# -*- coding: utf-8 -*-
"""短信生态服务（云超服平台统一短信）。

支持两类 provider（由系统配置 ``sms.provider`` 控制）：

- ``stub``：仅打印短信内容不发真实短信（默认，便于无短信资质联调）。
- ``aliyun``：阿里云短信服务（dysmsapi 2017-05-25），凭据/签名/模板全部来自
  ``system_configs`` 里的短信生态配置（admin 端「系统配置 → 短信生态」可在线维护）。

短信生态配置结构（system_configs 键值，均为 JSON 字符串或简单值）：

- ``sms.provider``           : provider 名（stub | aliyun）
- ``sms.aliyun``             : 阿里云总配置 JSON
      {"access_key_id": "", "access_key_secret": "", "sign_name": "",
       "region_id": "cn-hangzhou", "endpoint": "dysmsapi.aliyuncs.com"}
- ``sms.template.<scene>``   : 场景模板 JSON
      {"template_id": "SMS_xxx", "variables": ["code", "minute"]}
      场景（scene）：login 登录 / register 注册 / notification 通知 /
                     order_status 订单状态变动 / appointment 服务预约

验证码存储为内存（带 TTL 与尝试次数），进程重启即失效——生产应换 Redis。

模块保留无 db 依赖的验证码核心（issue/verify）；配置由调用方从
``system_configs`` 解析后传入（``load_sms_config(db)`` / ``parse_sms_config``）。
"""
from __future__ import annotations

import base64
import hashlib
import hmac
import json
import secrets
import threading
import time
import urllib.parse
from dataclasses import dataclass, field

import httpx

from .. import config

# ── 验证码存储（内存） ──────────────────────────────────────────────────────
# phone -> {"code": str, "expires_at": float, "attempts": int}
_STORE: dict[str, dict] = {}
_LOCK = threading.Lock()

_CODE_TTL = config.SMS_CODE_TTL_SECONDS
_MAX_ATTEMPTS = config.SMS_RATE_LIMIT

# 短信生态支持的全部场景（admin 端按此枚举展示/维护模板）。
SMS_SCENES = ("login", "register", "notification", "order_status", "appointment")
SMS_SCENE_LABELS = {
    "login": "登录验证码",
    "register": "注册验证码",
    "notification": "通知提醒",
    "order_status": "订单状态变动",
    "appointment": "服务预约",
}


class SmsError(Exception):
    """短信业务异常（校验失败 / 限流 / 发送失败等）。"""


# ── 配置模型 ────────────────────────────────────────────────────────────────

@dataclass
class AliyunSmsConfig:
    access_key_id: str = ""
    access_key_secret: str = ""
    sign_name: str = ""
    region_id: str = "cn-hangzhou"
    endpoint: str = "dysmsapi.aliyuncs.com"

    @property
    def configured(self) -> bool:
        return bool(self.access_key_id and self.access_key_secret and self.sign_name)


@dataclass
class TemplateConfig:
    scene: str = ""
    template_id: str = ""
    variables: list[str] = field(default_factory=list)


@dataclass
class SmsConfig:
    provider: str = "stub"
    aliyun: AliyunSmsConfig = field(default_factory=AliyunSmsConfig)
    templates: dict[str, TemplateConfig] = field(default_factory=dict)

    def template(self, scene: str) -> TemplateConfig | None:
        return self.templates.get(scene)


def _json_dct(raw: str) -> dict:
    try:
        v = json.loads(raw or "{}")
        return v if isinstance(v, dict) else {}
    except (json.JSONDecodeError, TypeError):
        return {}


def parse_sms_config(rows: dict[str, str]) -> SmsConfig:
    """从 system_configs 键值对（key -> value 字符串）解析短信生态配置。"""
    cfg = SmsConfig(provider=(rows.get("sms.provider") or "stub").strip().lower())
    al = _json_dct(rows.get("sms.aliyun") or "")
    cfg.aliyun = AliyunSmsConfig(
        access_key_id=str(al.get("access_key_id", "")).strip(),
        access_key_secret=str(al.get("access_key_secret", "")).strip(),
        sign_name=str(al.get("sign_name", "")).strip(),
        region_id=str(al.get("region_id", "") or "cn-hangzhou").strip(),
        endpoint=str(al.get("endpoint", "") or "dysmsapi.aliyuncs.com").strip(),
    )
    for scene in SMS_SCENES:
        tpl = _json_dct(rows.get(f"sms.template.{scene}") or "")
        vars_ = tpl.get("variables")
        if isinstance(vars_, str):
            vars_ = [v.strip() for v in vars_.split(",") if v.strip()]
        cfg.templates[scene] = TemplateConfig(
            scene=scene,
            template_id=str(tpl.get("template_id", "")).strip(),
            variables=[str(v).strip() for v in (vars_ or []) if str(v).strip()],
        )
    return cfg


async def load_sms_config(db) -> SmsConfig:
    """从数据库 system_configs 加载短信生态配置（未配置的键保持默认）。"""
    rows: dict[str, str] = {}
    for c in await db.config.all():
        rows[c["key"]] = str(c.get("value") or "")
    return parse_sms_config(rows)


# ── 验证码核心（无 db 依赖） ───────────────────────────────────────────────

def issue(phone: str) -> str:
    """为手机号生成 6 位验证码并写入存储，返回明文。

    真实发送由调用方依据场景模板调用 :func:`send_template` 完成；
    若 provider 为 stub 且未指定场景模板，也可直接调用 :func:`send_code`。
    """
    code = DEMO_CODE if config.SMS_PROVIDER == "stub" else f"{secrets.randbelow(1_000_000):06d}"
    with _LOCK:
        _STORE[phone] = {
            "code": code,
            "expires_at": time.monotonic() + _CODE_TTL,
            "attempts": 0,
        }
    return code


def verify(phone: str, code: str) -> bool:
    """校验验证码；成功即作废，失败累计次数超限则不可再试。"""
    with _LOCK:
        rec = _STORE.get(phone)
        if not rec:
            raise SmsError("verification code not issued")
        if time.monotonic() > rec["expires_at"]:
            _STORE.pop(phone, None)
            raise SmsError("verification code expired")
        if rec["attempts"] >= _MAX_ATTEMPTS:
            raise SmsError("too many attempts, request a new code")
        if rec["code"] != code.strip():
            rec["attempts"] += 1
            raise SmsError("invalid verification code")
        _STORE.pop(phone, None)
        return True


# 演示验证码：stub provider 统一用固定码（先跑通流程，生产换真实短信）。
DEMO_CODE = "123456"


def _pick_code(cfg: SmsConfig) -> str:
    """按 provider 决定验证码：stub 固定码，aliyun 随机码。"""
    if cfg.provider == "stub" or config.SMS_PROVIDER == "stub":
        return DEMO_CODE
    return f"{secrets.randbelow(1_000_000):06d}"


async def send_code(cfg: SmsConfig, phone: str, scene: str = "login",
                    extra: dict[str, str] | None = None) -> str:
    """生成并发送验证码（场景模板），返回明文供 stub 展示。

    - stub provider：仅打印（含模板信息），返回固定码 123456。
    - aliyun provider：按场景模板 + 变量（code/minute）真实发送，返回随机码。
    """
    scene = scene if scene in SMS_SCENES else "login"
    code = _pick_code(cfg)
    with _LOCK:
        _STORE[phone] = {
            "code": code,
            "expires_at": time.monotonic() + _CODE_TTL,
            "attempts": 0,
        }
    params = {"code": code, "minute": str(_CODE_TTL // 60)}
    if extra:
        params.update(extra)
    await send_template(cfg, scene, phone, params)
    return code


# ── 场景短信发送 ────────────────────────────────────────────────────────────

async def send_template(cfg: SmsConfig, scene: str, phone: str,
                        params: dict[str, str]) -> None:
    """按场景模板发送一条短信（非验证码也可用）。

    未配置该场景模板或 provider 为 stub 时仅打印（不报错），保证业务不因
    短信配置缺失而失败；aliyun 模板缺失 / 凭据未配置时抛 SmsError。
    """
    scene = scene if scene in SMS_SCENES else "notification"
    tpl = cfg.template(scene)
    if cfg.provider == "stub" or not tpl or not tpl.template_id:
        _print_stub(cfg, scene, phone, tpl, params)
        return
    if cfg.provider == "aliyun":
        if not cfg.aliyun.configured:
            raise SmsError("阿里云短信未配置（access_key_id/secret/sign_name）")
        await _send_aliyun(cfg.aliyun, tpl, phone, params)
        return
    raise SmsError(f"unsupported sms provider: {cfg.provider}")


def _print_stub(cfg: SmsConfig, scene: str, phone: str,
                tpl: TemplateConfig | None, params: dict[str, str]) -> None:
    label = SMS_SCENE_LABELS.get(scene, scene)
    tid = tpl.template_id if tpl else ""
    body = " ".join(f"{k}={v}" for k, v in params.items()) or "-"
    print(f"[sms:stub] [{label}] template={tid or '-'} -> {phone}: {body}")


# ── 阿里云短信（dysmsapi 2017-05-25, RPC 签名） ─────────────────────────────

def _percent_encode(s: str) -> str:
    res = urllib.parse.quote(str(s), safe="~")
    # RPC 规范：空格 → %20（quote 默认 safe 不含空格，已满足），/ 需编码
    res = res.replace("+", "%20").replace("*", "%2A").replace("%7E", "~")
    return res


def _aliyun_sign(secret: str, params: dict[str, str]) -> str:
    """阿里云 RPC 签名：HMAC-SHA1(secret + '&', 规范化查询串)。"""
    query = "&".join(
        f"{_percent_encode(k)}={_percent_encode(params[k])}"
        for k in sorted(params)
    )
    string_to_sign = "GET&%2F&" + _percent_encode(query)
    key = (secret + "&").encode("utf-8")
    digest = hmac.new(key, string_to_sign.encode("utf-8"), hashlib.sha1).digest()
    return base64.b64encode(digest).decode("utf-8")


async def _send_aliyun(aliyun: AliyunSmsConfig, tpl: TemplateConfig,
                       phone: str, params: dict[str, str]) -> None:
    common = {
        "AccessKeyId": aliyun.access_key_id,
        "Action": "SendSms",
        "Format": "JSON",
        "RegionId": aliyun.region_id or "cn-hangzhou",
        "SignatureMethod": "HMAC-SHA1",
        "SignatureNonce": secrets.token_hex(16),
        "SignatureVersion": "1.0",
        "Timestamp": time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime()),
        "Version": "2017-05-25",
        "PhoneNumbers": phone,
        "SignName": aliyun.sign_name,
        "TemplateCode": tpl.template_id,
    }
    if params:
        common["TemplateParam"] = json.dumps(params, ensure_ascii=False)
    common["Signature"] = _aliyun_sign(aliyun.access_key_secret, common)

    url = f"https://{aliyun.endpoint or 'dysmsapi.aliyuncs.com'}/"
    try:
        async with httpx.AsyncClient(timeout=10.0, trust_env=False) as client:
            resp = await client.get(url, params=common)
    except httpx.HTTPError as exc:
        raise SmsError(f"阿里云短信请求失败: {exc}")
    if resp.status_code != 200:
        raise SmsError(f"阿里云短信返回 {resp.status_code}: {resp.text[:200]}")
    try:
        data = resp.json()
    except ValueError:
        raise SmsError(f"阿里云短信响应解析失败: {resp.text[:200]}")
    code = str(data.get("Code", ""))
    if code != "OK":
        raise SmsError(f"阿里云短信发送失败: {code} {data.get('Message', '')}")