(* This Source Code Form is subject to the terms of the Mozilla Public License,
  v. 2.0. If a copy of the MPL was not distributed with this file, You can
  obtain one at https://mozilla.org/MPL/2.0/. *)
module;

from FIO import WriteString, WriteChar, WriteLine, StdErr;
import cstdlib, common;

type
  CommandLine = record
    input: ^Char;
    output: ^Char;
    lex: Bool;
    parse: Bool
  end;

proc parse_command_line*(argc: Int, argv: ^^Char) -> ^CommandLine;
var
  parameter: ^Char;
  i: Word;
  result: ^CommandLine;
  parsed: Bool;
begin
  i := 1u;
  NEW(result);
  result^.lex := false;
  result^.parse := false;
  memset(@result^.input, 0, 256);
  result^.output[1] := CHAR(0);

  while i < argc & result <> nil do
    parameter := (argv + i)^;
    parsed := false;

    if strcmp(parameter, "--lex\0".ptr) = 0 then
      parsed := true;
      result^.lex := true
    end;
    if strcmp(parameter, "--parse\0".ptr) = 0 then
      parsed := true;
      result^.parse := true
    end;
    if strcmp(parameter, "-o\0".ptr) = 0 then
      i := i + 1u;

      if i = argc then
        WriteString(StdErr, "Fatal error: expecting a file name following -o.");
        result := nil
      end;
      if i < argc then
        parameter := (argv + i)^;
        result^.output := parameter
      end;
      parsed := true
    end;
    if (parameter[1] <> '-') & ~parsed then
      parsed := true;

      if result^.input <> nil then
        WriteString(StdErr, "Fatal error: only one source file can be compiled at once. First given \"");
        WriteString(StdErr, result^.input);
        WriteString(StdErr, "\", then \"");
        WriteString(StdErr, parameter);
        WriteString(StdErr, "\".");
        WriteLine(StdErr);
        result := nil
      end;
      if result <> nil then
        result^.input := parameter
      end
    end;
    if ~parsed then
      WriteString(StdErr, "Fatal error: unknown command line options: ");

      WriteString(StdErr, parameter);
      WriteChar(StdErr, '.');
      WriteLine(StdErr);

      result := nil
    end;

    i := i + 1u
  end;
  if result <> nil & result^.input = nil then
    WriteString(StdErr, "Fatal error: no input files.");
    WriteLine(StdErr);
    result := nil
  end;

  return result
end;

end.