#
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements.  See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License.  You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# pylint: disable=no-value-for-parameter

import csv as lib_csv
import os
import re
import sys
from dataclasses import dataclass
from typing import Any, Dict, Iterator, List, Optional, Union

import click

try:
    from github import BadCredentialsException, Github, PullRequest
except ModuleNotFoundError:
    print("PyGithub is a required package for this script")
    exit(1)

SUPERSET_REPO = "apache/superset"


@dataclass
class GitLog:
    """
    Represents a git log entry
    """

    sha: str
    author: str
    time: str
    message: str
    pr_number: Union[int, None] = None
    author_email: str = ""

    def __eq__(self, other: object) -> bool:
        """ A log entry is considered equal if it has the same PR number """
        if isinstance(other, self.__class__):
            return other.pr_number == self.pr_number
        return False

    def __repr__(self) -> str:
        return f"[{self.pr_number}]: {self.message} {self.time} {self.author}"


class GitChangeLog:
    """
    Helper class to output a list of logs entries on a superset changelog format

    We want to map a git author to a github login, for that we call github's API
    """

    def __init__(
        self, version: str, logs: List[GitLog], access_token: Optional[str] = None
    ) -> None:
        self._version = version
        self._logs = logs
        self._github_login_cache: Dict[str, Optional[str]] = {}
        self._wait = 10
        github_token = access_token or os.environ.get("GITHUB_TOKEN")
        self._github = Github(github_token)
        self._superset_repo = ""

    def _fetch_github_pr(self, pr_number: int) -> PullRequest:
        """
        Fetches a github PR info
        """
        try:
            github_repo = self._github.get_repo(SUPERSET_REPO)
        except BadCredentialsException as ex:
            print(
                f"Bad credentials to github provided"
                f" use access_token parameter or set GITHUB_TOKEN"
            )
            sys.exit(1)

        return github_repo.get_pull(pr_number)

    def _get_github_login(self, git_log: GitLog) -> Optional[str]:
        """
        Tries to fetch a github login (username) from a git author
        """
        author_name = git_log.author
        github_login = self._github_login_cache.get(author_name)
        if github_login:
            return github_login
        if git_log.pr_number:
            pr_info = self._fetch_github_pr(git_log.pr_number)
            if pr_info:
                github_login = pr_info.user.login
            else:
                github_login = author_name
        # set cache
        self._github_login_cache[author_name] = github_login
        return github_login

    def _get_changelog_version_head(self) -> str:
        return f"### {self._version} ({self._logs[0].time})"

    def __repr__(self) -> str:
        result = f"\n{self._get_changelog_version_head()}\n"
        for i, log in enumerate(self._logs):
            github_login = self._get_github_login(log)
            if not github_login:
                github_login = log.author
            result = result + (
                f"- [#{log.pr_number}]"
                f"(https://github.com/{SUPERSET_REPO}/pull/{log.pr_number}) "
                f"{log.message} (@{github_login})\n"
            )
            print(f"\r {i}/{len(self._logs)}", end="", flush=True)
        return result

    def __iter__(self) -> Iterator[Dict[str, Any]]:
        for log in self._logs:
            yield {
                "pr_number": log.pr_number,
                "pr_link": f"https://github.com/{SUPERSET_REPO}/pull/"
                f"{log.pr_number}",
                "message": log.message,
                "time": log.time,
                "author": log.author,
                "email": log.author_email,
                "sha": log.sha,
            }


class GitLogs:
    """
    Manages git log entries from a specific branch/tag

    Can compare git log entries by PR number
    """

    def __init__(self, git_ref: str) -> None:
        self._git_ref = git_ref
        self._logs: List[GitLog] = []

    @property
    def git_ref(self) -> str:
        return self._git_ref

    @property
    def logs(self) -> List[GitLog]:
        return self._logs

    def fetch(self) -> None:
        self._logs = list(map(self._parse_log, self._git_logs()))[::-1]

    def diff(self, git_logs: "GitLogs") -> List[GitLog]:
        return [log for log in git_logs.logs if log not in self._logs]

    def __repr__(self) -> str:
        return f"{self._git_ref}, Log count:{len(self._logs)}"

    @staticmethod
    def _git_get_current_head() -> str:
        output = os.popen("git status | head -1").read()
        match = re.match("(?:HEAD detached at|On branch) (.*)", output)
        if not match:
            return ""
        return match.group(1)

    def _git_checkout(self, git_ref: str) -> None:
        os.popen(f"git checkout {git_ref}").read()
        current_head = self._git_get_current_head()
        if current_head != git_ref:
            print(f"Could not checkout {git_ref}")
            sys.exit(1)

    def _git_logs(self) -> List[str]:
        # let's get current git ref so we can revert it back
        current_git_ref = self._git_get_current_head()
        self._git_checkout(self._git_ref)
        output = (
            os.popen('git --no-pager log --pretty=format:"%h|%an|%ae|%ad|%s|"')
            .read()
            .split("\n")
        )
        # revert to git ref, let's be nice
        self._git_checkout(current_git_ref)
        return output

    @staticmethod
    def _parse_log(log_item: str) -> GitLog:
        pr_number = None
        split_log_item = log_item.split("|")
        # parse the PR number from the log message
        match = re.match(r".*\(\#(\d*)\)", split_log_item[4])
        if match:
            pr_number = int(match.group(1))
        return GitLog(
            sha=split_log_item[0],
            author=split_log_item[1],
            author_email=split_log_item[2],
            time=split_log_item[3],
            message=split_log_item[4],
            pr_number=pr_number,
        )


@dataclass
class BaseParameters:
    previous_logs: GitLogs
    current_logs: GitLogs


def print_title(message: str) -> None:
    print(f"{50*'-'}")
    print(message)
    print(f"{50*'-'}")


@click.group()
@click.pass_context
@click.option("--previous_version", help="The previous release version", required=True)
@click.option("--current_version", help="The current release version", required=True)
def cli(ctx, previous_version: str, current_version: str) -> None:
    """ Welcome to change log generator  """
    previous_logs = GitLogs(previous_version)
    current_logs = GitLogs(current_version)
    previous_logs.fetch()
    current_logs.fetch()
    base_parameters = BaseParameters(previous_logs, current_logs)
    ctx.obj = base_parameters


@cli.command("compare")
@click.pass_obj
def compare(base_parameters: BaseParameters) -> None:
    """ Compares both versions (by PR) """
    previous_logs = base_parameters.previous_logs
    current_logs = base_parameters.current_logs
    print_title(
        f"Pull requests from " f"{current_logs.git_ref} not in {previous_logs.git_ref}"
    )
    previous_diff_logs = previous_logs.diff(current_logs)
    for diff_log in previous_diff_logs:
        print(f"{diff_log}")

    print_title(
        f"Pull requests from " f"{previous_logs.git_ref} not in {current_logs.git_ref}"
    )
    current_diff_logs = current_logs.diff(previous_logs)
    for diff_log in current_diff_logs:
        print(f"{diff_log}")


@cli.command("changelog")
@click.option(
    "--csv", help="The csv filename to export the changelog to",
)
@click.option(
    "--access_token",
    help="The github access token,"
    " if not provided will try to fetch from GITHUB_TOKEN env var",
)
@click.pass_obj
def change_log(base_parameters: BaseParameters, csv: str, access_token: str) -> None:
    """ Outputs a changelog (by PR) """
    previous_logs = base_parameters.previous_logs
    current_logs = base_parameters.current_logs
    previous_diff_logs = previous_logs.diff(current_logs)
    logs = GitChangeLog(
        current_logs.git_ref, previous_diff_logs[::-1], access_token=access_token
    )
    if csv:
        with open(csv, "w") as csv_file:
            log_items = list(logs)
            field_names = log_items[0].keys()
            writer = lib_csv.DictWriter(
                csv_file,
                delimiter=",",
                quotechar='"',
                quoting=lib_csv.QUOTE_ALL,
                fieldnames=field_names,
            )
            writer.writeheader()
            for log in logs:
                writer.writerow(log)
    else:
        print("Fetching github usernames, this may take a while:")
        print(logs)


cli()