-- the privs players need some privs
-- npc_talk_owner is required to set up an NPC;
-- npc_talk_master allows to edit NPC of other players;
-- npc_master allows to set dangerous commands like execute lua code

local npc_master_priv_definition = {
    description="Can use the staffs to command NPCs",
    give_to_singleplayer = false,
    give_to_admin = true,
}
minetest.register_privilege("npc_master", npc_master_priv_definition)


local npc_talk_owner_priv_definition = {
    description="Can edit the dialogs of his/her own NPCs",
    give_to_singleplayer = false,
    give_to_admin = true,
}
minetest.register_privilege("npc_talk_owner", npc_talk_owner_priv_definition)


local npc_talk_master_priv_definition = {
    description="Can edit the dialogs of NPCs independent of owner",
    give_to_singleplayer = false,
    give_to_admin = true,
}
minetest.register_privilege("npc_talk_master", npc_talk_master_priv_definition)


-- NPC also need privs to execute more dangerous commands

-- this table will hold the actual privs in the form of
-- indices of the form t[<npc_name>][<priv_name>] = True
yl_speak_up.npc_priv_table = {}

-- where shall the privs be stored so that they will be available after server restart?
yl_speak_up.npc_priv_path = minetest.get_worldpath().."/yl_speak_up_npc_privs.data"

-- these are deemed dangerous and checked
yl_speak_up.npc_priv_names = {
	"precon_exec_lua",
	"effect_exec_lua", "effect_give_item", "effect_take_item", "effect_move_player",
}

yl_speak_up.npc_has_priv = function(n_id, priv_name)
	-- fallback: disallow
	if(not(n_id) or not(priv_name)) then
		return false
	end
	if(not(yl_speak_up.npc_priv_table[n_id])
	   or not(yl_speak_up.npc_priv_table[n_id][priv_name])) then
		minetest.log(
			"action",
			"[MOD] yl_speak_up: NPC with ID "..tostring(n_id)..
				" was denied the NPC priv "..tostring(priv_name)..".")
		return false
	end
	return true
end


yl_speak_up.npc_privs_load = function()
	local file,err = io.open( yl_speak_up.npc_priv_path, "rb")
	if (file == nil) then
		yl_speak_up.npc_priv_table = {}
		return
	end
	local data = file:read("*all")
	file:close()
	yl_speak_up.npc_priv_table = minetest.deserialize(data)
end


yl_speak_up.npc_privs_store = function()
	local file,err = io.open( yl_speak_up.npc_priv_path, "wb")
	if (file == nil) then
		return
	end
	file:write(minetest.serialize(yl_speak_up.npc_priv_table))
	file:close()
end


-- a chat command to grant or deny or disallow npc these privs;
-- it is not checked if the NPC exists
minetest.register_chatcommand( 'npc_talk_privs', {
        description = "Grants or revokes the privilege <priv> to the "..
		"yl_speak_up-NPC with the ID <n_id>.\n"..
		"Call:  [grant|revoke] <n_id> <priv>\n"..
		"If called with parameter [list], all granted privs for all NPC are shown.",
        privs = {privs = true},
        func = function(pname, param)
		if(not(param) or param == "") then
			minetest.chat_send_player(pname,
				"Usage: [grant|revoke|list] <n_id> <priv>\n"..
				"The following privilege exist:\n\t"..
				table.concat(yl_speak_up.npc_priv_names, ", ")..".")
			return
		end
		local parts = string.split(param, " ")
		if(parts[1] == "list") then
			local text = "This list contains the privs of each NPC in the form of "..
				"<npc_name>: <list of privs>"
			-- create list of all existing extra privs for npc
			for n_id, v in pairs(yl_speak_up.npc_priv_table) do
				text = text..".\n"..tostring(n_id)..":"
				local found = false
				for priv, w in pairs(v) do
					text = text.." "..tostring(priv)
					found = true
				end
				if(not(found)) then
					text = text.." <none>"
				end
			end
			minetest.chat_send_player(pname, text..".")
			return
		end
		if((parts[1] ~= "grant" and parts[1] ~= "revoke") or #parts ~= 3) then
			minetest.chat_send_player(pname, "Usage: [grant|revoke] <n_id> <priv>")
			return
		end
		local command = parts[1]
		local n_id = parts[2]
		local priv = parts[3]
		if(table.indexof(yl_speak_up.npc_priv_names, priv) == -1) then
			minetest.chat_send_player(pname,
				"Unknown priv \""..tostring(priv).."\".\n"..
				"The following privilege exist:\n\t"..
				table.concat(yl_speak_up.npc_priv_names, ", ")..".")
			return
		end
		if(command == "grant" and not(yl_speak_up.npc_priv_table[n_id])) then
			yl_speak_up.npc_priv_table[n_id] = {}
		end
		if(command == "grant") then
			yl_speak_up.npc_priv_table[n_id][priv] = true
		elseif(yl_speak_up.npc_priv_table[n_id]) then
			yl_speak_up.npc_priv_table[n_id][priv] = nil
		end
		local text = "New privs of NPC "..tostring(n_id)..":"
		local found = false
		if(yl_speak_up.npc_priv_table[n_id]) then
			for k, v in pairs(yl_speak_up.npc_priv_table[n_id]) do
				text = text.." "..tostring(k)
				found = true
			end
		end
		if(not(found)) then
			text = text.." <none>"
			yl_speak_up.npc_priv_table[n_id] = nil
		end
		minetest.chat_send_player(pname, text..".")
		yl_speak_up.npc_privs_store()
	end
})

-- when the game is started: load the npc privs
yl_speak_up.npc_privs_load()