let read_file path =
  let ic = open_in_bin path in
  let len = in_channel_length ic in
  let s = really_input_string ic len in
  close_in ic; Bytes.of_string s

let write_file path b =
  let oc = open_out_bin path in
  output_string oc (Bytes.to_string b);
  close_out oc

let () =
  match Array.to_list Sys.argv with
  | _ :: mode :: in_path :: out_path :: [] ->
    (try
       let input = read_file in_path in
       if mode = "compress" then begin
         let out = Encoder.compress input in
         write_file out_path out;
         Printf.printf "Original: %d bytes\n" (Bytes.length input);
         Printf.printf "Compressed: %d bytes\n" (Bytes.length out);
         let ratio = 100.0 *. (float_of_int (Bytes.length out)) /. (float_of_int (Bytes.length input)) in
         Printf.printf "Compression ratio: %.2f%%\n" ratio
       end else if mode = "decompress" then begin
         let out = Decoder.decompress input in
         write_file out_path out;
         Printf.printf "Decompressed to %d bytes\n" (Bytes.length out)
       end else begin
         prerr_endline "Invalid mode: use 'compress' or 'decompress'";
         exit 2
       end
     with
     | Sys_error e -> prerr_endline ("I/O error: " ^ e); exit 1
     | Failure e -> prerr_endline ("Error: " ^ e); exit 1
     | Invalid_argument e -> prerr_endline ("Invalid input: " ^ e); exit 1
    )
  | _ -> prerr_endline "Usage: lz77-cli (compress|decompress) <in> <out>"; exit 2