-- syncplayintf.lua -- An interface for communication between mpv and Syncplay
-- Author: Etoh
-- Thanks: RiCON, James Ross-Gowan, Argon-, wm4

local CANVAS_WIDTH = 1000
local CANVAS_HEIGHT = 1000
local ROW_HEIGHT = 100
local PIXELS_PER_CHAR = 16
local CHAT_FORMAT = "{\\fs60}{\an1}{\\q2}"
local MAX_ROWS = 7
local MOVEMENT_PER_TICK = 1
local TICK_DURATION = 0.01
local INPUT_PROMPT_FONT_SIZE = 25
local MAX_CHAT_MESSAGE_LENGTH = 50

local chat_log = {}

local assdraw = require "mp.assdraw"

function format_chat(xpos, ypos, text)
	chat_message = CHAT_FORMAT .. "{\\pos("..xpos..","..ypos..")}"..text.."\n"
    return string.format(chat_message)
end

function clear_chat()
	chat_log = {}
end

function add_chat(chat_message)
	local entry = #chat_log+1
	for i = 1, #chat_log do
		if chat_log[i].text == '' then
			entry = i
			break
		end
	end
	local row = ((entry-1) % MAX_ROWS)+1
	chat_log[entry] = { xpos=CANVAS_WIDTH, text=tostring(chat_message), row=row }
end

function chat_update()
    ass = assdraw.ass_new()
	local chat_ass = ''
	if #chat_log > 0 then
		for i = 1, #chat_log do
			local xpos = chat_log[i].xpos
			local text = chat_log[i].text
			if text ~= '' then
				local roughlen = string.len(text) * PIXELS_PER_CHAR
				if xpos > (-1*roughlen) then
					local row = chat_log[i].row
					local ypos = row * ROW_HEIGHT
					chat_ass = chat_ass .. format_chat(xpos,ypos,text)
					chat_log[i].xpos = xpos-MOVEMENT_PER_TICK
				else
					chat_log[i].text = ''
				end
			end
		end
	end
	ass:append(chat_ass)
	ass:append(input_ass())
	mp.set_osd_ass(CANVAS_WIDTH,CANVAS_HEIGHT, ass.text)
end
chat_timer=mp.add_periodic_timer(TICK_DURATION, chat_update)

mp.register_script_message('chat', function(e)
	add_chat(e)
end)

-- adapted from repl.lua -- A graphical REPL for mpv input commands
--
-- c 2016, James Ross-Gowan
--
-- 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.

-- Default options
local utils = require 'mp.utils'
local options = require 'mp.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 = 'monospace',
	-- Set the font size used for the REPL and the console. This will be
	-- multiplied by "scale."
	['font-size'] = INPUT_PROMPT_FONT_SIZE,
}

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/input-app-events', o) ~= o then
		return 'macos'
	end
	return 'linux'
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'
end

-- Apply user-set options
options.read_options(opts)

-- Escape a string for verbatim display on the OSD
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')
	return str
end

function update()
	return
end

local repl_active = false
local insert_mode = false
local line = ''
local cursor = 1

function input_ass()
	if not repl_active then
		return ""
	end

	local style = '{\\r' ..
	               '\\1a&H00&\\3a&H00&\\4a&H99&' ..
	               '\\1c&Heeeeee&\\3c&H111111&\\4c&H000000&' ..
	               '\\fn' .. opts.font .. '\\fs' .. opts['font-size'] ..
	               '\\bord2\\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))

	--mp.osd_message("",0)
	return "{\\an7}{\\pos(5,5)}"..style..'> '..before_cur..cglyph..style..after_cur

end

-- Set the REPL visibility (`, Esc)
function set_active(active)
	if active == repl_active then return end
	if active then
		repl_active = true
		insert_mode = false
		mp.enable_key_bindings('repl-input', 'allow-hide-cursor+allow-vo-dragging')
	else
		repl_active = false
		mp.disable_key_bindings('repl-input')
	end
end

-- Show the repl if hidden and replace its contents with 'text'
-- (script-message-to repl type)
function show_and_type(text)
	text = text or ''

	line = text
	cursor = line:len() + 1
	insert_mode = false
	if repl_active then
		update()
	else
		set_active(true)
	end
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.
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

-- Naive helper function to find the next UTF-8 character in 'str' after 'pos'
-- by skipping continuation bytes. Assumes 'str' contains valid UTF-8.


-- As above, but finds the previous UTF-8 charcter in 'str' before 'pos'
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

function trim_input()
	-- TODO
	return
end

-- Insert a character at the current cursor position (' '-'~', Shift+Enter)
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 + 1
    trim_input()
	update()
end

-- Remove the character behind the cursor (Backspace)
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)
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)
function handle_ins()
	insert_mode = not insert_mode
end

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

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

-- Clear the current line (Ctrl+C)
function clear()
	line = ''
	cursor = 1
	insert_mode = false
	update()
end

-- Close the REPL if the current line is empty, otherwise do nothing (Ctrl+D)
function maybe_exit()
	if line == '' then
		set_active(false)
	end
end

-- Run the current command and clear the line (Enter)
function handle_enter()
	if not repl_active then
		set_active(true)
		return
	end
	set_active(false)

	if line == '' then
		return
	end
	mp.command('print-text "<chat>'..line..'</chat>"')
	clear()
end

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

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

-- Delete from the cursor to the end of the line (Ctrl+K)
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)
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)
function get_clipboard(clip)
	if platform == 'linux' then
		local res = utils.subprocess({ args = {
			'xclip', '-selection', clip and 'clipboard' or 'primary', '-out'
		} })
		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)
			}]]
		} })
		if not res.error then
			return res.stdout
		end
	elseif platform == 'macos' then
		local res = utils.subprocess({ args = { 'pbpaste' } })
		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 only.)
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()
    trim_input()
	update()
end

-- The REPL has pretty specific requirements for key bindings that aren't
-- really satisified by any of mpv's helper methods, since they must be in
-- their own input section, but they must also raise events on key-repeat.
-- Hence, this function manually creates an input section and puts a list of
-- bindings in it.
function add_repl_bindings(bindings)
	local cfg = ''
	for i, binding in ipairs(bindings) do
		local key = binding[1]
		local fn = binding[2]
		local name = '__repl_binding_' .. i
		mp.add_key_binding(nil, name, fn, 'repeatable')
		cfg = cfg .. key .. ' script-binding ' .. mp.script_name .. '/' ..
		      name .. '\n'
	end
	mp.commandv('define-section', 'repl-input', cfg, 'force')
end

-- Mapping from characters to mpv key names
local binding_name_map = {
	[' '] = 'SPACE',
	['#'] = 'SHARP',
}

-- List of input bindings. This is a weird mashup between common GUI text-input
-- bindings and readline bindings.
local bindings = {
	{ 'esc',         function() set_active(false) end       },
	{ 'bs',          handle_backspace                       },
	{ 'shift+bs',    handle_backspace                       },
	{ 'del',         handle_del                             },
	{ 'shift+del',   handle_del                             },
	{ 'ins',         handle_ins                             },
	{ 'left',        function() prev_char() end             },
	{ 'right',       function() next_char() end             },
	{ 'up',          function() clear() end        },
	{ 'home',        go_home                                },
	{ 'end',         go_end                                 },
	{ 'ctrl+c',      clear                                  },
	{ 'ctrl+d',      maybe_exit                             },
	{ 'ctrl+k',      del_to_eol                             },
	{ 'ctrl+l',      clear_log_buffer                       },
	{ 'ctrl+u',      del_to_start                           },
	{ 'ctrl+v',      function() paste(true) end             },
	{ 'meta+v',      function() paste(true) end             },
}
-- Add bindings for all the printable US-ASCII characters from ' ' to '~'
-- inclusive. Note, this is a pretty hacky way to do text input. mpv's input
-- system was designed for single-key key bindings rather than text input, so
-- things like dead-keys and non-ASCII input won't work. This is probably okay
-- though, since all mpv's commands and properties can be represented in ASCII.
for b = (' '):byte(), ('~'):byte() do
	local c = string.char(b)
	local binding = binding_name_map[c] or c
	bindings[#bindings + 1] = {binding, function() handle_char_input(c) end}
end
add_repl_bindings(bindings)

-- Add a script-message to show the REPL and fill it with the provided text
mp.register_script_message('type', function(text)
	show_and_type(text)
end)

mp.add_key_binding('enter', handle_enter)
mp.add_key_binding('kp_enter', handle_enter)