#!/usr/bin/python3
#
# SPDX-License-Identifier: Apache-2.0
# Copyright (C) 2018 IBM Corp.

import argparse
import sys
from collections import namedtuple, OrderedDict
from enum import Enum, unique
from typing import (
    Dict,
    NamedTuple,
    Tuple,
    Iterator,
    Sequence,
    Union,
    Optional,
    List,
    cast,
    IO,
)
from pprint import pprint


@unique
class LineType(Enum):
    REPO = 1
    MAINTAINER = 2
    REVIEWER = 3
    FORKED = 4
    COMMENT = 5


@unique
class ParseState(Enum):
    BEGIN = 1
    BLOCK = 2


Email = NamedTuple("Email", [("name", str), ("address", str)])
Identity = NamedTuple("Identity", [("email", Email), ("irc", Optional[str])])
Entry = NamedTuple("Entry", [("type", LineType), ("content", str)])


def parse_line(line: str) -> Optional[Entry]:
    sline = line.strip()
    if not sline:
        return None

    if sline == "MAINTAINERS":
        return Entry(LineType.REPO, sline)

    tag = line[:2]
    if "@" in tag:
        return Entry(LineType.REPO, sline[1:].split(":")[0].strip())
    elif tag == "M:":
        return Entry(LineType.MAINTAINER, sline.split(":")[1].strip())
    elif tag == "R:":
        return Entry(LineType.REVIEWER, sline.split(":")[1].strip())
    elif tag == "F:":
        return Entry(LineType.FORKED, sline[2:].strip())
    elif "#" in tag:
        return Entry(LineType.COMMENT, line)

    return None


D = Union[str, List[Identity], List[str]]


def parse_repo(content: str) -> str:
    return content


def parse_forked(content: str) -> str:
    return content


def parse_irc(src: Iterator[str]) -> Optional[str]:
    irc = ""
    for c in src:
        if c == "#":
            return None
        if c == "<":
            break
    else:
        return None

    for c in src:
        if c in "!#":
            return irc.strip()
        irc += c

    raise ValueError("Unterminated IRC handle")


def parse_address(src: Iterator[str]) -> str:
    addr = ""
    for c in src:
        if c in ">#":
            return addr.strip()
        addr += c
    raise ValueError("Unterminated email address")


def parse_name(src: Iterator[str]) -> str:
    name = ""
    for c in src:
        if c in "<#":
            return name.strip()
        name += c
    raise ValueError("Unterminated name")


def parse_email(src: Iterator[str]) -> Email:
    name = parse_name(src)
    address = parse_address(src)
    return Email(name, address)


def parse_identity(content: str) -> Identity:
    ci = iter(content)
    email = parse_email(ci)
    irc = parse_irc(ci)
    return Identity(email, irc)


B = Dict[LineType, D]


def parse_block(src: Iterator[str]) -> Optional[B]:
    state = ParseState.BEGIN
    repo = cast(B, OrderedDict())
    for line in src:
        try:
            entry = parse_line(line)
            if state == ParseState.BEGIN and not entry:
                continue
            elif state == ParseState.BEGIN and entry:
                state = ParseState.BLOCK
            elif state == ParseState.BLOCK and not entry:
                return repo

            assert entry

            if entry.type == LineType.REPO:
                repo[entry.type] = parse_repo(entry.content)
            elif entry.type in {LineType.MAINTAINER, LineType.REVIEWER}:
                if not entry.type in repo:
                    repo[entry.type] = cast(List[Identity], list())
                cast(list, repo[entry.type]).append(parse_identity(entry.content))
            elif entry.type == LineType.FORKED:
                repo[entry.type] = parse_forked(entry.content)
            elif entry.type == LineType.COMMENT:
                if not entry.type in repo:
                    repo[entry.type] = cast(List[str], list())
                cast(list, repo[entry.type]).append(entry.content)
        except ValueError as e:
            print("Failed to parse line '{}': {}".format(line.strip(), e))

    if not repo:
        return None

    return repo


def trash_preamble(src: Iterator[str]) -> None:
    s = 0
    for line in src:
        sline = line.strip()
        if "START OF MAINTAINERS LIST" == sline:
            s = 1
        if s == 1 and sline == "-------------------------":
            break


def parse_maintainers(src: Iterator[str]) -> Dict[D, B]:
    maintainers = cast(Dict[D, B], OrderedDict())
    trash_preamble(src)
    while True:
        repo = cast(B, parse_block(src))
        if not repo:
            break
        maintainers[repo[LineType.REPO]] = repo
    return maintainers


def get_reviewers(mfile: str) -> Tuple[List[str], List[str]]:
    maintainers: List[str] = list()
    reviewers: List[str] = list()

    with open(mfile) as mstream:
        trash_preamble(mstream)
        block = parse_block(mstream)
        if not block:
            return (maintainers, reviewers)
        mlist = cast(List[Identity], block[LineType.MAINTAINER])
        maintainers.extend(i.email.address for i in mlist)
        if LineType.REVIEWER in block:
            rlist = cast(List[Identity], block[LineType.REVIEWER])
            reviewers.extend(i.email.address for i in rlist)
    return (maintainers, reviewers)


def assemble_name(name: str, dst: IO[str]) -> None:
    dst.write(name)


def assemble_address(address: str, dst: IO[str]) -> None:
    dst.write("<")
    dst.write(address)
    dst.write(">")


def assemble_email(email: Email, dst: IO[str]) -> None:
    assemble_name(email.name, dst)
    dst.write(" ")
    assemble_address(email.address, dst)


def assemble_irc(irc: Optional[str], dst: IO[str]) -> None:
    if irc:
        dst.write(" ")
        dst.write("<")
        dst.write(irc)
        dst.write("!>")


def assemble_identity(identity: Identity, dst: IO[str]) -> None:
    assemble_email(identity.email, dst)
    assemble_irc(identity.irc, dst)


def assemble_maintainers(identities: List[Identity], dst: IO[str]) -> None:
    for i in identities:
        dst.write("M:  ")
        assemble_identity(i, dst)
        dst.write("\n")


def assemble_reviewers(identities: List[Identity], dst: IO[str]) -> None:
    for i in identities:
        dst.write("R:  ")
        assemble_identity(i, dst)
        dst.write("\n")


def assemble_forked(content: str, dst: IO[str]) -> None:
    if content:
        dst.write("F:  ")
        dst.write(content)
        dst.write("\n")


def assemble_comment(content: List[str], dst: IO[str]) -> None:
    dst.write("".join(content))


def assemble_block(block: B, default: B, dst: IO[str]) -> None:
    if LineType.COMMENT in block:
        assemble_comment(cast(List[str], block[LineType.COMMENT]), dst)
    if LineType.MAINTAINER in block:
        maintainers = block[LineType.MAINTAINER]
    else:
        maintainers = default[LineType.MAINTAINER]
    assemble_maintainers(cast(List[Identity], maintainers), dst)
    if LineType.REVIEWER in block:
        assemble_reviewers(cast(List[Identity], block[LineType.REVIEWER]), dst)
    if LineType.FORKED in block:
        assemble_forked(cast(str, block[LineType.FORKED]), dst)


def main() -> None:
    parser = argparse.ArgumentParser()
    parser.add_argument("maintainers", type=argparse.FileType("r"), default=sys.stdin)
    parser.add_argument("output", type=argparse.FileType("w"), default=sys.stdout)
    args = parser.parse_args()
    blocks = parse_maintainers(args.maintainers)
    for block in blocks.values():
        print(block[LineType.REPO])
        assemble_block(block, blocks["MAINTAINERS"], args.output)
        print()


if __name__ == "__main__":
    main()