local mp = require 'mp'
local utils = require 'mp.utils'

-- resolve title using youtube-dl
function resolve_title(filename)
    -- workaround about poor man's mutex
    -- ensures that the actual check won't happen twice
    if title_cache[filename] then
        return title_cache[filename]
    end

end

mp.register_script_message("ytdl_resolve_title", function(filename)
        -- debug message
        -- print('[ytdl_resolve_title]:', 'resolving title for:', filename)

        -- title cannot be resolved using youtube-dl
        if not string.match(filename, "^https?://") then
            -- print('[ytdl_resolve_title]:', 'not a network resource')
            return
        end

        local res = io.popen('youtube-dl --flat-playlist -sJ '.. filename):read("*all")
        local err
        local json, err = utils.parse_json(res)
        if err then
            error('[ytdl_resolve_title]:', 'error parsing json')
            return
        else
            local playlist = json['_type'] and json['_type'] == 'playlist'
            local title = (playlist and '[playlist]: ' or '') .. json['title']
            mp.commandv('script-message', 'osc_update_title', filename, title)
        end

        -- print('finished resolving title for:', filename)
    end)