import { NextRequest, NextResponse } from "next/server";
import bcrypt from "bcryptjs";
import QRCode from "qrcode";
import { prisma } from "@/lib/db";
import { sameOriginJson } from "@/lib/csrf";
import { allow, clientIp } from "@/lib/ratelimit";
import { hashRecoveryCode, newRecoveryCodes, newTotpSecret, otpauthUrl, totpVerify } from "@/lib/totp";
import { currentOperator, logOperatorEvent } from "@/lib/ops/session";
import { decryptOpsSecret, encryptOpsSecret } from "@/lib/ops/totp";

export const dynamic = "force-dynamic";

/* An operator's second factor: the same three steps as a coordinator's (app/api/2fa/route.ts),
 * for the same reason — a secret stored the moment it is generated leaves an account
 * half-enrolled if the person never finishes, and their next sign-in asks for codes from an app
 * they never set up.
 *
 *   setup      — generate a secret and show the QR. Stored, but not yet in force.
 *   enable     — prove a code from it works, switch it on, hand back recovery codes once.
 *   disable    — password required; turning a factor off is a privileged act.
 *   regenerate — password required; new recovery codes, old ones gone.
 *
 * The secret is encrypted under the console's own key (lib/ops/totp.ts), never the product's.
 * The QR is generated here as SVG, as the product does it: the secret never has to be handed to
 * client-side code to render. */
export async function GET() {
  const op = await currentOperator();
  if (!op) return NextResponse.json({ error: "Not signed in" }, { status: 401 });
  const left = await prisma.operatorRecoveryCode.count({ where: { operatorId: op.id, usedAt: null } });
  return NextResponse.json({ enabled: op.totpEnabled, recoveryLeft: left, viaSso: op.viaSso });
}

export async function POST(req: NextRequest) {
  const csrf = sameOriginJson(req);
  if (csrf) return NextResponse.json({ error: csrf }, { status: 403 });
  const op = await currentOperator();
  if (!op) return NextResponse.json({ error: "Not signed in" }, { status: 401 });

  const ip = clientIp(req.headers);
  if (!allow("ops-2fa-manage:" + op.id, 30, 15 * 60 * 1000)) {
    return NextResponse.json({ error: "Too many attempts — try again in a few minutes." }, { status: 429 });
  }

  let body: { action?: unknown; code?: unknown; password?: unknown };
  try { body = await req.json(); } catch { return NextResponse.json({ error: "Bad request" }, { status: 400 }); }
  const action = String(body.action ?? "");

  const o = await prisma.operator.findUnique({
    where: { id: op.id },
    select: { id: true, email: true, passwordHash: true, totpSecret: true, totpEnabledAt: true },
  });
  if (!o) return NextResponse.json({ error: "Not signed in" }, { status: 401 });

  if (action === "setup") {
    if (o.totpEnabledAt) return NextResponse.json({ error: "Two-factor is already on for this account." }, { status: 400 });
    const secret = newTotpSecret();
    await prisma.operator.update({ where: { id: o.id }, data: { totpSecret: encryptOpsSecret(secret) } });
    const url = otpauthUrl(secret, o.email, "ThreadCount ops");
    const qr = await QRCode.toString(url, { type: "svg", margin: 1, width: 220, errorCorrectionLevel: "M" });
    logOperatorEvent({ operatorId: o.id, action: "ops:2fa.setup", ip });
    return NextResponse.json({ ok: true, secret, url, qr });
  }

  if (action === "enable") {
    if (o.totpEnabledAt) return NextResponse.json({ error: "Two-factor is already on." }, { status: 400 });
    const secret = decryptOpsSecret(o.totpSecret);
    if (!secret) return NextResponse.json({ error: "Start the setup again." }, { status: 400 });
    if (!totpVerify(secret, String(body.code ?? "").replace(/\s+/g, ""))) {
      return NextResponse.json({ error: "That code isn't right. Use the current one from your app." }, { status: 400 });
    }
    const codes = newRecoveryCodes();
    await prisma.$transaction(async (tx) => {
      await tx.operator.update({ where: { id: o.id }, data: { totpEnabledAt: new Date() } });
      await tx.operatorRecoveryCode.deleteMany({ where: { operatorId: o.id } });
      await tx.operatorRecoveryCode.createMany({ data: codes.map((c) => ({ operatorId: o.id, codeHash: hashRecoveryCode(c) })) });
    });
    logOperatorEvent({ operatorId: o.id, action: "ops:2fa.enable", ip });
    // The only time these are ever readable. Stored hashed, so there is no second chance.
    return NextResponse.json({ ok: true, codes });
  }

  if (action === "disable") {
    if (!o.totpEnabledAt) return NextResponse.json({ ok: true });
    const pw = String(body.password ?? "");
    if (!pw || !(await bcrypt.compare(pw, o.passwordHash))) {
      return NextResponse.json({ error: "That password isn't right." }, { status: 401 });
    }
    await prisma.$transaction(async (tx) => {
      await tx.operator.update({ where: { id: o.id }, data: { totpEnabledAt: null, totpSecret: "" } });
      await tx.operatorRecoveryCode.deleteMany({ where: { operatorId: o.id } });
    });
    logOperatorEvent({ operatorId: o.id, action: "ops:2fa.disable", ip });
    return NextResponse.json({ ok: true });
  }

  if (action === "regenerate") {
    if (!o.totpEnabledAt) return NextResponse.json({ error: "Two-factor isn't on." }, { status: 400 });
    const pw = String(body.password ?? "");
    if (!pw || !(await bcrypt.compare(pw, o.passwordHash))) {
      return NextResponse.json({ error: "That password isn't right." }, { status: 401 });
    }
    const codes = newRecoveryCodes();
    await prisma.$transaction(async (tx) => {
      await tx.operatorRecoveryCode.deleteMany({ where: { operatorId: o.id } });
      await tx.operatorRecoveryCode.createMany({ data: codes.map((c) => ({ operatorId: o.id, codeHash: hashRecoveryCode(c) })) });
    });
    logOperatorEvent({ operatorId: o.id, action: "ops:2fa.regenerate", ip });
    return NextResponse.json({ ok: true, codes });
  }

  return NextResponse.json({ error: "Unknown action" }, { status: 400 });
}