import collections
import logging
import optparse
import os
import sys

from packaging.utils import canonicalize_name
from pip._internal.commands.show import search_packages_info
from pip._internal.utils.misc import get_installed_distributions
from pip_check_reqs import common

log = logging.getLogger(__name__)


def find_extra_reqs(options, requirements_filename):
    # 1. find files used by imports in the code (as best we can without
    #    executing)
    used_modules = common.find_imported_modules(options)

    # 2. find which packages provide which files
    installed_files = {}
    all_pkgs = (pkg.project_name for pkg in get_installed_distributions())
    for package in search_packages_info(all_pkgs):
        log.debug('installed package: %s (at %s)', package['name'],
                  package['location'])
        for package_file in package.get('files', []) or []:
            path = os.path.realpath(
                os.path.join(package['location'], package_file),
            )
            installed_files[path] = package['name']
            package_path = common.is_package_file(path)
            if package_path:
                # we've seen a package file so add the bare package directory
                # to the installed list as well as we might want to look up
                # a package by its directory path later
                installed_files[package_path] = package['name']

    # 3. match imported modules against those packages
    used = collections.defaultdict(list)
    for modname, info in used_modules.items():
        # probably standard library if it's not in the files list
        if info.filename in installed_files:
            used_name = canonicalize_name(installed_files[info.filename])
            log.debug('used module: %s (from package %s)', modname,
                      installed_files[info.filename])
            used[used_name].append(info)
        else:
            log.debug(
                'used module: %s (from file %s, assuming stdlib or local)',
                modname, info.filename)

    # 4. compare with requirements.txt
    explicit = common.find_required_modules(
        options=options,
        requirements_filename=requirements_filename,
    )

    return [name for name in explicit if name not in used]


def main():
    from pip_check_reqs import __version__

    usage = 'usage: %prog [options] files or directories'
    parser = optparse.OptionParser(usage)
    parser.add_option("-f",
                      "--ignore-file",
                      dest="ignore_files",
                      action="append",
                      default=[],
                      help="file paths globs to ignore")
    parser.add_option("-m",
                      "--ignore-module",
                      dest="ignore_mods",
                      action="append",
                      default=[],
                      help="used module names (globs are ok) to ignore")
    parser.add_option("-r",
                      "--ignore-requirement",
                      dest="ignore_reqs",
                      action="append",
                      default=[],
                      help="reqs in requirements.txt to ignore")
    parser.add_option("-v",
                      "--verbose",
                      dest="verbose",
                      action="store_true",
                      default=False,
                      help="be more verbose")
    parser.add_option("-d",
                      "--debug",
                      dest="debug",
                      action="store_true",
                      default=False,
                      help="be *really* verbose")
    parser.add_option("--version",
                      dest="version",
                      action="store_true",
                      default=False,
                      help="display version information")

    (options, args) = parser.parse_args()

    if options.version:
        sys.exit(__version__)

    if not args:
        parser.error("no source files or directories specified")
        sys.exit(2)

    options.ignore_files = common.ignorer(options.ignore_files)
    options.ignore_mods = common.ignorer(options.ignore_mods)
    options.ignore_reqs = common.ignorer(options.ignore_reqs)

    options.paths = args

    logging.basicConfig(format='%(message)s')
    if options.debug:
        log.setLevel(logging.DEBUG)
    elif options.verbose:
        log.setLevel(logging.INFO)
    else:
        log.setLevel(logging.WARN)

    log.info('using pip_check_reqs-%s from %s', __version__, __file__)

    requirements_filename = 'requirements.txt'
    extras = find_extra_reqs(
        options=options,
        requirements_filename=requirements_filename,
    )

    if extras:
        log.warning('Extra requirements:')
    for name in extras:
        message = '{name} in {requirements_filename}'.format(
            name=name,
            requirements_filename=requirements_filename,
        )
        log.warning(message)

    if extras:
        sys.exit(1)


if __name__ == '__main__':  # pragma: no cover
    main()