local mp = require 'mp'

local default_visibility = 'auto'
local visibility_by_extension = default_visibility
local is_paused = false
local music_mode = false
local music_mode_timer = mp.add_periodic_timer(1, function ()
        local chapters = mp.get_property_number('chapters', 0)
        local playlist_count = 0
        if chapters == 0 then
            playlist_count = mp.get_property_number('playlist-count', 0)
            if playlist_count > 1 then
                mp.command('script-message osc-playlist 1 no-osd')
                return
            end
        end

        mp.command('script-message osc-chapterlist 1 no-osd')
    end)
music_mode_timer:stop()

-- extensions for which osc will be always hidden
local no_osc_extensions = { 'png', 'jpg', 'jpeg', 'bmp' }
-- helper function ran on file load that determines whether osc should be hidden or not
function determine_visibility_by_file_extension()
    local path = mp.get_property('path')
    if not path then
        visibility_by_extension = default_visibility
        return
    end

    local last_dot_pos = (path:reverse()):find('%.')
    if not last_dot_pos then
        visibility_by_extension = default_visibility
        return
    end

    local extension = (path:sub(-last_dot_pos+1))
    if not extension then
        visibility_by_extension = default_visibility
        return
    end

    for index, value in ipairs(no_osc_extensions) do
        if value == extension then
            visibility_by_extension = 'never'
            -- disable music mode automatically
            if music_mode then
                toggle_music_mode()
            end
            return
        end
    end

    visibility_by_extension = default_visibility
end

-- function that updates osc visibility based on file extension, pause state and music mode state
function my_osc_visibility()
    local visibility = visibility_by_extension
    if (is_paused or music_mode) and visibility_by_extension ~= 'never' then
        visibility = 'always'
    end

    mp.command('script-message osc-visibility ' .. visibility .. ' no-osd')
end

function determine_and_update()
    determine_visibility_by_file_extension()
    my_osc_visibility()
end

-- update paused state and osc visibility on "paused" property change
function on_pause(name, value)
    is_paused = value
    my_osc_visibility()
end

-- music mode function
-- keeps chapterlist and osc always visible
function toggle_music_mode()
    if music_mode then
        music_mode_timer:stop()
        music_mode = false
        mp.osd_message('Music mode: off')
        my_osc_visibility()

    -- don't apply music mode when in no-osc mode
    -- elseif visibility_by_extension ~= 'never' then
    else
        -- call once before the timer proceeds
        -- mp.command('script-message osc-chapterlist 1 no-osd')
        mp.osd_message('Music mode: on')
        music_mode_timer:resume()
        music_mode = true
        my_osc_visibility()
    -- else
    --     mp.osd_message('Music mode unavailable for this file type', 5)
    end
end

mp.register_script_message('my_osc_visibility', my_osc_visibility)
mp.register_script_message('toggle_music_mode', toggle_music_mode)

mp.add_hook('on_preloaded', 50, determine_and_update)
mp.observe_property('pause', 'bool', on_pause)

-- always show osc when opening a new file
-- useful for network streams - user can see what is happening in the background
mp.add_hook('on_load', 50, function()
        mp.command('script-message osc-visibility always no-osd')
    end)