import { HttpStatus, Inject, Injectable } from "@nestjs/common";
import { ErrorCode } from "@drift/contracts";
import { Prisma, type Account } from "@prisma/client";
import { randomInt, randomUUID } from "node:crypto";
import { DomainException } from "../common/domain.exception.js";
import { PrismaService } from "../database/prisma.service.js";
import { RedisService } from "../redis/redis.service.js";
import {
  codeHmac,
  demoSmsCodeEnabled,
  encryptPhone,
  envInt,
  phoneHmac,
  refreshHmac,
} from "./auth.config.js";
import { TokenService } from "./token.service.js";

export interface TokenPair {
  accessToken: string;
  refreshToken: string;
  expiresIn: number;
}
@Injectable()
export class AuthService {
  constructor(
    @Inject(PrismaService) private readonly prisma: PrismaService,
    @Inject(RedisService) private readonly redis: RedisService,
    @Inject(TokenService) private readonly tokens: TokenService,
  ) {}
  normalizePhone(raw: string): string {
    const compact = raw.replace(/[\s()-]/g, "");
    const local = compact.startsWith("+86")
      ? compact.slice(3)
      : compact.startsWith("86") && compact.length === 13
        ? compact.slice(2)
        : compact;
    if (!/^1[3-9]\d{9}$/.test(local))
      throw new DomainException(
        ErrorCode.AUTH_INVALID_CREDENTIALS,
        "Invalid credentials",
        HttpStatus.UNAUTHORIZED,
      );
    return `+86${local}`;
  }
  private prefix() {
    return process.env.REDIS_KEY_PREFIX ?? "drift:auth:";
  }
  private async limitAll(
    dimensions: Array<{
      kind: string;
      parts: string[];
      max: number;
      ttl: number;
    }>,
  ): Promise<void> {
    await this.redis.ensureConnected();
    const keys = dimensions.map(
      ({ kind, parts }) => `${this.prefix()}limit:${kind}:${parts.join(":")}`,
    );
    const args = dimensions.flatMap(({ max, ttl }) => [
      String(max),
      String(ttl),
    ]);
    // Atomic across all dimensions on the MVP's single Redis node. Redis Cluster
    // would require a colocated hash tag or a different distributed limiter.
    const result = Number(
      await this.redis.client.eval(
        `for i,key in ipairs(KEYS) do local n=tonumber(redis.call('GET',key) or '0'); local max=tonumber(ARGV[(i-1)*2+1]); if n+1>max then return 0 end end; for i,key in ipairs(KEYS) do local n=redis.call('INCR',key); if n==1 then redis.call('EXPIRE',key,ARGV[(i-1)*2+2]) end end; return 1`,
        { keys, arguments: args },
      ),
    );
    if (result !== 1)
      throw new DomainException(
        ErrorCode.RATE_LIMITED,
        "Too many requests",
        HttpStatus.TOO_MANY_REQUESTS,
      );
  }
  async sendSms(
    rawPhone: string,
    deviceId: string,
    ip: string,
  ): Promise<{ sent: true; debugCode?: string }> {
    const phone = this.normalizePhone(rawPhone);
    const digest = phoneHmac(phone);
    const window = envInt("SMS_RATE_WINDOW_SECONDS", 300);
    await this.limitAll([
      {
        kind: "send-phone",
        parts: [digest],
        max: envInt("SMS_SEND_LIMIT", 3),
        ttl: window,
      },
      {
        kind: "send-device",
        parts: [deviceId],
        max: envInt("SMS_SEND_DEVICE_LIMIT", 5),
        ttl: window,
      },
      {
        kind: "send-ip",
        parts: [phoneHmac(ip)],
        max: envInt("SMS_SEND_IP_LIMIT", 10),
        ttl: window,
      },
    ]);
    const code = randomInt(0, 1000000).toString().padStart(6, "0");
    await this.redis.client.set(
      `${this.prefix()}code:${digest}`,
      codeHmac(digest, code),
      { EX: envInt("SMS_CODE_TTL_SECONDS", 300) },
    );
    const result: { sent: true; debugCode?: string } = { sent: true };
    if (demoSmsCodeEnabled()) result.debugCode = code;
    return result;
  }
  async login(
    rawPhone: string,
    code: string,
    deviceId: string,
    ip: string,
  ): Promise<TokenPair> {
    const phone = this.normalizePhone(rawPhone);
    const digest = phoneHmac(phone);
    const window = envInt("SMS_RATE_WINDOW_SECONDS", 300);
    await this.limitAll([
      {
        kind: "verify-phone",
        parts: [digest],
        max: envInt("SMS_VERIFY_LIMIT", 5),
        ttl: window,
      },
      {
        kind: "verify-combined",
        parts: [digest, phoneHmac(ip), deviceId],
        max: envInt("SMS_VERIFY_COMBINED_LIMIT", 5),
        ttl: window,
      },
    ]);
    const key = `${this.prefix()}code:${digest}`;
    const consumed = await this.redis.client.eval(
      `local v=redis.call('GET',KEYS[1]); if v and v==ARGV[1] then redis.call('DEL',KEYS[1]); return 1 end; return 0`,
      { keys: [key], arguments: [codeHmac(digest, code)] },
    );
    if (Number(consumed) !== 1) throw this.invalid();
    let account = await this.prisma.account.findUnique({
      where: { phoneHmac: digest },
    });
    if (!account) account = await this.createAccount(phone, digest);
    if (account.status !== "ACTIVE") throw this.invalid();
    const now = new Date();
    const sanction = await this.prisma.sanction.findFirst({
      where: {
        accountId: account.id,
        type: { in: ["SUSPENSION", "BAN"] },
        revokedAt: null,
        startsAt: { lte: now },
        OR: [{ expiresAt: null }, { expiresAt: { gt: now } }],
      },
      select: { id: true },
    });
    if (sanction) throw this.invalid();
    return this.createSession(account, deviceId);
  }
  private async createAccount(phone: string, digest: string): Promise<Account> {
    try {
      return await this.prisma.account.create({
        data: {
          phoneHmac: digest,
          phoneCiphertext: new Uint8Array(encryptPhone(phone)),
        },
      });
    } catch (error) {
      if (
        error instanceof Prisma.PrismaClientKnownRequestError &&
        error.code === "P2002"
      ) {
        const found = await this.prisma.account.findUnique({
          where: { phoneHmac: digest },
        });
        if (found) return found;
      }
      throw error;
    }
  }
  private async createSession(
    account: Account,
    deviceId: string,
  ): Promise<TokenPair> {
    const id = randomUUID();
    const refresh = this.tokens.newRefresh();
    const expiresAt = new Date(
      Date.now() + envInt("REFRESH_TOKEN_TTL_SECONDS", 2592000) * 1000,
    );
    await this.prisma.session.create({
      data: {
        id,
        accountId: account.id,
        tokenVersion: account.tokenVersion,
        deviceId,
        refreshTokenHash: refreshHmac(refresh),
        tokenFamily: id,
        expiresAt,
        refreshTokens: {
          create: { tokenHash: refreshHmac(refresh), generation: 0, expiresAt },
        },
      },
    });
    return this.pair(account, id, deviceId, refresh);
  }
  private pair(
    account: Account,
    sessionId: string,
    deviceId: string,
    refreshToken: string,
  ): TokenPair {
    const expiresIn = envInt("ACCESS_TOKEN_TTL_SECONDS", 900);
    return {
      accessToken: this.tokens.issueAccess({
        sub: account.id,
        session_id: sessionId,
        device_id: deviceId,
        scopes: ["user"],
        token_version: account.tokenVersion,
      }),
      refreshToken,
      expiresIn,
    };
  }
  async refresh(
    token: string,
    ip: string,
    retryAttempt = 0,
  ): Promise<TokenPair> {
    if (!this.validRefreshShape(token)) throw this.invalid();
    if (retryAttempt === 0)
      await this.limitAll([
        {
          kind: "refresh-attempt-ip",
          parts: [phoneHmac(ip)],
          max: envInt("REFRESH_ATTEMPT_IP_LIMIT", 30),
          ttl: envInt("REFRESH_ATTEMPT_IP_WINDOW_SECONDS", 60),
        },
      ]);
    const hash = refreshHmac(token);
    const observed = await this.prisma.refreshToken.findUnique({
      where: { tokenHash: hash },
      include: { session: true },
    });
    if (!observed) throw this.invalid();
    if (retryAttempt === 0) {
      await this.limitAll([
        {
          kind: "refresh-token",
          parts: [hash],
          max: envInt("REFRESH_RATE_LIMIT", 60),
          ttl: 60,
        },
        {
          kind: "refresh-session",
          parts: [observed.sessionId],
          max: envInt("REFRESH_RATE_LIMIT", 60),
          ttl: 60,
        },
      ]);
      await this.cleanupExpiredRefreshTokens(observed.sessionId);
    }
    if (observed.status === "USED")
      return this.revokeReusedFamily(observed.session.tokenFamily);

    try {
      const result = await this.prisma.$transaction(
        async (tx): Promise<TokenPair | { reusedFamily: string }> => {
          const stored = await tx.refreshToken.findUnique({
            where: { tokenHash: hash },
            include: { session: { include: { account: true } } },
          });
          if (!stored) throw this.invalid();
          if (stored.status === "USED")
            return { reusedFamily: stored.session.tokenFamily };
          const session = stored.session;
          if (session.tokenVersion !== session.account.tokenVersion)
            return { reusedFamily: session.tokenFamily };
          if (
            session.revokedAt ||
            session.expiresAt <= new Date() ||
            stored.expiresAt <= new Date() ||
            session.account.status !== "ACTIVE"
          )
            throw this.invalid();
          const next = this.tokens.newRefresh();
          const nextHash = refreshHmac(next);
          const usedAt = new Date();
          const changed = await tx.refreshToken.updateMany({
            where: { id: stored.id, status: "ACTIVE" },
            data: { status: "USED", usedAt, replacedByHash: nextHash },
          });
          if (changed.count !== 1) return { reusedFamily: session.tokenFamily };
          await tx.refreshToken.create({
            data: {
              tokenHash: nextHash,
              sessionId: session.id,
              generation: stored.generation + 1,
              expiresAt: session.expiresAt,
            },
          });
          await tx.session.update({
            where: { id: session.id },
            data: {
              previousTokenHash: hash,
              refreshTokenHash: nextHash,
              generation: stored.generation + 1,
              rotatedAt: usedAt,
            },
          });
          return this.pair(
            session.account,
            session.id,
            session.deviceId ?? "",
            next,
          );
        },
        { isolationLevel: Prisma.TransactionIsolationLevel.Serializable },
      );
      if ("reusedFamily" in result)
        return this.revokeReusedFamily(result.reusedFamily);
      return result;
    } catch (error) {
      if (error instanceof DomainException) throw error;
      if (
        error instanceof Prisma.PrismaClientKnownRequestError &&
        (error.code === "P2034" || error.code === "P2002")
      ) {
        if (retryAttempt < 3) {
          await new Promise((resolve) =>
            setTimeout(resolve, 10 * 2 ** retryAttempt),
          );
          return this.refresh(token, ip, retryAttempt + 1);
        }
        const raced = await this.prisma.refreshToken.findUnique({
          where: { tokenHash: hash },
          include: { session: true },
        });
        if (raced?.status === "USED")
          return this.revokeReusedFamily(raced.session.tokenFamily);
        throw new DomainException(
          ErrorCode.SERVICE_UNAVAILABLE,
          "Authentication temporarily unavailable",
          HttpStatus.SERVICE_UNAVAILABLE,
        );
      }
      throw error;
    }
  }
  async cleanupExpiredRefreshTokens(sessionId?: string): Promise<number> {
    const deleted = await this.prisma.refreshToken.deleteMany({
      where: {
        expiresAt: { lt: new Date() },
        ...(sessionId ? { sessionId } : {}),
      },
    });
    return deleted.count;
  }
  private async revokeReusedFamily(family: string): Promise<never> {
    await this.prisma.session.updateMany({
      where: { tokenFamily: family },
      data: { revokedAt: new Date() },
    });
    throw new DomainException(
      ErrorCode.AUTH_REFRESH_REUSED,
      "Refresh token reused",
      HttpStatus.UNAUTHORIZED,
    );
  }
  async logout(token: string | undefined): Promise<void> {
    if (!token || !this.validRefreshShape(token)) return;
    const stored = await this.prisma.refreshToken.findUnique({
      where: { tokenHash: refreshHmac(token) },
      include: { session: true },
    });
    if (!stored) return;
    await this.prisma.session.updateMany({
      where: { tokenFamily: stored.session.tokenFamily },
      data: { revokedAt: new Date() },
    });
  }
  private validRefreshShape(token: string): boolean {
    return /^[A-Za-z0-9_-]{43}$/.test(token);
  }
  private invalid() {
    return new DomainException(
      ErrorCode.AUTH_INVALID_CREDENTIALS,
      "Invalid credentials",
      HttpStatus.UNAUTHORIZED,
    );
  }
}