#! /usr/bin/env lua
-- SPDX-FileCopyrightText: © 2026 FireFly
-- SPDX-License-Identifier: 0BSD

local wau = require("wau")
local xkbcommon = require("planar.xkbcommon")
local posix = require("posix")

wau:require("planar.protocol.river-window-management-v1")
wau:require("planar.protocol.river-xkb-bindings-v1")

local globals = {}
local required_globals = {
	["river_window_manager_v1"] = 4,
	["river_xkb_bindings_v1"] = 1,
}

local Mods = wau.river_seat_v1.Modifiers

local term = "foot"
local launcher = "rofi -show drun" -- broken on my end. pls check.
local xkb_bindings = {
	{"t", Mods.MOD1, {"spawn", term}},
	{"f", Mods.MOD1, {"spawn", launcher}}, -- broken on my end. pls check.
	{"q", Mods.MOD1, "close"},
	{"e", Mods.MOD1, "exit"},
	{"r", Mods.MOD1, {"goto", 0, 0}},
	{"F1", Mods.MOD1, {"goto", -2000, -2000}},
	{"F2", Mods.MOD1, {"goto", 2000, -2000}},
	{"F3", Mods.MOD1, {"goto", -2000, 2000}},
	{"F4", Mods.MOD1, {"goto", 2000, 2000}}
}

local pointer_bindings = {
	{"left", Mods.MOD1, "move"},
	{"right", Mods.MOD1, "resize"},
}

local wm = {
	outputs = {},
	seats = {},
	-- Windows are kept in rendering order; last window is topmost
	windows = {},
	cam = {x = 0, y = 0, dirty = false},
}

local function table_index_of(tbl, sought)
	for i, v in ipairs(tbl) do
		if v == sought then return i end
	end
	return 0
end

local function table_filter_inplace(tbl, pred)
	local removed = 0
	for i=1,#tbl do
		if pred(tbl[i]) then
			tbl[i - removed] = tbl[i]
		else
			removed = removed + 1
		end
		if removed > 0 then tbl[i] = nil end
	end
	return tbl
end


---- Output ---------------------------
local Output = { mt = {}, listener = {} }
Output.mt.__index = Output

function Output.create(obj)
	local output = { obj = obj }
	setmetatable(output, Output.mt)
	obj:set_user_data(output)
	obj:add_listener(Output.listener)
	return output
end

function Output:maybe_destroy()
	if self.removed then
		self.obj:destroy()
	else
		return self
	end
end

function Output.listener:removed()
	self:get_user_data().removed = true
end

---- Window ---------------------------
local Window = { mt = {}, listener = {} }
Window.mt.__index = Window

function Window.create(obj)
	local window = {
		obj = obj,
		node = obj:get_node(),
		new = true,
	}
	setmetatable(window, Window.mt)
	obj:set_user_data(window)
	obj:add_listener(Window.listener)
	return window
end

function Window:maybe_destroy()
	if self.closed then
		self.obj:destroy()
		self.node:destroy()
	else
		return self
	end
end

function Window:manage()
	if self.new then
		for i = 1,#wm.outputs do
			local output = wm.outputs[i]
			for k,v in pairs(output) do print(k,v) end
		end
	
		self.new = nil
		self:set_position(wm.cam.x, wm.cam.y)
		self.obj:propose_dimensions(0, 0)
	end

	local move = self.pointer_move_requested
	if move ~= nil then
		self.pointer_move_requested = nil
		move.seat:pointer_move(self)
	end

	local resize = self.pointer_resize_requested
	if resize ~= nil then
		self.pointer_resize_requested = nil
		resize.seat:pointer_resize(self, resize.edges)
	end
end

function Window:set_position(x, y)
	self.node:set_position(x - wm.cam.x, y - wm.cam.y)
	self.x = x
	self.y = y
end

function Window.listener:closed()
	self:get_user_data().closed = true
end
function Window.listener:dimensions(width, height)
	local window = self:get_user_data()
	window.width = width
	window.height = height
end
function Window.listener:pointer_move_requested(seat)
	self:get_user_data().pointer_move_requested = {
		seat = seat:get_user_data(),
	}
end
function Window.listener:pointer_resize_requested(seat, edges)
	local Edges = wau.river_window_v1.Edges
	self:get_user_data().pointer_resize_requested = {
		seat = seat:get_user_data(),
		edges = {
			left = (edges & Edges.LEFT) ~= 0,
			right = (edges & Edges.RIGHT) ~= 0,
			top = (edges & Edges.TOP) ~= 0,
			bottom = (edges & Edges.BOTTOM) ~= 0,
		},
	}
end


---- Seat -----------------------------
local Seat = { mt = {}, listener = {} }
Seat.mt.__index = Seat

function Seat.create(obj)
	local seat = {
		obj = obj,
		new = true,
		xkb_bindings = {},
		pointer_bindings = {},
	}
	setmetatable(seat, Seat.mt)
	obj:set_user_data(seat)
	obj:add_listener(Seat.listener)
	return seat
end

function Seat:focus(window)
	if window == nil and #wm.windows > 0 then
		-- Fall back to topmost window
		window = wm.windows[#wm.windows]
	end

	if window then
		if self.focused ~= window then
			self.obj:focus_window(window.obj)
			self.focused = window
			-- Move to top
			local i = table_index_of(wm.windows, window)
			table.remove(wm.windows, i)
			table.insert(wm.windows, window)
			window.node:place_top()
		end
	else
		self.obj:clear_focus()
		self.focused = nil
	end
end

function Seat:pointer_move(window)
	if window then
		if self.op == nil then
			self:focus(window)
			self.obj:op_start_pointer()
			self.op = {
				type = "move",
				window = window,
				start = { x = window.x, y = window.y },
				dx = 0,
				dy = 0,
			}
		end
	else
		if self.op == nil then
			self:focus(window)
			self.obj:op_start_pointer()
			self.op = {
				type = "world_move",
				dx = 0,
				dy = 0,
				pdx = 0,
				pdy = 0
			}
		end
	end
end

function Seat:pointer_resize(window, edges)
	if self.op == nil then
		self:focus(window)
		window.obj:inform_resize_start()
		self.obj:op_start_pointer()
		self.op = {
			type = "resize",
			window = window,
			edges = edges,
			start = {
				x = window.x,
				y = window.y,
				width = window.width,
				height = window.height,
			},
			dx = 0,
			dy = 0,
		}
	end
end

function Seat:action(action)
	if type(action) == "table" then
		if action[1] == "spawn" then
			if posix.unistd.fork() == 0 then
				posix.unistd.execp(action[2], {})
			end
		elseif action[1] == "goto" then
			wm.cam.x = action[2] or 0
			wm.cam.y = action[3] or 0
			wm.cam.dirty = true;
		end
	elseif action == "close" then
		if self.focused ~= nil then
			self.focused.obj:close()
		end
	elseif action == "focus-next" then
		self:focus(wm.windows[1])
	elseif action == "move" then
		-- if self.hovered ~= nil then
			self:pointer_move(self.hovered)
		-- end
	elseif action == "resize" then
		if self.hovered ~= nil then
			self:pointer_resize(self.hovered, { bottom = true, right = true })
		end
	elseif action == "exit" then
		globals["river_window_manager_v1"]:exit_session()
	else
		print("Seat:action: unimplemented", action)
	end
end

function Seat:add_pointer_binding(button, mods, action)
	-- From /usr/include/linux/input-event-codes.h
	local button_code = ({ left = 0x110, right = 0x111 })[button]
	local obj = self.obj:get_pointer_binding(button_code, mods)
	local binding = { obj = obj }

	obj:add_listener {
		["pressed"] = function (_)
			self.pending_action = action
		end,
	}
	obj:enable()
	table.insert(self.pointer_bindings, binding)
end

function Seat:add_xkb_binding(key, mods, action)
	local keysym = xkbcommon.keysym(key)
	local obj = globals["river_xkb_bindings_v1"]:get_xkb_binding(
					self.obj, keysym, mods)
	local binding = { obj = obj }

	obj:add_listener {
		["pressed"] = function (_)
			self.pending_action = action
		end,
	}
	obj:enable()
	table.insert(self.xkb_bindings, binding)
end

function Seat:manage()
	if self.new then
		self.new = nil

		for _, tbl in ipairs(xkb_bindings) do
			self:add_xkb_binding(table.unpack(tbl))
		end

		for _, tbl in ipairs(pointer_bindings) do
			self:add_pointer_binding(table.unpack(tbl))
		end
	end

	if self.focused and self.focused.closed then
		self.focused = nil
	end

	self:focus(self.interacted)
	self.interacted = nil

	if self.pending_action ~= nil then
		self:action(self.pending_action)
		self.pending_action = nil
	end

	if self.op then
		local op, window = self.op, self.op.window
		local window = self.op.window

		if window and window.closed then
			self.obj:op_end()
			self.op = nil

		elseif self.op_release then
			if window and op.type == "resize" then
				window.obj:inform_resize_end()
			end
			self.obj:op_end()
			self.op = nil

		elseif window and op.type == "resize" then
			local width = math.max(
				1,
				op.edges.left and (op.start.width - op.dx) or
				op.edges.right and (op.start.width + op.dx) or
				op.start.width
			)
			local height = math.max(
				1,
				op.edges.top and (op.start.height - op.dy) or
				op.edges.bottom and (op.start.height + op.dy) or
				op.start.height
			)
			window.obj:propose_dimensions(width, height)
		end
	end

	self.op_release = nil
end

function Seat:render()
	if self.op then
		local op, window = self.op, self.op.window
		if window and self.op.type == "move" then
			window:set_position(
				op.start.x + op.dx,
				op.start.y + op.dy
			)
		elseif window and self.op.type == "resize" then
			local x = op.edges.left
					  and (op.start.x + (op.start.width - window.width))
					  or op.start.x
			local y = op.edges.top
					  and (op.start.y + (op.start.height - window.height))
					  or op.start.y
			window:set_position(x, y)
		elseif self.op.type == "world_move" then
			local adx, ady = op.dx - op.pdx, op.dy - op.pdy

			wm.cam.x = wm.cam.x - adx -- TODO: make sure should be minus
			wm.cam.y = wm.cam.y - ady

			wm.cam.dirty = true;

			op.pdx, op.pdy = op.dx, op.dy
		end
	end
end

function Seat:maybe_destroy()
	if self.removed then
		for _, binding in ipairs(self.xkb_bindings) do
			binding.obj:destroy()
		end
		for _, binding in ipairs(self.pointer_bindings) do
			binding.obj:destroy()
		end
		self.obj:destroy()
	else
		return self
	end
end

function Seat.listener.removed(self)
	self:get_user_data().removed = true
end
function Seat.listener.pointer_enter(self, window)
	self:get_user_data().hovered = window:get_user_data()
end
function Seat.listener.pointer_leave(self)
	self:get_user_data().hovered = nil
end
function Seat.listener.window_interaction(self, window)
	self:get_user_data().interacted = window:get_user_data()
end
function Seat.listener.op_delta(self, dx, dy)
	local seat = self:get_user_data()
	seat.op.dx = dx
	seat.op.dy = dy
end
function Seat.listener.op_release(self)
	self:get_user_data().op_release = true
end


---- wm -------------------------------
local function wm_manage()
	table_filter_inplace(wm.outputs, Output.maybe_destroy)
	table_filter_inplace(wm.windows, Window.maybe_destroy)
	table_filter_inplace(wm.seats, Seat.maybe_destroy)

	for _, window in ipairs(wm.windows) do
		window:manage()
	end

	for _, seat in ipairs(wm.seats) do
		seat:manage()
	end

	globals["river_window_manager_v1"]:manage_finish()
end

local function wm_render()
	if wm.cam.dirty then
		for i = 1,#wm.windows do
			local window = wm.windows[i]

			window.node:set_position(window.x - wm.cam.x, window.y - wm.cam.y);
		end
		wm.cam.dirty = false;
	end

	for _, seat in ipairs(wm.seats) do
		seat:render()
	end

	globals["river_window_manager_v1"]:render_finish()
end

local wm_handlers = {
	["unavailable"] = function (self)
		io.stderr:write("another window manager is already running\n")
		os.exit(1)
	end,
	["finished"] = function (self)
		os.exit(0)
	end,
	["manage_start"] = wm_manage,
	["render_start"] = wm_render,
	["output"] = function (self, obj)
		table.insert(wm.outputs, Output.create(obj))
	end,
	["seat"] = function (self, obj)
		table.insert(wm.seats, Seat.create(obj))
	end,
	["window"] = function (self, obj)
		table.insert(wm.windows, Window.create(obj))
	end,
}


---- Entry point ----------------------
display = wau.wl_display.connect()
assert(display, "Failed to connect to wayland compositor")

-- Ensure we exit nonzero if an event handler errors
local function handle_callback_error(proxy, name, func, err)
	io.stderr:write(("-- Error calling event handler for %s %q:")
						:format(tostring(proxy), name))
	io.stderr:write(("%s\n"):format(tostring(err)))
	os.exit(1)
end
wau.wl_proxy.set_error_callback(handle_callback_error)

-- Avoid passing WAYLAND_DEBUG to our children
posix.stdlib.setenv("WAYLAND_DEBUG", nil)

-- Ensure children are automatically reaped
posix.signal.signal(posix.signal.SIGCHLD, posix.signal.SIG_IGN)

local registry = display:get_registry()
registry:add_listener {
	["global"] = function (self, name, iface, version)
		local required_version = required_globals[iface]
		if required_version ~= nil then
			assert(required_version <= version,
				("wayland compositor supported %s version too old (need %d, got %d)")
					:format(iface, required_version, version))
			globals[iface] = self:bind(name, wau[iface], required_version)
		end
	end,
}

display:roundtrip()

for k in pairs(required_globals) do
	assert(globals[k] ~= nil, ("wayland compositor does not support %s"):format(k))
end

globals["river_window_manager_v1"]:add_listener(wm_handlers)

while display:dispatch() do end