#!/usr/bin/env python3
# ===----------------------------------------------------------------------===##
#
# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
# See https://llvm.org/LICENSE.txt for license information.
# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#
# ===----------------------------------------------------------------------===##

from typing import List, Dict, Tuple, Optional
import csv
import itertools
import json
import os
import pathlib
import re
import subprocess

# Number of the 'Libc++ Standards Conformance' project on Github
LIBCXX_CONFORMANCE_PROJECT = '31'

class PaperStatus:
    TODO = 1
    IN_PROGRESS = 2
    PARTIAL = 3
    DONE = 4
    NOTHING_TO_DO = 5

    _status: int

    _original: Optional[str]
    """
    Optional string from which the paper status was created. This is used to carry additional
    information from CSV rows, like any notes associated to the status.
    """

    def __init__(self, status: int, original: Optional[str] = None):
        self._status = status
        self._original = original

    def __eq__(self, other) -> bool:
        return self._status == other._status

    def __lt__(self, other) -> bool:
        relative_order = {
            PaperStatus.TODO: 0,
            PaperStatus.IN_PROGRESS: 1,
            PaperStatus.PARTIAL: 2,
            PaperStatus.DONE: 3,
            PaperStatus.NOTHING_TO_DO: 3,
        }
        return relative_order[self._status] < relative_order[other._status]

    @staticmethod
    def from_csv_entry(entry: str):
        """
        Parse a paper status out of a CSV row entry. Entries can look like:
        - '' (an empty string, which means the paper is not done yet)
        - '|In Progress|'
        - '|Partial|'
        - '|Complete|'
        - '|Nothing To Do|'

        Note that since we sometimes add additional notes after the status, we only check that the entry
        starts with the above patterns.
        """
        if entry == '':
            return PaperStatus(PaperStatus.TODO, entry)
        elif entry.startswith('|In Progress|'):
            return PaperStatus(PaperStatus.IN_PROGRESS, entry)
        elif entry.startswith('|Partial|'):
            return PaperStatus(PaperStatus.PARTIAL, entry)
        elif entry.startswith('|Complete|'):
            return PaperStatus(PaperStatus.DONE, entry)
        elif entry.startswith('|Nothing To Do|'):
            return PaperStatus(PaperStatus.NOTHING_TO_DO, entry)
        else:
            raise RuntimeError(f'Unexpected CSV entry for status: {entry}')

    @staticmethod
    def from_github_issue(issue: Dict):
        """
        Parse a paper status out of a Github issue obtained from querying a Github project.
        """
        if 'status' not in issue:
            return PaperStatus(PaperStatus.TODO)
        elif issue['status'] == 'Todo':
            return PaperStatus(PaperStatus.TODO)
        elif issue['status'] == 'In Progress':
            return PaperStatus(PaperStatus.IN_PROGRESS)
        elif issue['status'] == 'Partial':
            return PaperStatus(PaperStatus.PARTIAL)
        elif issue['status'] == 'Done':
            return PaperStatus(PaperStatus.DONE)
        elif issue['status'] == 'Nothing To Do':
            return PaperStatus(PaperStatus.NOTHING_TO_DO)
        else:
            raise RuntimeError(f"Received unrecognizable Github issue status: {issue['status']}")

    def to_csv_entry(self) -> str:
        """
        Return the issue state formatted for a CSV entry. The status is formatted as '|Complete|',
        '|In Progress|', etc.
        """
        mapping = {
            PaperStatus.TODO: '',
            PaperStatus.IN_PROGRESS: '|In Progress|',
            PaperStatus.PARTIAL: '|Partial|',
            PaperStatus.DONE: '|Complete|',
            PaperStatus.NOTHING_TO_DO: '|Nothing To Do|',
        }
        return self._original if self._original is not None else mapping[self._status]

    def is_done(self) -> bool:
        return self._status == PaperStatus.DONE or self._status == PaperStatus.NOTHING_TO_DO

class PaperInfo:
    paper_number: str
    """
    Identifier for the paper or the LWG issue. This must be something like 'PnnnnRx', 'Nxxxxx' or 'LWGxxxxx'.
    """

    paper_name: str
    """
    Plain text string representing the name of the paper.
    """

    status: PaperStatus
    """
    Status of the paper/issue. This can be complete, in progress, partial, or done.
    """

    meeting: Optional[str]
    """
    Plain text string representing the meeting at which the paper/issue was voted.
    """

    first_released_version: Optional[str]
    """
    First version of LLVM in which this paper/issue was resolved.
    """

    labels: Optional[List[str]]
    """
    List of labels to associate to the issue in the status-tracking table. Supported labels are
    'format', 'ranges', 'spaceship', 'flat_containers', 'concurrency TS' and 'DR'.
    """

    original: Optional[object]
    """
    Object from which this PaperInfo originated. This is used to track the CSV row or Github issue that
    was used to generate this PaperInfo and is useful for error reporting purposes.
    """

    def __init__(self, paper_number: str, paper_name: str,
                       status: PaperStatus,
                       meeting: Optional[str] = None,
                       first_released_version: Optional[str] = None,
                       labels: Optional[List[str]] = None,
                       original: Optional[object] = None):
        self.paper_number = paper_number
        self.paper_name = paper_name
        self.status = status
        self.meeting = meeting
        self.first_released_version = first_released_version
        self.labels = labels
        self.original = original

    def for_printing(self) -> Tuple[str, str, str, str, str, str]:
        return (
            f'`{self.paper_number} <https://wg21.link/{self.paper_number}>`__',
            self.paper_name,
            self.meeting if self.meeting is not None else '',
            self.status.to_csv_entry(),
            self.first_released_version if self.first_released_version is not None else '',
            ' '.join(f'|{label}|' for label in self.labels) if self.labels is not None else '',
        )

    def __repr__(self) -> str:
        return repr(self.original) if self.original is not None else repr(self.for_printing())

    @staticmethod
    def from_csv_row(row: Tuple[str, str, str, str, str, str]):# -> PaperInfo:
        """
        Given a row from one of our status-tracking CSV files, create a PaperInfo object representing that row.
        """
        # Extract the paper number from the first column
        match = re.search(r"((P[0-9R]+)|(LWG[0-9]+)|(N[0-9]+))\s+", row[0])
        if match is None:
            raise RuntimeError(f"Can't parse paper/issue number out of row: {row}")

        return PaperInfo(
            paper_number=match.group(1),
            paper_name=row[1],
            status=PaperStatus.from_csv_entry(row[3]),
            meeting=row[2] or None,
            first_released_version=row[4] or None,
            labels=[l.strip('|') for l in row[5].split(' ') if l] or None,
            original=row,
        )

    @staticmethod
    def from_github_issue(issue: Dict):# -> PaperInfo:
        """
        Create a PaperInfo object from the Github issue information obtained from querying a Github Project.
        """
        # Extract the paper number from the issue title
        match = re.search(r"((P[0-9R]+)|(LWG[0-9]+)|(N[0-9]+)):", issue['title'])
        if match is None:
            raise RuntimeError(f"Issue doesn't have a title that we know how to parse: {issue}")
        paper = match.group(1)

        # Handle labels
        valid_labels = ('format', 'ranges', 'spaceship', 'flat_containers', 'concurrency TS', 'DR')
        labels = [label for label in issue['labels'] if label in valid_labels]

        return PaperInfo(
            paper_number=paper,
            paper_name=issue['title'],
            status=PaperStatus.from_github_issue(issue),
            meeting=issue.get('meeting Voted', None),
            first_released_version=None, # TODO
            labels=labels if labels else None,
            original=issue,
        )

def load_csv(file: pathlib.Path) -> List[Tuple]:
    rows = []
    with open(file, newline='') as f:
        reader = csv.reader(f, delimiter=',')
        for row in reader:
            rows.append(row)
    return rows

def write_csv(output: pathlib.Path, rows: List[Tuple]):
    with open(output, 'w', newline='') as f:
        writer = csv.writer(f, quoting=csv.QUOTE_ALL, lineterminator='\n')
        for row in rows:
            writer.writerow(row)

def sync_csv(rows: List[Tuple], from_github: List[PaperInfo]) -> List[Tuple]:
    """
    Given a list of CSV rows representing an existing status file and a list of PaperInfos representing
    up-to-date (but potentially incomplete) tracking information from Github, this function returns the
    new CSV rows synchronized with the up-to-date information.

    Note that this only tracks changes from 'not implemented' issues to 'implemented'. If an up-to-date
    PaperInfo reports that a paper is not implemented but the existing CSV rows report it as implemented,
    it is an error (i.e. the result is not a CSV row where the paper is *not* implemented).
    """
    results = [rows[0]] # Start with the header
    for row in rows[1:]: # Skip the header
        # If the row contains empty entries, this is a "separator row" between meetings.
        # Preserve it as-is.
        if row[0] == "":
            results.append(row)
            continue

        paper = PaperInfo.from_csv_row(row)

        # Find any Github issues tracking this paper. Each row must have one and exactly one Github
        # issue tracking it, which we validate below.
        tracking = [gh for gh in from_github if paper.paper_number == gh.paper_number]

        # If there is no tracking issue for that row in the CSV, this is an error since we're
        # missing a Github issue.
        if len(tracking) == 0:
            print(f"Can't find any Github issue for CSV row: {row}")
            results.append(row)
            continue

        # If there's more than one tracking issue, something is weird too.
        if len(tracking) > 1:
            print(f"Found a row with more than one tracking issue: {row}\ntracked by: {tracking}")
            results.append(row)
            continue

        gh = tracking[0]

        # If the CSV row has a status that is "less advanced" than the Github issue, simply update the CSV
        # row with the newer status. Otherwise, report an error if they have a different status because
        # something must be wrong.
        if paper.status < gh.status:
            results.append(gh.for_printing())
            continue
        elif paper.status != gh.status:
            print(f"We found a CSV row and a Github issue with different statuses:\nrow: {row}\nGithub issue: {gh}")
        results.append(row)

    return results

CSV_FILES_TO_SYNC = [
    'Cxx17Issues.csv',
    'Cxx17Papers.csv',
    'Cxx20Issues.csv',
    'Cxx20Papers.csv',
    'Cxx23Issues.csv',
    'Cxx23Papers.csv',
    'Cxx2cIssues.csv',
    'Cxx2cPapers.csv',
]

def main():
    libcxx_root = pathlib.Path(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))

    # Extract the list of PaperInfos from issues we're tracking on Github.
    print("Loading all issues from Github")
    gh_command_line = ['gh', 'project', 'item-list', LIBCXX_CONFORMANCE_PROJECT, '--owner', 'llvm', '--format', 'json', '--limit', '9999999']
    project_info = json.loads(subprocess.check_output(gh_command_line))
    from_github = [PaperInfo.from_github_issue(i) for i in project_info['items']]

    for filename in CSV_FILES_TO_SYNC:
        print(f"Synchronizing {filename} with Github issues")
        file = libcxx_root / 'docs' / 'Status' / filename
        csv = load_csv(file)
        synced = sync_csv(csv, from_github)
        write_csv(file, synced)

if __name__ == '__main__':
    main()