from __future__ import annotations

from abc import ABC, abstractmethod
from dataclasses import dataclass


@dataclass
class BaseChannelAccount:
    """渠道账户基类（所有可多账户的适配器共用）"""

    account_id: str = "default"
    enabled: bool = True
    dm_policy: str = "allowlist"
    group_policy: str = "allowlist"
    name: str = ""
    upgrade_url: str = ""
    upgrade_mode: str = ""


class BaseAccountManager(ABC):
    """多账户管理器基类

    定义四个标准接口：
    - resolve_account(cfg, account_id) → BaseChannelAccount
    - is_configured(account_id) → bool
    - default_account_id(cfg) → str
    - list_account_ids(cfg) → list[str]
    """

    @abstractmethod
    def resolve_account(self, cfg: dict, account_id: str = "default") -> BaseChannelAccount: ...

    @abstractmethod
    def is_configured(self, account_id: str = "default") -> bool: ...

    @abstractmethod
    def default_account_id(self, cfg: dict) -> str: ...

    @abstractmethod
    def list_account_ids(self, cfg: dict) -> list[str]: ...


def resolve_account_from_config_section(
    config: dict,
    account_id: str,
    section_key: str = "accounts",
) -> dict:
    """从配置中提取指定账户的配置段

    兼容两种配置结构：
    1. 多账户（推荐）：
       { accounts: { default: {...}, second: {...} }, defaultAccount: 'default' }

    2. 单账户（兼容旧格式）：
       { app_id: "...", client_secret: "..." }  — 平铺格式

    返回：账户配置 dict（可能为空）
    """
    accounts = config.get(section_key, {})
    if not accounts:
        return config

    account_cfg = accounts.get(account_id, {})
    if not account_cfg and account_id == "default":
        first = next(iter(accounts.values()), {})
        return first
    return account_cfg


def resolve_account_ids(
    config: dict,
    section_key: str = "accounts",
) -> list[str]:
    """从配置中提取所有账户 ID"""
    accounts = config.get(section_key, {})
    if not accounts:
        return ["default"]
    return list(accounts.keys())


def resolve_default_account_id(
    config: dict,
    section_key: str = "accounts",
) -> str:
    """解析默认账户 ID

    优先级：defaultAccount > 'default' > 第一个账户
    """
    explicit = config.get("defaultAccount", config.get("default_account", ""))
    if explicit:
        return explicit

    accounts = config.get(section_key, {})
    if not accounts:
        return "default"
    if "default" in accounts:
        return "default"
    return next(iter(accounts.keys()), "default")


def resolve_effective_dm_scope(config: dict) -> str:
    """解析会话隔离策略（多账户场景的关键配置）

    - 'merged': 所有账户的 DM 合并到同一个会话
    - 'per-account-channel-peer': 按 账户/渠道/发送者 独立隔离会话（推荐默认值）
    """
    return config.get("dmScope", config.get("dm_scope", "per-account-channel-peer"))