user-input.lua

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-----------------------------------
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-- 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)

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-------------------------------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)