local S = classroom.S
local FS = classroom.FS
local infos = {
	{
		title = S"Shout?",
		type = "priv",
		privs = { shout = true },
	},
	{
		title = S"Fly?",
		type = "priv",
		privs = { fly = true },
	},
	{
		title = S"Fast?",
		type = "priv",
		privs = { fast = true },
	},
}

local function get_group(context)
	if context and context.groupname then
		return classroom.get_group_students(context.groupname)
	else
		return classroom.get_students()
	end
end

local function check_perm(player)
	return minetest.check_player_privs(player:get_player_name(), { teacher = true })
end

local DASHBOARD_HEADER = "formspec_version[3]size[13,10.85]"

local function get_formspec(player, context)
	if not check_perm(player) then
		return "label[0,0;" .. FS"Access denied" .. "]"
	end

	local function button(def)
		local x = assert(def.x)
		local y = assert(def.y)
		local w = assert(def.w)
		local h = assert(def.h)
		local name = assert(def.name)
		local text = assert(def.text)
		local state = def.state
		local tooltip = def.tooltip
		local bgcolor = "#222"

		-- Map different state values
		if state == true or state == nil then
			state = "active"
		elseif state == false then
			state = "disabled"
		elseif state == "selected" then
			state = "disabled"
			bgcolor = "#53ac56"
		end

		-- Generate FS code
		local fs
		if state == "active" then
			fs = {
				("button[%f,%f;%f,%f;%s;%s]"):format(x, y, w, h, name, text)
			}
		elseif state == "disabled" then
			name = "disabled_" .. name

			fs = {
				"container[", tostring(x), ",", tostring(y), "]",

				"box[0,0;", tostring(w), ",", tostring(h), ";", bgcolor, "]",

				"style[", name, ";border=false]",
				"button[0,0;", tostring(w), ",", tostring(h), ";", name, ";", text, "]",

				"container_end[]",
			}
		else
			error("Unknown state: " .. state)
		end

		if tooltip then
			fs[#fs + 1] = ("tooltip[%s;%s]"):format(name, tooltip)
		end

		return table.concat(fs, "")
	end

	local fs = {
		"container[0.375,1.1]",
		"tablecolumns[color;text",
	}

	context.select_toggle = context.select_toggle or "all"

	for i, col in pairs(infos) do
		fs[#fs + 1] = ";color;text,align=center"
		if i == 1 then
			fs[#fs + 1] = ",padding=2"
		end
	end
	fs[#fs + 1] = "]"

	do
		fs[#fs + 1] = "tabheader[0,0;5.375,0.8;group;"
		fs[#fs + 1] = FS"All"
		local selected_group_idx = 1
		local i = 2
		for name, group in pairs(classroom.get_all_groups()) do
			fs[#fs + 1] = ","
			fs[#fs + 1] = minetest.formspec_escape(name)
			if context.groupname and name == context.groupname then
				selected_group_idx = i
			end
			i = i + 1
		end
		fs[#fs + 1] = ";"
		fs[#fs + 1] = tostring(selected_group_idx)
		fs[#fs + 1] = ";false;true]"
	end
	fs[#fs + 1] = "table[0,0;5.375,9.375;students;,Name"
	for _, col in pairs(infos) do
		fs[#fs + 1] = ",," .. col.title
	end

	local students = get_group(context)
	local selection_id = ""
	context.students = table.copy(students)
	for i, student in pairs(students) do
		fs[#fs + 1] = ",,"
		fs[#fs + 1] = minetest.formspec_escape(student)

		if student == context.selected_student then
			selection_id = tostring(i + 1)
		end

		for _, col in pairs(infos) do
			local color, value
			if col.type == "priv" then
				local has_priv = minetest.check_player_privs(student, col.privs)
				color = has_priv and "green" or "red"
				value = has_priv and FS"Yes" or FS"No"
			end

			fs[#fs + 1] = ","
			fs[#fs + 1] = color
			fs[#fs + 1] = ","
			fs[#fs + 1] = minetest.formspec_escape(value)
		end
	end

	fs[#fs + 1] = ";"
	fs[#fs + 1] = selection_id
	fs[#fs + 1] = "]"

	fs[#fs + 1] = "container_end[]"

	fs[#fs + 1] = "container[6.125,0.375]"

	fs[#fs + 1] = "button[0,0;1.4,0.8;new_group;"
	fs[#fs + 1] = FS"New Group"
	fs[#fs + 1] = "]"

	do
		local btn = {
			x = 0, y = 0,
			w = 2.1, h = 0.8,
			name = "new_group",
			text = FS"New Group",
		}

		fs[#fs + 1] = button(btn)
	end

	do
		local btn = {
			x = 2.2, y = 0,
			w = 2.1, h = 0.8,
			name = "edit_group",
			text = FS"Edit Group",
			state = context.groupname ~= nil,
			tooltip = not context.groupname and FS"Please select a group first",
		}

		fs[#fs + 1] = button(btn)
	end

	fs[#fs + 1] = "container[0,1.6]"
	fs[#fs + 1] = "label[0,-0.3;"
	fs[#fs + 1] = FS"Run actions on:"
	fs[#fs + 1] = "]"

	do
		local btn = {
			x = 0, y = 0,
			w = 2.1, h = 0.8,
			name = "select_all",
			text = FS"All",
			state = context.select_toggle == "all" and "selected" or "active",
		}

		fs[#fs + 1] = button(btn)
	end

	do
		local btn = {
			x = 2.2, y = 0,
			w = 2.1, h = 0.8,
			name = "select_group",
			text = FS"Group",
		}

		if not context.groupname then
			btn.state = "disabled"
			btn.tooltip = FS"Please select a group first"
		elseif context.select_toggle == "group" then
			btn.state = "selected"
		else
			btn.state = "active"
		end

		fs[#fs + 1] = button(btn)
	end

	do
		local btn = {
			x = 4.4, y = 0,
			w = 2.1, h = 0.8,
			name = "select_selected",
			text = FS"Selected",
		}

		if not context.selected_student then
			btn.state = "disabled"
			btn.tooltip = FS"Please select a student first"
		elseif context.select_toggle == "selected" then
			btn.state = "selected"
		else
			btn.state = "active"
		end

		fs[#fs + 1] = button(btn)
	end

	fs[#fs + 1] = "label[0,1.4;"
	fs[#fs + 1] = FS"Actions:"
	fs[#fs + 1] = "]"

	local y = 1.7
	do
		local spacing = 0.1
		local btn = {
			x = 0, y = y,
			w = (6.5 - spacing*2) / 3, h = 0.8,
		}

		for _, action in pairs(classroom.get_actions()) do
			btn.state = "active"
			btn.name  = "action_" .. action.name
			btn.text  = minetest.formspec_escape(action.title)
			btn.tooltip = minetest.formspec_escape(action.description)
			fs[#fs + 1] = button(btn)

			btn.x = btn.x + btn.w + spacing
			if btn.x > 6.5 - btn.w then
				y = y + btn.h + spacing
				btn.x = 0
				btn.y = y
			end
		end

		if btn.x > 0 then
			y = y + btn.h + spacing
		end
	end

	y = y + 0.4

	context.selected_student = "student1"
	if context.selected_student then
		fs[#fs + 1] = "container[0,"
		fs[#fs + 1] = tostring(y)
		fs[#fs + 1] = "]"

		fs[#fs + 1] = "label[0,0;"
		fs[#fs + 1] = FS("Selected user: @1", context.selected_student)
		fs[#fs + 1] = "]"
		fs[#fs + 1] = "button[0,0.3;2.1,0.8;teleport;"
		fs[#fs + 1] = FS"Teleport to"
		fs[#fs + 1] = "]"

		fs[#fs + 1] = "container_end[]"
	end

	fs[#fs + 1] = "container_end[]"
	fs[#fs + 1] = "container_end[]"

	-- (8-1)*5/4 + 0.375*2 + 1 = 10.5
	-- (8.6-1)*5/4 + 0.375*2 + 1 = 11.25
	return table.concat(fs, "")
end

local function handle_results(player, context, fields)
	if not check_perm(player) then
		return false
	end

	if fields.students then
		local evt = minetest.explode_table_event(fields.students)
		local i = (evt.row or 0) - 1
		if evt.type == "CHG" and i >= 1  and i <= #context.students then
			context.selected_student = context.students[i]
			return true
		end
	end

	if fields.group then
		if fields.group == "1" then
			context.groupname = nil
		else
			local i = 2
			for name, _ in pairs(classroom.get_all_groups()) do
				if i == tonumber(fields.group) then
					context.groupname = name
					break
				end
				i = i + 1
			end
		end
		return true
	end

	if fields.select_all then
		context.select_toggle = "all"
		return true
	elseif fields.select_group then
		context.select_toggle = "group"
		return true
	elseif fields.select_selected then
		context.select_toggle = "selected"
		return true
	end

	if fields.teleport and context.selected_student then
		local student = minetest.get_player_by_name(context.selected_student)
		if student then
			player:set_pos(student:get_pos())
			return false
		else
			context.selected_student = nil
			return true
		end
	end

	if fields.new_group then
		classroom.show_new_group(player)
		return false
	end

	if fields.edit_group and context.groupname then
		classroom.show_edit_group(player, context.groupname)
		return false
	end

	for _, action in pairs(classroom.get_actions()) do
		if fields["action_" .. action.name] then
			local selector
			if context.select_toggle == "all" then
				selector = "*"
			elseif context.select_toggle == "group" then
				selector = "group:" .. context.groupname
			elseif context.select_toggle == "selected" then
				selector = "user:" .. context.selected_student
			else
				error("Unknown selector")
			end

			classroom.run_action(action.name, player, selector)
			return true
		end
	end

end


--
-- Show formspec
--
local _contexts = {}
function classroom.show_dashboard_formspec(player)
	if not check_perm(player) then
		return nil
	end

	local name = player:get_player_name()
	local context = _contexts[name] or {}
	_contexts[name] = context

	minetest.show_formspec(player:get_player_name(), "classroom:dashboard",
			DASHBOARD_HEADER .. get_formspec(player, context))
end
minetest.register_on_player_receive_fields(function(player, formname, fields)
	if formname ~= "classroom:dashboard" or not check_perm(player) then
		return false
	end

	local context = _contexts[player:get_player_name()]
	if not context then
		return false
	end

	local ret = handle_results(player, context, fields)
	if ret then
		classroom.show_dashboard_formspec(player)
	end
	return ret
end)


--
-- Sfinv
--
if minetest.get_modpath("sfinv") then
	sfinv.register_page("classroom:edu", {
		title = S"Classroom",
		is_in_nav = function(self, player, context)
			return check_perm(player)
		end,
		get = function(self, player, context)
			return sfinv.make_formspec(player, context, get_formspec(player, context),
					false, DASHBOARD_HEADER)
		end,
		on_player_receive_fields = function(self, player, context, fields)
			local ret = handle_results(player, context, fields)
			if ret then
				sfinv.set_player_inventory_formspec(player)
			end
			return ret
		end,
	})

	local function on_grant_revoke(grantee, granter, priv)
		if priv ~= "teacher" then
			return
		end

		local player = minetest.get_player_by_name(grantee)
		if not player then
			return
		end

		minetest.after(0, function()
			sfinv.set_player_inventory_formspec(player)
		end)
	end

	minetest.register_on_priv_grant(on_grant_revoke)
	minetest.register_on_priv_revoke(on_grant_revoke)
end


--
-- Chatcommand
--
minetest.register_chatcommand("classroom", {
	privs = { teacher = true },
	func = function(name, params)
		local player = minetest.get_player_by_name(name)
		if not player then
			return false, "You must be online to open the GUI"
		end

		classroom.show_dashboard_formspec(player)
		return true
	end,
})


--
-- Unified Inventory
--
if minetest.get_modpath("unified_inventory") ~= nil then
	unified_inventory.register_button("classroom", {
		type = "image",
		image = "classroom_icon.png",
		tooltip = S("Classroom"),
		action = classroom.show_dashboard_formspec,
	})
end