#!/usr/bin/env python3

# Copyright (c) 2022 Intel Corp.
# SPDX-License-Identifier: Apache-2.0

import argparse
import sys
import os
import time
import datetime
from github import Github, GithubException
from github.GithubException import UnknownObjectException
from collections import defaultdict

TOP_DIR = os.path.join(os.path.dirname(__file__))
sys.path.insert(0, os.path.join(TOP_DIR, "scripts"))
from get_maintainer import Maintainers

def log(s):
    if args.verbose > 0:
        print(s, file=sys.stdout)

def parse_args():
    global args
    parser = argparse.ArgumentParser(
        description=__doc__,
        formatter_class=argparse.RawDescriptionHelpFormatter)

    parser.add_argument("-M", "--maintainer-file", required=False, default="MAINTAINERS.yml",
                        help="Maintainer file to be used.")
    parser.add_argument("-P", "--pull_request", required=False, default=None, type=int,
                        help="Operate on one pull-request only.")
    parser.add_argument("-s", "--since", required=False,
                        help="Process pull-requests since date.")

    parser.add_argument("-y", "--dry-run", action="store_true", default=False,
                        help="Dry run only.")

    parser.add_argument("-o", "--org", default="zephyrproject-rtos",
                        help="Github organisation")

    parser.add_argument("-r", "--repo", default="zephyr",
                        help="Github repository")

    parser.add_argument("-v", "--verbose", action="count", default=0,
                        help="Verbose Output")

    args = parser.parse_args()

def process_pr(gh, maintainer_file, number):

    gh_repo = gh.get_repo(f"{args.org}/{args.repo}")
    pr = gh_repo.get_pull(number)

    log(f"working on https://github.com/{args.org}/{args.repo}/pull/{pr.number} : {pr.title}")

    labels = set()
    area_counter = defaultdict(int)
    maint = defaultdict(int)

    num_files = 0
    all_areas = set()
    fn = list(pr.get_files())
    if len(fn) > 500:
        log(f"Too many files changed ({len(fn)}), skipping....")
        return
    for f in pr.get_files():
        num_files += 1
        log(f"file: {f.filename}")
        areas = maintainer_file.path2areas(f.filename)

        if areas:
            all_areas.update(areas)
            for a in areas:
                area_counter[a.name] += 1
                labels.update(a.labels)
                for p in a.maintainers:
                    maint[p] += 1

    ac = dict(sorted(area_counter.items(), key=lambda item: item[1], reverse=True))
    log(f"Area matches: {ac}")
    log(f"labels: {labels}")
    if len(labels) > 10:
        log(f"Too many labels to be applied")
        return

    # Create a list of collaborators ordered by the area match
    collab = list()
    for a in ac:
        collab += maintainer_file.areas[a].maintainers
        collab += maintainer_file.areas[a].collaborators
    collab = list(dict.fromkeys(collab))
    log(f"collab: {collab}")

    sm = dict(sorted(maint.items(), key=lambda item: item[1], reverse=True))

    log(f"Submitted by: {pr.user.login}")
    log(f"candidate maintainers: {sm}")

    maintainer = "None"
    maintainers = list(sm.keys())

    prop = 0
    if maintainers:
        maintainer = maintainers[0]

        if len(ac) > 1 and list(ac.values())[0] == list(ac.values())[1]:
            for aa in ac:
                if 'Documentation' in aa:
                    log("++ With multiple areas of same weight including docs, take something else other than Documentation as the maintainer")
                    for a in all_areas:
                        if (a.name == aa and
                            a.maintainers and a.maintainers[0] == maintainer and
                            len(maintainers) > 1):
                            maintainer = maintainers[1]
                elif 'Platform' in aa:
                    log("++ Platform takes precedence over subsystem...")
                    log(f"Set maintainer of area {aa}")
                    for a in all_areas:
                        if a.name == aa:
                            if a.maintainers:
                                maintainer = a.maintainers[0]
                                break


        # if the submitter is the same as the maintainer, check if we have
        # multiple maintainers
        if pr.user.login == maintainer:
            log("Submitter is same as Assignee, trying to find another assignee...")
            aff = list(ac.keys())[0]
            for a in all_areas:
                if a.name == aff:
                    if len(a.maintainers) > 1:
                        maintainer = a.maintainers[1]
                    else:
                        log(f"This area has only one maintainer, keeping assignee as {maintainer}")

        prop = (maint[maintainer] / num_files) * 100
        if prop < 20:
            maintainer = "None"

    log(f"Picked maintainer: {maintainer} ({prop:.2f}% ownership)")
    log("+++++++++++++++++++++++++")

    # Set labels
    if labels and len(labels) < 10:
        for l in labels:
            log(f"adding label {l}...")
            if not args.dry_run:
                pr.add_to_labels(l)

    if collab:
        reviewers = []
        existing_reviewers = set()

        revs = pr.get_reviews()
        for review in revs:
            existing_reviewers.add(review.user)

        rl = pr.get_review_requests()
        page = 0
        for r in rl:
            existing_reviewers |= set(r.get_page(page))
            page += 1

        for c in collab:
            try:
                u = gh.get_user(c)
                if pr.user != u and gh_repo.has_in_collaborators(u):
                    if u not in existing_reviewers:
                        reviewers.append(c)
            except UnknownObjectException as e:
                log(f"Can't get user '{c}', account does not exist anymore? ({e})")

        if len(existing_reviewers) < 15:
            reviewer_vacancy = 15 - len(existing_reviewers)
            reviewers = reviewers[:reviewer_vacancy]

            if reviewers:
                try:
                    log(f"adding reviewers {reviewers}...")
                    if not args.dry_run:
                        pr.create_review_request(reviewers=reviewers)
                except GithubException:
                    log("cant add reviewer")
        else:
            log("not adding reviewers because the existing reviewer count is greater than or "
                "equal to 15")

    ms = []
    # assignees
    if maintainer != 'None' and not pr.assignee:
        try:
            u = gh.get_user(maintainer)
            ms.append(u)
        except GithubException:
            log(f"Error: Unknown user")

        for mm in ms:
            log(f"Adding assignee {mm}...")
            if not args.dry_run:
                pr.add_to_assignees(mm)
    else:
        log("not setting assignee")

    time.sleep(1)

def main():
    parse_args()

    token = os.environ.get('GITHUB_TOKEN', None)
    if not token:
        sys.exit('Github token not set in environment, please set the '
                 'GITHUB_TOKEN environment variable and retry.')

    gh = Github(token)
    maintainer_file = Maintainers(args.maintainer_file)

    if args.pull_request:
        process_pr(gh, maintainer_file, args.pull_request)
    else:
        if args.since:
            since = args.since
        else:
            today = datetime.date.today()
            since = today - datetime.timedelta(days=1)

        common_prs = f'repo:{args.org}/{args.repo} is:open is:pr base:main -is:draft no:assignee created:>{since}'
        pulls = gh.search_issues(query=f'{common_prs}')

        for issue in pulls:
            process_pr(gh, maintainer_file, issue.number)


if __name__ == "__main__":
    main()