def read_m3u8(m3u8)
    File.open(m3u8, 'r') do |file|
        keyfile = nil
        iv = 0
        file.each_line do |line|
            line.chomp!
            if line =~ /^#EXT-X-KEY:METHOD=AES-128,URI="(.*?)"(,IV=0x(.*))?/
                keyfile = $1
                if $2
                    iv = $3
                    iv_gen = :random
                else
                    iv_gen = :sequence
                end
            elsif not line =~ /^#/
                in_file = File.join(File.dirname(m3u8), line)
                ext = File.extname(in_file)
                out_file = File.join(File.dirname(in_file), File.basename(in_file, ext) + '.clear' + ext)
                decrypt(in_file, keyfile, iv, out_file)
                if iv_gen == :sequence
                    iv += 1
                end
            end
        end
    end
end

def decrypt(in_file, keyfile, iv, out_file)
    key = load_key(keyfile)
    iv_hex = sprintf('%032x', iv)
    %x{openssl aes-128-cbc -d -K #{key} -iv #{iv_hex} -nosalt -in #{in_file} -out #{out_file}}
end

def load_key(keyfile)
    File.open(keyfile, 'rb') do |file|
        file.read.unpack('H*')[0]
    end
end

read_m3u8(ARGV[0])