local p = {}

local utils = require('Modul:Sources/utils')

local i18nDefaultLanguage = 'az'

local i18nEtAlDefault = ' et al.'
local i18nEtAl = {
	az	= ' və b.',
	ru	= ' и др.',
}

local i18nEditors = {
	fr	= '',
	de	= 'Hrsg.: ',
	es	= '',
	en	= '',
	it	= '',
	az	= 'red. ',
	ru	= 'под ред. ',
}

local i18nTranslators = {
	fr	= '',
	de	= '',
	es	= '',
	en	= '',
	it	= '',
	ru	= 'пер. ',
	az	= 'tər. ',
}

local i18nVolume = {
    de  = 'Vol.',
	fr	= 'Vol.',
	es	= 'Vol.',
	en	= 'Vol.',
	it	= 'Vol.',
	az	= 'C.',
	ru	= 'Т.',
}

local i18nIssue = {
	en	= 'Iss.',
	az	= 'burax.',
	ru	= 'вып.',
}

local i18nPages = {
	fr = 'P.',
	de = 'S.',
	es = 'P.',
	en = 'P.',
	it = 'P.',
	az = 'S.',
	ru = 'С.',
}

local i18nNumberOfPages = {
	en = 'p.',
	az = 's.',
	ru = 'с.',
}

local i18nTirage = {
	en	= 'ed. size: %d',
	az	= '%d nüs.',
	ru	= '%d экз.',
}


local monthg = {'yanvar', 'fevral', 'mart', 'aprel', 'may', 'iyun', 'iyul', 'avqust', "sentyabr", "oktyabr", "noyabr", "dekabr"};

local PREFIX_CITEREF = "CITEREF_";

-- Returns formatted pair {Family name(s), First name(s)}
local function tokenizeName( fullName )
	local start = '^%s*' -- matches beginning of the string + arbitrary number of spaces
	local finish = '%s*$' -- matches end of the string + arbitrary number of spaces
	local comma = '\,%s+' -- matches comma + single or more spacing character
	local space = '%s+' -- matches single or more spacing character
	local name = '(%a[%a\-\']*)\.?' -- matches single name, have to start with letter, can contain apostrophe and hyphen, may end with dot
	local surname = '(%a[%a\-\']*)' -- same as name, but can't end with dot
	
	local f, i = mw.ustring.match(fullName, start .. surname .. comma .. name .. finish)
	if f then
		mw.log('tokenizeName: "' .. fullName .. '": have "Fa, Im" match')
		return {f, mw.ustring.sub( i, 1, 1 ) .. '.'}
	end
	
	local f, i, o = mw.ustring.match(fullName, start .. surname .. comma .. name .. space .. name .. finish)
	if f then
		mw.log( 'tokenizeName: "' .. fullName .. '": have "Fa, Im Ot" match')
		return {f, mw.ustring.sub( i, 1, 1 ) .. '. '
				.. mw.ustring.sub( o, 1, 1 ) .. '.'}
	end

	local f1, f2, i = mw.ustring.match(fullName, start .. surname .. space .. surname .. comma .. name .. finish)
	if f1 then
		mw.log('tokenizeName: "' .. fullName .. '": have "Fa Fa, Im" match')
		return {f1 .. ' ' .. f2, mw.ustring.sub( i, 1, 1 ) .. '.'}
	end
	
	local i, o, f = mw.ustring.match(fullName, start .. name .. space .. name .. space .. 'оглы' .. space .. surname .. finish)
	if f then
		mw.log('tokenizeName: "' .. fullName .. '": have "Im Ot оглы Fa" match')
		return {f, mw.ustring.sub(i, 1, 1) .. '. ' .. mw.ustring.sub(o, 1, 1) .. '.'}
	end

	local i1, i2, f = mw.ustring.match(fullName, start .. name .. space .. name .. space .. 'de' .. space .. surname .. finish)
	if f then
		mw.log('tokenizeName: "' .. fullName .. '": have "Im Im de Fa" match')
		return {f, mw.ustring.sub( i1, 1, 1 ) .. '. ' .. mw.ustring.sub( i2, 1, 1 ) .. '.'}
	end
	
	-- Try matching k names + surname
	for k = 1, 4 do
		pattern = start .. string.rep(name .. space, k) .. surname .. finish
		matched = {mw.ustring.match(fullName, pattern)}
		if #matched ~= 0 then
			mw.log('tokenizeName: "' .. fullName .. '": have "Im (x' .. k .. ') Fa" match')
			for i = 1, k do
				matched[i] = mw.ustring.sub(matched[i], 1, 1)
			end
			return {matched[k + 1], table.concat(matched, '. ', 1, k) .. '.'}
		end
	end
	
	mw.log('Unmatched any pattern: "' .. fullName .. '"')
	return {fullName}
end

local function personNameToAuthorName( fullName )
	if not fullName then return fullName end
	local tokenized = tokenizeName(fullName)
	if #tokenized == 1 then
		return tokenized[1]
	else
		return tokenized[1] .. ' ' .. tokenized[2]
	end
end

local function personNameToResponsibleName( fullName )
	if not fullName then return fullName end
	local tokenized = tokenizeName(fullName)
	if #tokenized == 1 then
		return tokenized[1]
	else
		return tokenized[2] .. ' ' .. tokenized[1]
	end
end


local options_commas = { separator = ', ', conjunction = ', ', format = function( src ) return src end, nolinks = false, preferids = false };
local options_commas_short = { separator = ', ', conjunction = ', ', format = function( src ) return src end, nolinks = false, preferids = false, short = true };
local options_commas_nolinks = { separator = ', ', conjunction = ', ', format = function( src ) return src end, nolinks = true, preferids = false };
local options_commas_it = { separator = ', ', conjunction = ', ', format = function( src ) return "''" .. src .. "''" end, nolinks = false, preferids = false };
local options_commas_it_short = { separator = ', ', conjunction = ', ', format = function( src ) return "''" .. src .. "''" end, nolinks = false, preferids = false, short = true };
local options_commas_it_nolinks = { separator = ', ', conjunction = ', ', format = function( src ) return "''" .. src .. "''" end, nolinks = true , preferids = false };
local options_citetypes = { separator = ' ', conjunction = ' ', format = function( src ) return 'citetype_' .. src end, nolinks = true , preferids = true };

local options_commas_authors = { separator = ', ', conjunction = ', ', format = personNameToAuthorName, nolinks = false, preferids = false };
local options_commas_responsible = { separator = ', ', conjunction = ', ', format = personNameToResponsibleName, nolinks = false, preferids = false };

local options_arxiv = { separator = '; ', conjunction = '; ', format = function( id ) return '[http://arxiv.org/abs/' .. id .. ' arXiv:' .. id .. ']' end, nolinks = true, preferids = false };
local options_doi = { separator = '; ', conjunction = '; ', format = function( doi ) return '[http://dx.doi.org/' .. doi .. ' doi:' .. doi .. ']' end, nolinks = true, preferids = false };
local options_issn = { separator = '; ', conjunction = '; ', format = function( issn ) return '[https://www.worldcat.org/issn/' .. issn .. ' ' .. issn .. ']' end, nolinks = true, preferids = false };
local options_pmid = { separator = '; ', conjunction = '; ', format = function( pmid ) return '[https://www.ncbi.nlm.nih.gov/pubmed/?term=' .. pmid .. ' PMID:' .. pmid .. ']' end, nolinks = true, preferids = false };

local function getPersonNameAsLabel( context, entityId, providedLabel, options )
	-- would custom label provided we don't need to check entity at all
	if ( not utils.isEmpty( providedLabel ) ) then
		mw.log( 'Custom label provided for ' .. entityId );
		return options.format( providedLabel );
	end

	local entity = utils.getEntity( context, entityId );
	if ( not entity ) then return '\'\'(entity ' .. entityId .. ' is missing)\'\'' end;

	local personName = nil;
	-- support only labels so far
	if ( entity.labels[ context.lang ] ) then
		personName = entity.labels[ context.lang ].value;
		mw.log('Got person name of ' .. entityId .. ' from label: "' .. personName .. '"' )
	end

	if ( not utils.isInstanceOf( entity, 'Q5' ) ) then
		mw.log( 'Entity ' .. entityId .. ' is not a person' );
		return personName;
	end

	if ( utils.isEmpty( personName ) ) then
		return '\'\'(not translated to ' .. context.lang .. ')\'\'';
	else
		return options.format( personName );
	end
end

local function getPersonNameAsWikitext( context, entityId, customLabel, options )
	local personName = getPersonNameAsLabel( context, entityId, customLabel, options);
	if ( personName == nil ) then
		return nil;
	end

	local link = utils.getElementLink( context, entityId, nil );
	return utils.wrapInUrl( link, personName );
end

local function getPeopleAsWikitext( context, value, options )
	if type( value ) == 'string' then
		return options.format( value )
	elseif type( value ) == 'table' then
		if value.id then
			-- this is link
			if options.preferids then
				return value.id
			else
				if options.nolinks then
					return getPersonNameAsLabel( context, value.id, value.label, options )
				else
					return getPersonNameAsWikitext( context, value.id, value.label, options )
				end
			end
		end
		
		local maxAuthors = 10 -- need some restrictions, as some publications have enormous amount of authors (e.g. 115 authors of Q68951544)
		local resultList = {}
		for i, tableValue in pairs( value ) do
			local nextWikitext = getPeopleAsWikitext( context, tableValue, options )
			if not utils.isEmpty( nextWikitext ) then
				table.insert( resultList, nextWikitext )
				if #resultList == maxAuthors + 1 then
					-- keep one more to indicate that there are too many
					break
				end
			end
		end

		local resultWikitext = ''
		for i, wikitext in pairs( resultList ) do
			if i == maxAuthors + 1 then
				resultWikitext = resultWikitext .. ( i18nEtAl[ context.lang ] or i18nEtAlDefault )
				break;
			end
			if i ~= 1 then
				resultWikitext = resultWikitext .. ', '
			end
			resultWikitext = resultWikitext .. wikitext
		end

		return resultWikitext
	end

	return options.format( '(unknown type)' )
end

local function generateAuthorLinks(context, src)
	local result = ''
	if src.author then
		result = getPeopleAsWikitext( context, src.author, options_commas_authors )
		result = '<i class="wef_low_priority_links">' .. result .. '</i> '
	end
	return result
end

local function appendProperty(result, context, src, conjunctor, property, url)
	if src[property] then
		if url and src[url] then
			result = result .. conjunctor .. utils.wrapInUrl( src[url], utils.toString( context, src[property], options_commas_nolinks ) )
		else
			result = result .. conjunctor .. utils.toString( context, src[property], options_commas )
		end
	end
	return result
end

local function appendTitle(result, context, src)
	conjunctor = ''
 	if src.part then
 		result = appendProperty(result, context, src, '', 'part', 'parturl')
 		conjunctor = ' // '
 	end
 	result = appendProperty(result, context, src, conjunctor, 'title', 'url')
 	return result
end

local function appendLanguage(result, context, src)
	if context.lang ~= i18nDefaultLanguage then
		local langs = require('Module:Languages')
		result = result .. langs.list_ref(p.currentFrame:newChild{ args = {context.lang} })
	end
	return result
end

local function appendSubtitle(result, context, src)
	return appendProperty(result, context, src, ': ', 'subtitle') .. '.'
end

local function appendOriginalTitle(result, context, src)
	return appendProperty(result, context, src, ' = ', 'originaltitle')
end

local function appendPublication(result, context, src)
	if src.publication then
		if type( src.publication.title or '') ~= 'string' then
			error('type of src.publication.title is not string but ' .. type( src.publication.title ) )
		end
		
		result = result .. ' // ' .. utils.toString( context, src.publication, options_commas_it_short )
		if src.publication.subtitle then
			result = result .. ': ' .. utils.toString( context, src.publication.subtitle, options_commas_it_short )
		end
	end
	return result
end

local function appendEditor(result, context, src)
	if src.editor or src.translator then
		result = result .. ' / '
		if src.editor then
			local prefix = i18nEditors[ context.lang ] or i18nEditors[ i18nDefaultLanguage ]
			result = result .. prefix .. getPeopleAsWikitext( context, src.editor, options_commas_responsible )
			if src.translator then
				result = result .. ', '
			end
		end
		if src.translator then
			local prefix = i18nTranslators[ context.lang ] or i18nTranslators[ i18nDefaultLanguage ]
			result = result .. prefix .. getPeopleAsWikitext( context, src.translator, options_commas_responsible )
		end
	end
	return result
end

local function appendEdition(result, context, src)
	return appendProperty(result, context, src, ' ', 'edition')
end

local function appendPublicationData(result, context, src)
	if src.place or src.publisher or src.year then
		result = result .. ' '
		if src.place then
			result = result .. utils.toString( context, src.place, options_commas_short )
			if src.publisher or src.year then
				result = result .. ': '
			end
		end
		if src.publisher then
			result = result .. utils.toString( context, src.publisher, options_commas_short )
			if src.year then
				result = result .. ', '
			end
		end
		if src.year then
			result = result .. utils.toString( context, src.year, options_commas )
		end
		result = result .. '.';
	end
	return result
end

local function appendVolumeAndIssue(result, context, src)
 	if src.volume or src.issue then
 		result = result .. ' '
		local letter_vol = i18nVolume[ context.lang ] or i18nVolume[ i18nDefaultLanguage ]
		local letter_iss = i18nIssue[ context.lang ] or i18nIssue[ i18nDefaultLanguage ]
		if src.volume then
			result = appendProperty(result, context, src, letter_vol .. '&nbsp;', 'volume')
			result = appendProperty(result, context, src, ', ' .. letter_iss .. '&nbsp;', 'issue')
		else
			result = appendProperty(result, context, src, letter_iss .. '&nbsp;', 'issue')
		end
		result = result .. '.'
 	end
 	return result
end

local function appendPages(result, context, src)
	if src.pages then
		local letter = i18nPages[ context.lang ] or i18nPages[ i18nDefaultLanguage ]
		local strPages = utils.toString( context, src.pages, options_commas )
		strPages = mw.ustring.gsub( strPages, '[-—]', '–' );
		result = result .. ' ' .. letter .. '&nbsp;' .. strPages .. '.'
	end
	return result
end

local function appendNumberOfPages(result, context, src)
	if src.numberOfPages then
		local letter = i18nNumberOfPages[ context.lang ] or i18nNumberOfPages[ i18nDefaultLanguage ]
		result = appendProperty(result, context, src, ' ', 'numberOfPages') .. '&nbsp;' .. letter
	end
	return result
end

local function appendBookSeries(result, context, src)
	if src.bookSeries then
		result = appendProperty(result, context, src, ' — (', 'bookSeries')
	 	if src.bookSeriesVolume or src.bookSeriesIssue then
	 		result = result .. '; '
	 		local letter_vol = i18nVolume[ context.lang ] or i18nVolume[ i18nDefaultLanguage ]
	 		local letter_iss = i18nIssue[ context.lang ] or i18nIssue[ i18nDefaultLanguage ]
			if ( src.bookSeriesVolume ) then
				result = appendProperty(result, context, src, letter_vol .. '&nbsp;', 'bookSeriesVolume')
				result = appendProperty(result, context, src, ', ' .. letter_iss .. '&nbsp;', 'bookSeriesIssue')
			else
				result = appendProperty(result, context, src, letter_iss .. '&nbsp;', 'bookSeriesIssue')
			end
	 	end
		result = result .. ')'
	end
	return result
end

local function appendTirage(result, context, src)
	if src.tirage then
		local tirageTemplate = i18nTirage[ context.lang ] or i18nTirage[ i18nDefaultLanguage ]
		result = result .. ' ' .. utils.toString( context, src.tirage, { separator = '; ', conjunction = '; ', format = function( data ) return mw.ustring.format(tirageTemplate, data) end } )
	end
	return result
end

local function appendIdentifiers(result, context, src)
	if src.isbn  then result = result .. ' ISBN ' .. utils.toString( context, src.isbn, options_commas )	end
	if src.issn  then result = result .. ' ISSN ' .. utils.toString( context, src.issn, options_issn )	end
	if src.doi   then result = result .. ' ' .. utils.toString( context, src.doi, options_doi )			end
	if src.pmid  then result = result .. ' ' .. utils.toString( context, src.pmid, options_pmid )			end
	if src.arxiv then result = result .. ' ' .. utils.toString( context, src.arxiv, options_arxiv )		end
	return result
end

local function appendSourceId(result, context, src)
	if src.sourceId then
		local citetype = src.type and utils.toString(context, src.type, options_citetypes) or 'citetype_unknown'
		result = '<span class="wikidata_cite ' .. citetype .. '" data-entity-id="' .. utils.getSingle(src.sourceId) .. '">' .. result .. '</span>'
	end
	return result
end

local function appendAccessDate(result, context, src)
	if src.accessdate then
			local date = utils.getSingle(src.accessdate)
			local pattern = "(%-?%d+)%-(%d+)%-(%d+)T";
			local y, m, d = mw.ustring.match(date, pattern)
			y, m, d = tonumber(y), tonumber(m), tonumber(d)
			local date_str = (d > 0 and ' ' .. tostring(d) or '') 
						  .. (m > 0 and ' ' .. monthg[m] or '')
						  .. (y > 0 and ' ' .. tostring(y) or '')
			result = result .. " <small>İstifadə tarixi" .. date_str .. ".</small>"
	end
	return result
end

local function populateUrl(context, src)
	if src.sourceId and not src.url then
		local entity = utils.getEntity(context, src.sourceId)
		if entity.sitelinks and entity.sitelinks[context.lang .. 'wikisource'] then
			src.url = ':' .. context.lang .. ':s:' .. entity.sitelinks[context.lang .. 'wikisource'].title
		end
	end
end

local function populateYear(src)
	if not src.year and src.dateOfPublication then
		local date = utils.getSingle(src.dateOfPublication)
		src.year = mw.ustring.sub(date, 2, 5)
	end
	if not src.year and src.dateOfCreation then
		local date = utils.getSingle(src.dateOfCreation)
		src.year = mw.ustring.sub(date, 2, 5)
	end
end

local function populateTitle(src)
	src.title = src.title or utils.getSingle(src.url) or '\'\'(unspecified title)\'\''
end

local function renderSource(context, src)
	options_commas_authors.format = personNameToAuthorName
	options_commas_responsible.format = personNameToResponsibleName

	context.lang = utils.getLangCode(utils.getSingle(src.lang)) or i18nDefaultLanguage

	utils.preprocessPlaces(src, context.lang)

	populateUrl(context, src)
	populateTitle(src)
	populateYear(src)

	local result = generateAuthorLinks(context, src)
	result = appendTitle(result, context, src)
	result = appendLanguage(result, context, src)
	result = appendSubtitle(result, context, src)
	result = appendOriginalTitle(result, context, src)
	result = appendPublication(result, context, src)
	
	result = result .. '<span class="wef_low_priority_links">'
	result = appendEditor(result, context, src) -- Might take current editor instead of actual. Use with caution
	result = appendEdition(result, context, src)
	result = appendPublicationData(result, context, src)
	result = appendVolumeAndIssue(result, context, src)
	result = appendPages(result, context, src)
	result = appendNumberOfPages(result, context, src)
	result = appendBookSeries(result, context, src)
	result = appendTirage(result, context, src)
	result = appendIdentifiers(result, context, src)
	result = appendSourceId(result, context, src)
	result = appendAccessDate(result, context, src)
	result = result .. '</span>'

	return result
end

local function renderReferenceImpl(currentEntity, reference, refAnchor, refAnchorYear)
	if not reference.snaks then
		return nil
	end

	-- контекст, содержит также кеш элементов
	local context = {
		cache = {}
	}

	-- данные в простом формате, согласованном с модулями формирования библиографического описания
	local data = {}

    -- забрать данные из reference
    utils.populateDataFromClaims(context, nil, reference.snaks, data)

	utils.expandSpecials(context, currentEntity, reference, data)

	local sourceEntity = nil
	if data.sourceId then
		sourceEntity = utils.getEntity(context, data.sourceId)
		if sourceEntity then
			utils.populateSourceDataImpl(context, sourceEntity, data)
		end
	end

	if data.publication then
		utils.expandPublication(context, sourceEntity, data)
	end

	utils.expandBookSeries(context, data)

	if next(data) == nil then
		return nil
	end

	local rendered = renderSource(context, data)
	if mw.ustring.len(rendered) == 0 then
		return nil
	end

	if refAnchor then
		local anchorValue = 'CITEREF' .. refAnchor .. (utils.coalesce(refAnchorYear, data.year) or '')
		rendered = '<span class="citation" id="' .. mw.uri.anchorEncode(anchorValue) .. '">' .. rendered .. '</span>'
	end

	return rendered
end

local function artificialSnaks(args)
	local snaks = {}
	if args[1] then
		entityId = mw.text.trim(args[1])
		snaks.P248 = {utils.toWikibaseEntityIdSnak("P248", entityId)}
		snaks.P805 = {utils.toWikibaseEntityIdSnak("P805", entityId)}
	end
	utils.copyArgsToSnaks(args, snaks)
	return mw.wikibase.getEntity(), {snaks = snaks}
end

function p.renderReference(frame, currentEntity, reference)
	p.currentFrame = frame

	-- template call
	if frame and not currentEntity and not reference then
		currentEntity, reference = artificialSnaks(frame.args)
	end

	local rendered = renderReferenceImpl(currentEntity, reference)
	if not rendered then
		return ''
	end
	-- Про выбор алгоритма хеширования см. [[Модуль:Hash]]. Знак подчёркивания в начале позволяет
	-- исключить ошибку, когда имя сноски — чисто числовое значение, каковыми иногда бывают хеши.
	return frame:extensionTag('ref', rendered, {name = '_' .. mw.hash.hashValue('fnv164', rendered)}) .. '[[Category:Vikipediya:Vikidatada mənbələri olan məqalələr]]'
end

function p.renderSource(frame)
	p.currentFrame = frame
	currentEntity, reference = artificialSnaks(frame.args)
	return renderReferenceImpl(currentEntity, reference, frame.args['ref'], frame.args['ref-year'])
end

return p;