#!/usr/bin/python3

import argparse
import collections
import fuzzywuzzy.fuzz
import itertools
import json
import os
import re
import sys

parser = argparse.ArgumentParser(description="Format changelog for given PRs.")
parser.add_argument(
    "file",
    metavar="FILE",
    type=argparse.FileType("r", encoding="utf-8"),
    nargs="?",
    default=sys.stdin,
    help="File with PR numbers, one per line.",
)
args = parser.parse_args()

# This function mirrors the PR description checks in ClickhousePullRequestTrigger.
# Returns False if the PR should not be mentioned changelog.
def parse_one_pull_request(item):
    description = item["body"]
    # Don't skip empty lines because they delimit parts of description
    lines = [
        line
        for line in [
            x.strip() for x in (description.split("\n") if description else [])
        ]
    ]
    lines = [re.sub(r"\s+", " ", l) for l in lines]

    category = ""
    entry = ""

    if lines:
        i = 0
        while i < len(lines):
            if re.match(r"(?i).*change\s*log\s*category", lines[i]):
                i += 1
                if i >= len(lines):
                    break
                # Can have one empty line between header and the category itself. Filter it out.
                if not lines[i]:
                    i += 1
                    if i >= len(lines):
                        break
                category = re.sub(r"^[-*\s]*", "", lines[i])
                i += 1

            elif re.match(r"(?i).*change\s*log\s*entry", lines[i]):
                i += 1
                # Can have one empty line between header and the entry itself. Filter it out.
                if i < len(lines) and not lines[i]:
                    i += 1
                # All following lines until empty one are the changelog entry.
                entry_lines = []
                while i < len(lines) and lines[i]:
                    entry_lines.append(lines[i])
                    i += 1
                entry = " ".join(entry_lines)
            else:
                i += 1

    if not category:
        # Shouldn't happen, because description check in CI should catch such PRs.
        # Fall through, so that it shows up in output and the user can fix it.
        category = "NO CL CATEGORY"

    # Filter out the PR categories that are not for changelog.
    if re.match(
        r"(?i)doc|((non|in|not|un)[-\s]*significant)|(not[ ]*for[ ]*changelog)",
        category,
    ):
        return False

    if not entry:
        # Shouldn't happen, because description check in CI should catch such PRs.
        category = "NO CL ENTRY"
        entry = "NO CL ENTRY:  '" + item["title"] + "'"

    entry = entry.strip()
    if entry[-1] != ".":
        entry += "."

    item["entry"] = entry
    item["category"] = category

    return True


# This array gives the preferred category order, and is also used to
# normalize category names.
categories_preferred_order = [
    "Backward Incompatible Change",
    "New Feature",
    "Performance Improvement",
    "Improvement",
    "Bug Fix",
    "Build/Testing/Packaging Improvement",
    "Other",
]

category_to_pr = collections.defaultdict(lambda: [])
users = {}
for line in args.file:
    pr = json.loads(open(f"pr{line.strip()}.json").read())
    assert pr["number"]
    if not parse_one_pull_request(pr):
        continue

    assert pr["category"]

    # Normalize category name
    for c in categories_preferred_order:
        if fuzzywuzzy.fuzz.ratio(pr["category"].lower(), c.lower()) >= 90:
            pr["category"] = c
            break

    category_to_pr[pr["category"]].append(pr)
    user_id = pr["user"]["id"]
    users[user_id] = json.loads(open(f"user{user_id}.json").read())


def print_category(category):
    print(("#### " + category))
    print()
    for pr in category_to_pr[category]:
        user = users[pr["user"]["id"]]
        user_name = user["name"] if user["name"] else user["login"]

        # Substitute issue links.
        # 1) issue number w/o markdown link
        pr["entry"] = re.sub(
            r"([^[])#([0-9]{4,})",
            r"\1[#\2](https://github.com/ClickHouse/ClickHouse/issues/\2)",
            pr["entry"],
        )
        # 2) issue URL w/o markdown link
        pr["entry"] = re.sub(
            r"([^(])https://github.com/ClickHouse/ClickHouse/issues/([0-9]{4,})",
            r"\1[#\2](https://github.com/ClickHouse/ClickHouse/issues/\2)",
            pr["entry"],
        )

        print(
            f'* {pr["entry"]} [#{pr["number"]}]({pr["html_url"]}) ([{user_name}]({user["html_url"]})).'
        )

    print()


# Print categories in preferred order
for category in categories_preferred_order:
    if category in category_to_pr:
        print_category(category)
        category_to_pr.pop(category)

# Print the rest of the categories
for category in category_to_pr:
    print_category(category)