local mp = require("mp")
local msg = require("mp.msg")
local utils = require("mp.utils")
local options = require("mp.options")

-- Default options
local opts = {
	-- All drawing is scaled by this value, including the text borders and the
	-- cursor. Change it if you have a high-DPI display.
	scale = 1,
	-- Set the font used for the REPL and the console. This probably doesn't
	-- have to be a monospaced font.
	font = "",
	-- Set the font size used for the REPL and the console. This will be
	-- multiplied by "scale."
	font_size = 16,
}

options.read_options(opts, "user_input")

local API_VERSION = "0.1.0"
local API_MAJOR_MINOR = API_VERSION:match("%d+%.%d+")

local co = nil
local queue = {}
local active_ids = {}
local histories = {}
local request = nil

local line = ""

--[[
    The below code is a modified implementation of text input from mpv's console.lua:
    https://github.com/mpv-player/mpv/blob/7ca14d646c7e405f3fb1e44600e2a67fc4607238/player/lua/console.lua

    Modifications:
        removed support for log messages, sending commands, tab complete, help commands
        removed update timer
        Changed esc key to call handle_esc function
        handle_esc and handle_enter now resume the main coroutine with a response table
        made history specific to request ids
        localised all functions - reordered some to fit
        keybindings use new names
]]
--

------------------------------START ORIGINAL MPV CODE-----------------------------------
----------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------

-- Copyright (C) 2019 the mpv developers
--
-- Permission to use, copy, modify, and/or distribute this software for any
-- purpose with or without fee is hereby granted, provided that the above
-- copyright notice and this permission notice appear in all copies.
--
-- THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
-- WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
-- MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
-- SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
-- WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
-- OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
-- CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

local assdraw = require("mp.assdraw")

local function detect_platform()
	local o = {}
	-- Kind of a dumb way of detecting the platform but whatever
	if mp.get_property_native("options/vo-mmcss-profile", o) ~= o then
		return "windows"
	elseif mp.get_property_native("options/macos-force-dedicated-gpu", o) ~= o then
		return "macos"
	elseif os.getenv("WAYLAND_DISPLAY") then
		return "wayland"
	end
	return "x11"
end

-- Pick a better default font for Windows and macOS
local platform = detect_platform()
if platform == "windows" then
	opts.font = "Consolas"
elseif platform == "macos" then
	opts.font = "Menlo"
else
	opts.font = "monospace"
end

local repl_active = false
local insert_mode = false
local cursor = 1
local key_bindings = {}
local global_margin_y = 0

-- Escape a string for verbatim display on the OSD
local function ass_escape(str)
	-- There is no escape for '\' in ASS (I think?) but '\' is used verbatim if
	-- it isn't followed by a recognised character, so add a zero-width
	-- non-breaking space
	str = str:gsub("\\", "\\\239\187\191")
	str = str:gsub("{", "\\{")
	str = str:gsub("}", "\\}")
	-- Precede newlines with a ZWNBSP to prevent ASS's weird collapsing of
	-- consecutive newlines
	str = str:gsub("\n", "\239\187\191\\N")
	-- Turn leading spaces into hard spaces to prevent ASS from stripping them
	str = str:gsub("\\N ", "\\N\\h")
	str = str:gsub("^ ", "\\h")
	return str
end

-- Render the REPL and console as an ASS OSD
local function update()
	local dpi_scale = mp.get_property_native("display-hidpi-scale", 1.0)

	dpi_scale = dpi_scale * opts.scale

	local screenx, screeny, aspect = mp.get_osd_size()
	screenx = screenx / dpi_scale
	screeny = screeny / dpi_scale

	-- Clear the OSD if the REPL is not active
	if not repl_active then
		mp.set_osd_ass(screenx, screeny, "")
		return
	end

	local ass = assdraw.ass_new()
	local style = "{\\r"
		.. "\\1a&H00&\\3a&H00&\\4a&H99&"
		.. "\\1c&Heeeeee&\\3c&H111111&\\4c&H000000&"
		.. "\\fn"
		.. opts.font
		.. "\\fs"
		.. opts.font_size
		.. "\\bord1\\xshad0\\yshad1\\fsp0\\q1}"

	local queue_style = "{\\r"
		.. "\\1a&H00&\\3a&H00&\\4a&H99&"
		.. "\\1c&Heeeeee&\\3c&H111111&\\4c&H000000&"
		.. "\\fn"
		.. opts.font
		.. "\\fs"
		.. opts.font_size
		.. "\\c&H66ccff&"
		.. "\\bord1\\xshad0\\yshad1\\fsp0\\q1}"

	-- Create the cursor glyph as an ASS drawing. ASS will draw the cursor
	-- inline with the surrounding text, but it sets the advance to the width
	-- of the drawing. So the cursor doesn't affect layout too much, make it as
	-- thin as possible and make it appear to be 1px wide by giving it 0.5px
	-- horizontal borders.
	local cheight = opts.font_size * 8
	local cglyph = "{\\r"
		.. "\\1a&H44&\\3a&H44&\\4a&H99&"
		.. "\\1c&Heeeeee&\\3c&Heeeeee&\\4c&H000000&"
		.. "\\xbord0.5\\ybord0\\xshad0\\yshad1\\p4\\pbo24}"
		.. "m 0 0 l 1 0 l 1 "
		.. cheight
		.. " l 0 "
		.. cheight
		.. "{\\p0}"
	local before_cur = ass_escape(line:sub(1, cursor - 1))
	local after_cur = ass_escape(line:sub(cursor))

	ass:new_event()
	ass:an(1)
	ass:pos(2, screeny - 2 - global_margin_y * screeny)

	if #queue == 2 then
		ass:append(queue_style .. string.format("There is 1 more request queued\\N"))
	elseif #queue > 2 then
		ass:append(queue_style .. string.format("There are %d more requests queued\\N", #queue - 1))
	end
	ass:append(style .. request.text .. "\\N")
	ass:append("> " .. before_cur)
	ass:append(cglyph)
	ass:append(style .. after_cur)

	-- Redraw the cursor with the REPL text invisible. This will make the
	-- cursor appear in front of the text.
	ass:new_event()
	ass:an(1)
	ass:pos(2, screeny - 2)
	ass:append(style .. "{\\alpha&HFF&}> " .. before_cur)
	ass:append(cglyph)
	ass:append(style .. "{\\alpha&HFF&}" .. after_cur)

	mp.set_osd_ass(screenx, screeny, ass.text)
end

-- Naive helper function to find the next UTF-8 character in 'str' after 'pos'
-- by skipping continuation bytes. Assumes 'str' contains valid UTF-8.
local function next_utf8(str, pos)
	if pos > str:len() then
		return pos
	end
	repeat
		pos = pos + 1
	until pos > str:len() or str:byte(pos) < 0x80 or str:byte(pos) > 0xbf
	return pos
end

-- As above, but finds the previous UTF-8 charcter in 'str' before 'pos'
local function prev_utf8(str, pos)
	if pos <= 1 then
		return pos
	end
	repeat
		pos = pos - 1
	until pos <= 1 or str:byte(pos) < 0x80 or str:byte(pos) > 0xbf
	return pos
end

-- Insert a character at the current cursor position (any_unicode)
local function handle_char_input(c)
	if insert_mode then
		line = line:sub(1, cursor - 1) .. c .. line:sub(next_utf8(line, cursor))
	else
		line = line:sub(1, cursor - 1) .. c .. line:sub(cursor)
	end
	cursor = cursor + #c
	update()
end

-- Remove the character behind the cursor (Backspace)
local function handle_backspace()
	if cursor <= 1 then
		return
	end
	local prev = prev_utf8(line, cursor)
	line = line:sub(1, prev - 1) .. line:sub(cursor)
	cursor = prev
	update()
end

-- Remove the character in front of the cursor (Del)
local function handle_del()
	if cursor > line:len() then
		return
	end
	line = line:sub(1, cursor - 1) .. line:sub(next_utf8(line, cursor))
	update()
end

-- Toggle insert mode (Ins)
local function handle_ins()
	insert_mode = not insert_mode
end

-- Move the cursor to the next character (Right)
local function next_char(amount)
	cursor = next_utf8(line, cursor)
	update()
end

-- Move the cursor to the previous character (Left)
local function prev_char(amount)
	cursor = prev_utf8(line, cursor)
	update()
end

-- Clear the current line (Ctrl+C)
local function clear()
	line = ""
	cursor = 1
	insert_mode = false
	request.history.pos = #request.history.list + 1
	update()
end

-- Close the REPL if the current line is empty, otherwise do nothing (Ctrl+D)
local function maybe_exit()
	if line == "" then
	else
		handle_del()
	end
end

local function handle_esc()
	coroutine.resume(co, {
		line = nil,
		err = "exited",
	})
end

-- Run the current command and clear the line (Enter)
local function handle_enter()
	if request.history.list[#request.history.list] ~= line and line ~= "" then
		request.history.list[#request.history.list + 1] = line
	end
	coroutine.resume(co, {
		line = line,
	})
end

-- Go to the specified position in the command history
local function go_history(new_pos)
	local old_pos = request.history.pos
	request.history.pos = new_pos

	-- Restrict the position to a legal value
	if request.history.pos > #request.history.list + 1 then
		request.history.pos = #request.history.list + 1
	elseif request.history.pos < 1 then
		request.history.pos = 1
	end

	-- Do nothing if the history position didn't actually change
	if request.history.pos == old_pos then
		return
	end

	-- If the user was editing a non-history line, save it as the last history
	-- entry. This makes it much less frustrating to accidentally hit Up/Down
	-- while editing a line.
	if old_pos == #request.history.list + 1 and line ~= "" and request.history.list[#request.history.list] ~= line then
		request.history.list[#request.history.list + 1] = line
	end

	-- Now show the history line (or a blank line for #history + 1)
	if request.history.pos <= #request.history.list then
		line = request.history.list[request.history.pos]
	else
		line = ""
	end
	cursor = line:len() + 1
	insert_mode = false
	update()
end

-- Go to the specified relative position in the command history (Up, Down)
local function move_history(amount)
	go_history(request.history.pos + amount)
end

-- Go to the first command in the command history (PgUp)
local function handle_pgup()
	go_history(1)
end

-- Stop browsing history and start editing a blank line (PgDown)
local function handle_pgdown()
	go_history(#request.history.list + 1)
end

-- Move to the start of the current word, or if already at the start, the start
-- of the previous word. (Ctrl+Left)
local function prev_word()
	-- This is basically the same as next_word() but backwards, so reverse the
	-- string in order to do a "backwards" find. This wouldn't be as annoying
	-- to do if Lua didn't insist on 1-based indexing.
	cursor = line:len() - select(2, line:reverse():find("%s*[^%s]*", line:len() - cursor + 2)) + 1
	update()
end

-- Move to the end of the current word, or if already at the end, the end of
-- the next word. (Ctrl+Right)
local function next_word()
	cursor = select(2, line:find("%s*[^%s]*", cursor)) + 1
	update()
end

-- Move the cursor to the beginning of the line (HOME)
local function go_home()
	cursor = 1
	update()
end

-- Move the cursor to the end of the line (END)
local function go_end()
	cursor = line:len() + 1
	update()
end

-- Delete from the cursor to the beginning of the word (Ctrl+Backspace)
local function del_word()
	local before_cur = line:sub(1, cursor - 1)
	local after_cur = line:sub(cursor)

	before_cur = before_cur:gsub("[^%s]+%s*$", "", 1)
	line = before_cur .. after_cur
	cursor = before_cur:len() + 1
	update()
end

-- Delete from the cursor to the end of the word (Ctrl+Del)
local function del_next_word()
	if cursor > line:len() then
		return
	end

	local before_cur = line:sub(1, cursor - 1)
	local after_cur = line:sub(cursor)

	after_cur = after_cur:gsub("^%s*[^%s]+", "", 1)
	line = before_cur .. after_cur
	update()
end

-- Delete from the cursor to the end of the line (Ctrl+K)
local function del_to_eol()
	line = line:sub(1, cursor - 1)
	update()
end

-- Delete from the cursor back to the start of the line (Ctrl+U)
local function del_to_start()
	line = line:sub(cursor)
	cursor = 1
	update()
end

-- Returns a string of UTF-8 text from the clipboard (or the primary selection)
local function get_clipboard(clip)
	if platform == "x11" then
		local res = utils.subprocess({
			args = { "xclip", "-selection", clip and "clipboard" or "primary", "-out" },
			playback_only = false,
		})
		if not res.error then
			return res.stdout
		end
	elseif platform == "wayland" then
		local res = utils.subprocess({
			args = { "wl-paste", clip and "-n" or "-np" },
			playback_only = false,
		})
		if not res.error then
			return res.stdout
		end
	elseif platform == "windows" then
		local res = utils.subprocess({
			args = {
				"powershell",
				"-NoProfile",
				"-Command",
				[[& {
                Trap {
                    Write-Error -ErrorRecord $_
                    Exit 1
                }

                $clip = ""
                if (Get-Command "Get-Clipboard" -errorAction SilentlyContinue) {
                    $clip = Get-Clipboard -Raw -Format Text -TextFormatType UnicodeText
                } else {
                    Add-Type -AssemblyName PresentationCore
                    $clip = [Windows.Clipboard]::GetText()
                }

                $clip = $clip -Replace "`r",""
                $u8clip = [System.Text.Encoding]::UTF8.GetBytes($clip)
                [Console]::OpenStandardOutput().Write($u8clip, 0, $u8clip.Length)
            }]],
			},
			playback_only = false,
		})
		if not res.error then
			return res.stdout
		end
	elseif platform == "macos" then
		local res = utils.subprocess({
			args = { "pbpaste" },
			playback_only = false,
		})
		if not res.error then
			return res.stdout
		end
	end
	return ""
end

-- Paste text from the window-system's clipboard. 'clip' determines whether the
-- clipboard or the primary selection buffer is used (on X11 and Wayland only.)
local function paste(clip)
	local text = get_clipboard(clip)
	local before_cur = line:sub(1, cursor - 1)
	local after_cur = line:sub(cursor)
	line = before_cur .. text .. after_cur
	cursor = cursor + text:len()
	update()
end

-- List of input bindings. This is a weird mashup between common GUI text-input
-- bindings and readline bindings.
local function get_bindings()
	local bindings = {
		{ "esc", handle_esc },
		{ "enter", handle_enter },
		{ "kp_enter", handle_enter },
		{
			"shift+enter",
			function()
				handle_char_input("\n")
			end,
		},
		{ "ctrl+j", handle_enter },
		{ "ctrl+m", handle_enter },
		{ "bs", handle_backspace },
		{ "shift+bs", handle_backspace },
		{ "ctrl+h", handle_backspace },
		{ "del", handle_del },
		{ "shift+del", handle_del },
		{ "ins", handle_ins },
		{
			"shift+ins",
			function()
				paste(false)
			end,
		},
		{
			"mbtn_mid",
			function()
				paste(false)
			end,
		},
		{
			"left",
			function()
				prev_char()
			end,
		},
		{
			"ctrl+b",
			function()
				prev_char()
			end,
		},
		{
			"right",
			function()
				next_char()
			end,
		},
		{
			"ctrl+f",
			function()
				next_char()
			end,
		},
		{
			"up",
			function()
				move_history(-1)
			end,
		},
		{
			"ctrl+p",
			function()
				move_history(-1)
			end,
		},
		{
			"wheel_up",
			function()
				move_history(-1)
			end,
		},
		{
			"down",
			function()
				move_history(1)
			end,
		},
		{
			"ctrl+n",
			function()
				move_history(1)
			end,
		},
		{
			"wheel_down",
			function()
				move_history(1)
			end,
		},
		{ "wheel_left", function() end },
		{ "wheel_right", function() end },
		{ "ctrl+left", prev_word },
		{ "alt+b", prev_word },
		{ "ctrl+right", next_word },
		{ "alt+f", next_word },
		{ "ctrl+a", go_home },
		{ "home", go_home },
		{ "ctrl+e", go_end },
		{ "end", go_end },
		{ "pgup", handle_pgup },
		{ "pgdwn", handle_pgdown },
		{ "ctrl+c", clear },
		{ "ctrl+d", maybe_exit },
		{ "ctrl+k", del_to_eol },
		{ "ctrl+u", del_to_start },
		{
			"ctrl+v",
			function()
				paste(true)
			end,
		},
		{
			"meta+v",
			function()
				paste(true)
			end,
		},
		{ "ctrl+bs", del_word },
		{ "ctrl+w", del_word },
		{ "ctrl+del", del_next_word },
		{ "alt+d", del_next_word },
		{
			"kp_dec",
			function()
				handle_char_input(".")
			end,
		},
	}

	for i = 0, 9 do
		bindings[#bindings + 1] = {
			"kp" .. i,
			function()
				handle_char_input("" .. i)
			end,
		}
	end

	return bindings
end

local function text_input(info)
	if info.key_text and (info.event == "press" or info.event == "down" or info.event == "repeat") then
		handle_char_input(info.key_text)
	end
end

local function define_key_bindings()
	if #key_bindings > 0 then
		return
	end
	for _, bind in ipairs(get_bindings()) do
		-- Generate arbitrary name for removing the bindings later.
		local name = "_userinput_" .. bind[1]
		key_bindings[#key_bindings + 1] = name
		mp.add_forced_key_binding(bind[1], name, bind[2], { repeatable = true })
	end
	mp.add_forced_key_binding("any_unicode", "_userinput_text", text_input, { repeatable = true, complex = true })
	key_bindings[#key_bindings + 1] = "_userinput_text"
end

local function undefine_key_bindings()
	for _, name in ipairs(key_bindings) do
		mp.remove_key_binding(name)
	end
	key_bindings = {}
end

-- Set the REPL visibility ("enable", Esc)
local function set_active(active)
	if active == repl_active then
		return
	end
	if active then
		repl_active = true
		insert_mode = false
		define_key_bindings()
	else
		clear()
		repl_active = false
		undefine_key_bindings()
		collectgarbage()
	end
	update()
end

mp.observe_property("user-data/osc/margins", "native", function(_, val)
	if val then
		global_margins = val
	else
		global_margins = { t = 0, b = 0 }
	end
	update()
end)

-- Redraw the REPL when the OSD size changes. This is needed because the
-- PlayRes of the OSD will need to be adjusted.
mp.observe_property("osd-width", "native", update)
mp.observe_property("osd-height", "native", update)
mp.observe_property("display-hidpi-scale", "native", update)

----------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------
-------------------------------END ORIGINAL MPV CODE------------------------------------

--[[
    sends a response to the original script in the form of a json string
    it is expected that all requests get a response, if the input is nil then err should say why
    current error codes are:
        exited          the user closed the input instead of pressing Enter
        already_queued  a request with the specified id was already in the queue
        cancelled       a script cancelled the request
        replace         replaced by another request
]]
local function send_response(res)
	if res.source then
		mp.commandv("script-message-to", res.source, res.response, (utils.format_json(res)))
	else
		mp.commandv("script-message", res.response, (utils.format_json(res)))
	end
end

-- push new request onto the queue
-- if a request with the same id already exists and the queueable flag is not enabled then
-- a nil result will be returned to the function
function push_request(req)
	if active_ids[req.id] then
		if req.replace then
			for i, q_req in ipairs(queue) do
				if q_req.id == req.id then
					send_response({ err = "replaced", response = q_req.response, source = q_req.source })
					queue[i] = req
					if i == 1 then
						request = req
					end
				end
			end
			update()
			return
		end

		if not req.queueable then
			send_response({ err = "already_queued", response = req.response, source = req.source })
			return
		end
	end

	table.insert(queue, req)
	active_ids[req.id] = (active_ids[req.id] or 0) + 1
	if #queue == 1 then
		coroutine.resume(co)
	end
	update()
end

-- safely removes an item from the queue and updates the set of active requests
function remove_request(index)
	local req = table.remove(queue, index)
	active_ids[req.id] = active_ids[req.id] - 1

	if active_ids[req.id] == 0 then
		active_ids[req.id] = nil
	end
	return req
end

--an infinite loop that moves through the request queue
--uses a coroutine to handle asynchronous operations
local function driver()
	while true do
		while queue[1] do
			request = queue[1]
			line = request.default_input
			cursor = request.cursor_pos

			if repl_active then
				update()
			else
				set_active(true)
			end

			res = coroutine.yield()
			if res then
				res.source, res.response = request.source, request.response
				send_response(res)
				remove_request(1)
			end
		end

		set_active(false)
		coroutine.yield()
	end
end

co = coroutine.create(driver)

--cancels any input request that returns true for the given predicate function
local function cancel_input_request(pred)
	for i = #queue, 1, -1 do
		if pred(i) then
			req = remove_request(i)
			send_response({ err = "cancelled", response = req.response, source = req.source })

			--if we're removing the first item then that means the coroutine is waiting for a response
			--we will need to tell the coroutine to resume, upon which it will move to the next request
			--if there is something in the buffer then save it to the history before erasing it
			if i == 1 then
				local old_line = line
				if old_line ~= "" then
					table.insert(histories[req.id].list, old_line)
				end
				clear()
				coroutine.resume(co)
			end
		end
	end
end

mp.register_script_message("cancel-user-input/uid", function(uid)
	cancel_input_request(function(i)
		return queue[i].response == uid
	end)
end)

-- removes all requests with the specified id from the queue
mp.register_script_message("cancel-user-input/id", function(id)
	cancel_input_request(function(i)
		return queue[i].id == id
	end)
end)

-- ensures a request has the correct fields and is correctly formatted
local function format_request_fields(req)
	assert(req.version, "input requests require an API version string")
	if not string.find(req.version, API_MAJOR_MINOR, 1, true) then
		error(("input request has invalid version: expected %s.x, got %s"):format(API_MAJOR_MINOR, req.version))
	end

	assert(req.response, "input requests require a response string")
	assert(req.id, "input requests require an id string")

	req.text = ass_escape(req.request_text or "")
	req.default_input = req.default_input or ""
	req.cursor_pos = tonumber(req.cursor_pos) or 1
	req.id = req.id or "mpv"

	if req.cursor_pos ~= 1 then
		if req.cursor_pos < 1 then
			req.cursor_pos = 1
		elseif req.cursor_pos > #req.default_input then
			req.cursor_pos = #req.default_input + 1
		end
	end

	if not histories[req.id] then
		histories[req.id] = { pos = 1, list = {} }
	end
	req.history = histories[req.id]
	return req
end

-- updates the fields of a specific request
mp.register_script_message("update-user-input/uid", function(uid, req_opts)
	req_opts = utils.parse_json(req_opts)
	req_opts.response = uid
	for i, req in ipairs(queue) do
		if req.response == uid then
			local success, result = pcall(format_request_fields, req_opts)
			if not success then
				return msg.error(result)
			end

			queue[i] = result
			if i == 1 then
				request = queue[1]
			end
			update()
			return
		end
	end
end)

--the function that parses the input requests
local function input_request(req)
	req = format_request_fields(req)
	push_request(req)
end

-- script message to recieve input requests, get-user-input.lua acts as an interface to call this script message
mp.register_script_message("request-user-input", function(req)
	msg.debug(req)
	req = utils.parse_json(req)
	local success, err = pcall(input_request, req)
	if not success then
		send_response({ err = err, response = req.response, source = req.source })
		msg.error(err)
	end
end)