(* 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 Args import GetArg, Narg;
from FIO import WriteString, WriteChar, WriteLine, StdErr;
from Storage import ALLOCATE;
from Strings import CompareStr, Length;
from MemUtils import MemZero;

from Common import ShortString;

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

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

  while (i < Narg()) & (result <> nil) do
    parsed := GetArg(parameter, i);
    parsed := false;

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

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

      if Length(result^.input) > 0 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 = false then
      WriteString(StdErr, 'Fatal error: unknown command line options: ');

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

      result := nil
    end;

    i := i + 1
  end;
  if (result <> nil) & (Length(result^.input) = 0) then
    WriteString(StdErr, 'Fatal error: no input files.');
    WriteLine(StdErr);
    result := nil
  end;

  return result
end;

end.