--[[

	Tower Crane Mod
	===============

	v0.17 by JoSt

	Copyright (C) 2017-2018 Joachim Stolberg
	LGPLv2.1+
	See LICENSE.txt for more information

	History:
	2017-06-04  v0.01  first version
	2017-06-06  v0.02  Hook bugfix
	2017-06-07  v0.03  fixed 2 bugs, added config.lua and sound
	2017-06-08  v0.04  recipe and rope length now configurable
	2017-06-10  v0.05  resizing bugfix, area protection added
	2017-07-11  v0.06  fixed the space check bug, settingtypes added
	2017-07-16  v0.07  crane remove bug fix
	2017-07-16  v0.08  player times out bugfix
	2017-08-19  v0.09  crane protection area to prevent crane clusters
	2017-08-27  v0.10  hook instance and sound switch off bug fixes
	2017-09-09  v0.11  further player bugfixes
	2017-09-24  v0.12  Switched from entity hook model to real fly privs
	2017-10-17  v0.13  Area protection bugfix
	2017-11-01  v0.14  Crane handing over bugfix
	2017-11-07  v0.15  Working zone is now restricted to areas with necessary rights
	2018-02-27  v0.16  "fly privs" bug fixed (issue #2)
	2018-04-12  v0.17  "area owner changed" bug fixed (issue #3)

]]--

-- crane minimum size
MIN_SIZE = 8		

towercrane = {}

dofile(minetest.get_modpath("towercrane") .. "/config.lua")

local function chat(owner, text)
	if owner ~= nil then
		minetest.chat_send_player(owner, "[Tower Crane] "..text)
	end
end

local PlayerList = {}

local function maintain_playerlist()
	PlayerList = {}
	for _,player in ipairs(minetest.get_connected_players()) do
		PlayerList[player:get_player_name()] = true
	end
end

--##################################################################################################
--##  Construction Area
--##################################################################################################

-- Areas = {
--     pos_key = {owner="...", pos1=pos, pos2=pos},
-- }
local storage = minetest.get_mod_storage()
local Areas = minetest.deserialize(storage:get_string("Areas")) or {}

local function update_mod_storage()
	storage:set_string("Areas", minetest.serialize(Areas))
end

minetest.register_on_shutdown(function()
	update_mod_storage()
end)

----------------------------------------------------------------------------------------------------
-- The same player can't place a crane within the same protection area
----------------------------------------------------------------------------------------------------
local function no_area_violation(owner, pos)
	local res = true
	local px, py, pz = pos.x, pos.y, pos.z
	for key, area in pairs(Areas) do
		if owner == area.owner then
			local pos1, pos2 = area.pos1, area.pos2
			if (px >= pos1.x and px <= pos2.x) and (py >= pos1.y and py <= pos2.y) and
					(pz >= pos1.z and pz <= pos2.z) then
				res = false
				break
			end
		end
	end
	return res
end


local function store_crane_data(owner, pos, pos1, pos2)
	-- normalize x/z so that pos2 > pos1
	if pos2.x < pos1.x then
		pos2.x, pos1.x = pos1.x, pos2.x
	end
	if pos2.z < pos1.z then
		pos2.z, pos1.z = pos1.z, pos2.z
	end
	-- store data
	local key = minetest.pos_to_string(pos)
	Areas[key] = {owner=owner, pos1=pos1, pos2=pos2}
	update_mod_storage()
end
	
local function remove_crane_data(pos)
	local key = minetest.pos_to_string(pos)
	Areas[key] = nil
	update_mod_storage()
end

	
--##################################################################################################
--##  Tower Crane Hook (player)
--##################################################################################################

-- give/take player the necessary privs/physics
local function fly_privs(pos, player, enable)
	local privs = minetest.get_player_privs(player:get_player_name())
	local physics = player:get_physics_override()
	if privs and physics then
		if enable == true then
			local spos = minetest.pos_to_string(pos)
			player:set_attribute("tower_crane_active", spos)
			privs["fly"] = true
			privs["fast"] = nil
			physics.speed = 0.7
		else
			privs["fast"] = minetest.deserialize(player:get_attribute("tower_crane_store_fast"))
			privs["fly"] = minetest.deserialize(player:get_attribute("tower_crane_store_fly"))
			physics.speed = minetest.deserialize(player:get_attribute("tower_crane_store_speed"))
			player:set_attribute("tower_crane_active", nil)
		end
		player:set_physics_override(physics)
		minetest.set_player_privs(player:get_player_name(), privs)
	end
end

-- Normalize the player privs
local function remove_hook(pos, player)
	if player then
		if pos then
			local meta = minetest.get_meta(pos)
			meta:set_int("running", 0)
		end
		fly_privs(pos, player, nil)
	end
end

local function control_player(pos, pos1, pos2, player)
	if player and PlayerList[player:get_player_name()] then
		local meta = minetest.get_meta(pos)
		local running = meta:get_int("running")
		if running == 1 then
			-- check if outside of the construction area
			local correction = false
			local pl_pos = player:getpos()
			if pl_pos then
				if pl_pos.x < pos1.x then pl_pos.x = pos1.x; correction = true end
				if pl_pos.x > pos2.x then pl_pos.x = pos2.x; correction = true end
				if pl_pos.y < pos1.y then pl_pos.y = pos1.y; correction = true end
				if pl_pos.y > pos2.y then pl_pos.y = pos2.y; correction = true end
				if pl_pos.z < pos1.z then pl_pos.z = pos1.z; correction = true end
				if pl_pos.z > pos2.z then pl_pos.z = pos2.z; correction = true end
				-- check if a protected area is violated
				if correction == false and minetest.is_protected(pl_pos, player:get_player_name()) then
					chat(player:get_player_name(), "Area is protected.")
					correction = true
				end
				if correction == true then
					local last_pos = minetest.string_to_pos(meta:get_string("last_known_pos"))
					if last_pos then
						player:setpos(last_pos)	
					end
				else  -- store last known correct position
					meta:set_string("last_known_pos", minetest.pos_to_string(pl_pos))
				end
				
				minetest.after(1, control_player, pos, pos1, pos2, player)
			else
				remove_hook(pos, player)
			end
		else
			remove_hook(pos, player)
		end
	else
		local meta = minetest.get_meta(pos)
		meta:set_int("running", 0)
	end
end	
	
-- Place the player in front of the base and give fly privs
local function place_hook(pos, dir, player, pos1, pos2)
	if player then
		local switch_pos = {x=pos.x, y=pos.y, z=pos.z}
		local meta = minetest.get_meta(switch_pos)
		meta:set_int("running", 1)
		-- set privs
		fly_privs(pos, player, true)
		-- place the player
		pos.y = pos.y - 1
		pos.x = pos.x + dir.x
		pos.z = pos.z + dir.z
		player:setpos(pos)
		meta:set_string("last_known_pos", minetest.pos_to_string(pos))
		-- control player every second
		minetest.after(1, control_player, switch_pos, pos1, pos2, player)
	end
end	

--##################################################################################################
--##  Tower Crane
--##################################################################################################

local function turnright(dir)
	local facedir = minetest.dir_to_facedir(dir)
	return minetest.facedir_to_dir((facedir + 1) % 4)
end

local function turnleft(dir)
	local facedir = minetest.dir_to_facedir(dir)
	return minetest.facedir_to_dir((facedir + 3) % 4)
end

----------------------------------------------------------------------------------------------------
-- generic function for contruction and removement
----------------------------------------------------------------------------------------------------
local function crane_body_plan(pos, dir, height, width, clbk, tArg)
	pos.y = pos.y + 1
	clbk(pos, "towercrane:mast_ctrl_off", tArg)

	for i = 1,height+1 do
		pos.y = pos.y + 1
		clbk(pos, "towercrane:mast", tArg)
	end

	pos.y = pos.y - 2
	pos.x = pos.x - dir.x
	pos.z = pos.z - dir.z
	clbk(pos, "towercrane:arm2", tArg)
	pos.x = pos.x - dir.x
	pos.z = pos.z - dir.z
	clbk(pos, "towercrane:arm", tArg)
	pos.x = pos.x - dir.x
	pos.z = pos.z - dir.z
	clbk(pos, "towercrane:balance", tArg)
	pos.x = pos.x + 3 * dir.x
	pos.z = pos.z + 3 * dir.z

	for i = 1,width do
		pos.x = pos.x + dir.x
		pos.z = pos.z + dir.z
		if i % 2 == 0 then
			clbk(pos, "towercrane:arm2", tArg)
		else
			clbk(pos, "towercrane:arm", tArg)
		end
	end
end

----------------------------------------------------------------------------------------------------
-- Check space are protection for mast and arm
----------------------------------------------------------------------------------------------------
local function check_space(pos, dir, height, width, owner)
	local remove = function(pos, node_name, tArg)
		if minetest.get_node(pos).name ~= "air" then
			tArg.res = false
		elseif minetest.is_protected(pos, tArg.owner) then
			tArg.res = false
		end
	end
		
	local tArg = {res = true, owner = owner}
	crane_body_plan(pos, dir, height, width, remove, tArg)
	return tArg.res
end

----------------------------------------------------------------------------------------------------
-- Constuct mast and arm
----------------------------------------------------------------------------------------------------
local function construct_crane(pos, dir, height, width, owner)
	local add = function(pos, node_name, tArg)
		minetest.add_node(pos, {name=node_name, param2=minetest.dir_to_facedir(tArg.dir)})
	end
	
	local tArg = {dir = dir}
	crane_body_plan(table.copy(pos), dir, height, width, add, tArg)
	
	pos.y = pos.y + 1
	local meta = minetest.get_meta(pos)
	meta:set_string("dir", minetest.pos_to_string(dir))
	meta:set_string("owner", owner)
	meta:set_int("height", height)
	meta:set_int("width", width)
end

----------------------------------------------------------------------------------------------------
-- Remove the crane
----------------------------------------------------------------------------------------------------
local function remove_crane(pos, dir, height, width)
	local remove = function(pos, node_name, tArg)
		if minetest.get_node(pos).name == node_name or
				minetest.get_node(pos).name == "towercrane:mast_ctrl_on" then
			minetest.remove_node(pos)
		end
	end
	
	crane_body_plan(table.copy(pos), dir, height, width, remove, {})
end

----------------------------------------------------------------------------------------------------
-- Calculate and set the protection area (pos1, pos2)
----------------------------------------------------------------------------------------------------
local function protect_area(pos, dir, height, width, owner)
	if not areas then return 0 end
	-- pos1 = close/right/below
	dir = turnright(dir)
	dir = turnright(dir)
	local pos1 = vector.add(pos, vector.multiply(dir, 2))
	dir = turnleft(dir)
	pos1 = vector.add(pos1, vector.multiply(dir, width/2))
	dir = turnleft(dir)
	pos1.y = pos.y - 2

	-- pos2 = far/left/above
	local pos2 = vector.add(pos1, vector.multiply(dir, width+2))
	dir = turnleft(dir)
	pos2 = vector.add(pos2, vector.multiply(dir, width))
	pos2.y = pos.y + 2 + height

	store_crane_data(owner, pos, pos1, pos2)

	-- add area
	local canAdd, errMsg = areas:canPlayerAddArea(pos1, pos2, owner)
	if canAdd then
		local id = areas:add(owner, "Construction site", pos1, pos2, nil)
		areas:save()
		return id
	end
	return nil
end

----------------------------------------------------------------------------------------------------
-- Remove the protection area
----------------------------------------------------------------------------------------------------
local function remove_area(id, owner)
	if not areas then return end
	if areas:isAreaOwner(id, owner) then
		areas:remove(id)
		areas:save()
	end
end

----------------------------------------------------------------------------------------------------
-- Check user input (height, width)
----------------------------------------------------------------------------------------------------
local function check_input(fields)
	local size = string.split(fields.size, ",")
	if #size == 2  then
		local height = tonumber(size[1])
		local width = tonumber(size[2])
		if height ~= nil and width ~= nil then
			height = math.max(height, MIN_SIZE)
			height = math.min(height, towercrane.max_height)
			width = math.max(width, MIN_SIZE)
			width = math.min(width, towercrane.max_width)
			return height, width
		end
	end
	return 0, 0
end

----------------------------------------------------------------------------------------------------
-- Register Crane base
----------------------------------------------------------------------------------------------------
minetest.register_node("towercrane:base", {
	description = "Tower Crane Base",
	inventory_image = "towercrane_invent.png",
	tiles = {
		"towercrane_base_top.png",
		"towercrane_base.png",
		"towercrane_base.png",
		"towercrane_base.png",
		"towercrane_base.png",
		"towercrane_base.png",
	},
	paramtype = "light",
	paramtype2 = "facedir",
	sunlight_propagates = true,
	sounds = default.node_sound_stone_defaults(),
	is_ground_content = false,
	groups = {cracky=2},

	-- set meta data (form for crane height and width, dir of the arm)
	after_place_node = function(pos, placer)
		local meta = minetest.get_meta(pos)
		local owner = placer:get_player_name()
		meta:set_string("owner", owner)
		local formspec = "size[5,4]"..
			"label[0,0;Construction area size]" ..
			"field[1,1.5;3,1;size;height,width;]" ..
			"button_exit[1,2;2,1;exit;Save]"
		meta:set_string("formspec", formspec)

		local fdir = minetest.dir_to_facedir(placer:get_look_dir(), false)
		local dir = minetest.facedir_to_dir(fdir)
		meta:set_string("dir", minetest.pos_to_string(dir))
	end,

	-- evaluate user input (height, width), destroyed old crane and build a new one with
	-- the given size
	on_receive_fields = function(pos, formname, fields, player)
		local switch_pos = {x=pos.x, y=pos.y+1, z=pos.z}
		if fields.size == nil then
			return
		end
		local meta = minetest.get_meta(switch_pos)
		local running = meta:get_int("running")
		if running == 1 then
			return
		end
		
		meta = minetest.get_meta(pos)
		local owner = meta:get_string("owner")
		local dir = minetest.string_to_pos(meta:get_string("dir"))
		local height = meta:get_int("height")
		local width = meta:get_int("width")
		local id = meta:get_int("id")

		if not player or not player:is_player() then
			return
		end
		if player:get_player_name() ~= owner then
			return
		end
		-- destroy area and crane
		if dir ~= nil and height ~= nil and width ~= nil then
			remove_crane_data(pos)
			remove_area(id, owner)
			remove_crane(table.copy(pos), dir, height, width)
		end

		-- evaluate user input
		height, width = check_input(fields)
		if height ~= 0 then
			meta:set_int("height", height)
			meta:set_int("width", width)
			meta:set_string("infotext", "Owner: ".. owner ..", Crane size: " .. height .. "," .. width)
			if no_area_violation(owner, pos) then
				if dir ~= nil then
					if check_space(table.copy(pos), dir, height, width, owner) then
						-- add protection area
						meta:set_int("id", protect_area(table.copy(pos), table.copy(dir), height, width, owner))
						construct_crane(table.copy(pos), table.copy(dir), height, width, owner)
					else
						chat(owner, "area is protected or too less space to raise up the crane!")
					end
				end
			else
				chat(owner, "Too less distance to your other crane(s)!")
			end
		else
			chat(owner, "Invalid input!")
		end
	end,

	can_dig = function(pos, player)
		local switch_pos = {x=pos.x, y=pos.y+1, z=pos.z}
		local meta = minetest.get_meta(pos)
		local owner = meta:get_string("owner")
		if player:get_player_name() ~= owner and 
				not minetest.check_player_privs(player:get_player_name(), "creative") then
			return false
		end
		meta = minetest.get_meta(switch_pos)
		local running = meta:get_int("running")
		if running == 1 then
			return false
		end
		return true
	end,
	
	-- remove mast and arm if base gets destroyed
	on_destruct = function(pos)
		local meta = minetest.get_meta(pos)
		local dir = minetest.string_to_pos(meta:get_string("dir"))
		local height = meta:get_int("height")
		local width = meta:get_int("width")
		local id = meta:get_int("id")
		local owner = meta:get_string("owner")

		-- remove protection area
		if id ~= nil then
			remove_area(id, owner)
		end
		-- remove crane
		if dir ~= nil and height ~= nil and width ~= nil then
			remove_crane_data(pos)
			remove_crane(pos, dir, height, width)
		end
		-- remove hook
		local player = minetest.get_player_by_name(owner)
	end,
})

----------------------------------------------------------------------------------------------------
-- Register Crane balance
----------------------------------------------------------------------------------------------------
minetest.register_node("towercrane:balance", {
	description = "Tower Crane Balance",
	tiles = {
		"towercrane_base.png",
		"towercrane_base.png",
		"towercrane_base.png",
		"towercrane_base.png",
		"towercrane_base.png",
		"towercrane_base.png",
	},
	paramtype = "light",
	paramtype2 = "facedir",
	sunlight_propagates = true,
	is_ground_content = false,
	groups = {crumbly=0, not_in_creative_inventory=1},
})

----------------------------------------------------------------------------------------------------
-- Register Crane mast
----------------------------------------------------------------------------------------------------
minetest.register_node("towercrane:mast", {
	description = "Tower Crane Mast",
	drawtype = "glasslike_framed",
	tiles = {
		"towercrane_mast.png",
		"towercrane_mast.png",
		"towercrane_mast.png",
		"towercrane_mast.png",
		"towercrane_mast.png",
		"towercrane_mast.png",
	},
	paramtype = "light",
	paramtype2 = "facedir",
	sunlight_propagates = true,
	is_ground_content = false,
	groups = {crumbly=0, not_in_creative_inventory=1},
})

----------------------------------------------------------------------------------------------------
-- Register Crane Switch (on)
----------------------------------------------------------------------------------------------------
minetest.register_node("towercrane:mast_ctrl_on", {
	description = "Tower Crane Mast Ctrl On",
	drawtype = "node",
	tiles = {
		"towercrane_mast_ctrl.png",
		"towercrane_mast_ctrl.png",
		"towercrane_mast_ctrl.png",
		"towercrane_mast_ctrl.png",
		"towercrane_mast_ctrl_on.png",
		"towercrane_mast_ctrl_on.png",
	},
	-- switch the crane OFF
	on_rightclick = function (pos, node, clicker)
		local meta = minetest.get_meta(pos)
		if not clicker or not clicker:is_player() then
			return
		end
		if clicker:get_player_name() ~= meta:get_string("owner") then
			return
		end
		-- Check if this is the wrong crane
		local spos = minetest.pos_to_string(pos)
		if clicker:get_attribute("tower_crane_active") ~= nil 
		and clicker:get_attribute("tower_crane_active") ~= spos then  
			return
		end
		node.name = "towercrane:mast_ctrl_off"
		minetest.swap_node(pos, node)

		remove_hook(pos, clicker)
	end,

	on_construct = function(pos)
		local meta = minetest.get_meta(pos)
		meta:set_string("infotext", "Switch crane on/off")
	end,

	after_place_node = function(pos, placer, itemstack, pointed_thing)
		local meta = minetest.get_meta(pos)
		local owner = placer:get_player_name()
		meta:set_string("owner", owner)
	end,

	paramtype = "light",
	paramtype2 = "facedir",
	sunlight_propagates = true,
	is_ground_content = false,
	groups = {crumbly=0, not_in_creative_inventory=1},
})

----------------------------------------------------------------------------------------------------
-- Register Crane Switch (off)
----------------------------------------------------------------------------------------------------
minetest.register_node("towercrane:mast_ctrl_off", {
	description = "Tower Crane Mast Ctrl Off",
	drawtype = "node",
	tiles = {
		"towercrane_mast_ctrl.png",
		"towercrane_mast_ctrl.png",
		"towercrane_mast_ctrl.png",
		"towercrane_mast_ctrl.png",
		"towercrane_mast_ctrl_off.png",
		"towercrane_mast_ctrl_off.png",
	},
	-- switch the crane ON
	on_rightclick = function (pos, node, clicker)
		-- calculate the construction area, and place the hook
		local meta = minetest.get_meta(pos)
		-- only the owner is allowed to switch
		if not clicker or not clicker:is_player() then
			return
		end
		if clicker:get_player_name() ~= meta:get_string("owner") then
			return
		end
		-- prevent handing over to the next crane
		if clicker:get_attribute("tower_crane_active") ~= nil then  
			return
		end
		-- swap to the other node
		node.name = "towercrane:mast_ctrl_on"
		minetest.swap_node(pos, node)
		local dir = minetest.string_to_pos(meta:get_string("dir"))
		if pos ~= nil and dir ~= nil then
			--
			-- calculate the construction area dimension (pos1, pos2)
			--
			local height = meta:get_int("height")
			local width = meta:get_int("width")

			-- pos1 = close/right/below
			dir = turnright(dir)
			local pos1 = vector.add(pos, vector.multiply(dir, width/2))
			dir = turnleft(dir)
			pos1 = vector.add(pos1, vector.multiply(dir, 1))
			pos1.y = pos.y - 2 + height - towercrane.rope_length

			-- pos2 = far/left/above
			local pos2 = vector.add(pos1, vector.multiply(dir, width-1))
			dir = turnleft(dir)
			pos2 = vector.add(pos2, vector.multiply(dir, width))
			pos2.y = pos.y - 3 + height

			-- normalize x/z so that pos2 > pos1
			if pos2.x < pos1.x then
				pos2.x, pos1.x = pos1.x, pos2.x
			end
			if pos2.z < pos1.z then
				pos2.z, pos1.z = pos1.z, pos2.z
			end
			
			dir = minetest.string_to_pos(meta:get_string("dir"))
			place_hook(pos, dir, clicker, pos1, pos2)
		end
	end,

	on_construct = function(pos)
		-- add infotext
		local meta = minetest.get_meta(pos)
		meta:set_string("infotext", "Switch crane on/off")
	end,

	after_place_node = function(pos, placer, itemstack, pointed_thing)
		-- store owner for dig protection
		local meta = minetest.get_meta(pos)
		local owner = placer:get_player_name()
		meta:set_string("owner", owner)
	end,

	paramtype = "light",
	paramtype2 = "facedir",
	sunlight_propagates = true,
	is_ground_content = false,
	groups = {crumbly=0, not_in_creative_inventory=1},
})

----------------------------------------------------------------------------------------------------
-- Register Crane arm 1
----------------------------------------------------------------------------------------------------
minetest.register_node("towercrane:arm", {
	description = "Tower Crane Arm",
	drawtype = "glasslike_framed",
	tiles = {
		"towercrane_arm.png",
		"towercrane_arm.png",
		"towercrane_arm.png",
		"towercrane_arm.png",
		"towercrane_arm.png",
		"towercrane_arm.png",
	},
	paramtype = "light",
	paramtype2 = "facedir",
	sunlight_propagates = true,
	is_ground_content = false,
	groups = {crumbly=0, not_in_creative_inventory=1},
})

----------------------------------------------------------------------------------------------------
-- Register Crane arm 2
----------------------------------------------------------------------------------------------------
minetest.register_node("towercrane:arm2", {
	description = "Tower Crane Arm2",
	drawtype = "glasslike_framed",
	tiles = {
		"towercrane_arm2.png",
		"towercrane_arm2.png",
		"towercrane_arm2.png",
		"towercrane_arm2.png",
		"towercrane_arm2.png",
		"towercrane_arm2.png",
	},
	paramtype = "light",
	paramtype2 = "facedir",
	sunlight_propagates = true,
	is_ground_content = false,
	groups = {crumbly=0, not_in_creative_inventory=1},
})


----------------------------------------------------------------------------------------------------
-- Register Recipe
----------------------------------------------------------------------------------------------------
if towercrane.recipe then
	minetest.register_craft({
		output = "towercrane:base",
		recipe = {
			{"default:steel_ingot", "default:steel_ingot", "default:steel_ingot"},
			{"default:steel_ingot", "", ""},
			{"default:steel_ingot", "dye:yellow", ""}
		}
	})
end

-- store standard player privs
minetest.register_on_joinplayer(function(player)
	local privs = minetest.get_player_privs(player:get_player_name())
	local physics = player:get_physics_override()
	-- player still hanging on the crane?
	if player:get_attribute("tower_crane_active") ~= nil then
		fly_privs(nil, player, nil)
	else
		-- store the player privs default values
		player:set_attribute("tower_crane_store_fast", minetest.serialize(privs["fast"]))
		player:set_attribute("tower_crane_store_fly", minetest.serialize(privs["fly"]))
		player:set_attribute("tower_crane_store_speed", minetest.serialize(physics.speed))
	end
	maintain_playerlist()
end)

-- switch back to normal player privs
minetest.register_on_leaveplayer(function(player, timed_out)
	maintain_playerlist()
	remove_hook(nil, player)
end)