import logging
import re
from dataclasses import dataclass
from datetime import datetime, timezone

from bson import ObjectId

from app.models import MailDomain
from app.services.handoff_email_templates import external_reply_subject
from app.services.mail_sender import deliver_email
from app.services.message_ids import normalize_message_id
from app.services.thread_service import (
    attach_message_to_thread,
    message_event_at,
    threading_fields_from_parent,
)

logger = logging.getLogger(__name__)

MESSAGE_SCOPE_EXTERNAL = "EXTERNAL"


@dataclass(frozen=True)
class ExternalReplyThreading:
    in_reply_to: str | None
    references: list[str]
    parent_internal_message_id: ObjectId
    replying_to_internet_message_id: str | None


@dataclass(frozen=True)
class ExternalReplyPlan:
    subject: str
    body_text: str
    body_html: str | None
    threading: ExternalReplyThreading
    recipients: list[str]


def internet_message_id_of(message: dict) -> str | None:
    return normalize_message_id(
        message.get("internet_message_id") or message.get("message_id")
    )


def build_external_reply_plan(
    *,
    parent_external_message: dict,
    body_text: str,
    body_html: str | None = None,
    subject_override: str | None = None,
    recipients: list[str],
) -> ExternalReplyPlan:
    threading_fields = threading_fields_from_parent(parent_external_message)
    parent_internet_id = internet_message_id_of(parent_external_message)
    if subject_override:
        subject = subject_override
    else:
        parent_subject = parent_external_message.get("subject", "")
        subject = (
            parent_subject
            if re.match(r"^re:\s*", parent_subject, flags=re.IGNORECASE)
            else external_reply_subject(parent_subject)
        )
    return ExternalReplyPlan(
        subject=subject,
        body_text=body_text,
        body_html=body_html,
        threading=ExternalReplyThreading(
            in_reply_to=threading_fields.get("in_reply_to"),
            references=threading_fields.get("references", []),
            parent_internal_message_id=parent_external_message["_id"],
            replying_to_internet_message_id=parent_internet_id,
        ),
        recipients=recipients,
    )


def log_smtp_message_sending(
    *,
    generated_message_id: str | None,
    in_reply_to: str | None,
    references: list[str] | None,
    sender: str,
    recipients: list[str],
    subject: str,
    external_thread_id: ObjectId | str | None = None,
    replying_to_internal_message_id: ObjectId | str | None = None,
    replying_to_internet_message_id: str | None = None,
) -> None:
    logger.info(
        "smtp_message_sending generated_message_id=%s in_reply_to=%s references=%s "
        "from=%s to=%s subject=%s external_thread_id=%s "
        "replying_to_internal_message_id=%s replying_to_internet_message_id=%s",
        generated_message_id,
        in_reply_to,
        " ".join(references or []),
        sender,
        ",".join(recipients),
        subject,
        external_thread_id,
        replying_to_internal_message_id,
        replying_to_internet_message_id,
    )


async def send_external_reply(
    database,
    *,
    account_id: str,
    sender: str,
    sender_name: str,
    external_thread_id: ObjectId,
    plan: ExternalReplyPlan,
    domain: MailDomain,
    resolution_method: str = "in_reply_to",
) -> dict:
    log_smtp_message_sending(
        generated_message_id=None,
        in_reply_to=plan.threading.in_reply_to,
        references=plan.threading.references,
        sender=sender,
        recipients=plan.recipients,
        subject=plan.subject,
        external_thread_id=external_thread_id,
        replying_to_internal_message_id=plan.threading.parent_internal_message_id,
        replying_to_internet_message_id=plan.threading.replying_to_internet_message_id,
    )

    internet_message_id = await deliver_email(
        sender=sender,
        recipients=plan.recipients,
        cc=[],
        bcc=[],
        subject=plan.subject,
        body_text=plan.body_text,
        body_html=plan.body_html,
        domain=domain,
        in_reply_to=plan.threading.in_reply_to,
        references=plan.threading.references,
    )
    normalized_id = normalize_message_id(internet_message_id)
    log_smtp_message_sending(
        generated_message_id=normalized_id,
        in_reply_to=plan.threading.in_reply_to,
        references=plan.threading.references,
        sender=sender,
        recipients=plan.recipients,
        subject=plan.subject,
        external_thread_id=external_thread_id,
        replying_to_internal_message_id=plan.threading.parent_internal_message_id,
        replying_to_internet_message_id=plan.threading.replying_to_internet_message_id,
    )

    now = datetime.now(timezone.utc)
    document = {
        "direction": "outbound",
        "message_scope": MESSAGE_SCOPE_EXTERNAL,
        "account_id": account_id,
        "sender": {"name": sender_name, "address": sender},
        "to": [{"name": value.split("@")[0], "address": value} for value in plan.recipients],
        "subject": plan.subject,
        "snippet": re.sub(r"\s+", " ", plan.body_text).strip()[:240],
        "body_text": plan.body_text,
        "body_html": plan.body_html,
        "attachments": [],
        "created_at": now,
        "sent_at": now,
        "status": "accepted",
        "message_id": normalized_id,
        "internet_message_id": normalized_id,
        "in_reply_to": plan.threading.in_reply_to,
        "references": plan.threading.references,
        "parent_message_id": plan.threading.parent_internal_message_id,
        "thread_relation": "reply",
        "thread_resolution_method": resolution_method,
    }
    result = await database.messages.insert_one(document)
    document["_id"] = result.inserted_id
    await attach_message_to_thread(
        database,
        account_id=account_id,
        thread_id=external_thread_id,
        message_id=result.inserted_id,
        subject=plan.subject,
        event_at=now,
    )
    await database.mailbox_entries.insert_one(
        {
            "account_id": account_id,
            "message_id": result.inserted_id,
            "thread_id": external_thread_id,
            "mailbox": "sent",
            "message_scope": MESSAGE_SCOPE_EXTERNAL,
            "direction": "outbound",
            "sender": document["sender"],
            "recipients": document["to"],
            "subject": plan.subject,
            "snippet": document["snippet"],
            "attachments": [],
            "status": "accepted",
            "is_read": True,
            "is_starred": False,
            "event_at": now,
            "created_at": now,
            "trashed_at": None,
            "deletion_state": None,
        }
    )
    return document