local Device = require("ui/device")
local GestureDetector = require("ui/gesturedetector")
local Event = require("ui/event")
local TimeVal = require("ui/timeval")
local Screen = require("ui/screen")
local Dbg = require("dbg")

-- constants from <linux/input.h>
local EV_SYN = 0
local EV_KEY = 1
local EV_ABS = 3

-- key press event values (KEY.value)
local EVENT_VALUE_KEY_PRESS = 1
local EVENT_VALUE_KEY_REPEAT = 2
local EVENT_VALUE_KEY_RELEASE = 0

-- Synchronization events (SYN.code).
local SYN_REPORT = 0
local SYN_CONFIG = 1
local SYN_MT_REPORT = 2

-- For single-touch events (ABS.code).
local ABS_X = 00
local ABS_Y = 01
local ABS_PRESSURE = 24

-- For multi-touch events (ABS.code).
local ABS_MT_SLOT = 47
local ABS_MT_POSITION_X = 53
local ABS_MT_POSITION_Y = 54
local ABS_MT_TRACKING_ID = 57
local ABS_MT_PRESSURE = 58

--[[
an interface for key presses
]]

local Key = {}

function Key:new(key, modifiers)
	local o = { key = key, modifiers = modifiers }

	-- we're a hash map, too
	o[key] = true
	for mod, pressed in pairs(modifiers) do
		if pressed then
			o[mod] = true
		end
	end

	setmetatable(o, self)
	self.__index = self
	return o
end

function Key:__tostring()
	return table.concat(self:getSequence(), "-")
end

--[[
get a sequence that can be matched against later

use this to let the user press a sequence and then
store this as configuration data (configurable
shortcuts)
]]
function Key:getSequence()
	local seq = {}
	for mod, pressed in pairs(self.modifiers) do
		if pressed then
			table.insert(seq, mod)
		end
	end
	table.insert(seq, self.key)
end

--[[
this will match a key against a sequence

the sequence should be a table of key names that
must be pressed together to match.
if an entry in this table is itself a table, at
least one key in this table must match.

E.g.:

Key:match({ "Alt", "K" }) -- match Alt-K
Key:match({ "Alt", { "K", "L" }}) -- match Alt-K _or_ Alt-L
]]
function Key:match(sequence)
	local mod_keys = {} -- a hash table for checked modifiers
	for _, key in ipairs(sequence) do
		if type(key) == "table" then
			local found = false
			for _, variant in ipairs(key) do
				if self[variant] then
					found = true
					break
				end
			end
			if not found then
				-- one of the needed keys is not pressed
				return false
			end
		elseif not self[key] then
			-- needed key not pressed
			return false
		elseif self.modifiers[key] ~= nil then
			-- checked key is a modifier key
			mod_keys[key] = true
		end
	end

	for mod, pressed in pairs(self.modifiers) do
		if pressed and not mod_keys[mod] then
			-- additional modifier keys are pressed, don't match
			return false
		end
	end

	return true
end

--[[
an interface to get input events
]]
local Input = {
	event_map = {},
	modifiers = {},
	rotation_map = {
		[0] = {},
		[1] = { Up = "Right", Right = "Down", Down = "Left", Left = "Up" },
		[2] = { Up = "Down", Right = "Left", Down = "Up", Left = "Right" },
		[3] = { Up = "Left", Right = "Up", Down = "Right", Left = "Down" }
	},
	timer_callbacks = {},
	disable_double_tap = DGESDETECT_DISABLE_DOUBLE_TAP,
}

function Input:initKeyMap()
	self.event_map = {
		[2]  = "1", [3]  = "2", [4]  = "3", [5]  = "4", [6]  = "5", [7]  = "6", [8]  = "7", [9]  = "8", [10] = "9", [11] = "0",
		[16] = "Q", [17] = "W", [18] = "E", [19] = "R", [20] = "T", [21] = "Y", [22] = "U", [23] = "I", [24] = "O", [25] = "P",
		[30] = "A", [31] = "S", [32] = "D", [33] = "F", [34] = "G", [35] = "H", [36] = "J", [37] = "K", [38] = "L", [14] = "Del",
		[44] = "Z", [45] = "X", [46] = "C", [47] = "V", [48] = "B", [49] = "N", [50] = "M", [52] = ".", [53] = "/", -- only KDX

		[28] = "Enter",
		[29] = "ScreenKB", -- K[4]
		[42] = "Shift",
		[56] = "Alt",
		[57] = " ",
		[90] = "AA", -- KDX
		[91] = "Back", -- KDX
		[92] = "Press", -- KDX
		[94] = "Sym", -- KDX
		[98] = "Home", -- KDX
		[102] = "Home", -- K[3] & k[4]
		[104] = "LPgBack", -- K[3] only
		[103] = "Up", -- K[3] & k[4]
		[105] = "Left",
		[106] = "Right",
		[108] = "Down", -- K[3] & k[4]
		[109] = "RPgBack",
		[114] = "VMinus",
		[115] = "VPlus",
		[122] = "Up", -- KDX
		[123] = "Down", -- KDX
		[124] = "RPgFwd", -- KDX
		[126] = "Sym", -- K[3]
		[139] = "Menu",
		[158] = "Back", -- K[3] & K[4]
		[190] = "AA", -- K[3]
		[191] = "RPgFwd", -- K[3] & k[4]
		[193] = "LPgFwd", -- K[3] only
		[194] = "Press", -- K[3] & k[4]
	}
	self.sdl_event_map = {
		[10] = "1", [11] = "2", [12] = "3", [13] = "4", [14] = "5", [15] = "6", [16] = "7", [17] = "8", [18] = "9", [19] = "0",
		[24] = "Q", [25] = "W", [26] = "E", [27] = "R", [28] = "T", [29] = "Y", [30] = "U", [31] = "I", [32] = "O", [33] = "P",
		[38] = "A", [39] = "S", [40] = "D", [41] = "F", [42] = "G", [43] = "H", [44] = "J", [45] = "K", [46] = "L",
		[52] = "Z", [53] = "X", [54] = "C", [55] = "V", [56] = "B", [57] = "N", [58] = "M",

		[22] = "Back", -- Backspace
		[36] = "Enter", -- Enter
		[50] = "Shift", -- left shift
		[60] = ".",
		[61] = "/",
		[62] = "Sym", -- right shift key
		[64] = "Alt", -- left alt
		[65] = " ", -- Spacebar
		[67] = "Menu", -- F[1]
		[72] = "LPgBack", -- F[6]
		[73] = "LPgFwd", -- F[7]
		[95] = "VPlus", -- F[11]
		[96] = "VMinus", -- F[12]
		[105] = "AA", -- right alt key
		[110] = "Home", -- Home
		[111] = "Up", -- arrow up
		[112] = "RPgBack", -- normal PageUp
		[113] = "Left", -- arrow left
		[114] = "Right", -- arrow right
		[115] = "Press", -- End (above arrows)
		[116] = "Down", -- arrow down
		[117] = "RPgFwd", -- normal PageDown
		[119] = "Del", -- Delete
	}
	self.modifiers = {
		Alt = false,
		Shift = false
	}
	-- these groups are just helpers:
	self.group = {
		Cursor = { "Up", "Down", "Left", "Right" },
		PgFwd = { "RPgFwd", "LPgFwd" },
		PgBack = { "RPgBack", "LPgBack" },
		Alphabet = {
			"A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M",
			"N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"
		},
		AlphaNumeric = {
			"0", "1", "2", "3", "4", "5", "6", "7", "8", "9",
			"A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M",
			"N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"
		},
		Numeric = {
			"0", "1", "2", "3", "4", "5", "6", "7", "8", "9"
		},
		Text = {
			" ", ".", "/",
			"0", "1", "2", "3", "4", "5", "6", "7", "8", "9",
			"A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M",
			"N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"
		},
		Any = {
			" ", ".", "/",
			"0", "1", "2", "3", "4", "5", "6", "7", "8", "9",
			"A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M",
			"N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z",
			"Up", "Down", "Left", "Right", "Press",
			"Back", "Enter", "Sym", "AA", "Menu", "Home", "Del",
			"LPgBack", "RPgBack", "LPgFwd", "RPgFwd"
		}
	}
end

function Input:initTouchState()
	self.cur_slot = 0
	self.MTSlots = {}
	self.ev_slots = {
		[0] = {
			slot = 0,
		}
	}
end

function Input:init()
	if Device:hasKeyboard() then
		self:initKeyMap()
	end
	if Device:isTouchDevice() then
		self:initTouchState()
	end
	-- set up fake event map
	self.event_map[10000] = "IntoSS" -- go into screen saver
	self.event_map[10001] = "OutOfSS" -- go out of screen saver
	self.event_map[10020] = "Charging"
	self.event_map[10021] = "NotCharging"

	if util.isEmulated() then
		self:initKeyMap()
		os.remove("/tmp/emu_event")
		os.execute("mkfifo /tmp/emu_event")
		input.open("/tmp/emu_event")
		-- SDL key codes
		self.event_map = self.sdl_event_map
	else
		local dev_mod = Device:getModel()
		if not Device:isKobo() then
			input.open("fake_events")
		end
		if dev_mod ~= "KindleTouch" and not Device:isKobo() then
			-- event0 in KindleTouch is "WM8962 Beep Generator" (useless)
			Device:setTouchInputDev("/dev/input/event0")
			input.open("/dev/input/event0")
		end
		if dev_mod ~= "KindleTouch" and dev_mod ~= "KindlePaperWhite" then
			-- event1 in KindleTouch is "imx-yoshi Headset" (useless)
			-- and we don't have event1 in KindlePaperWhite
			input.open("/dev/input/event1")
		end
		if dev_mod == "KindlePaperWhite" then
			print(_("Auto-detected Kindle PaperWhite"))
		elseif dev_mod == "KindleTouch" then
			Device:setTouchInputDev("/dev/input/event3")
			input.open("/dev/input/event2") -- Home button
			input.open("/dev/input/event3") -- touchscreen
			-- KT does have one key!
			self.event_map[102] = "Home"
			-- update event hook
			function Input:eventAdjustHook(ev)
				if ev.type == EV_ABS then
					--@TODO handle coordinates properly after
					--screen rotate.    (houqp)
					if ev.code == ABS_MT_POSITION_X then
						ev.value = math.round(ev.value * (600/4095))
					elseif ev.code == ABS_MT_POSITION_Y then
						ev.value = math.round(ev.value * (800/4095))
					end
				end
				return ev
			end
			print(_("Auto-detected Kindle Touch"))
		elseif Device:isKobo() then
			local firm_rev = Device:getFirmVer()
			input.open("/dev/input/event1")
			Device:setTouchInputDev("/dev/input/event1")
			input.open("/dev/input/event0") -- Light button and sleep slider
			print(_("Auto-detected Kobo"))
			self:adjustKoboEventMap()
			if dev_mod ~= 'Kobo_trilogy' then
				function Input:eventAdjustHook(ev)
					if ev.type == EV_ABS then
						if ev.code == ABS_X then
							ev.code = ABS_Y
						elseif ev.code == ABS_Y then
							ev.code = ABS_X						
							-- We always have to substract from the physical x,
							-- regardless of the orientation
							if (Screen.width<Screen.height) then
								ev.value = Screen.width - ev.value
							else
								ev.value = Screen.height - ev.value
							end
						end
					end
					return ev
				end
			else
				function Input:eventAdjustHook(ev)
					if ev.code == ABS_X then
						-- We always have to substract from the physical x,
						-- regardless of the orientation
						if (Screen.width<Screen.height) then
							ev.value = Screen.width - ev.value
						else
							ev.value = Screen.height - ev.value
						end
					end
					return ev
				end
			end
		elseif dev_mod == "Kindle4" then
			print(_("Auto-detected Kindle 4"))
			self:adjustKindle4EventMap()
		elseif dev_mod == "Kindle3" then
			input.open("/dev/input/event2")
			print(_("Auto-detected Kindle 3"))
		elseif dev_mod == "KindleDXG" then
			print(_("Auto-detected Kindle DXG"))
		elseif dev_mod == "Kindle2" then
			print(_("Auto-detected Kindle 2"))
		else
			print(_("Not supported device model!"))
			os.exit(-1)
		end
	end
end

--[[
different device models shoudl overload this method if
necessary to make event compatible to KPV.
--]]
function Input:eventAdjustHook(ev)
	-- do nothing by default
	return ev
end

function Input:adjustKindle4EventMap()
	self.event_map[193] = "LPgBack"
	self.event_map[104] = "LPgFwd"
end

function Input:adjustKoboEventMap()
	self.event_map[59] = "Power_SleepCover"
	self.event_map[90] = "Light"
	self.event_map[116] = "Power"
end

function Input:setTimeout(cb, tv_out)
	local item = {
		callback = cb,
		deadline = tv_out,
	}
	for k,v in ipairs(self.timer_callbacks) do
		if v.deadline > tv_out then
			table.insert(self.timer_callbacks, k, item)
			break
		end
	end
	if #self.timer_callbacks <= 0 then
		self.timer_callbacks[1] = item
	end
end

function Input:handleKeyBoardEv(ev)
	local keycode = self.event_map[ev.code]
	if not keycode then
		-- do not handle keypress for keys we don't know
		return
	end

	-- take device rotation into account
	if self.rotation_map[Screen:getRotationMode()][keycode] then
		keycode = self.rotation_map[Screen:getRotationMode()][keycode]
	end

	if keycode == "IntoSS" or keycode == "OutOfSS"
	or keycode == "Charging" or keycode == "NotCharging" then
		return keycode
	end

	-- Kobo sleep
	if keycode == "Power_SleepCover" then
		if ev.value == EVENT_VALUE_KEY_PRESS then
			return "Suspend"
		else
			return "Resume"
		end
	end

	if ev.value == EVENT_VALUE_KEY_RELEASE
	and (keycode == "Light" or keycode == "Power") then
		return keycode
	end

	-- handle modifier keys
	if self.modifiers[keycode] ~= nil then
		if ev.value == EVENT_VALUE_KEY_PRESS then
			self.modifiers[keycode] = true
		elseif ev.value == EVENT_VALUE_KEY_RELEASE then
			self.modifiers[keycode] = false
		end
		return
	end

	local key = Key:new(keycode, self.modifiers)

	if ev.value == EVENT_VALUE_KEY_PRESS then
		return Event:new("KeyPress", key)
	elseif ev.value == EVENT_VALUE_KEY_RELEASE then
		return Event:new("KeyRelease", key)
	end
end

function Input:setMtSlot(slot, key, val)
	if not self.ev_slots[slot] then
		self.ev_slots[slot] = {
			slot = slot
		}
	end

	self.ev_slots[slot][key] = val
end

function Input:setCurrentMtSlot(key, val)
	self:setMtSlot(self.cur_slot, key, val)
end

function Input:getMtSlot(slot)
	return self.ev_slots[slot]
end

function Input:getCurrentMtSlot()
	return self:getMtSlot(self.cur_slot)
end

function Input:confirmAbsxy()
	self:setCurrentMtSlot("x", self.ev_slots[self.cur_slot]["abs_x"])
	self:setCurrentMtSlot("y", self.ev_slots[self.cur_slot]["abs_y"])
end

function Input:cleanAbsxy()
	self:setCurrentMtSlot("abs_x", nil)
	self:setCurrentMtSlot("abs_y", nil)
end

--[[
parse each touch ev from kernel and build up tev.
tev will be sent to GestureDetector:feedEvent

Events for a single tap motion from Linux kernel (MT protocol B):

	MT_TRACK_ID: 0
	MT_X: 222
	MT_Y: 207
	SYN REPORT
	MT_TRACK_ID: -1
	SYN REPORT

Notice that each line is a single event.

From kernel document:
For type B devices, the kernel driver should associate a slot with each
identified contact, and use that slot to propagate changes for the contact.
Creation, replacement and destruction of contacts is achieved by modifying
the ABS_MT_TRACKING_ID of the associated slot.  A non-negative tracking id
is interpreted as a contact, and the value -1 denotes an unused slot.  A
tracking id not previously present is considered new, and a tracking id no
longer present is considered removed.  Since only changes are propagated,
the full state of each initiated contact has to reside in the receiving
end.  Upon receiving an MT event, one simply updates the appropriate
attribute of the current slot.
--]]
function Input:handleTouchEv(ev)
	if ev.type == EV_SYN then
		if ev.code == SYN_REPORT then
			for _, MTSlot in pairs(self.MTSlots) do
				self:setMtSlot(MTSlot.slot, "timev", TimeVal:new(ev.time))
			end
			-- feed ev in all slots to state machine
			local touch_ges = GestureDetector:feedEvent(self.MTSlots)
			self.MTSlots = {}
			if touch_ges then
				return Event:new("Gesture",
					GestureDetector:adjustGesCoordinate(touch_ges)
				)
			end
		end
	elseif ev.type == EV_ABS then
		if #self.MTSlots == 0 then
			table.insert(self.MTSlots, self:getMtSlot(self.cur_slot))
		end
		if ev.code == ABS_MT_SLOT then
			if self.cur_slot ~= ev.value then
				table.insert(self.MTSlots, self:getMtSlot(ev.value))
			end
			self.cur_slot = ev.value
		elseif ev.code == ABS_MT_TRACKING_ID then
			self:setCurrentMtSlot("id", ev.value)
		elseif ev.code == ABS_MT_POSITION_X then
			self:setCurrentMtSlot("x", ev.value)
		elseif ev.code == ABS_MT_POSITION_Y then
			self:setCurrentMtSlot("y", ev.value)

		-- code to emulate mt protocol on kobos
		-- we "confirm" abs_x, abs_y only when pressure ~= 0
		elseif ev.code == ABS_X then
			self:setCurrentMtSlot("abs_x", ev.value)
		elseif ev.code == ABS_Y then
			self:setCurrentMtSlot("abs_y", ev.value)
		elseif ev.code == ABS_PRESSURE then
			if ev.value ~= 0 then
				self:setCurrentMtSlot("id", 1)
				self:confirmAbsxy()
			else
				self:cleanAbsxy()
				self:setCurrentMtSlot("id", -1)
			end
		end
	end
end

function Input:waitEvent(timeout_us, timeout_s)
	-- wrapper for input.waitForEvents that will retry for some cases
	local ok, ev
	local wait_deadline = TimeVal:now() + TimeVal:new{
			sec = timeout_s,
			usec = timeout_us
		}
	while true do
		if #self.timer_callbacks > 0 then
			-- we don't block if there is any timer, set wait to 10us
			while #self.timer_callbacks > 0 do
				ok, ev = pcall(input.waitForEvent, 100)
				if ok then break end
				local tv_now = TimeVal:now()
				if ((not timeout_us and not timeout_s) or tv_now < wait_deadline) then
					-- check whether timer is up
					if tv_now >= self.timer_callbacks[1].deadline then
						local touch_ges = self.timer_callbacks[1].callback()
						table.remove(self.timer_callbacks, 1)
						if touch_ges then
							-- Do we really need to clear all setTimeout after
							-- decided a gesture? FIXME
							Input.timer_callbacks = {}
							return Event:new("Gesture",
								GestureDetector:adjustGesCoordinate(touch_ges)
							)
						end -- EOF if touch_ges
					end -- EOF if deadline reached
				else
					break
				end -- EOF if not exceed wait timeout
			end -- while #timer_callbacks > 0
		else
			ok, ev = pcall(input.waitForEvent, timeout_us)
		end -- EOF if #timer_callbacks > 0
		if ok then
			break
		end
		if ev == "Waiting for input failed: timeout\n" then
			-- don't report an error on timeout
			ev = nil
			break
		elseif ev == "application forced to quit" then
			os.exit(0)
		end
		--DEBUG("got error waiting for events:", ev)
		if ev ~= "Waiting for input failed: 4\n" then
			-- we only abort if the error is not EINTR
			break
		end
	end

	if ok and ev then
		if Dbg.is_on and ev then
			Dbg:logEv(ev)
		end
		ev = self:eventAdjustHook(ev)
		if ev.type == EV_KEY then
			return self:handleKeyBoardEv(ev)
		elseif ev.type == EV_ABS or ev.type == EV_SYN then
			return self:handleTouchEv(ev)
		else
			-- some other kind of event that we do not know yet
			return Event:new("GenericInput", ev)
		end
	elseif not ok and ev then
		return Event:new("InputError", ev)
	end
end

--[[
helper function for formatting sequence definitions for output
]]
function Input:sequenceToString(sequence)
	local modifiers = {}
	local keystring = {"",""} -- first entries reserved for modifier specification
	for _, key in ipairs(sequence) do
		if type(key) == "table" then
			local alternatives = {}
			for _, alternative in ipairs(key) do
				table.insert(alternatives, alternative)
			end
			table.insert(keystring, "{")
			table.insert(keystring, table.concat(alternatives, "|"))
			table.insert(keystring, "}")
		elseif self.modifiers[key] ~= nil then
			table.insert(modifiers, key)
		else
			table.insert(keystring, key)
		end
	end
	if #modifiers then
		keystring[1] = table.concat(modifiers, "-")
		keystring[2] = "-"
	end
	return table.concat(keystring)
end

-- initialize the GestureDectector
-- so it can modify our (Input) state
GestureDetector.input = Input

return Input