from __future__ import annotations

from enum import StrEnum
from typing import Any

from pydantic import BaseModel, ConfigDict, Field, model_validator


class StrictModel(BaseModel):
    model_config = ConfigDict(extra="forbid", populate_by_name=True)


class TransportSecurity(StrEnum):
    PLAIN = "plain"
    TLS = "tls"
    STARTTLS = "starttls"


class TransportCredentials(StrictModel):
    username: str | None = None
    password: str | None = None


class SmtpServerConfig(StrictModel):
    host: str | None = None
    port: int | None = Field(default=None, ge=1, le=65535)
    security: TransportSecurity = TransportSecurity.STARTTLS
    timeout_seconds: int = Field(default=30, ge=1)

    @model_validator(mode="after")
    def apply_default_port(self) -> "SmtpServerConfig":
        if self.port is None:
            self.port = default_smtp_port(self.security)
        return self


class ImapServerConfig(StrictModel):
    host: str | None = None
    port: int | None = Field(default=None, ge=1, le=65535)
    security: TransportSecurity = TransportSecurity.TLS
    sent_folder: str = "auto"
    timeout_seconds: int = Field(default=30, ge=1)

    @model_validator(mode="before")
    @classmethod
    def discard_legacy_enabled(cls, value: Any) -> Any:
        if isinstance(value, dict) and "enabled" in value:
            data = dict(value)
            data.pop("enabled", None)
            return data
        return value

    @model_validator(mode="after")
    def apply_default_port(self) -> "ImapServerConfig":
        if self.port is None:
            self.port = default_imap_port(self.security)
        return self


class SmtpConfig(SmtpServerConfig):
    username: str | None = None
    password: str | None = None


class ImapConfig(ImapServerConfig):
    username: str | None = None
    password: str | None = None


def normalize_split_transport_credentials(value: object) -> object:
    """Move legacy transport username/password fields into credentials."""
    if not isinstance(value, dict):
        return value
    data = dict(value)
    credentials = data.get("credentials") if isinstance(data.get("credentials"), dict) else {}
    credentials = {key: dict(item) for key, item in credentials.items() if isinstance(item, dict)}
    for protocol in ("smtp", "imap"):
        transport = data.get(protocol)
        if not isinstance(transport, dict):
            continue
        next_transport = dict(transport)
        next_credentials = dict(credentials.get(protocol) or {})
        for field in ("username", "password"):
            if field in next_transport and field not in next_credentials:
                next_credentials[field] = next_transport[field]
            next_transport.pop(field, None)
        next_transport.pop("enabled", None)
        data[protocol] = next_transport
        if next_credentials:
            credentials[protocol] = next_credentials
    if credentials:
        data["credentials"] = credentials
    return data


def default_smtp_port(security: TransportSecurity | str | None) -> int:
    if security == TransportSecurity.TLS or security == "tls":
        return 465
    if security == TransportSecurity.PLAIN or security == "plain":
        return 25
    return 587


def default_imap_port(security: TransportSecurity | str | None) -> int:
    if security == TransportSecurity.TLS or security == "tls":
        return 993
    return 143