#!/usr/bin/env python3
# Copyright 2017 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""Linter for various README.md files."""

import difflib
import logging
import os
import re
import sys

TOP_DIR = os.path.dirname(os.path.dirname(os.path.realpath(__file__)))

# Find chromite!
sys.path.insert(0, os.path.join(TOP_DIR, '..', '..'))

# pylint: disable=wrong-import-position
from chromite.lib import commandline
from chromite.lib import git
from chromite.lib import osutils
# pylint: enable=wrong-import-position


def GetActiveProjects():
    """Return the list of active projects."""
    # Look at all the paths (files & dirs) in the top of the git repo. This way
    # we ignore local directories devs created that aren't actually committed.
    cmd = ['ls-tree', '--name-only', '-z', 'HEAD']
    result = git.RunGit(TOP_DIR, cmd)

    # Split the output on NULs to avoid whitespace/etc... issues.
    paths = result.stdout.split('\0')

    # ls-tree -z will include a trailing NUL on all entries, not just
    # separation, so filter it out if found (in case ls-tree behavior changes
    # on us).
    for path in [x for x in paths if x]:
        if os.path.isdir(os.path.join(TOP_DIR, path)):
            yield path


def CheckTopLevel():
    """Check the top level README.md list."""
    ret = 0
    path = os.path.join(TOP_DIR, 'README.md')
    data = osutils.ReadFile(path).splitlines()

    # Look for the directory header.
    try:
        i = data.index('# Local Project Directory')
    except ValueError:
        logging.error('README.md index out of sync')
        return 1
    data = data[i + 1:]

    # Pull out all the linked projects.
    listed_projs = []
    listed_dirs = []
    for line in data:
        # Break once we hit the end of the table.
        if line.startswith('#'):
            break

        m = re.match(r'^[|] \[([^]]+)*\]\(\./([^)]*)/\)', line)
        if m:
            listed_projs.append(m.group(1))
            listed_dirs.append(m.group(2))
    logging.debug('README.md projects: %s', listed_projs)

    sorted_projs = sorted(listed_projs)
    if listed_projs != sorted_projs:
        ret = 1
        lines = list(
            difflib.unified_diff(listed_projs, sorted_projs, lineterm=''))
        logging.error('README.md project listing should be kept sorted:\n%s',
                      '\n'.join(lines[2:]))

    # Check the list in README.md for outdated entries.
    old_dirs = []
    for project_dir in listed_dirs:
        path = os.path.join(TOP_DIR, project_dir)
        if not os.path.isdir(path):
            old_dirs.append(path)
    if old_dirs:
        ret = 1
        logging.error('README.md: found stale project entries: %s', old_dirs)

    # Check the local source repo for missing entries.
    existing_projs = sorted(GetActiveProjects())
    logging.debug('Found active projects: %s', existing_projs)
    new_projs = []
    for proj in existing_projs:
        path = os.path.join(TOP_DIR, proj)
        if os.path.isdir(path) and proj not in listed_projs:
            new_projs.append(proj)
    if new_projs:
        ret = 1
        logging.error('README.md: document new projects: %s', new_projs)

    return ret


def CheckSubdirs():
    """Check the subdir README.md files exist."""
    # Legacy projects that don't have a README.md file.
    # Someone should write some docs :D.
    LEGACYLIST = (
        'attestation',
        'avtest_label_detect',
        'cros-disks',
        'fitpicker',
        'image-burner',
        'init',
        'libchromeos-ui',
        'libcontainer',
        'modem-utilities',
        'mtpd',
        'salsa',
        'timberslide',
        'tpm_manager',
        'trim',
        'userfeedback',
        'userspace_touchpad',
        'vpn-manager',
    )

    ret = 0
    for proj in GetActiveProjects():
        readme = os.path.join(TOP_DIR, proj, 'README.md')
        if os.path.exists(readme):
            if proj in LEGACYLIST:
                logging.error(
                    '*** Project "%s" is in no-README LEGACYLIST, but '
                    'actually has one. Please remove it from '
                    'LEGACYLIST!', proj)
        else:
            if not proj in LEGACYLIST:
                logging.error('*** Project "%s" needs a README.md file', proj)
                ret = 1
    return ret


def GetParser():
    """Return an argument parser."""
    parser = commandline.ArgumentParser(description=__doc__)
    parser.add_argument(
        '--extensions',
        default='gyp,gypi',
        help='Comma delimited file extensions to check. '
        '(default: %(default)s)')
    parser.add_argument('files', nargs='*', help='Files to run lint.')
    return parser


def main(argv):
    parser = GetParser()
    opts = parser.parse_args(argv)
    opts.Freeze()

    return CheckTopLevel() | CheckSubdirs()


if __name__ == '__main__':
    commandline.ScriptWrapperMain(lambda _: main)