-- 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 utils = require 'mp.utils'
local assdraw = require 'mp.assdraw'

-- 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 has 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,
    border_size = 1,
    case_sensitive = true,
    -- Remove duplicate entries in history as to only keep the latest one.
    history_dedup = true,
    -- The ratio of font height to font width.
    -- Adjusts table width of completion suggestions.
    -- Values in the range 1.8..2.5 make sense for common monospace fonts.
    font_hw_ratio = 'auto',
}

function detect_platform()
    local platform = mp.get_property_native('platform')
    if platform == 'darwin' or platform == 'windows' then
        return platform
    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'
    opts.case_sensitive = false
elseif platform == 'darwin' then
    opts.font = 'Menlo'
else
    opts.font = 'monospace'
end

-- Apply user-set options
require 'mp.options'.read_options(opts)

local styles = {
    -- Colors are stolen from base16 Eighties by Chris Kempson
    -- and converted to BGR as is required by ASS.
    -- 2d2d2d 393939 515151 697374
    -- 939fa0 c8d0d3 dfe6e8 ecf0f2
    -- 7a77f2 5791f9 66ccff 99cc99
    -- cccc66 cc9966 cc99cc 537bd2

    debug = '{\\1c&Ha09f93&}',
    v = '{\\1c&H99cc99&}',
    warn = '{\\1c&H66ccff&}',
    error = '{\\1c&H7a77f2&}',
    fatal = '{\\1c&H5791f9&\\b1}',
    suggestion = '{\\1c&Hcc99cc&}',
    selected_suggestion = '{\\1c&H2fbdfa&\\b1}',
}

local terminal_styles = {
    debug = '\027[1;30m',
    v = '\027[32m',
    warn = '\027[33m',
    error = '\027[31m',
    fatal = '\027[1;31m',
    selected_suggestion = '\027[7m',
}

local repl_active = false
local insert_mode = false
local pending_update = false
local line = ''
local cursor = 1
local default_prompt = '>'
local prompt = default_prompt
local default_id = 'default'
local id = default_id
local histories = {[id] = {}}
local history = histories[id]
local history_pos = 1
local log_buffers = {[id] = {}}
local key_bindings = {}
local global_margins = { t = 0, b = 0 }
local input_caller

local suggestion_buffer = {}
local selected_suggestion_index
local completion_start_position
local completion_append
local file_commands = {}
local path_separator = platform == 'windows' and '\\' or '/'
local completion_old_line
local completion_old_cursor

local update_timer = nil
update_timer = mp.add_periodic_timer(0.05, function()
    if pending_update then
        update()
    else
        update_timer:kill()
    end
end)
update_timer:kill()

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)

do
    local width_length_ratio = 0.5
    local osd_width, osd_height = 100, 100

    ---Update osd resolution if valid
    local function update_osd_resolution()
        local dim = mp.get_property_native('osd-dimensions')
        if not dim or dim.w == 0 or dim.h == 0 then
            return
        end
        osd_width = dim.w
        osd_height = dim.h
    end

    local text_osd = mp.create_osd_overlay('ass-events')
    text_osd.compute_bounds, text_osd.hidden = true, true

    local function measure_bounds(ass_text)
        update_osd_resolution()
        text_osd.res_x, text_osd.res_y = osd_width, osd_height
        text_osd.data = ass_text
        local res = text_osd:update()
        return res.x0, res.y0, res.x1, res.y1
    end

    ---Measure text width and normalize to a font size of 1
    ---text has to be ass safe
    local function normalized_text_width(text, size, horizontal)
        local align, rotation = horizontal and 7 or 1, horizontal and 0 or -90
        local template = '{\\pos(0,0)\\rDefault\\blur0\\bord0\\shad0\\q2\\an%s\\fs%s\\fn%s\\frz%s}%s'
        local x1, y1 = nil, nil
        size = size / 0.8
        -- prevent endless loop
        local repetitions_left = 5
        repeat
            size = size * 0.8
            local ass = assdraw.ass_new()
            ass.text = template:format(align, size, opts.font, rotation, text)
            _, _, x1, y1 = measure_bounds(ass.text)
            repetitions_left = repetitions_left - 1
            -- make sure nothing got clipped
        until (x1 and x1 < osd_width and y1 < osd_height) or repetitions_left == 0
        local width = (repetitions_left == 0 and not x1) and 0 or (horizontal and x1 or y1)
        return width / size, horizontal and osd_width or osd_height
    end

    local function fit_on_osd(text)
        local estimated_width = #text * width_length_ratio
        if osd_width >= osd_height then
            -- Fill the osd as much as possible, bigger is more accurate.
            return math.min(osd_width / estimated_width, osd_height), true
        else
            return math.min(osd_height / estimated_width, osd_width), false
        end
    end

    local measured_font_hw_ratio = nil
    function get_font_hw_ratio()
        local font_hw_ratio = tonumber(opts.font_hw_ratio)
        if font_hw_ratio then
            return font_hw_ratio
        end
        if not measured_font_hw_ratio then
            local alphabet = 'abcdefghijklmnopqrstuvwxyz'
            local text = alphabet:rep(3)
            update_osd_resolution()
            local size, horizontal = fit_on_osd(text)
            local normalized_width = normalized_text_width(text, size * 0.9, horizontal)
            measured_font_hw_ratio = #text / normalized_width * 0.95
        end
        return measured_font_hw_ratio
    end
end

-- Add a line to the log buffer (which is limited to 100 lines)
function log_add(text, style, terminal_style)
    local log_buffer = log_buffers[id]
    log_buffer[#log_buffer + 1] = {
        text = text,
        style = style or '',
        terminal_style = terminal_style or '',
    }
    if #log_buffer > 100 then
        table.remove(log_buffer, 1)
    end

    if repl_active then
        if not update_timer:is_enabled() then
            update()
            update_timer:resume()
        else
            pending_update = true
        end
    end
end

-- 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')
    -- 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

-- Takes a list of strings, a max width in characters and
-- optionally a max row count.
-- The result contains at least one column.
-- Rows are cut off from the top if rows_max is specified.
-- returns a string containing the formatted table and the row count
function format_table(list, width_max, rows_max)
    if #list == 0 then
        return '', 0
    end

    local spaces_min = 2
    local spaces_max = 8
    local list_size = #list
    local column_count = 1
    local row_count = list_size
    local column_widths
    -- total width without spacing
    local width_total = 0

    local list_widths = {}
    for i, item in ipairs(list) do
        list_widths[i] = len_utf8(item)
    end

    -- use as many columns as possible
    for columns = 2, list_size do
        local rows_lower_bound = math.min(rows_max, math.ceil(list_size / columns))
        local rows_upper_bound = math.min(rows_max, list_size, math.ceil(list_size / (columns - 1) - 1))
        for rows = rows_upper_bound, rows_lower_bound, -1 do
            cw = {}
            width_total = 0

            -- find out width of each column
            for column = 1, columns do
                local width = 0
                for row = 1, rows do
                    local i = row + (column - 1) * rows
                    local item_width = list_widths[i]
                    if not item_width then break end
                    if width < item_width then
                        width = item_width
                    end
                end
                cw[column] = width
                width_total = width_total + width
                if width_total + (columns - 1) * spaces_min > width_max then
                    break
                end
            end

            if width_total + (columns - 1) * spaces_min <= width_max then
                row_count = rows
                column_count = columns
                column_widths = cw
            else
                break
            end
        end
        if width_total + (columns - 1) * spaces_min > width_max then
            break
        end
    end

    local spaces = math.floor((width_max - width_total) / (column_count - 1))
    spaces = math.max(spaces_min, math.min(spaces_max, spaces))
    local spacing = column_count > 1
                    and ass_escape(string.format('%' .. spaces .. 's', ' '))
                    or ''

    local rows = {}
    for row = 1, row_count do
        local columns = {}
        for column = 1, column_count do
            local i = row + (column - 1) * row_count
            if i > #list then break end
            -- more then 99 leads to 'invalid format (width or precision too long)'
            local format_string = column == column_count and '%s'
                                  or '%-' .. math.min(column_widths[column], 99) .. 's'
            columns[column] = ass_escape(string.format(format_string, list[i]))

            if i == selected_suggestion_index then
                columns[column] = styles.selected_suggestion .. columns[column]
                                  .. '{\\b0}'.. styles.suggestion
            end
        end
        -- first row is at the bottom
        rows[row_count - row + 1] = table.concat(columns, spacing)
    end
    return table.concat(rows, ass_escape('\n')), row_count
end

local function print_to_terminal()
    -- Clear the log after closing the console.
    if not repl_active then
        mp.osd_message('')
        return
    end

    local log = ''
    for _, log_line in ipairs(log_buffers[id]) do
        log = log .. log_line.terminal_style .. log_line.text .. '\027[0m'
    end

    local suggestions = ''
    for i, suggestion in ipairs(suggestion_buffer) do
        if i == selected_suggestion_index then
            suggestions = suggestions .. terminal_styles.selected_suggestion ..
                          suggestion .. '\027[0m'
        else
            suggestions = suggestions .. suggestion
        end
        suggestions = suggestions .. (i < #suggestion_buffer and '\t' or '\n')
    end

    local before_cur = line:sub(1, cursor - 1)
    local after_cur = line:sub(cursor)
    -- Ensure there is a character with inverted colors to print.
    if after_cur == '' then
        after_cur = ' '
    end

    mp.osd_message(log .. suggestions .. prompt .. ' ' .. before_cur ..
                  '\027[7m' .. after_cur:sub(1, 1) .. '\027[0m' ..
                   after_cur:sub(2), 999)
end

-- Render the REPL and console as an ASS OSD
function update()
    pending_update = false

    -- Unlike vo-configured, current-vo doesn't become falsy while switching VO,
    -- which would print the log to the OSD.
    if not mp.get_property('current-vo') then
        print_to_terminal()
        return
    end

    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 coordinate_top = math.floor(global_margins.t * screeny + 0.5)
    local clipping_coordinates = '0,' .. coordinate_top .. ',' ..
                                 screenx .. ',' .. screeny
    local ass = assdraw.ass_new()
    local has_shadow = mp.get_property('osd-back-color'):sub(2, 3) == '00'
    local style = '{\\r' ..
                  '\\1a&H00&\\3a&H00&\\1c&Heeeeee&\\3c&H111111&' ..
                  (has_shadow and '\\4a&H99&\\4c&H000000&' or '') ..
                  '\\fn' .. opts.font .. '\\fs' .. opts.font_size ..
                  '\\bord' .. opts.border_size .. '\\xshad0\\yshad1\\fsp0\\q1' ..
                  '\\clip(' .. clipping_coordinates .. ')}'
    -- 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' ..
                   (mp.get_property_native('focused') == false
                    and '\\alpha&HFF&' or '\\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))

    -- Render log messages as ASS.
    -- This will render at most screeny / font_size - 1 messages.

    -- lines above the prompt
    -- subtract 1.5 to account for the input line
    local screeny_factor = (1 - global_margins.t - global_margins.b)
    local lines_max = math.ceil(screeny * screeny_factor / opts.font_size - 1.5)
    -- Estimate how many characters fit in one line
    local width_max = math.ceil(screenx / opts.font_size * get_font_hw_ratio())

    local suggestions, rows = format_table(suggestion_buffer, width_max, lines_max)
    local suggestion_ass = style .. styles.suggestion .. suggestions

    local log_ass = ''
    local log_buffer = log_buffers[id]
    local log_messages = #log_buffer
    local log_max_lines = math.max(0, lines_max - rows)
    if log_max_lines < log_messages then
        log_messages = log_max_lines
    end
    for i = #log_buffer - log_messages + 1, #log_buffer do
        log_ass = log_ass .. style .. log_buffer[i].style .. ass_escape(log_buffer[i].text)
    end

    ass:new_event()
    ass:an(1)
    ass:pos(2, screeny - 2 - global_margins.b * screeny)
    ass:append(log_ass .. '\\N')
    if #suggestions > 0 then
        ass:append(suggestion_ass .. '\\N')
    end
    ass:append(style .. ass_escape(prompt) .. ' ' .. 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 - global_margins.b * screeny)
    ass:append(style .. '{\\alpha&HFF&}' .. ass_escape(prompt) .. ' ' .. before_cur)
    ass:append(cglyph)
    ass:append(style .. '{\\alpha&HFF&}' .. after_cur)

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

-- Set the REPL visibility ("enable", 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('console-input', 'allow-hide-cursor+allow-vo-dragging')
        define_key_bindings()

        if not input_caller then
            prompt = default_prompt
            id = default_id
            history = histories[id]
            history_pos = #history + 1
            mp.enable_messages('terminal-default')
        end
    else
        repl_active = false
        suggestion_buffer = {}
        undefine_key_bindings()
        mp.enable_messages('silent:terminal-default')

        if input_caller then
            mp.commandv('script-message-to', input_caller, 'input-event',
                        'closed', line, cursor)
            input_caller = nil
            line = ''
            cursor = 1
        end
        collectgarbage()
    end
    update()
end

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

    -- Save the line currently being edited, just in case
    if line ~= text and line ~= '' and history[#history] ~= line then
        history_add(line)
    end

    line = text
    if cursor_pos ~= nil and cursor_pos >= 1
       and cursor_pos <= line:len() + 1 then
        cursor = math.floor(cursor_pos)
    else
        cursor = line:len() + 1
    end
    history_pos = #history + 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

-- As above, but finds the previous UTF-8 character 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 len_utf8(str)
    local len = 0
    local pos = 1
    while pos <= str:len() do
        pos = next_utf8(str, pos)
        len = len + 1
    end
    return len
end

local function handle_edit()
    suggestion_buffer = {}
    update()

    if input_caller then
        mp.commandv('script-message-to', input_caller, 'input-event', 'edited',
                    line)
    end
end

-- Insert a character at the current cursor position (any_unicode)
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
    handle_edit()
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
    handle_edit()
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))
    handle_edit()
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)
    suggestion_buffer = {}
    update()
end

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

-- Clear the current line (Ctrl+C)
function clear()
    line = ''
    cursor = 1
    insert_mode = false
    history_pos = #history + 1
    handle_edit()
end

-- Close the REPL if the current line is empty, otherwise delete the next
-- character (Ctrl+D)
function maybe_exit()
    if line == '' then
        set_active(false)
    else
        handle_del()
    end
end

function help_command(param)
    local cmdlist = mp.get_property_native('command-list')
    table.sort(cmdlist, function(c1, c2)
        return c1.name < c2.name
    end)
    local output = ''
    if param == '' then
        output = 'Available commands:\n'
        for _, cmd in ipairs(cmdlist) do
            output = output  .. '  ' .. cmd.name
        end
        output = output .. '\n'
        output = output .. 'Use "help command" to show information about a command.\n'
        output = output .. "ESC or Ctrl+d exits the console.\n"
    else
        local cmd = nil
        for _, curcmd in ipairs(cmdlist) do
            if curcmd.name:find(param, 1, true) then
                cmd = curcmd
                if curcmd.name == param then
                    break -- exact match
                end
            end
        end
        if not cmd then
            log_add('No command matches "' .. param .. '"!\n', styles.error,
                    terminal_styles.error)
            return
        end
        output = output .. 'Command "' .. cmd.name .. '"\n'
        for _, arg in ipairs(cmd.args) do
            output = output .. '    ' .. arg.name .. ' (' .. arg.type .. ')'
            if arg.optional then
                output = output .. ' (optional)'
            end
            output = output .. '\n'
        end
        if cmd.vararg then
            output = output .. 'This command supports variable arguments.\n'
        end
    end
    log_add(output)
end

-- Add a line to the history and deduplicate
function history_add(text)
    if opts.history_dedup then
        -- More recent entries are more likely to be repeated
        for i = #history, 1, -1 do
            if history[i] == text then
                table.remove(history, i)
                break
            end
        end
    end

    history[#history + 1] = text
end

-- Run the current command and clear the line (Enter)
function handle_enter()
    if line == '' and input_caller == nil then
        return
    end
    if history[#history] ~= line and line ~= '' then
        history_add(line)
    end

    if input_caller then
        mp.commandv('script-message-to', input_caller, 'input-event', 'submit',
                    line)
    else
        -- match "help [<text>]", return <text> or "", strip all whitespace
        local help = line:match('^%s*help%s+(.-)%s*$') or
                     (line:match('^%s*help$') and '')
        if help then
            help_command(help)
        else
            mp.command(line)
        end
    end

    clear()
end

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

    -- Restrict the position to a legal value
    if history_pos > #history + 1 then
        history_pos = #history + 1
    elseif history_pos < 1 then
        history_pos = 1
    end

    -- Do nothing if the history position didn't actually change
    if 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 == #history + 1 and line ~= '' and history[#history] ~= line then
        history_add(line)
    end

    -- Now show the history line (or a blank line for #history + 1)
    if history_pos <= #history then
        line = history[history_pos]
    else
        line = ''
    end
    cursor = line:len() + 1
    insert_mode = false
    suggestion_buffer = {}
    update()
end

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

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

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

-- Move to the start of the current word, or if already at the start, the start
-- of the previous word. (Ctrl+Left)
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
    suggestion_buffer = {}
    update()
end

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

local function command_list()
    local commands = {}
    for i, command in ipairs(mp.get_property_native('command-list')) do
        commands[i] = command.name
    end

    return commands
end

local function command_list_and_help()
    local commands = command_list()
    commands[#commands + 1] = 'help'

    return commands
end

local function property_list()
    local properties = mp.get_property_native('property-list')

    for _, sub_property in pairs({'video', 'audio', 'sub', 'sub2'}) do
        properties[#properties + 1] = 'current-tracks/' .. sub_property
    end

    for _, option in ipairs(mp.get_property_native('options')) do
        properties[#properties + 1] = 'options/' .. option
        properties[#properties + 1] = 'file-local-options/' .. option
        properties[#properties + 1] = 'option-info/' .. option

        for _, sub_property in pairs({
            'name', 'type', 'set-from-commandline', 'set-locally',
            'default-value', 'min', 'max', 'choices',
        }) do
            properties[#properties + 1] = 'option-info/' .. option .. '/' ..
                                          sub_property
        end
    end

    return properties
end

local function profile_list()
    local profiles = {}

    for i, profile in ipairs(mp.get_property_native('profile-list')) do
        profiles[i] = profile.name
    end

    return profiles
end

local function list_option_list()
    local options = {}

    -- Don't log errors for renamed and removed properties.
    -- (Just mp.enable_messages('fatal') still logs them to the terminal.)
    local msg_level_backup = mp.get_property('msg-level')
    mp.set_property('msg-level', msg_level_backup == '' and 'cplayer=no'
                                 or msg_level_backup .. ',cplayer=no')

    for _, option in pairs(mp.get_property_native('options')) do
        if mp.get_property('option-info/' .. option .. '/type', ''):find(' list$') then
            options[#options + 1] = option
        end
    end

    mp.set_property('msg-level', msg_level_backup)

    return options
end

local function list_option_verb_list(option)
    local type = mp.get_property('option-info/' .. option .. '/type')

    if type == 'Key/value list' then
        return {'add', 'append', 'set', 'remove'}
    end

    if type == 'String list' or type == 'Object settings list' then
        return {'add', 'append', 'clr', 'pre', 'set', 'remove', 'toggle'}
    end

    return {}
end

local function choice_list(option)
    local info = mp.get_property_native('option-info/' .. option, {})

    if info.type == 'Flag' then
        return { 'no', 'yes' }
    end

    return info.choices or {}
end

local function find_commands_with_file_argument()
    if #file_commands > 0 then
        return file_commands
    end

    for _, command in pairs(mp.get_property_native('command-list')) do
        if command.args[1] and
           (command.args[1].name == 'filename' or command.args[1].name == 'url') then
            file_commands[#file_commands + 1] = command.name
        end
    end

    return file_commands
end

local function file_list(directory)
    if directory == '' then
        directory = '.'
    end

    local files = utils.readdir(directory, 'files') or {}

    for _, dir in pairs(utils.readdir(directory, 'dirs') or {}) do
        files[#files + 1] = dir .. path_separator
    end

    return files
end

-- List of tab-completions:
--   pattern: A Lua pattern used in string:match. It should return the start
--            position of the word to be completed in the first capture (using
--            the empty parenthesis notation "()"). In patterns with 2
--            captures, the first determines the completions, and the second is
--            the start of the word to be completed.
--   list: A function that returns a list of candidate completion values.
--   append: An extra string to be appended to the end of a successful
--           completion. It is only appended if 'list' contains exactly one
--           match.
function build_completers()
    local completers = {
        { pattern = '^%s*()[%w_-]*$', list = command_list_and_help, append = ' ' },
        { pattern = '^%s*help%s+()[%w_-]*$', list = command_list },
        { pattern = '^%s*set%s+"?([%w_-]+)"?%s+()%S*$', list = choice_list },
        { pattern = '^%s*set%s+"?([%w_-]+)"?%s+"()%S*$', list = choice_list, append = '"' },
        { pattern = '^%s*cycle[-_]values%s+"?([%w_-]+)"?.-%s+()%S*$', list = choice_list, append = " " },
        { pattern = '^%s*cycle[-_]values%s+"?([%w_-]+)"?.-%s+"()%S*$', list = choice_list, append = '" ' },
        { pattern = '^%s*apply[-_]profile%s+"()%S*$', list = profile_list, append = '"' },
        { pattern = '^%s*apply[-_]profile%s+()%S*$', list = profile_list },
        { pattern = '^%s*change[-_]list%s+()[%w_-]*$', list = list_option_list, append = ' ' },
        { pattern = '^%s*change[-_]list%s+()"[%w_-]*$', list = list_option_list, append = '" ' },
        { pattern = '^%s*change[-_]list%s+"?([%w_-]+)"?%s+()%a*$', list = list_option_verb_list, append = ' ' },
        { pattern = '^%s*change[-_]list%s+"?([%w_-]+)"?%s+"()%a*$', list = list_option_verb_list, append = '" ' },
        { pattern = '^%s*([av]f)%s+()%a*$', list = list_option_verb_list, append = ' ' },
        { pattern = '^%s*([av]f)%s+"()%a*$', list = list_option_verb_list, append = '" ' },
        { pattern = '${=?()[%w_/-]*$', list = property_list, append = '}' },
    }

    for _, command in pairs({'set', 'add', 'cycle', 'cycle[-_]values', 'multiply'}) do
        completers[#completers + 1] = {
            pattern = '^%s*' .. command .. '%s+()[%w_/-]*$',
            list = property_list,
            append = ' ',
        }
        completers[#completers + 1] = {
            pattern = '^%s*' .. command .. '%s+"()[%w_/-]*$',
            list = property_list,
            append = '" ',
        }
    end


    for _, command in pairs(find_commands_with_file_argument()) do
        completers[#completers + 1] = {
            pattern = '^%s*' .. command:gsub('-', '[-_]') ..
                      '%s+["\']?(.-)()[^' .. path_separator ..']*$',
            list = file_list,
            -- Unfortunately appending " here would append it everytime a
            -- directory is fully completed, even if you intend to browse it
            -- afterwards.
        }
    end

    return completers
end

-- Find the longest common case-sensitive prefix of the entries in "list".
local function find_common_prefix(list)
    local prefix = list[1]

    for i = 2, #list do
        prefix = prefix:sub(1, common_prefix_length(prefix, list[i]))
    end

    return prefix
end

-- Return the entries of "list" beginning with "part" and the longest common
-- prefix of the matches.
local function complete_match(part, list)
    local completions = {}

    for _, candidate in pairs(list) do
        if candidate:sub(1, part:len()) == part then
            completions[#completions + 1] = candidate
        end
    end

    local prefix = find_common_prefix(completions)

    if opts.case_sensitive then
        return completions, prefix
    end

    completions = {}
    local lower_case_completions = {}
    local lower_case_part = part:lower()

    for _, candidate in pairs(list) do
        if candidate:sub(1, part:len()):lower() == lower_case_part then
            completions[#completions + 1] = candidate
            lower_case_completions[#lower_case_completions + 1] = candidate:lower()
        end
    end

    local lower_case_prefix = find_common_prefix(lower_case_completions)

    -- Behave like GNU readline with completion-ignore-case On.
    -- part = 'fooBA', completions = {'foobarbaz', 'fooBARqux'} =>
    -- prefix = 'fooBARqux', lower_case_prefix = 'foobar', return 'fooBAR'
    if prefix then
        return completions, prefix:sub(1, lower_case_prefix:len())
    end

    -- part = 'fooba', completions = {'fooBARbaz', 'fooBarqux'} =>
    -- prefix = nil, lower_case_prefix ='foobar', return 'fooBAR'
    if lower_case_prefix then
        return completions, completions[1]:sub(1, lower_case_prefix:len())
    end

    return {}, part
end

function common_prefix_length(s1, s2)
    local common_count = 0
    for i = 1, #s1 do
        if s1:byte(i) ~= s2:byte(i) then
            break
        end
        common_count = common_count + 1
    end
    return common_count
end

function max_overlap_length(s1, s2)
    for s1_offset = 0, #s1 - 1 do
        local match = true
        for i = 1, #s1 - s1_offset do
            if s1:byte(s1_offset + i) ~= s2:byte(i) then
                match = false
                break
            end
        end
        if match then
            return #s1 - s1_offset
        end
    end
    return 0
end

-- If str starts with the first or last characters of prefix, strip them.
local function strip_common_characters(str, prefix)
    return str:sub(1 + math.max(
        common_prefix_length(prefix, str),
        max_overlap_length(prefix, str)))
end

local function cycle_through_suggestions(backwards)
    selected_suggestion_index = selected_suggestion_index + (backwards and -1 or 1)

    if selected_suggestion_index > #suggestion_buffer then
        selected_suggestion_index = 1
    elseif selected_suggestion_index < 1 then
        selected_suggestion_index = #suggestion_buffer
    end

    local before_cur = line:sub(1, completion_start_position - 1) ..
                       suggestion_buffer[selected_suggestion_index] .. completion_append
    line = before_cur .. strip_common_characters(line:sub(cursor), completion_append)
    cursor = before_cur:len() + 1
    update()
end

-- Complete the option or property at the cursor (TAB)
function complete(backwards)
    if #suggestion_buffer > 0 then
        cycle_through_suggestions(backwards)
        return
    end

    if input_caller then
        completion_old_line = line
        completion_old_cursor = cursor
        mp.commandv('script-message-to', input_caller, 'input-event',
                    'complete', line:sub(1, cursor - 1))
        return
    end

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

    -- Try the first completer that works
    for _, completer in ipairs(build_completers()) do
        -- Completer patterns should return the start of the word to be
        -- completed as the first capture.
        local s2
        completion_start_position, s2 = before_cur:match(completer.pattern)
        if not completion_start_position then
            -- Multiple input commands can be separated by semicolons, so all
            -- completions that are anchored at the start of the string with
            -- '^' can start from a semicolon as well. Replace ^ with ; and try
            -- to match again.
            completion_start_position, s2 =
                before_cur:match(completer.pattern:gsub('^^', ';'))
        end
        if completion_start_position then
            local hint
            if s2 then
                hint = completion_start_position
                completion_start_position = s2
            end

            -- Expand ~ in file completion.
            if completer.list == file_list and hint:find('^~' .. path_separator) then
                local home = mp.command_native({'expand-path', '~/'})
                before_cur = before_cur:sub(1, completion_start_position - #hint - 1) ..
                             home ..
                             before_cur:sub(completion_start_position - #hint + 1)
                hint = home .. hint:sub(2)
                completion_start_position = completion_start_position + #home - 1
            end

            -- If the completer's pattern found a word, check the completer's
            -- list for possible completions
            local part = before_cur:sub(completion_start_position)
            local completions, prefix = complete_match(part, completer.list(hint))
            if #completions > 0 then
                -- If there was only one full match from the list, add
                -- completer.append to the final string. This is normally a
                -- space or a quotation mark followed by a space.
                completion_append = completer.append or ''
                if #completions == 1 then
                    prefix = prefix .. completion_append
                    after_cur = strip_common_characters(after_cur, completion_append)
                else
                    table.sort(completions)
                    suggestion_buffer = completions
                    selected_suggestion_index = 0
                end

                -- Insert the completion and update
                before_cur = before_cur:sub(1, completion_start_position - 1) ..
                             prefix
                cursor = before_cur:len() + 1
                line = before_cur .. after_cur
                update()
                return
            end
        end
    end
end

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

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

-- Delete from the cursor to the beginning of the word (Ctrl+Backspace)
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
    handle_edit()
end

-- Delete from the cursor to the end of the word (Ctrl+Del)
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
    handle_edit()
end

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

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

-- Empty the log buffer of all messages (Ctrl+L)
function clear_log_buffer()
    log_buffers[id] = {}
    update()
end

-- Returns a string of UTF-8 text from the clipboard (or the primary selection)
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 == 'darwin' 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.)
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()
    handle_edit()
end

-- List of input bindings. This is a weird mashup between common GUI text-input
-- bindings and readline bindings.
function get_bindings()
    local bindings = {
        { 'esc',         function() set_active(false) end       },
        { 'ctrl+[',      function() set_active(false) end       },
        { '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                              },
        { 'tab',         complete                               },
        { 'ctrl+i',      complete                               },
        { 'shift+tab',   function() complete(true) end          },
        { '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+l',      clear_log_buffer                       },
        { '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

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 = "_console_" .. (#key_bindings + 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", "_console_text", text_input,
        {repeatable = true, complex = true})
    key_bindings[#key_bindings + 1] = "_console_text"
end

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

-- Add a global binding for enabling the REPL. While it's enabled, its bindings
-- will take over and it can be closed with ESC.
mp.add_key_binding(nil, 'enable', function()
    set_active(true)
end)

mp.register_script_message('disable', function()
    set_active(false)
end)

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

mp.register_script_message('get-input', function (script_name, args)
    if repl_active then
        return
    end

    input_caller = script_name
    args = utils.parse_json(args)
    prompt = args.prompt or default_prompt
    line = args.default_text or ''
    cursor = tonumber(args.cursor_position) or line:len() + 1
    id = args.id or script_name .. prompt
    if histories[id] == nil then
        histories[id] = {}
        log_buffers[id] = {}
    end
    history = histories[id]
    history_pos = #history + 1

    set_active(true)
    mp.commandv('script-message-to', input_caller, 'input-event', 'opened')
end)

mp.register_script_message('log', function (message)
    -- input.get's edited handler is invoked after submit, so avoid modifying
    -- the default log.
    if input_caller == nil then
        return
    end

    message = utils.parse_json(message)

    log_add(message.text .. '\n',
            message.error and styles.error or message.style,
            message.error and terminal_styles.error or message.terminal_style)
end)

mp.register_script_message('set-log', function (log)
    if input_caller == nil then
        return
    end

    log = utils.parse_json(log)
    log_buffers[id] = {}

    for i = 1, #log do
        if type(log[i]) == 'table' then
            log[i].text = log[i].text .. '\n'
            log[i].style = log[i].style or ''
            log[i].terminal_style = log[i].terminal_style or ''
            log_buffers[id][i] = log[i]
        else
            log_buffers[id][i] = {
                text = log[i] .. '\n',
                style = '',
                terminal_style = '',
            }
        end
    end

    update()
end)

mp.register_script_message('complete', function(list, start_pos)
    if line ~= completion_old_line or cursor ~= completion_old_cursor then
        return
    end

    local completions, prefix = complete_match(line:sub(start_pos, cursor),
                                               utils.parse_json(list))
    local before_cur = line:sub(1, start_pos - 1) .. prefix
    local after_cur = line:sub(cursor)
    cursor = before_cur:len() + 1
    line = before_cur .. after_cur

    if #completions > 1 then
        suggestion_buffer = completions
        selected_suggestion_index = 0
        completion_start_position = start_pos
        completion_append = ''
    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)
mp.observe_property('focused', 'native', update)

-- Enable log messages. In silent mode, mpv will queue log messages in a buffer
-- until enable_messages is called again without the silent: prefix.
mp.enable_messages('silent:terminal-default')

mp.register_event('log-message', function(e)
    -- Ignore log messages from the OSD because of paranoia, since writing them
    -- to the OSD could generate more messages in an infinite loop.
    if e.prefix:sub(1, 3) == 'osd' then return end

    -- Ignore messages output by this script.
    if e.prefix == mp.get_script_name() then return end

    -- Ignore buffer overflow warning messages. Overflowed log messages would
    -- have been offscreen anyway.
    if e.prefix == 'overflow' then return end

    -- Filter out trace-level log messages, even if the terminal-default log
    -- level includes them. These aren't too useful for an on-screen display
    -- without scrollback and they include messages that are generated from the
    -- OSD display itself.
    if e.level == 'trace' then return end

    -- Use color for debug/v/warn/error/fatal messages.
    log_add('[' .. e.prefix .. '] ' .. e.text, styles[e.level],
            terminal_styles[e.level])
end)

collectgarbage()
