#!/usr/bin/env python
# Generate a Markdown table of all lints, and put it in README.md.
# With -n option, only print the new table to stdout.
# With -c option, print a warning and set exit status to 1 if a file would be
# changed.

import os
import re
import sys

declare_lint_re = re.compile(r'''
    declare_lint! \s* [{(] \s*
    pub \s+ (?P<name>[A-Z_][A-Z_0-9]*) \s*,\s*
    (?P<level>Forbid|Deny|Warn|Allow) \s*,\s*
    " (?P<desc>(?:[^"\\]+|\\.)*) " \s* [})]
''', re.X | re.S)

nl_escape_re = re.compile(r'\\\n\s*')

wiki_link = 'https://github.com/Manishearth/rust-clippy/wiki'


def collect(lints, fn):
    """Collect all lints from a file.

    Adds entries to the lints list as `(module, name, level, desc)`.
    """
    with open(fn) as fp:
        code = fp.read()
    for match in declare_lint_re.finditer(code):
        # remove \-newline escapes from description string
        desc = nl_escape_re.sub('', match.group('desc'))
        lints.append((os.path.splitext(os.path.basename(fn))[0],
                      match.group('name').lower(),
                      match.group('level').lower(),
                      desc.replace('\\"', '"')))


def gen_table(lints, link=None):
    """Write lint table in Markdown format."""
    if link:
        lints = [(p, '[%s](%s#%s)' % (l, link, l), lvl, d)
                 for (p, l, lvl, d) in lints]
    # first and third column widths
    w_name = max(len(l[1]) for l in lints)
    w_desc = max(len(l[3]) for l in lints)
    # header and underline
    yield '%-*s | default | meaning\n' % (w_name, 'name')
    yield '%s-|-%s-|-%s\n' % ('-' * w_name, '-' * 7, '-' * w_desc)
    # one table row per lint
    for (_, name, default, meaning) in sorted(lints, key=lambda l: l[1]):
        yield '%-*s | %-7s | %s\n' % (w_name, name, default, meaning)


def gen_group(lints, levels=None):
    """Write lint group (list of all lints in the form module::NAME)."""
    if levels:
        lints = [tup for tup in lints if tup[2] in levels]
    for (module, name, _, _) in sorted(lints):
        yield '        %s::%s,\n' % (module, name.upper())


def gen_mods(lints):
    """Declare modules"""

    for module in sorted(set(lint[0] for lint in lints)):
        yield 'pub mod %s;\n' % module


def replace_region(fn, region_start, region_end, callback,
                   replace_start=True, write_back=True):
    """Replace a region in a file delimited by two lines matching regexes.

    A callback is called to write the new region.  If `replace_start` is true,
    the start delimiter line is replaced as well.  The end delimiter line is
    never replaced.
    """
    # read current content
    with open(fn) as fp:
        lines = list(fp)

    # replace old region with new region
    new_lines = []
    in_old_region = False
    for line in lines:
        if in_old_region:
            if re.search(region_end, line):
                in_old_region = False
                new_lines.extend(callback())
                new_lines.append(line)
        elif re.search(region_start, line):
            if not replace_start:
                new_lines.append(line)
            # old region starts here
            in_old_region = True
        else:
            new_lines.append(line)

    # write back to file
    if write_back:
        with open(fn, 'w') as fp:
            fp.writelines(new_lines)

    # if something changed, return true
    return lines != new_lines


def main(print_only=False, check=False):
    lints = []

    # check directory
    if not os.path.isfile('src/lib.rs'):
        print('Error: call this script from clippy checkout directory!')
        return

    # collect all lints from source files
    for root, dirs, files in os.walk('src'):
        for fn in files:
            if fn.endswith('.rs'):
                collect(lints, os.path.join(root, fn))

    if print_only:
        sys.stdout.writelines(gen_table(lints))
        return

    # replace table in README.md
    changed = replace_region(
        'README.md', r'^name +\|', '^$',
        lambda: gen_table(lints, link=wiki_link),
        write_back=not check)

    changed |= replace_region(
        'README.md',
        r'^There are \d+ lints included in this crate:', "",
        lambda: ['There are %d lints included in this crate:\n' % len(lints)],
        write_back=not check)

    # update the `pub mod` list
    changed |= replace_region(
        'src/lib.rs', r'begin lints modules', r'end lints modules',
        lambda: gen_mods(lints),
        replace_start=False, write_back=not check)

    # same for "clippy" lint collection
    changed |= replace_region(
        'src/lib.rs', r'reg.register_lint_group\("clippy"', r'\]\);',
        lambda: gen_group(lints, levels=('warn', 'deny')),
        replace_start=False, write_back=not check)

    # same for "clippy_pedantic" lint collection
    changed |= replace_region(
        'src/lib.rs', r'reg.register_lint_group\("clippy_pedantic"', r'\]\);',
        lambda: gen_group(lints, levels=('allow',)),
        replace_start=False, write_back=not check)

    if check and changed:
        print('Please run util/update_lints.py to regenerate lints lists.')
        return 1


if __name__ == '__main__':
    sys.exit(main(print_only='-n' in sys.argv, check='-c' in sys.argv))