local p = {}

--codes from bvf that may be in use
local version_num_codes = {
	[9] = 'kjv', [31] = 'niv', [45] = 'amp', [49] = 'nasb', [64] = 'nivuk',
	[51] = 'nlt', [65] = 'msg', [76] = 'nirv', [105] = 'he', [104] = 'jps',
	[120] = 'opb', [121] = 'bb', [122] = 'bbc', [123] = 'bbl', [131] = 'nrsv',

--possible book inputs, based on Chicago Manual
local book_aliases = {
	['genesis'] = {'gen', 'gn'}, --old testament/tanakh
	['exodus'] = {'exod', 'ex'},
	['leviticus'] = {'lev', 'lv'},
	['numbers'] = {'num', 'nm'},
	['deuteronomy'] = {'deut', 'dt'},
	['joshua'] = {'josh' , 'jo'},
	['judges'] = {'judg', 'jgs'},
	['ruth'] = {'ru'},
	['1_samuel'] = {'1sam', '1sm'},
	['2_samuel'] = {'2sam', '2sm'},
	['1_kings'] = {'1kgs'},
	['2_kings'] = {'2kgs'},
	['1_chronicles'] = {'1chron', '1chr'},
	['2_chronicles'] = {'2chron', '2chr'},
	['ezra'] = {'ezr'},
	['nehemiah'] = {'neh'},
	['esther'] = {'est'},
	['job'] = {'jb'},
	['psalms'] = {'ps', 'pss', 'psalm'},
	['proverbs'] = {'prov', 'prv'},
	['ecclesiastes'] = {'eccles', 'eccl', 'qoheleth'},
	['song_of_solomon'] = {'songofsol', 'songofsongs', 'song', 'sg', 'canticles', 'canticleofcanticles'},
	['isaiah'] = {'isa', 'is'},
	['jeremiah'] = {'jer'},
	['lamentations'] = {'lam'},
	['ezekiel'] = {'ezek', 'ez'},
	['daniel'] = {'dan', 'dn'},
	['hosea'] = {'hos'},
	['joel'] = {'jl'},
	['amos'] = {'am'},
	['obadiah'] = {'obad', 'ob'},
	['jonah'] = {'jon'},
	['micah'] = {'mic', 'mi'},
	['nahum'] = {'nah', 'na'},
	['habakkuk'] = {'hab', 'hb'},
	['zephaniah'] = {'zeph', 'zep'},
	['haggai'] = {'hag', 'hg'},
	['zechariah'] = {'zech', 'zec'},
	['malachi'] = {'mal'},
	['baruch'] = {'bar'}, --apocrypha/deuterocanon
	['ecclesiasticus'] = {'ecclus', 'wisdomofsirach', 'sirach', 'sir'},
	['1_esdras'] = {'1esd'},
	['2_esdras'] = {'2esd'},
	['judith'] = {'jth', 'jdt'},
	['1_maccabees'] = {'1macc', '1mc'},
	['2_maccabees'] = {'2macc', '2mc'},
	['3_maccabees'] = {'3macc', '3mc'},
	['4_maccabees'] = {'4macc', '4mc'},
	['prayer_of_manasseh'] = {'profman', 'prayerofmanasses'},
	['susanna'] = {'sus'},
	['tobit'] = {'tob', 'tb'},
	['wisdom_of_solomon'] = {'ws', 'wisdom', 'wisofsol'},
	['prayer_of_azariah'] = {'prayerofazariahandhymnofthethreechildren'},
	['rest_of_esther'] = {'additionstoesther'},
	['bel_and_the_dragon'] = {'bel'},
	['epistle_of_jeremiah'] = {'letterofjeremiah'},
	['matthew'] = {'matt', 'mt'}, --new testament
	['mark'] = {'mk'},
	['luke'] = {'lk'},
	['john'] = {'jn'},
	['acts'] = {'actsoftheapostles'},
	['romans'] = {'rom'},
	['1_corinthians'] = {'1cor'},
	['2_corinthians'] = {'2cor'},
	['galatians'] = {'gal'},
	['ephesians'] = {'eph'},
	['philippians'] = {'phil'},
	['colossians'] = {'col'},
	['1_thessalonians'] = {'1thess', '1thes'},
	['2_thessalonians'] = {'2thess', '2thes'},
	['1_timothy'] = {'1tim', '1tm'},
	['2_timothy'] = {'2tim', '2tm'},
	['titus'] = {'ti'},
	['philemon'] = {'philem', 'phlm'},
	['hebrews'] = {'heb'},
	['james'] = {'jas'},
	['1_peter'] = {'1pet', '1pt'},
	['2_peter'] = {'2pet', '2pt'},
	['1_john'] = {'1jn'},
	['2_john'] = {'2jn'},
	['3_john'] = {'3jn'},
	['jude'] = {'jude'},
	['revelation'] = {'rev', 'apocalypse', 'apoc', 'rv'},

local apoc = {
	['1_esdras'] = true, ['2_esdras'] = true, ['judith'] = true, ['1_maccabees'] = true,
	['2_maccabees'] = true, ['3_maccabees'] = true, ['4_maccabees'] = true,
	['prayer_of_manasseh'] = true, ['susanna'] = true, ['tobit'] = true,
	['wisdom_of_solomon'] = true, ['prayer_of_azariah'] = true, ['rest_of_esther'] = true,
	['bel_and_the_dragon'] = true, ['epistle_of_jeremiah'] = true,
	['sirach'] = true, ['ecclesiasticus'] = true,

--these books only have one chapter, have to be handled differently
local no_chapters = {
	['obadiah'] = true, ['epistle_of_jeremiah'] = true, ['prayer_of_azariah'] = true,
	['susanna'] = true, ['bel_and_the_dragon'] = true, ['prayer_of_manasseh'] = true,
	['philemon'] = true, ['2_john'] = true, ['3_john'] = true, ['jude'] = true,

--sets the website to be used for each version, biblegateway is the fallback so don't define any for it
local site_tbl = {
	nrsv = 'oremus', nrsvae = 'oremus',
	kjv = 'wikisource', asv = 'wikisource', wyc = 'wikisource', ws = 'wikisource', web = 'wikisource',
	he = 'mechon_mamre', jps = 'mechon_mamre',
	niv = 'biblica', nivuk = 'biblica', amp = 'biblica', ab = 'biblica',
	msg = 'biblica', nlt = 'biblica', nirv = 'biblica',
	nab = 'usccb',
	bb = 'bible_hub', bbc = 'bible_hub', bbl = 'bible_hub', opb = 'bible_hub',
	esv = 'esv_bible',

--pattern for the url of each site using _book etc. (underscore then letters [a-z]) for variables
local urlpat_tbl = {
	oremus = 'https://bible.oremus.org/?passage=_book%20_vrange&version=_version',
	wikisource = 's:Bible (_version)/_book#_schap:_svers',
	mechon_mamre = 'https://mechon-mamre.org/_version_book_schap.htm#_svers',
	biblica = 'https://www.biblica.com/bible/?osis=_version:_book%20_vrange',
	usccb = 'https://bible.usccb.org/bible/_book/_schap?_svers',
	biblegateway = 'https://www.biblegateway.com/passage/?search=_book+_vrange&version=_version',
	bible_hub = 'https://_version/_book/_schap-_svers.htm',
	esv_bible = 'https://www.esv.org/_book+_schap:_svers',

--changes book name to use in url for each site, only if necessary
local site_book_tbl = {
	oremus = {
		['epistle_of_jeremiah'] = 'letter of jeremiah',
	usccb = {
		['song_of_solomon'] = 'song_of_songs',
		['wisdom_of_solomon'] = 'wisdom',
		['ecclesiasticus'] = 'sirach',
	mechon_mamre = {
		['genesis'] = '01', ['exodus'] = '02', ['leviticus'] = '03',
		['numbers'] = '04', ['deuteronomy'] = '05', ['joshua'] = '06',
		['judges'] = '07', ['1_samuel'] = '08a', ['2_samuel'] = '08b',
		['1_kings'] = '09a', ['2_kings'] = '09b', ['isaiah'] = '10',
		['jeremiah'] = '11', ['ezekiel'] = '12', ['hosea'] = '13',
		['joel'] = '14', ['amos'] = '15', ['obadiah'] = '16', ['jonah'] = '17',
		['micah'] = '18', ['nahum'] = '19', ['habakkuk'] = '20',
		['zephaniah'] = '21', ['haggai'] = '22', ['zechariah'] = '23',
		['malachi'] = '24', ['1_chronicles'] = '25a', ['2_chronicles'] = '25b',
		['psalms'] = '26', ['job'] = '27', ['proverbs'] = '28', ['ruth'] = '29',
		['song_of_solomon'] = '30', ['ecclesiastes'] = '31', ['lamentations'] = '32',
		['esther'] = '33', ['daniel'] = '34', ['ezra'] = '35a', ['nehemiah'] = '35b',

--changes to the version name to be used in urls, only if necessary
local site_version_tbl = {
	mechon_mamre = {
		he = 'p/pt/pt',
		jps = 'e/et/et',
	wikisource = {
		kjv = 'King James', ['9'] = 'King James',
		asv = 'American Standard',
		ws = 'Wikisource',
		web = 'World English',
		wyc = 'Wycliffe',
	bible_hub = {
		bb = 'biblebrowser.com',
		bbc = 'biblecommenter.com',
		bbl = 'scripturetext.com',
		opb = 'bible.cc',

local function trimArg(text)
	if type(text) == 'string' then
		text = text:match('(%S.-)%s*$') --trimmed text or nil if empty
	end
	return text
end

local function valueExists
	for _, v in pairs(tbl) do
		if value == v then
			return true
		end
	end
	return false
end

local function titlecase(arg)
	-- http://grammar.yourdictionary.com/capitalization/rules-for-capitalization-in-titles.html
	-- recommended by The U.S. Government Printing Office Style Manual:
	-- 'Capitalize all words in titles of publications and documents,
	-- except a, an, the, at, by, for, in, of, on, to, up, and, as, but, or, and nor.'
	local alwayslower = {
		['a'] = true, ['an'] = true, ['the'] = true,
		['and'] = true, ['but'] = true, ['or'] = true, ['for'] = true,
		['nor'] = true, ['on'] = true, ['in'] = true, ['at'] = true, ['to'] = true,
		['from'] = true, ['by'] = true, ['of'] = true, ['up'] = true,
	local words = mw.text.split(mw.text.trim(arg or ''), '_')
	for i, s in ipairs(words) do
		s = string.lower(s)
		if i > 1 then
			if not alwayslower[s] then
				s = mw.getContentLanguage:ucfirst(s)
			end
		else
			s = mw.getContentLanguage:ucfirst(s)
		end
		words[i] = s
	end
	return table.concat
end

function p.main(frame)
	local targs = frame:getParent.args
	local args = {}
	for _, param in ipairs do
		args[param] = trimArg(targs[param])
	end
	local default_version = 'nrsv'
	local input_book = ''
	local ref = ''
	local version = ''
	local version_num
	local text = ''
	local wikilink = ''
	local mainspace = mw.title.getCurrentTitle:inNamespaces(0)
	if args[1] == nil or args[2] == nil or tonumber(args[1]) ~= nil then
		-- first argument is a numeric prefix and second is book name
		input_book = trimArg((args[1] or '') .. ' ' .. (args[2] or '')) or ''
		wikilink = trimArg((args[1] or 'Book of') .. ' ' .. (args[2] or '')) or ''
		ref = args[3] or ''
		version = mw.ustring.lower(args[4] or default_version)
		text = args[5] or trimArg((input_book .. ' ' .. ref))
	else
		-- first argument is the whole book name
		input_book = args[1] or ''
		wikilink = 'Book of ' .. args[1]
		ref = args[2] or ''
		version = mw.ustring.lower(args[3] or default_version)
		text = args[4] or (input_book .. ' ' .. ref)
	end
	if args.nobook == 'yes' then
		text = ref
	end
	if args.wlink == 'yes' then
		text = ref
		wikilink = '' .. input_book .. ' '
	else
		wikilink = ''	
	end
	if args.multi == 'yes' then
		local linktext = text:gsub
		return '[https://www.biblegateway.com/passage/?search=' .. linktext .. '&version=NRSV' .. ' ' .. text .. ']'
	end
	
	text = text:gsub --change hyphens to en dashes (3:2-5 → 3:2–5)

	if tonumber(version) then
		version = version_num_codes[tonumber(version)] or version
		version_num = true
	end

	local errors = {}
	if version == 'jpr' or version == 'jp' then --chabad doesn't work so reroute
		version = 'he'
		if mainspace then
			table.insert
		end
	end

	local book = input_book:gsub:gsub
	book = mw.ustring.lower(book)

	local book_found = false
	local standard = book:gsub
	for full_book, aliases in pairs(book_aliases) do
		if standard == full_book:gsub or valueExists then
			book = full_book
			book_found = true
			break
		end
	end

	local site = site_tbl[version] or 'biblegateway' --fall back on biblegateway for unrecognized version because it has so many versions

	if apoc[book] and version == 'nrsv' and site == 'oremus' then --oremus's nrsv doesn't have the apocrypha
		version = 'nrsvae' --the anglicized version does
	end

	local urlpat = urlpat_tbl[site]

	local split_ref = mw.text.split --split the ref into the part before and after the dash/hyphen
	local s_ref = mw.text.split --any punctuation can be used to separate chapter from verse
	local e_ref = split_ref[2] or split_ref[1]
	e_ref = mw.text.split
	for i, v in ipairs(s_ref) do s_ref[i] = v:gsub end --remove any non-numeric character (such as f)
	for i, v in ipairs(e_ref) do e_ref[i] = v:gsub end

	local e_chap, e_vers, s_chap, s_vers
	local chapter_only = not s_ref[2]
	if no_chapters[book] then
		chapter_only = false
		s_chap = 1
		s_vers = s_ref[2] or s_ref[1] or 1 --verse 3 can be specified as "3" or "1:3"
		e_chap = 1
		e_vers = e_ref[2] or e_ref[1] or 1
	else
		s_chap = s_ref[1] or 1
		s_vers = s_ref[2] or 1
		if e_ref[2] or not s_ref[2] then --chapter-chapter or chapter(:verse)?-chapter:verse
			e_chap = e_ref[1] or s_chap
		else --chapter:verse-verse
			e_chap = s_chap
		end
		e_vers = e_ref[2] or e_ref[1] or s_vers
	end

	if type(site_book_tbl[site]) == 'table' then
		book = site_book_tbl[site][book] or book
	end

	book = titlecase(book) --title case looks better at oremus where they display the input

	if site == 'mechon_mamre' then --special case handling for components of the url
		if not tonumber(s_chap) then --non-numeric characters were omitted above so this may not be what was entered
			error
		end
		s_chap = string.format .. (s_chap % 10)
	elseif site == 'biblica' or site == 'oremus' then
		book = book:gsub
	elseif site == 'esv_bible' or site == 'biblegateway' then
		book = book:gsub
	elseif site == 'bible_hub' then
		book = string.lower(book)
	elseif site == 'usccb' then
		book = book:gsub
	end
	if type(site_version_tbl[site]) == 'table' then
		version = site_version_tbl[site][version]
	end

	local v_range
	if chapter_only then
		if e_chap == s_chap then
			v_range = s_chap
		else
			v_range = s_chap .. '–' .. e_chap
		end
	else
		if e_chap == s_chap and e_vers == s_vers then
			v_range = s_chap ..':' .. s_vers
		elseif e_chap == s_chap then
			v_range = s_chap .. ':' .. s_vers .. '–' .. e_vers
		else
			v_range = s_chap .. ':' .. s_vers .. '–' .. e_chap .. ':' .. e_vers
		end
	end

	local url = urlpat:gsub('_%l+', { --get the components into the url
					_book = book,
					_schap = s_chap,
					_svers = s_vers,
					_echap = e_chap,
					_evers = e_vers,
					_vrange = v_range,
					_version = version,

	local fulllink
	if site == 'wikisource' then --interwikilink
		fulllink = wikilink .. '' .. text .. ''
	else
		fulllink = wikilink .. '[' .. url .. ' ' .. text .. ']'
	end

	if mainspace then
		if not book_found then
			table.insert
		end
		if version_num then
			table.insert
		end
	end
	return fulllink .. table.concat(errors)
end