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-- @author https://github.com/Kasper24
-- @copyright 2021-2022 Kasper24
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local GLib = require("lgi").GLib
local gobject = require("gears.object")
local gtable = require("gears.table")
local subscribable = require("lib.animation.subscribable")
local tween = require("lib.animation.tween")
local ipairs = ipairs
local table = table
local pairs = pairs

local animation_manager = {}
animation_manager.easing = {
	linear = "linear",
	inQuad = "inQuad",
	outQuad = "outQuad",
	inOutQuad = "inOutQuad",
	outInQuad = "outInQuad",
	inCubic = "inCubic",
	outCubic = "outCubic",
	inOutCubic = "inOutCubic",
	outInCubic = "outInCubic",
	inQuart = "inQuart",
	outQuart = "outQuart",
	inOutQuart = "inOutQuart",
	outInQuart = "outInQuart",
	inQuint = "inQuint",
	outQuint = "outQuint",
	inOutQuint = "inOutQuint",
	outInQuint = "outInQuint",
	inSine = "inSine",
	outSine = "outSine",
	inOutSine = "inOutSine",
	outInSine = "outInSine",
	inExpo = "inExpo",
	outExpo = "outExpo",
	inOutExpo = "inOutExpo",
	outInExpo = "outInExpo",
	inCirc = "inCirc",
	outCirc = "outCirc",
	inOutCirc = "inOutCirc",
	outInCirc = "outInCirc",
	inElastic = "inElastic",
	outElastic = "outElastic",
	inOutElastic = "inOutElastic",
	outInElastic = "outInElastic",
	inBack = "inBack",
	outBack = "outBack",
	inOutBack = "inOutBack",
	outInBack = "outInBack",
	inBounce = "inBounce",
	outBounce = "outBounce",
	inOutBounce = "inOutBounce",
	outInBounce = "outInBounce",
}

local animation = {}

local instance = nil

local ANIMATION_FRAME_DELAY = 5

local function second_to_micro(sec)
	return sec * 1000000
end

function animation:start(args)
	args = args or {}

	-- Awestoer/Rubbto compatibility
	-- I'd rather this always be a table, but Awestoer/Rubbto
	-- except the :set() method to have 1 number value parameter
	-- used to set the target
	local is_table = type(args) == "table"
	local initial = is_table and (args.pos or self.pos) or self.pos
	local subject = is_table and (args.subject or self.subject) or self.subject
	local target = is_table and (args.target or self.target) or args
	local duration = is_table and (args.duration or self.duration) or self.duration
	local easing = is_table and (args.easing or self.easing) or self.easing

	duration = self._private.anim_manager._private.instant == true and 0.01 or duration

	if self.tween == nil or self.reset_on_stop == true then
		self.tween = tween.new({
			initial = initial,
			subject = subject,
			target = target,
			duration = second_to_micro(duration),
			easing = easing,
		})
	end

	if self._private.anim_manager._private.animations[self.index] == nil then
		table.insert(self._private.anim_manager._private.animations, self)
	end

	self.state = true
	self.last_elapsed = GLib.get_monotonic_time()

	self.started:fire()
	self:emit_signal("started")
end

function animation:set(args)
	self:start(args)
	self:emit_signal("set")
end

function animation:stop()
	self.state = false
	self:emit_signal("stopped")
end

function animation:abort()
	animation:stop()
	self:emit_signal("aborted")
end

function animation:initial()
	return self._private.initial
end

function animation_manager:set_instant(value)
	self._private.instant = value
end

function animation_manager:new(args)
	args = args or {}

	args.pos = args.pos or 0
	args.subject = args.subject or nil
	args.target = args.target or nil
	args.duration = args.duration or 0
	args.easing = args.easing or nil
	args.loop = args.loop or false
	args.signals = args.signals or {}
	args.update = args.update or nil
	args.reset_on_stop = args.reset_on_stop == nil and true or args.reset_on_stop

	-- Awestoer/Rubbto compatibility
	args.subscribed = args.subscribed or nil
	local ret = subscribable()
	ret.started = subscribable()
	ret.ended = subscribable()
	if args.subscribed ~= nil then
		ret:subscribe(args.subscribed)
	end

	for sig, sigfun in pairs(args.signals) do
		ret:connect_signal(sig, sigfun)
	end
	if args.update ~= nil then
		ret:connect_signal("update", args.update)
	end

	gtable.crush(ret, args, true)
	gtable.crush(ret, animation, true)

	ret._private = {}
	ret._private.anim_manager = self
	ret._private.initial = args.pos

	return ret
end

local function new()
	local ret = gobject({})
	gtable.crush(ret, animation_manager, true)

	ret._private = {}
	ret._private.animations = {}
	ret._private.instant = false

	GLib.timeout_add(GLib.PRIORITY_DEFAULT, ANIMATION_FRAME_DELAY, function()
		---@diagnostic disable-next-line: redefined-local
		for index, animation in ipairs(ret._private.animations) do
			if animation.state == true then
				-- compute delta time
				local time = GLib.get_monotonic_time()
				local delta = time - animation.last_elapsed
				animation.last_elapsed = time

				-- If pos is true, the animation has ended
				local pos = animation.tween:update(delta)
				if pos == true then
					-- Loop the animation, don't end it.
					-- Useful for widgets like the spinning cicle
					if animation.loop == true then
						animation.tween:reset()
					else
						-- Snap to end
						animation.pos = animation.tween.target
						animation:fire(animation.pos)
						animation:emit_signal("update", animation.pos)

						animation.state = false
						animation.ended:fire(pos)
						table.remove(ret._private.animations, index)
						animation:emit_signal("ended", animation.pos)
					end
					-- Animation in process, keep updating
				else
					animation.pos = pos
					animation:fire(animation.pos)
					animation:emit_signal("update", animation.pos)
				end
			else
				table.remove(ret._private.animations, index)
			end
		end

		-- call again the function after cooldown
		return true
	end)

	return ret
end

if not instance then
	instance = new()
end
return instance