"""

    AUTHOR:

        Khushal P Soonderji

    DATE:

        Tuesday, 26th Nov., 2024

    OBJECTIVE:

        To parse raw mail bodies and give a structure that is suitable for storing in No-SQL databases like MongoDB. The
        raw mail's text is expected to be compliant with standard defined in RFC 5322, RFC 2045, and maybe a few more.

    REFERENCES:

        1. GitHub: https://github.com/SpamScope/mail-parser
        2. RFC 5322: https://datatracker.ietf.org/doc/html/rfc5322
        3. RFC 2045: https://datatracker.ietf.org/doc/html/rfc2045

    DOWNLOADS:

        N/A

"""


#   *****************************************************************************************************************
#  *****                                                                                                          ****
# ***                                                   IMPORT                                                      ***
#  *****                                                                                                          ****
#   *****************************************************************************************************************


# To make sibling directories accessible for imports:
import sys
sys.path.append(".")
sys.path.append("..")

# System-level activities:
import io

# My utils:
from utils_v2.string import json
from utils_v2.string import regex
from utils_v2.date_time import date_time

# To work with mails:
import mailparser

# To parse the HTML content in the mail:
from bs4 import BeautifulSoup

# To work with datatypes:
from typing import Any, Dict

# To work with base-64 encoding:
import base64


#   *****************************************************************************************************************
#  *****                                                                                                          ****
# ***                                           MACROS / ONE-TIME INIT                                              ***
#  *****                                                                                                          ****
#   *****************************************************************************************************************


# --- Nothing Yet


#   *****************************************************************************************************************
#  *****                                                                                                          ****
# ***                                                VARIABLES                                                      ***
#  *****                                                                                                          ****
#   *****************************************************************************************************************


# --- Nothing Yet


#   *****************************************************************************************************************
#  *****                                                                                                          ****
# ***                                                  FUNCTIONS                                                    ***
#  *****                                                                                                          ****
#   *****************************************************************************************************************


def parse(raw_mail: str | bytes) -> Dict[str, Any]:

    """
    To parse the raw mail text to a usable JSON that can even be stored on a No-SQL database like MongoDB.
    DOCUMENTATION:
        1. GitHub: https://github.com/SpamScope/mail-parser
        2. RFC 5322: https://datatracker.ietf.org/doc/html/rfc5322
        3. RFC 2045: https://datatracker.ietf.org/doc/html/rfc2045
    :param raw_mail: The raw mail body that adheres to RFC 5322 and RFC 2045 (among others).
    :return: The parsed JSON format (dict) of the mail.
    """

    # Parse the raw format:
    if isinstance(raw_mail, str): parsed_mail = mailparser.parse_from_string(raw_mail)
    else: parsed_mail = mailparser.parse_from_bytes(raw_mail)

    # Format the attachments:
    message_attachments = [
        {
            "filename": attachment["filename"],
            "type": attachment["mail_content_type"],
            "cid": regex.find_first(text = attachment["content-id"], pattern = r"(?<=<).*(?=>)"),
            "rawCid": attachment["content-id"],
            "contentDisposition": (cd := attachment["content-disposition"]),
            "isInline": True if cd.lower().find("inline") >= 0 else False,
            "charset": attachment["charset"],
            "contentTransferEncoding": attachment["content_transfer_encoding"],
            "payload": attachment["payload"]
        } for attachment in parsed_mail.attachments
    ]

    # Figure out which entity (text and HTML) came in which sequence.
    # The library doesn't give us any sequence info so we do some custom string processing here to figure out the order
    # in which to render the contents of the page.
    parts = [
        {
            "no": None,
            "offset": max(
                parsed_mail.message_as_string.find(t),
                parsed_mail.message_as_string.find(base64.b64encode(t.encode()).decode())
            ),
            "type": "text/plain",
            "data": t
        } for t in parsed_mail.text_plain
    ]
    parts = parts + [
        {
            "partNo": None,
            "offset": max(
                parsed_mail.message_as_string.find(h),
                parsed_mail.message_as_string.find(base64.b64encode(h.encode()).decode())
            ),
            "type": "text/html",
            "data": h
        } for h in parsed_mail.text_html
    ]
    parts = sorted(parts, key = lambda x: x["offset"])
    for i, p in enumerate(parts): p["no"] = i

    # Get the unformatted text from everything in the mail:
    unformatted_text = []
    for p in parts:
        if p["type"] == "text/html":
            html_parser = BeautifulSoup(p["data"], "html.parser")
            unformatted_text.append(html_parser.get_text())
        else: unformatted_text.append(p["data"])

    # Put everything together:
    return {
        "ts": date_time.to_timezone(parsed_mail.date, timezone = date_time.TIMEZONE_UTC),
        "readTs": date_time.get_current_utc_date_time(as_string = False),
        "headers": parsed_mail.headers,
        "from": [{"name": _[0] or _[1], "email": _[1]} for _ in parsed_mail.headers["From"]],
        "to": [{"name": _[0] or _[1], "email": _[1]} for _ in parsed_mail.headers["To"]],
        "cc": [{"name": _[0] or _[1], "email": _[1]} for _ in parsed_mail.headers.get("Cc", [])],
        "bcc": [{"name": _[0] or _[1], "email": _[1]} for _ in parsed_mail.headers.get("Bcc", [])],
        "subject": parsed_mail.headers["Subject"],
        "text": parsed_mail.text_plain,
        "html": parsed_mail.text_html,
        "parts": parts,
        "unformattedText": "\n".join(unformatted_text),
        "attachments": message_attachments,
        "isInbox": None
    }


#   *****************************************************************************************************************
#  *****                                                                                                          ****
# ***                                               MAIN PROGRAM                                                    ***
#  *****                                                                                                          ****
#   *****************************************************************************************************************


if __name__ == "__main__":

    pass