Add mpv user-input script

From https://github.com/CogentRedTester/mpv-user-input

1 files changed, 781 insertions, 0 deletions

diff --git a/.config/mpv/scripts/user-input.lua b/.config/mpv/scripts/user-input.lua
new file mode 100644
index 0000000..b378ddc
--- /dev/null
+++ b/.config/mpv/scripts/user-input.lua
@@ -0,0 +1,781 @@
+--[[
+MIT License
+
+Copyright (c) 2021 Oscar Manglaras
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+]]
+
+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)
+