"""Multi-account support for Synology Chat channel.

Manages multiple DSM connections with independent configurations,
credential management, and default account routing.
"""

from __future__ import annotations

from dataclasses import dataclass, field
from typing import Any

DEFAULT_ACCOUNT_ID = "default"

_BASE_FIELD_KEYS = (
    "dsm_url",
    "username",
    "password",
    "password_file",
    "verify_ssl",
    "name",
)


@dataclass
class AccountConfig:
    id: str
    dsm_url: str = ""
    username: str = ""
    password: str = ""
    password_file: str = ""
    verify_ssl: bool = True
    name: str = ""
    extra: dict[str, Any] = field(default_factory=dict)


def list_account_ids(config: dict[str, Any]) -> list[str]:
    accounts = config.get("accounts", {})
    if not isinstance(accounts, dict) or not accounts:
        return [DEFAULT_ACCOUNT_ID]
    return sorted(accounts.keys())


def resolve_account(config: dict[str, Any], account_id: str = DEFAULT_ACCOUNT_ID) -> AccountConfig:
    """Resolve configuration for a specific account with priority chain:
    account > base > env.

    For named accounts (non-default), base fields that are NOT explicitly
    overridden in the account config are cleared to prevent unwanted
    inheritance of sensitive values.
    """
    base = {
        "dsm_url": config.get("dsm_url", ""),
        "username": config.get("username", ""),
        "password": config.get("password", ""),
        "password_file": config.get("password_file", ""),
        "verify_ssl": config.get("verify_ssl", True),
        "name": config.get("name", "synologychat"),
    }

    accounts = config.get("accounts", {})
    account_cfg = accounts.get(account_id, {}) if isinstance(accounts, dict) else {}

    if account_id != DEFAULT_ACCOUNT_ID:
        merged = {}
        for k in _BASE_FIELD_KEYS:
            if k in account_cfg:
                merged[k] = account_cfg[k]
            else:
                merged[k] = "" if k not in ("verify_ssl", "name") else base[k]
        if "name" not in account_cfg:
            merged["name"] = merged["name"] or f"synologychat-{account_id}"
    else:
        merged = {k: account_cfg.get(k, base[k]) for k in base}

    return AccountConfig(
        id=account_id,
        dsm_url=merged["dsm_url"],
        username=merged["username"],
        password=merged["password"],
        password_file=merged["password_file"],
        verify_ssl=merged["verify_ssl"],
        name=merged["name"],
        extra={k: v for k, v in account_cfg.items() if k not in base},
    )


def get_default_account_id(config: dict[str, Any]) -> str:
    return config.get("default_account", DEFAULT_ACCOUNT_ID)


def has_multi_account(config: dict[str, Any]) -> bool:
    accounts = config.get("accounts", {})
    return isinstance(accounts, dict) and len(accounts) > 0