"""

    AUTHOR:

        Khushal P Soonderji

    DATE:

        Thursday, 19th Dec., 2024.

    OBJECTIVE:

        To provide a structure to send mails.

    REFERENCES:

        N/A

    DOWNLOADS:

        N/A

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

# For making data behaviour_models:
from pydantic import BaseModel, Field, field_validator, PastDatetime, EmailStr, model_validator
from typing import Union, Literal, List

# 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 date and time:
import datetime

# To work with Base64 data:
import base64

# To work with MongoDB:
from bson.objectid import ObjectId


#   *****************************************************************************************************************
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# ***                                           MACROS / ONE-TIME INIT                                              ***
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# RegEx Patterns:
REGEX_SESSION_TOKEN = r"^[a-f0-9]{8}-[a-f0-9]{4}-[1-5][a-f0-9]{3}-[89ab][a-f0-9]{3}-[a-f0-9]{12}$"


#   *****************************************************************************************************************
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# ***                                                VARIABLES                                                      ***
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# --- Nothing Yet


#   *****************************************************************************************************************
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# ***                                                  FUNCTIONS                                                    ***
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class MailSendRequestHeaders(BaseModel):

    sessionToken: str = Field(
        description = "the session token of the user who is requesting the service",
        pattern = REGEX_SESSION_TOKEN,
        frozen = True,
        alias = "X-Session-Token"
    )

    # ┏┓    ┏•
    # ┃ ┏┓┏┓╋┓┏┓
    # ┗┛┗┛┛┗┛┗┗┫
    #          ┛

    class Config:
        extra = "allow"

    def model_dump(self, *args, **kwargs):
        return super().model_dump(*args, by_alias = True, **kwargs)


# ---------------------------------------------------------------------------------------------------------------------


class MailSendPlainText(BaseModel):

    content: str = Field(
        description = "The string to add to the mail as plain text.",
        frozen = True
    )

    # ┏┓    ┏•
    # ┃ ┏┓┏┓╋┓┏┓
    # ┗┛┗┛┛┗┛┗┗┫
    #          ┛

    class Config:
        extra = "forbid"


# ---------------------------------------------------------------------------------------------------------------------


class MailSendHTMLText(BaseModel):

    content: str = Field(
        description = "The HTML string to add to the mail.",
        frozen = True
    )

    # ┏┓    ┏•
    # ┃ ┏┓┏┓╋┓┏┓
    # ┗┛┗┛┛┗┛┗┗┫
    #          ┛

    class Config:
        extra = "forbid"


# ---------------------------------------------------------------------------------------------------------------------


class MailSendAttachment(BaseModel):

    content: str | io.BytesIO = Field(
        description = "The Base64 string to add to the mail as a file.",
        frozen = True
    )

    fileName: str = Field(
        description = "The name of the file that will be downloaded when the recipient tries to access the content.",
        frozen = True
    )

    # ┏┓    ┏•
    # ┃ ┏┓┏┓╋┓┏┓
    # ┗┛┗┛┛┗┛┗┗┫
    #          ┛

    class Config:
        extra = "forbid"
        arbitrary_types_allowed = True

    # ┓┏  ┓• ┓   •
    # ┃┃┏┓┃┓┏┫┏┓╋┓┏┓┏┓
    # ┗┛┗┻┗┗┗┻┗┻┗┗┗┛┛┗

    @field_validator("content", mode = "before")
    def parse_base64_file(cls, value):
        if isinstance(value, str):
            base64_parts = value.split(",", 1)
            if len(base64_parts) == 1: header, base64_string = None, base64_parts[0]
            else: header, base64_string = base64_parts[0], base64_parts[1]
            value = io.BytesIO(base64.b64decode(base64_string))
        return value


# ---------------------------------------------------------------------------------------------------------------------


class MailSendInlineImage(BaseModel):

    content: str | io.BytesIO = Field(
        description = "The image content to add to the mail as an inline image file.",
        frozen = True
    )

    fileName: str = Field(
        description = "The name of the file that will be downloaded when the recipient tries to access the content.",
        frozen = True
    )

    cid: str | None = Field(
        description = "A custom Content-Id to assign to the inline attachment.",
        frozen = True,
        default = None
    )

    # ┏┓    ┏•
    # ┃ ┏┓┏┓╋┓┏┓
    # ┗┛┗┛┛┗┛┗┗┫
    #          ┛

    class Config:
        extra = "forbid"
        arbitrary_types_allowed = True

    # ┓┏  ┓• ┓   •
    # ┃┃┏┓┃┓┏┫┏┓╋┓┏┓┏┓
    # ┗┛┗┻┗┗┗┻┗┻┗┗┗┛┛┗

    @field_validator("content", mode = "before")
    def parse_base64_file(cls, value):
        if isinstance(value, str):
            base64_parts = value.split(",", 1)
            if len(base64_parts) == 1: header, base64_string = None, base64_parts[0]
            else: header, base64_string = base64_parts[0], base64_parts[1]
            value = io.BytesIO(base64.b64decode(base64_string))
        return value


# ---------------------------------------------------------------------------------------------------------------------


class MailSendPart(BaseModel):

    type: Literal["plain", "html", "attachment", "inline"] = Field(
        description = "The kind of part this is.",
        frozen = True
    )

    part: dict | Union[
        MailSendPlainText, MailSendHTMLText,  # ...... Textual content.
        MailSendAttachment, MailSendInlineImage  # ... Media content.
    ] = Field(
        description = "One of the structured types of data that can be put in the mail.",
        frozen = True
    )

    # ┏┓    ┏•
    # ┃ ┏┓┏┓╋┓┏┓
    # ┗┛┗┛┛┗┛┗┗┫
    #          ┛

    class Config:
        extra = "forbid"

    # ┓┏  ┓• ┓   •
    # ┃┃┏┓┃┓┏┫┏┓╋┓┏┓┏┓
    # ┗┛┗┻┗┗┗┻┗┻┗┗┗┛┛┗

    @model_validator(mode = "before")
    def ensure_harmony(cls, values):
        kind_map = {
            "plain": MailSendPlainText,
            "html": MailSendHTMLText,
            "attachment": MailSendAttachment,
            "inline": MailSendInlineImage,
        }
        part_dict = values["part"] if isinstance(values["part"], dict) else values["part"].model_dump()
        values["part"] = kind_map[values["type"]](**part_dict)
        return values


# ---------------------------------------------------------------------------------------------------------------------


class MailSendRequestData(BaseModel):

    tokenKey: ObjectId = Field(
        description = "The identifier (Mongo ObjectId) of the account from which the mail has to be sent.",
        frozen = True
    )

    to: List[EmailStr] = Field(
        description = "The list of e-mail addresses to send the mail to.",
        frozen = True
    )

    cc: List[EmailStr] = Field(
        description = "The list of e-mail addresses to add as CC.",
        default = None,
        validate_default = True,
        frozen = True
    )

    bcc: List[EmailStr] = Field(
        description = "The list of e-mail addresses to add as BCC.",
        default = None,
        validate_default = True,
        frozen = True
    )

    subject: str = Field(
        description = "The subject of the mail.",
        frozen = True
    )

    clientThreadId: str | int | None = Field(
        description = "The id of the mail-chain if you would like to reply in one.",
        frozen = True,
        default = None
    )

    body: List[MailSendPart] = Field(
        description = "The actual payload to send as the mail.",
        frozen = True
    )

    # ┏┓    ┏•
    # ┃ ┏┓┏┓╋┓┏┓
    # ┗┛┗┛┛┗┛┗┗┫
    #          ┛

    class Config:
        extra = "forbid"
        arbitrary_types_allowed = True

    # ┓┏  ┓• ┓   •
    # ┃┃┏┓┃┓┏┫┏┓╋┓┏┓┏┓
    # ┗┛┗┻┗┗┗┻┗┻┗┗┗┛┛┗

    @field_validator("tokenKey", mode = "before")
    def parse_oid(cls, value):
        try: value = ObjectId(value)
        except: pass
        return value

    @field_validator("to", "cc", "bcc", mode = "before")
    def parse_recipients(cls, value):

        # Ensure that we are working with some kind of list:
        if value is None: value = []
        if isinstance(value, str): value = [value]

        # # Ensure that all values of the list look like valid mails:
        # for index, email_id in enumerate(value):
        #     if not regex.match(
        #         text = email_id,
        #         pattern = regex.REGEX_START + regex.REGEX_EMAIL_ID + regex.REGEX_END,
        #         case_sensitive = False,
        #     ): raise ValueError(f"'{email_id}' does not seem to be a valid e-mail id.")

        # Done here:
        return value


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# ***                                               MAIN PROGRAM                                                    ***
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if __name__ == "__main__":

    pass