local astal = require("astal")
local Widget = require("astal.gtk3.widget")
local App = require("astal.gtk3.app")
local Gdk = require("astal.gtk3").Gdk
local Gtk = require("astal.gtk3").Gtk
local astalify = require("astal.gtk3").astalify
local Apps = astal.require("AstalApps")
local Variable = astal.Variable
local lib = require("lib")

local MAX_ENTRIES = 20
local WIDTH = 7

local FlowBox = astalify(Gtk.FlowBox)
local FlowBoxChild = astalify(Gtk.FlowBoxChild)

local apps = Apps.Apps()

local text = Variable("")
local visible = Variable(false)
local selection = Variable(1)
local entry = Variable(nil)

local list = text(function(text)
	return lib.slice(apps:exact_query(text), 0, MAX_ENTRIES)
end)

local function on_show()
	text:set("")
	selection:set(0)
	entry:get():grab_focus()
end

local function hide()
	visible:set(false)
end

local function on_enter()
	local found = apps:exact_query(text:get())[selection:get() + 1]
	if found then
		found:launch()
		hide()
	end
end

local function update_pos(change_x, change_y)
	local pos = selection:get()
	local pos_x = (pos % WIDTH) + change_x
	local pos_y = math.floor(pos / WIDTH) + change_y

	local count = lib.count(list:get())
	local height = math.floor((count + WIDTH - 1) / WIDTH)

	pos_x = pos_x % WIDTH
	pos_y = pos_y % height
	pos = lib.clamp(pos_y * WIDTH + pos_x, 0, count - 1)
	selection:set(pos)
end

local function on_key_press(_, event)
	if event.keyval == Gdk.KEY_Escape then
		hide()
	elseif event.keyval == Gdk.KEY_Return then
		on_enter()
	elseif event.keyval == Gdk.KEY_Left then
		update_pos(-1, 0)
	elseif event.keyval == Gdk.KEY_Right then
		update_pos(1, 0)
	elseif event.keyval == Gdk.KEY_Up then
		update_pos(0, -1)
	elseif event.keyval == Gdk.KEY_Down then
		update_pos(0, 1)
	end
end

function Application(app, idx)
	return FlowBoxChild({
		Widget.Button({
			class_name = selection():as(function(c)
				if (c + 1) == idx then
					return "app selected"
				else
					return "app"
				end
			end),
			on_clicked = function()
				app:launch()
				hide()
			end,
			Widget.Box({
				halign = "CENTER",
				valign = "CENTER",
				vertical = true,
				Widget.Icon({
					icon = app.icon_name,
				}),
				Widget.Label({
					class_name = "name",
					label = app.name,
					valign = "CENTER",
					ellipsize = "END",
					max_width_chars = 16,
				}),
			}),
		}),
	})
end

function Applications(apps)
	return FlowBox({
		hexpand = true,
		homogeneous = true,
		class_name = "apps",
		lib.map(apps, Application)
	})
end

function Launcher()
	return Widget.Box({
		vertical = true,
		Widget.Entry({
			class_name = "search",
			placeholder_text = "Search",
			halign = "CENTER",
			text = text(),
			setup = function(self)
				entry:set(self)
			end,
			on_changed = function(self)
				text:set(self.text)
				selection:set(0)
			end,
		}),
		Widget.Box({
			class_name = "apps",
			list:as(Applications),
		}),
	})
end

return function()
	local Anchor = astal.require('Astal').WindowAnchor

	Widget.Window({
		class_name = "launcher",
		anchor = Anchor.TOP + Anchor.BOTTOM + Anchor.LEFT + Anchor.RIGHT,
		exclusivity = "EXCLUSIVE",
		keymode = "ON_DEMAND",
		application = App,
		on_show = on_show,
		on_key_press_event = on_key_press,
		visible = visible(),
		Launcher(),
	})

	return visible
end