#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Copyright 2016 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""Prints all non-system dependencies for the given module.

The primary use-case for this script is to generate the list of python
modules required for .isolate files.
"""

import argparse
import imp
import os
import pipes
import sys

# Don't use any helper modules, or else they will end up in the results.

_SRC_ROOT = os.path.abspath(os.path.join(os.path.dirname(__file__), os.pardir))


def _compute_python_dependencies():
    """Gets the paths of imported non-system python modules.

    A path is assumed to be a "system" import if it is outside of chromium's
    src/. The paths will be relative to the current directory.
    """
    module_paths = (m.__file__ for m in sys.modules.values()
                    if m and hasattr(m, '__file__'))

    src_paths = set()
    for path in module_paths:
        if path == __file__:
            continue
        path = os.path.abspath(path)
        if not path.startswith(_SRC_ROOT):
            continue

        if (path.endswith('.pyc')
                or (path.endswith('c') and not os.path.splitext(path)[1])):
            path = path[:-1]
        src_paths.add(path)

    return src_paths


def _normalize_command_line(options):
    """Returns a string that when run from SRC_ROOT replicates the command."""
    args = ['build/print_python_deps.py']
    root = os.path.relpath(options.root, _SRC_ROOT)
    if root != '.':
        args.extend(('--root', root))
    if options.output:
        args.extend(('--output', os.path.relpath(options.output, _SRC_ROOT)))
    if options.gn_paths:
        args.extend(('--gn-paths', ))
    for allowlist in sorted(options.allowlists):
        args.extend(('--allowlist', os.path.relpath(allowlist, _SRC_ROOT)))
    args.append(os.path.relpath(options.module, _SRC_ROOT))
    return ' '.join(pipes.quote(x) for x in args)


def _find_python_in_directory(directory):
    """Returns an iterable of all non-test python files in the given directory."""
    for root, _dirnames, filenames in os.walk(directory):
        for filename in filenames:
            if filename.endswith('.py') and not filename.endswith('_test.py'):
                yield os.path.join(root, filename)


def main():
    parser = argparse.ArgumentParser(
        description='Prints all non-system dependencies for the given module.')
    parser.add_argument('module', help='The python module to analyze.')
    parser.add_argument('--root',
                        default='.',
                        help='Directory to make paths relative to.')
    parser.add_argument('--output',
                        help='Write output to a file rather than stdout.')
    parser.add_argument(
        '--inplace',
        action='store_true',
        help='Write output to a file with the same path as the '
        'module, but with a .pydeps extension. Also sets the '
        'root to the module\'s directory.')
    parser.add_argument('--no-header',
                        action='store_true',
                        help='Do not write the "# Generated by" header.')
    parser.add_argument('--gn-paths',
                        action='store_true',
                        help='Write paths as //foo/bar/baz.py')
    parser.add_argument('--allowlist',
                        default=[],
                        action='append',
                        dest='allowlists',
                        help='Recursively include all non-test python files '
                        'within this directory. '
                        'May be specified multiple times.')
    options = parser.parse_args()
    # Replace the path entry for print_python_deps.py with the one for the given
    # module.
    sys.path[0] = os.path.dirname(options.module)
    imp.load_source('NAME', options.module)

    if options.inplace:
        if options.output:
            parser.error('Cannot use --inplace and --output at the same time!')
        if not options.module.endswith('.py'):
            parser.error('Input module path should end with .py suffix!')
        options.output = options.module + 'deps'
        options.root = os.path.dirname(options.module)

    paths_set = _compute_python_dependencies()
    for path in options.allowlists:
        paths_set.update(
            os.path.abspath(p) for p in _find_python_in_directory(path))

    paths = [os.path.relpath(p, options.root) for p in paths_set]

    normalized_cmdline = _normalize_command_line(options)
    try:
        with (open(options.output, 'w')
              if options.output else sys.stdout) as out:
            if not options.no_header:
                out.write('# Generated by running:\n')
                out.write('#   %s\n' % normalized_cmdline)
            prefix = '//' if options.gn_paths else ''
            for path in sorted(paths):
                out.write(prefix + path + '\n')
    except OSError as err:
        raise err
    finally:
        out.close()


if __name__ == '__main__':
    sys.exit(main())