import { FastifyInstance } from "fastify";
import { z } from "zod";
import { randomBytes } from "node:crypto";
import bcrypt from "bcrypt";
import prisma from "../lib/prisma.js";
import { blindIndex, hashToken } from "../services/encryption.js";
import { blindIndexKey } from "../config.js";
import { verifyChallenge } from "../services/altcha.js";
import { generateRecoveryPhrase } from "../lib/wordlist.js";

const EXPIRY_DAYS = 90;

const recoverBody = z.object({
  phrase: z.string().regex(/^[a-z]+-[a-z]+-[a-z]+-[a-z]+-[a-z]+-[a-z]+$/),
  altcha: z.string(),
});

async function getFailedAttempts(ip: string): Promise<number> {
  const cutoff = new Date(Date.now() - 15 * 60 * 1000);
  const count = await prisma.blockedToken.count({
    where: { tokenHash: { startsWith: `recovery:${ip}:` }, createdAt: { gt: cutoff } },
  });
  return count;
}

async function recordFailedAttempt(ip: string): Promise<void> {
  await prisma.blockedToken.create({
    data: {
      tokenHash: `recovery:${ip}:${Date.now()}`,
      expiresAt: new Date(Date.now() + 15 * 60 * 1000),
    },
  });
}

export default async function recoveryRoutes(app: FastifyInstance) {
  // check if user has a recovery code
  app.get(
    "/me/recovery-code",
    { preHandler: [app.requireUser], config: { rateLimit: { max: 30, timeWindow: "1 minute" } } },
    async (req, reply) => {
      const code = await prisma.recoveryCode.findUnique({
        where: { userId: req.user!.id },
        select: { expiresAt: true },
      });
      if (code && code.expiresAt > new Date()) {
        reply.send({ hasCode: true, expiresAt: code.expiresAt });
      } else {
        reply.send({ hasCode: false });
      }
    }
  );

  // generate a new recovery code
  app.post(
    "/me/recovery-code",
    { preHandler: [app.requireUser], config: { rateLimit: { max: 3, timeWindow: "1 hour" } } },
    async (req, reply) => {
      if (req.user!.authMethod === "PASSKEY") {
        reply.status(400).send({ error: "Passkey users don't need recovery codes" });
        return;
      }

      const phrase = generateRecoveryPhrase();
      const codeHash = await bcrypt.hash(phrase, 12);
      const phraseIdx = blindIndex(phrase, blindIndexKey);
      const expiresAt = new Date(Date.now() + EXPIRY_DAYS * 24 * 60 * 60 * 1000);

      await prisma.recoveryCode.upsert({
        where: { userId: req.user!.id },
        create: { codeHash, phraseIdx, userId: req.user!.id, expiresAt },
        update: { codeHash, phraseIdx, expiresAt },
      });

      reply.send({ phrase, expiresAt });
    }
  );

  // recover identity using a code (unauthenticated)
  app.post(
    "/auth/recover",
    { config: { rateLimit: { max: 3, timeWindow: "15 minutes" } } },
    async (req, reply) => {
      const body = recoverBody.parse(req.body);

      const valid = await verifyChallenge(body.altcha);
      if (!valid) {
        reply.status(400).send({ error: "Invalid challenge response" });
        return;
      }

      // exponential backoff per IP (persistent)
      const attempts = await getFailedAttempts(req.ip);
      if (attempts >= 3) {
        const delay = Math.min(1000 * Math.pow(2, attempts - 3), 30000);
        await new Promise((r) => setTimeout(r, delay));
      }

      const phrase = body.phrase.toLowerCase().trim();
      const idx = blindIndex(phrase, blindIndexKey);

      const record = await prisma.recoveryCode.findUnique({
        where: { phraseIdx: idx },
        include: { user: { select: { id: true } } },
      });

      if (!record || record.expiresAt < new Date()) {
        await recordFailedAttempt(req.ip);
        reply.status(401).send({ error: "Invalid or expired recovery code" });
        return;
      }

      const matches = await bcrypt.compare(phrase, record.codeHash);
      if (!matches) {
        await recordFailedAttempt(req.ip);
        reply.status(401).send({ error: "Invalid or expired recovery code" });
        return;
      }

      // success - issue new session token and delete used code
      const token = randomBytes(32).toString("hex");
      const hash = hashToken(token);

      await prisma.$transaction([
        prisma.user.update({
          where: { id: record.userId },
          data: { tokenHash: hash },
        }),
        prisma.recoveryCode.delete({ where: { id: record.id } }),
      ]);

      reply
        .setCookie("echoboard_token", token, {
          path: "/",
          httpOnly: true,
          sameSite: "strict",
          secure: process.env.NODE_ENV === "production",
          maxAge: 60 * 60 * 24 * 90,
        })
        .send({ recovered: true });
    }
  );
}