#!/usr/bin/env python3
# encoding: utf-8
"""
Flag an error if a single file uses both tabs and spaces for indenting.

This does not change files, on the assumption that the mess is better
handled with a text editor or a code reformatting tool.
"""

import  argparse, re, sys

def check_indent(file):
    has_tabs = False
    with open(file, encoding="utf8") as lines:
        for line in lines:
            if re.match("\t", line):
                has_tabs = True
                break

        if has_tabs:
            lines.seek(0)
            for line in lines:
                if re.match("    ", line):
                    print("{file} uses both tabs and spaces for indents".format(file=file))
                    return False

        # Only one type of indent appears at the start of each line, so this only needs to
        # check one way round for mixtures on the same line.
        if has_tabs:
            mixed_line_re = re.compile("\t+ ")
        else:
            mixed_line_re = re.compile(" +\t")
        lines.seek(0)
        for line in lines:
            if mixed_line_re.match(line):
                print("{file} indents with tabs and spaces on the same line".format(file=file))
                return False

    return True

if __name__ == "__main__":
    ap = argparse.ArgumentParser(usage=__doc__)
    ap.add_argument("files", metavar="string", nargs="*", help="Read input from these files")
    options = ap.parse_args()

    all_files_ok = True

    for file in options.files:
        try:
            if not check_indent(file):
                all_files_ok = False
        except UnicodeDecodeError:
            all_files_ok = False
            print("{file}: invalid utf-8".format(file=file))
        except:
            all_files_ok = False
            print("{file}: raised exception {error}".format(file=file, error=sys.exc_info()[0]))

    if not all_files_ok:
        sys.exit(1)

    sys.exit(0)