concat( infobox )
		local parameters = Transcluder.getParameters( infobox )
		local file, captions, caption
		for _, pair in pairs( config.captions ) do
			file = pair[1]
			file = parameters[file]
			if file and Transcluder.matchAny then
				file = mw.ustring.match( file, '%[?%[?.-:([^{|]+)%]?%]?' ) or file -- File:Example.jpgupright=1.5 to Example.jpg
				captions = pair[2]
				for _, p in pairs( captions ) do
					if parameters[ p ] then caption = parameters[ p ] break end
				end
				excerpt = 'thumb|' .. ( caption or '' ) .. '' .. excerpt
				if ( onlyFreeFiles ) then
					excerpt = Transcluder.removeNonFreeFiles( excerpt )
				end
				break
			end
		end
	end

	-- Unlike other elements, templates are filtered here
	-- because we had to search the infoboxes for files
	local trash
	if only and ( only == 'template' or only == 'templates' ) then
		trash, excerpt = Transcluder.getTemplates;
	else -- Remove blacklisted templates
		local blacklist = config.blacklist and table.concat or ''
		if templates then
			if string.sub == '-' then --Unwanted templates. Append to blacklist
				blacklist = templates .. ',' .. blacklist
			else --Wanted templates. Replaces blacklist and acts as whitelist
				blacklist = templates
			end
		else
			blacklist = '-' .. blacklist
		end
		trash, excerpt = Transcluder.getTemplates;
	end

	-- Remove extra line breaks but leave one before and after so the parser interprets lists, tables, etc. correctly
	excerpt = mw.text.trim( excerpt )
	excerpt = string.gsub
	excerpt = '\n' .. excerpt .. '\n'

	-- Remove nested categories
	excerpt = frame:preprocess( excerpt )
	local categories, excerpt = Transcluder.getCategories

	-- Add tracking categories
	if config.categories then
		local contentCategory = config.categories.content
		if contentCategory and mw.title.getCurrentTitle.isContentPage then
			excerpt = excerpt .. 'Category:' .. contentCategory .. ''
		end
		local namespaceCategory = config.categories[ mw.title.getCurrentTitle.namespace ]
		if namespaceCategory then
			excerpt = excerpt .. 'Category:' .. namespaceCategory .. ''
		end
	end

	-- Load the styles
	local styles
	if config.styles then
		styles = frame:extensionTag
	end

	-- Combine and return the elements
	if inline then
		return mw.text.trim( excerpt )
	end
	local tag = 'div'
	if quote then
		tag = 'blockquote'
	end
	excerpt = mw.html.create( 'div' ):addClass( 'excerpt' ):wikitext( excerpt )
	local block = mw.html.create( tag ):addClass( 'excerpt-block' ):addClass( class )
	return block:node( styles ):node( hat ):node( excerpt ):node( more )
end

-- Entry points for backwards compatibility
function p.lead( frame ) return p.main( frame ) end
function p.excerpt( frame ) return p.main( frame ) end