#!/usr/bin/env python3.8
# Copyright 2021 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""
Suggests OWNERS for projects in a jiri manifest without owners.

For each project in a given jiri manifest file, do the following:
1. Check if it has an OWNERS file at the root path. If so, skip.
2. Find references to the project via `gn refs`. If none, skip.
3. Find immediate owners for all referrers. If none, for each referrer travel
   one directory up and continue the search. Ignore root owners.

Example usage:
$ fx set ...
$ scripts/owner/suggest_owners.py \
--jiri_manifest integration/third_party/flower
"""

import argparse
import os
import re
import subprocess
import sys
import xml.etree.ElementTree as ET

# Matches a valid email address, more or less.
EMAIL = re.compile("^[\w%+-]+@[\w.-]+\.[a-zA-Z]{2,}$")


def check_output(*command, **kwargs):
    try:
        return subprocess.check_output(
            command, stderr=subprocess.STDOUT, encoding="utf8", **kwargs)
    except subprocess.CalledProcessError as e:
        print("Failed: " + " ".join(command), file=sys.stderr)
        print(e.output, file=sys.stderr)
        raise e


def get_project_paths(jiri_manifest_path):
    manifest = ET.parse(jiri_manifest_path)
    root = manifest.getroot()
    projects = root.find("projects")
    return [project.get("path") for project in projects.findall("project")]


def get_referencing_paths(path):
    build_dir = check_output("fx", "get-build-dir").strip()
    try:
        refs_out = check_output("fx", "gn", "refs", build_dir, path + ":*")
    except Exception as e:
        print(f"Failed to find refs to {path}", file=sys.stderr)
        print(e.output, file=sys.stderr)
        return []
    # Remove empty lines, turn labels to paths, unique, sort
    return sorted(
        {line[2:].partition(":")[0] for line in refs_out.splitlines() if line})


def get_owners(path):
    owners_path = os.path.join(path, "OWNERS")
    if not os.path.exists(owners_path):
        return set()
    owners = set()
    for line in open(owners_path):
        line = line.strip()
        if line.startswith("include "):
            owners.update(get_owners(line[len("include /"):]))
        elif line.startswith("per-file "):
            owners.update(
                line[len("per-file "):].partition("=")[2].strip().split(","))
        elif line.startswith("#"):
            continue
        else:
            owners.add(line)
    # Remove stuff that doesn't look like an email address
    return {owner for owner in owners if EMAIL.match(owner)}


def main():
    parser = argparse.ArgumentParser(
        description="Suggests owners for jiri projects")
    parser.add_argument(
        "--jiri_manifest", help="Input jiri manifest file", required=True)
    parser.add_argument(
        "--csv",
        help="Output csv file",
        type=argparse.FileType('w'),
        required=True)
    args = parser.parse_args()

    # Set working directory to //
    fuchsia_root = os.path.dirname(  # //
        os.path.dirname(             # scripts/
        os.path.dirname(             # owner/
        os.path.abspath(__file__))))
    os.chdir(fuchsia_root)

    project_paths = get_project_paths(args.jiri_manifest)
    for project_path in project_paths:
        if get_owners(project_path):
            print(f"{project_path} has OWNERS, skipping.")
            continue
        refs = get_referencing_paths(project_path)
        if not refs:
            print(f"{project_path} has no references, skipping.")
            continue
        # Filter // and internal references (paths inside the project)
        refs = {ref for ref in refs if ref and not ref.startswith(project_path)}

        owners = set()
        while not owners and refs:
            for ref in refs:
                owners.update(get_owners(ref))
            if not owners:
                # Go one directory up, terminating before //
                refs = {os.path.dirname(ref) for ref in refs}
                refs = {
                    ref for ref in refs
                    if ref and not ref.startswith(project_path)
                }
        if not owners:
            print(f"{project_path} not referenced by anything owned, skipping.")
            continue

        print()
        print(f"{project_path} suggested owners:")
        print("\n".join(sorted(owners)))
        print()
        print(f"This is based on incoming references from:")
        print("\n".join(sorted(refs)))
        print()
        args.csv.write(f"{project_path},{owners},{refs}\n")

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