-- Copyright 2025 David Vazgenovich Shakaryan

local config = require('config')

local mp_utils = require('mp.utils')

local osd = {}
local mt = {}
mt.__index = mt

local colours = {}
for k, v in pairs(config.colours) do
	-- constructed backwards as ASS colour tags expect BGR but we configure
	-- them as RGB
	tag = '&}'
	for byte in v:gmatch('..') do
		tag = byte:upper() .. tag
	end
	colours[k] = '{\\c&H' .. tag
end

local function draw_rect(x1, y1, x2, y2)
	return string.format(
		'{\\p1}m %f %f l %f %f %f %f %f %f{\\p0}',
		x1, y1, x2, y1, x2, y2, x1, y2)
end

local cursor_glyph = '{\\pbo' .. math.floor(config.font_size / 5) .. '}' ..
	draw_rect(0, 0, math.ceil(config.font_size / 32), config.font_size)

local function asscape(str)
	-- remove newlines before escaping, since we don't want output to
	-- unexpectedly span multiple lines
	return mp.command_native({'escape-ass', (str:gsub('\n', ' '))})
end

function osd.new(init)
	local lines = math.floor((720 / config.font_size) + 0.5) - 1
	local t = setmetatable({
		fg = mp.create_osd_overlay('ass-events'),
		bg = mp.create_osd_overlay('ass-events'),
		width = 0,
		height = 0,
		scale = 1,
		lines = lines,
		padding = math.floor((720 - (lines * config.font_size)) / 2),
	}, mt)
	t.bg.z = -1

	for k, v in pairs(init or {}) do
		t[k] = v
	end

	return t
end

function mt:resize(w, h)
	self.width = w
	self.height = h
	self.scale = h / 720
end

function mt:menu_lines(state)
	if state.depth > 1 then
		-- leaves an extra line for padding between titles and options
		return self.lines - state.depth
	else
		return self.lines
	end
end

function mt:menu_title(menu)
	local str = asscape(menu.title)
	local col = menu.search_active and colours.selected or colours.title

	if menu.type == 'search' then
		str = str:gsub('<text>', asscape(menu.search_text))

		if str:find('<text_with_cursor>', 1, true) then
			str = str:gsub('<text_with_cursor>',
				asscape(menu.search_text:sub(
						1, menu.search_cursor - 1)) ..
					cursor_glyph ..
					asscape(menu.search_text:sub(
						menu.search_cursor)))
		end

		str = str:gsub('<colours.info>', colours.info)
		str = str:gsub('<num_matches>', #menu.options)
		str = str:gsub('<num_total>', #menu.search_options)
	end

	if menu.sorted then
		str = colours.icon_sorted .. '⇅ ' .. col .. str
	end

	return col .. ' » ' .. str
end

function mt:option_icons(opt, info)
	local str = ''
	if info.selected then
		str = colours.selected .. '› '
	end
	if info.playing then
		str = str .. colours.icon_playing .. '\226\143\186 '
	end
	if info.favourited then
		str = str .. colours.icon_favourite .. '★ '
	end
	if opt.active then
		str = str .. colours.icon_active .. '\226\143\186 '
	end
	if opt.missing then
		str = str .. colours.icon_missing .. '!!!MISSING!!! '
	end
	return str
end

function mt:option_text(opt, info)
	local str = opt.name
	local col = colours.option
	if info.selected then
		col = info.empty and colours.selected_empty or colours.selected
	elseif info.empty then
		col = colours.group_empty
	elseif opt.type == 'group' then
		col = colours.group
	end

	if opt.matches then
		local buf = ''
		local hl_col = info.empty and colours.search_hl_empty or
			colours.search_hl
		local n = 0

		for _, match in ipairs(opt.matches) do
			buf = buf .. col ..
				asscape(str:sub(n + 1, match.start - 1)) ..
				hl_col ..
				asscape(str:sub(match.start, match.stop))
			n = match.stop
		end
		str = buf .. col .. asscape(str:sub(n + 1))
	else
		str = col .. asscape(str)
	end

	if opt.type == 'group' then
		str = col .. '[' .. str .. ']'
	end

	if opt.info and #opt.info > 0 then
		str = str .. colours.info .. ' (' .. asscape(opt.info) .. ')'
	end

	return str
end

function mt:option_path(opt, info)
	if not opt.path or #opt.path == 0 then
		return ''
	end

	local str = info.empty and colours.search_path_empty or
		colours.search_path
	for i = #opt.path, 1, -1 do
		str = str .. ' « ' .. asscape(opt.path[i].name)
	end
	return str
end

function mt:load_img()
	local f = mp_utils.file_info(self.img.path)
	if not f then
		return
	end

	if self.magick_cmd_id then
		mp.abort_async_command(self.magick_cmd_id)
	end

	local magick_cmd = {
		'magick', self.img.path,
		'-depth', '8',
		'-resize', string.format(
			'x%%[fx:max(%d, min(%d, %d*h/w))]',
			self.img.min_h, self.img.max_h, self.img.max_w),
		'-print', '%w %h',
		'tmp.bgra'
	}
	print('exec: ' .. mp_utils.to_string(magick_cmd))
	self.img.magick_cmd = magick_cmd
	self.magick_cmd = magick_cmd
	self.magick_cmd_id = mp.command_native_async({
		name = 'subprocess',
		args = magick_cmd,
		capture_stdout = true,
		playback_only = false,
	}, function (_, res)
		if magick_cmd ~= self.magick_cmd then
			return
		end

		self.magick_cmd = nil
		self.magick_cmd_id = nil

		if not self.img or not res or res.status ~= 0 then
			return
		end

		local w, h = res.stdout:match('(.+) (.+)')
		self.img.cmd = {
			name = 'overlay-add',
			id = 0,
			file = 'tmp.bgra',
			w = w,
			h = h,
			x = self.img.right - w,
			y = self.img.top,
			fmt = 'bgra',
			offset = 0,
			stride = 4*w,
		}

		self:draw_img()
	end)
end

function mt:clear_img(purge)
	if self.img_overlay_id then
		mp.command_native(
			{name = 'overlay-remove', id = self.img_overlay_id})
		self.img_overlay_id = nil
	end

	if purge then
		self.img = nil
	end
end

function mt:draw_img()
	if not self.img then
		return
	end

	if not self.img.magick_cmd then
		self:load_img()
		return
	end

	if self.img.cmd and not self:is_hidden() then
		mp.command_native(self.img.cmd)
		self.img_overlay_id = self.img.cmd.id
	end
end

-- returns (upd, new)
-- upd: if anything changed, e.g. position
-- new: if the image also changed, i.e. different path or size
function mt:set_img(path, menu_res)
	-- images require *real* dimensions and coordinates, unlike other OSD
	-- functions which scale the given values automatically
	local padding = self.scale * self.padding
	local start = self.scale * menu_res.x1
	local fs = self.scale * config.font_size

	-- images are scaled to fit the available OSD area when treated as
	-- having the 2:3 aspect ratio of a standard film poster. when this
	-- results in an image height less than a minimum font-size-derived
	-- value, the image is instead scaled to this minimum height. this
	-- ensures that a given screen has all images, regardless of original
	-- aspect ratio, scaled to either a common width or a common height.
	--
	-- because we have only the total width of the current OSD text, we
	-- cannot slightly reduce the image width to avoid overlapping some
	-- longer line at the bottom, as we do not know where the offending
	-- line is. if it were possible to place images *under* text, maybe
	-- we'd allow overlap, but mpv currently hard-codes this order.
	local min_h = math.floor(3 * fs)
	local max_h = math.floor(math.max(min_h, math.min(
		self.height - 2*padding,
		(self.width - start - 2*padding) * 3/2)))
	local max_w = math.floor(max_h * 2/3)
	local top = math.floor(padding)
	local right = math.floor(self.width - padding)

	if self.img and path == self.img.path and
			min_h == self.img.min_h and
			max_h == self.img.max_h and
			max_w == self.img.max_w then
		if top == self.img.top and right == self.img.right then
			return false, false
		end

		self.img.top = top
		self.img.right = right
		if self.img.cmd then
			self.img.cmd.x = right - self.img.cmd.w
			self.img.cmd.y = top
		end
		return true, false
	end

	self.img = {
		path = path,
		min_h = min_h,
		max_h = max_h,
		max_w = max_w,
		top = top,
		right = right,
	}
	return true, true
end

function mt:draw_scrollbar(state)
	local menu = state:menu()
	local opts = #menu.options
	local lines = self:menu_lines(state)
	if opts <= lines then
		return
	end

	local top = self.padding + ((self.lines - lines) * config.font_size)
	local h = 720 - self.padding - top
	local w = self.padding - 4
	local hh = math.max(config.font_size / 2, h * lines / opts)
	local pos = (h - hh) * (menu.view_top - 1) / (opts - lines)

	return (
		-- bg
		colours.scrollbar_bg ..
		'{\\pos(2,' .. top .. ')}' .. draw_rect(0, 0, w, h) .. '\n' ..
		-- fg
		colours.scrollbar_fg .. '{\\bord0}' ..
		'{\\pos(2,' .. top + pos .. ')}' .. draw_rect(0, 0, w, hh))
end

function mt:redraw(state)
	local out = {}

	if state.depth > 1 then
		for i = 2, state.depth do
			out[#out+1] = self:menu_title(state.menus[i])
		end
		out[#out+1] = ' ' -- space character for correct line height
	end

	local menu = state:menu()

	local img
	if menu.img_url then
		img = menu.img_url
	end

	for i = menu.view_top, math.min(
			menu.view_top + self:menu_lines(state) - 1,
			#menu.options) do
		local opt = menu.options[i]

		-- use real-time count for favourites
		if opt.id == 'favourites' then
			opt.info = tostring(#state.favourites)
		end

		local selected = i == menu.cursor and not menu.search_active
		local info = {
			selected = selected,
			empty = (opt.type == 'group' and not opt.lazy and
				#opt.children == 0),
			playing = not not (
				opt.id and opt.id == state.playing_id),
			favourited = not not (
				opt.id and state:favourited(opt.id)),
		}
		out[#out+1] = self:option_icons(opt, info) ..
			self:option_text(opt, info) ..
			self:option_path(opt, info)

		if selected and opt.img_url then
			img = opt.img_url
		end
	end

	-- \q2 disables line wrapping
	self.fg.data = '{\\q2\\fs' .. config.font_size ..
		'\\pos(' .. self.padding .. ',' .. self.padding .. ')}' ..
		table.concat(out, '\\N')
	self.bg.data =
		'{\\pos(0,0)\\alpha&H' .. config.bg_alpha .. '&\\c&H&}' ..
		draw_rect(0, 0, 7680, 720)
	local sb = self:draw_scrollbar(state)
	if sb then
		self.bg.data = self.bg.data .. '\n' .. sb
	end

	self.fg.compute_bounds = not not img
	local res = self.fg:update()
	self.fg.compute_bounds = false
	self.bg:update()
	if img and self.img_path_func then
		local path = self.img_path_func(img, function(path)
			if self.img and path == self.img.path then
				self:draw_img()
			end
		end)

		local upd, new = self:set_img(path, res)
		if upd then
			if new then
				self:clear_img()
			end
			self:draw_img()
		end
	else
		self:clear_img(true)
	end
end

function mt:toggle_hidden()
	local hidden = not self:is_hidden()

	self.fg.hidden = hidden
	self.fg:update()
	self.bg.hidden = hidden
	self.bg:update()

	if hidden then
		self:clear_img()
	else
		self:draw_img()
	end
end

function mt:is_hidden()
	return self.fg.hidden
end

return osd