-- HELPER FUNCTIONS --
local function notblank(v) return (v or '' ) ~= '' end
local function ifblank(v, alt1, alt2) return notblank(v) and v or (notblank(alt1) and alt1 or alt2) end
local function red(v) return '<span style="color: red;">' .. v .. '</span>' end
local function getContent(page) return string.gsub(mw.title.new(page).content, '^Date,"[^"]+"', '') end
local function diffDays(dargs)
	return require('Module:diff days')['diff_days'](
		mw.getCurrentFrame():newChild{ title = 'Template:Diff_days', args = dargs }
	)
end
local showTimeLine = require('Module:Horizontal timeline')._showTimeLine
local Text = require('Module:Text').Text()

-- EXPORTED CONSTANTS --
local p = {
	gAGING = function() return 7 end,  --global for representing the age in days after which a pageviews file, and any chart based on it, is no longer fresh and should be updated. Charts are still displayed for articles with aging pageviews files; when the pageviews file reaches gSTALE, the chart is no longer displayed.
	gCOUNT = function() return 75 end, --global for representing the default number of days to display in the chart; overridable with param {{para|ct}}.
	gSTALE = function() return 30 end, --global for representing the age in days after which a pageviews file, and any chart based on it, becomes stale and no longer appropriate for display on a Talk page. Stale pages should have their pageviews file updated.
}

-- TEMPLATE FUNCTIONS --
function p._xviews(args)														-- {{User:Mathglot/sandbox/Templates/Xviews}}
	-- args contains stale, days, ct, log, and mode
	local page = ifblank(args[1], mw.title.getCurrentTitle().fullText .. '/pageviews')
	if mw.title.new(page).exists then
		local stale = tonumber(ifblank(args.stale, p.gSTALE()))
		if tonumber(p._age(page)) > stale then --stale:
			return red(mw.ustring.format(
				'The pageviews file [[%s]] is more than %d days old; please see [[User:Mathglot/sandbox/Templates/Xviews#Instructions|Instructions]].',
				page, stale
			))
		else --not stale:
			return p._xvmain(page, {ct = ifblank(args.days, args.ct, p.gCOUNT())}) ..
				((notblank(args.log) or notblank(args.mode)) and '' or p._xAxis(page, {})) -- p._xAxis() doesn't handle log values or vertical bars yet
		end
	else
		return red('Missing required pageviews file.') ..
			' See [[User:Mathglot/sandbox/Templates/Xviews#Instructions|Instructions]].'
	end
	
end
function p.xviews(frame)
	return p._xviews(frame.args)
end
	
function p._age(page)															-- {{User:Mathglot/sandbox/Templates/Xviews/age}}
	local nthview = p._nthView(page, p._viewCount(page))
	nthview = Text.split(nthview, ':', true)[1]
	return diffDays({nthview, mw.getContentLanguage():formatDate('j F Y'), precision=0})
end
function p.age(frame)
	return p._age(ifblank(frame.args[1] or 'Talk:Liberation of France/pageviews'))
end

function p._latest(page)															-- {{User:Mathglot/sandbox/Templates/Xviews/age}}
	return Text.split(p._nthView(page, p._viewCount(page)), ':', true)[2]
end
function p.latest(frame)
	return p._latest(ifblank(frame.args[1] or 'Talk:Liberation of France/pageviews'))
end

function p._nthView(page, index)												-- {{User:Mathglot/sandbox/Templates/Xviews/nth view}}
	local content = string.gsub(getContent(page), '.?(202%d%-%d%d%-%d%d)%,?(%d+)', '%1:%2,')
	content = string.gsub(content, "^%s*,%s*(.-)%s*,$", "%1")
	local items = {}
    for item in string.gmatch(content, "([^,]+)") do
        table.insert(items, mw.text.trim(item))
    end
	index = tonumber(index)
    if index < 0 then
        index = #items + index + 1
    end
	return items[index]
end
function p.nthView(frame)
	return p._nthView(
		ifblank(frame.args[1] or 'Talk:Liberation of France/pageviews'),
		ifblank(frame.args[2] or 3)
	)
end

function p._viewCount(page)														-- {{User:Mathglot/sandbox/Templates/Xviews/view count}}
	local str = string.gsub(getContent(page), '.?202%d%-%d%d%-%d%d', '')
	str = string.gsub(str, ',', '', 1)
	-- Remove leading and trailing delimiters (along with any surrounding whitespace)
    str = str:gsub("^%s*,%s*", ""):gsub("%s*,%s*$", "")
	-- Normalize internal consecutive delimiters to a single delimiter (replace ",," with ",")
    str = str:gsub("%s*,%s*,%s*", ',')
    return select(2, str:gsub(',', '')) + 1
end
function p.viewCount(frame)
	return p._viewCount(ifblank(frame.args[1], 'Talk:Liberation of France/pageviews'))
end

function p._xvmain(page, xargs)													-- {{User:Mathglot/sandbox/Templates/Xviews/xvmain}}
	-- xargs contains ct, log, mode, and debug
	local output = {}
	local stop = p._viewCount(page)
	local start = stop - math.min(152, ifblank(xargs.ct, 93)) + 1
	local iargs = {
		page = page,
		max = p._maxViews(page),
		log = xargs.log, -- logarithmic scale (not implemented yet)
		mode = xargs.mode, -- bar display orientation  (mode=vert not implemented yet)
		debug = xargs.debug, -- set to non-empty for loop debug output emitted by p._itemBar()
	}
	for n = start, stop do
		iargs.n = n
		table.insert(output, p._itemBar(iargs))
	end
	return table.concat(output)
end
function p.xvmain(frame)
	local xargs = frame.args
	xargs.ct = ifblank(xargs.ct, 93)
	return p._xvmain(ifblank(xargs[1], 'Talk:Liberation of France/pageviews'), xargs)
end

function p._itemBar(iargs)														-- {{User:Mathglot/sandbox/Templates/Xviews/item bar}}
	-- iargs contains n, page, max, log, mode, and debug
	if iargs.debug then
		return mw.ustring.format("page=%s, n=%s, label=%s",
			ifblank(iargs.page, 'missing'),
			ifblank(iargs.n, 'missing'),
			ifblank(iargs.label, 'missing')
		)
	end
	local nthview = p._nthView(iargs.page, ifblank(iargs.n, 1))
	if not nthview then
		error("Error generating item bar for item #" .. ifblank(iargs.n, 1) .. ". Range may be invalid")
	end
	local val = Text.split(nthview, ':', true)[2]
	local width = val * 100 * 0.88 / p._maxViews(iargs.page)
	width = tonumber(string.format("%.2f", width))
	local label = p._xlabel(Text.split(nthview, ':', true)[1], 'y')
	return p._vbar(width, val, {label = label})
end
function p.itemBar(frame)
	local iargs = frame.args
	iargs.page = ifblank(iargs.page, 'Talk:House of the Dragon/pageviews')
	iargs.n = ifblank(iargs.n, 1)
	return p._itemBar(iargs)
end

function p._vbar(width, val, vargs)												-- {{User:Mathglot/sandbox/Templates/Xviews/vbar}}
	-- vargs contains label, label-style, thick, style, val, and val-style
	local ts =  mw.getCurrentFrame():extensionTag{
		name = 'templatestyles',
		args = {src = 'User:Mathglot/sandbox/Templates/Xviews/vbar/styles.css'}
	}
	local div = mw.html.create('div'):addClass('vbar')
	if notblank(vargs.label) then
		div:tag('span')
			:addClass('vbar-labelh')
			:cssText(ifblank(vargs['label-style']))
			:wikitext(vargs.label)
	end
	div:tag('span')
		:addClass('vbar-h')
		:attr('alt', 'Page views for (date) = (views).')
		:css('height', ifblank(vargs['thick']))
		:css('width', width .. '%')
		:cssText(ifblank(vargs.style))
	if notblank(val) then
		div:tag('span')
			:addClass('vbar-valh')
			:cssText(ifblank(vargs['val-style']))
			:wikitext(val)
	end
	return ts .. tostring(div)
end
function p.vbar(frame)
	local vargs = frame.args
	return p._vbar(ifblank(vargs[1], 75), ifblank(vargs[2], vargs.val, 2136), vargs)
end

function p._xlabel(date, bold01)												-- {{User:Mathglot/sandbox/Templates/Xviews/xlabel}}
	local replace = ((date:sub(-3) == '-01') and notblank(bold01)) and "'''%1'''" or "%1"
	return string.gsub(date, '20[23]%d%-(%d%d%-%d%d)', replace)
end
function p.xlabel(frame)
	return p._xlabel(ifblank(frame.date, '2024-06-01'), frame.bold01)
end

function p._minViews(page)														-- {{User:Mathglot/sandbox/Templates/Xviews/min views}}
	local views = nil
	local content = string.gsub(getContent(page), '.?202%d%-%d%d%-%d%d', '')
	for v in Text.gsplit(content, ',', true) do
		v = tonumber(v)
		if views == nil or (v and v < views) then
			views = v
		end
	end
	return views
end
function p.minViews(frame)
	return p._minViews(ifblank(frame.args[1], 'Talk:Liberation of France/pageviews'))
end

function p._maxViews(page)														-- {{User:Mathglot/sandbox/Templates/Xviews/max views}}
	local views = 0
	local content = string.gsub(getContent(page), '.?202%d%-%d%d%-%d%d', '')
	for v in Text.gsplit(content, ',', true) do
		v = tonumber(v)
		if (v and v > views) then views = v end
	end
	return views
end
function p.maxViews(frame)
	return p._maxViews(ifblank(frame.args[1], 'Talk:Liberation of France/pageviews'))
end

function p._xAxis(page, xargs)													-- {{User:Mathglot/sandbox/Templates/Xviews/x-axis}}
	-- xargs contains shift, caption, ff
	local div = mw.html.create('div')
		:css('margin', '-22px 0 0 ' .. ifblank(xargs.shift, '16px'))
		:wikitext(
			showTimeLine({
				caption = ifblank(xargs.caption, 'page views for ' .. mw.title.new(page).rootText),
				border = 'none',
				from = 0,
				to = p._maxViews(page),
				inc = tonumber(string.format("%.0f", ifblank(xargs.ff, 1.0) * p._maxViews(page)/100)) * 10,
				row1 = 'scale',
				['axis-nudge'] = '-0.8em',
				['axis-0'] = '<span style="padding-left:10px">0</span>'
			})
		)
	return tostring(div)
end
function p.xAxis(frame)
	return p._xArgs(ifblank(frame.args[1], 'Talk:Liberation of France/pageviews'), frame.args)
end

function p._summary(page, sargs)												-- {{User:Mathglot/sandbox/Templates/Xviews/summary}}
	-- sargs contains days
	page = ifblank(page, mw.title.getCurrentTitle().fullText .. '/pageviews')
	if not mw.title.new(page).exists then return '' end
	return 'Pageviews [[User:Mathglot/sandbox/Templates/Xviews/summary#Description|summary]]: ' ..
		'size=' .. p._viewCount(page) ..
		', age=' .. p._age(page) ..
		', days=' .. ifblank(sargs.days, p.gCOUNT()) ..
		', min=' .. p._minViews(page) ..
		', max=' .. p._maxViews(page) ..
		', latest=' .. p._latest(page)
end
function p.summary(frame)
	return p._summary(frame.args[1], frame.args)
end

function p._isStale(page, days)													-- {{User:Mathglot/sandbox/Templates/Xviews/is stale}}
	page = ifblank(page, mw.title.getCurrentTitle().fullText .. '/pageviews')
	if not mw.title.new(page).exists then return 'missing' end
	local age = tonumber(p._age(page))
	if age > tonumber(ifblank(days, p.gSTALE())) then return 'stale' end
	if age > tonumber(ifblank(days, p.gAGING())) then return 'aging' end
	return ''
end
function p.isStale(frame)
	return p._isStale(frame.args[1], frame.args[2])
end

return p