"""
Wrapper for the `mu` command line.
"""

import email.message
import email.policy
from email.parser import BytesParser
import subprocess
from subprocess import PIPE
import xml.dom.minidom
import xml.dom

from typing import (
    Optional,
)

parser = BytesParser(policy=email.policy.default)


def find_file(id: str) -> Optional[str]:
    cmd = subprocess.run(['mu', 'find', '-u', f'i:{id}',
                          '--fields', 'l'],
                         stdout=PIPE)
    filename = cmd.stdout.decode('UTF-8').strip()

    if cmd.returncode == 4:
        return None
    if cmd.returncode != 0:
        raise MuError(cmd.returncode)
    return filename


def get_mail(id: str) -> email.message.Message:
    """
    Lookup email by Message-ID.

    [Raises]
        MuError
    """
    with open(find_file(id), "rb") as f:
        mail = parser.parse(f)
    return mail


class MuError(Exception):
    codes = {
        1: 'General Error',
        2: 'No Matches',
        4: 'Database is corrupted'
    }

    def __init__(self, returncode: int):
        self.returncode: int = returncode
        self.msg: str = MuError.codes.get(returncode, 'Unknown Error')

    def __repr__(self):
        return f'MuError({self.returncode}, "{self.msg}")'

    def __str__(self):
        return repr(self)


def search(query: str,
           sortfield: Optional[str] = 'subject',
           reverse: bool = False) -> list[dict[str, str]]:
    """
    [Parameters]
        query     - Search query as per mu-find(1).
        sortfield - Field to sort the values by
        reverse   - If the sort should be reversed

    [Returns]
    >>> {'from': 'Hugo Hörnquist <hugo@example.com>',
         'date': '1585678375',
         'size': '377',
         'msgid': 'SAMPLE-ID@localhost',
         'path': '/home/hugo/.local/var/mail/INBOX/cur/filename',
         'maildir': '/INBOX'
         }
    """

    if not query:
        raise ValueError('Query required for mu_search')
    cmdline = ['mu', 'find',
               '--format=xml',
               query]
    if sortfield:
        cmdline.extend(['--sortfield', sortfield])
    if reverse:
        cmdline.append('--reverse')
    cmd = subprocess.run(cmdline, capture_output=True)
    if cmd.returncode == 1:
        raise MuError(cmd.returncode)
    if cmd.returncode == 4:
        # no matches
        return []
    if cmd.returncode != 0:
        raise MuError(cmd.returncode)
    dom = xml.dom.minidom.parseString(cmd.stdout.decode('UTF-8'))

    message_list = []
    messages = dom.childNodes[0]
    assert messages.localName == 'messages'
    for message in messages.childNodes:
        msg_dict = {}
        if message.nodeType != xml.dom.Node.ELEMENT_NODE:
            continue
        for kv in message.childNodes:
            if kv.nodeType != xml.dom.Node.ELEMENT_NODE:
                continue
            msg_dict[kv.localName] = kv.childNodes[0].data
        message_list.append(msg_dict)

    return message_list


def info():
    cmd = subprocess.Popen('mu info --nocolor'.split(' '),
                           stdout=subprocess.PIPE,
                           text=True)
    out = {}
    for line in cmd.stdout:
        if not line:
            continue
        if line[0] == '+':
            continue
        key, *value = [s.strip() for s in line.split('|') if s and not s.isspace()]
        out[key] = '|'.join(value)
    return out