--[[

     Licensed under GNU General Public License v2
      * (c) 2018, Luca CPZ

--]]

local helpers = require('lain.helpers')
local markup = require('lain.util.markup')
local awful = require('awful')
local naughty = require('naughty')
local floor = math.floor
local os = os
local pairs = pairs
local string = string
local tconcat = table.concat
local type = type
local tonumber = tonumber
local tostring = tostring

-- Calendar notification
-- lain.widget.cal

local function factory(args)
	args = args or {}
	local cal = {
		attach_to = args.attach_to or {},
		week_start = args.week_start or 2,
		three = args.three or false,
		followtag = args.followtag or false,
		week_number = args.week_number or 'none',
		week_number_format = args.week_number_format or args.week_number == 'left' and '%3d | ' or '| %-3d',
		icons = args.icons or helpers.icons_dir .. 'cal/white/',
		notification_preset = args.notification_preset or {
			font = 'Monospace 10',
			fg = '#FFFFFF',
			bg = '#000000',
		},
	}

	function cal.get_week_number(m, st_day, x)
		local date = os.date('*t', m)

		local week_step = (x ~= 0 and floor((x + st_day) / 7) - 1 or 0)

		local display_time = os.time({
			year = date.year,
			month = date.month,
			day = date.day + 7 * week_step,
		})

		return string.format(cal.week_number_format, os.date('%V', display_time))
	end

	function cal.sum_week_days(x, y)
		return (x + y) % 7
	end

	function cal.build(month, year)
		local current_month, current_year = tonumber(os.date('%m')), tonumber(os.date('%Y'))
		local is_current_month = (not month or not year) or (month == current_month and year == current_year)
		local today = is_current_month and tonumber(os.date('%d')) -- otherwise nil and not highlighted
		local t = os.time({ year = year or current_year, month = month and month + 1 or current_month + 1, day = 0 })
		local d = os.date('*t', t)
		local mth_days, st_day, this_month = d.day, (d.wday - d.day - cal.week_start + 1) % 7, os.date('%B %Y', t)
		local notifytable = {
			[1] = string.format('%s%s\n', string.rep(' ', floor((28 - this_month:len()) / 2)), markup.bold(this_month)),
		}
		for day_num = 0, 6 do
			notifytable[#notifytable + 1] = string.format(
				'%3s ',
				os.date('%a', os.time({ year = 2006, month = 1, day = day_num + cal.week_start }))
			)
		end
		notifytable[#notifytable] =
			string.format('%s\n%s', notifytable[#notifytable]:sub(1, -2), string.rep(' ', st_day * 4))
		local strx
		for x = 1, mth_days do
			strx = x
			if x == today then
				if x < 10 then
					x = ' ' .. x
				end
				strx = markup.bold(markup.color(cal.notification_preset.bg, cal.notification_preset.fg, x) .. ' ')
			end
			strx = string.format('%s%s', string.rep(' ', 3 - tostring(x):len()), strx)
			notifytable[#notifytable + 1] =
				string.format('%-4s%s', strx, (x + st_day) % 7 == 0 and x ~= mth_days and '\n' or '')
		end
		if string.len(cal.icons or '') > 0 and today then
			cal.icon = cal.icons .. today .. '.png'
		end
		cal.month, cal.year = d.month, d.year

		if cal.week_number ~= 'none' then
			local m = os.time({ year = year or current_year, month = month and month or current_month, day = 1 })
			local head_prepend = string.rep(' ', tostring(string.format(cal.week_number_format, 0)):len())

			if cal.week_number == 'left' then
				notifytable[1] = head_prepend .. notifytable[1] -- month-year row
				notifytable[2] = head_prepend .. notifytable[2] -- weekdays row
				notifytable[8] = notifytable[8]:gsub('\n', '\n' .. cal.get_week_number(m, st_day, 0)) -- first week of the month

				for x = 10, #notifytable do
					if cal.sum_week_days(st_day, x) == 2 then
						notifytable[x] = cal.get_week_number(m, st_day, x) .. notifytable[x]
					end
				end
			elseif cal.week_number == 'right' then
				notifytable[8] = notifytable[8]:gsub('\n', head_prepend .. '\n') -- weekdays row
				for x = 9, #notifytable do
					if cal.sum_week_days(st_day, x) == 1 then
						notifytable[x] = notifytable[x]:gsub('\n', cal.get_week_number(m, st_day, x - 7) .. '\n')
					end
				end
				-- last week of the month
				local end_days = cal.sum_week_days(st_day, mth_days)
				if end_days ~= 0 then
					end_days = 7 - end_days
				end
				notifytable[#notifytable] = notifytable[#notifytable]
					.. string.rep(' ', 4 * end_days)
					.. cal.get_week_number(m, st_day, mth_days + end_days)
			end
		end

		return notifytable
	end

	function cal.getdate(month, year, offset)
		if not month or not year then
			month = tonumber(os.date('%m'))
			year = tonumber(os.date('%Y'))
		end

		month = month + offset

		while month > 12 do
			month = month - 12
			year = year + 1
		end

		while month < 1 do
			month = month + 12
			year = year - 1
		end

		return month, year
	end

	function cal.hide()
		if not cal.notification then
			return
		end
		naughty.destroy(cal.notification)
		cal.notification = nil
	end

	function cal.show(seconds, month, year, scr)
		local text = tconcat(cal.build(month, year))

		if cal.three then
			local current_month, current_year = cal.month, cal.year
			local prev_month, prev_year = cal.getdate(cal.month, cal.year, -1)
			local next_month, next_year = cal.getdate(cal.month, cal.year, 1)
			text = string.format(
				'%s\n\n%s\n\n%s',
				tconcat(cal.build(prev_month, prev_year)),
				text,
				tconcat(cal.build(next_month, next_year))
			)
			cal.month, cal.year = current_month, current_year
		end

		if cal.notification then
			local title = cal.notification_preset.title or nil
			naughty.replace_text(cal.notification, title, text)
			return
		end

		cal.notification = naughty.notify({
			preset = cal.notification_preset,
			screen = cal.followtag and awful.screen.focused() or scr or 1,
			--icon = cal.icon,
			timeout = type(seconds) == 'number' and seconds or cal.notification_preset.timeout or 5,
			text = text,
		})
	end

	function cal.hover_on()
		cal.show(0)
	end
	function cal.move(offset)
		offset = offset or 0
		cal.month, cal.year = cal.getdate(cal.month, cal.year, offset)
		cal.show(0, cal.month, cal.year)
	end
	function cal.prev()
		cal.move(-1)
	end
	function cal.next()
		cal.move(1)
	end

	function cal.attach(widget)
		widget:connect_signal('mouse::enter', cal.hover_on)
		widget:connect_signal('mouse::leave', cal.hide)
		widget:buttons(
			awful.util.table.join(
				awful.button({}, 1, cal.prev),
				awful.button({}, 3, cal.next),
				awful.button({}, 2, cal.hover_on),
				awful.button({}, 5, cal.prev),
				awful.button({}, 4, cal.next)
			)
		)
	end

	for _, widget in pairs(cal.attach_to) do
		cal.attach(widget)
	end

	return cal
end

return factory