import { eq } from "drizzle-orm";

import { readJsonBody } from "@/worker/api/request";
import { users } from "@/worker/db/schema";
import type { AppContext } from "@/worker/hono";
import { HttpError } from "@/worker/http";
import { requireSession } from "@/worker/middleware/auth";

// Slugs that would clash with tessera's own routes or with conventional
// system roles in downstream RPs (git-on-cloudflare's `:owner` URL segment,
// for example). Keep this list narrow — RFC says `preferred_username` need
// not be unique, so this is just a footgun guard, not an identity policy.
const RESERVED_HANDLES = new Set([
  "admin",
  "api",
  "auth",
  "oauth",
  "oauth2",
  "well-known",
  "wellknown",
  "callback",
  "callbacks",
  "consent",
  "sign-in",
  "sign-out",
  "sign-up",
  "signin",
  "signout",
  "signup",
  "account",
  "accounts",
  "invite",
  "invites",
  "user",
  "users",
  "anonymous",
  "system",
]);

interface UpdateHandleBody {
  preferredUsername?: unknown;
}

const validateHandle = (raw: string): { ok: true; value: string } | { ok: false; error: string } => {
  const v = raw.trim().toLowerCase();
  if (v.length < 1) return { ok: false, error: "Username can't be empty." };
  if (v.length > 32) return { ok: false, error: "Username must be 32 characters or fewer." };
  if (!/^[a-z0-9][a-z0-9_-]*$/.test(v)) {
    return {
      ok: false,
      error: "Use lowercase letters, digits, hyphens, or underscores. Must start with a letter or digit.",
    };
  }
  if (RESERVED_HANDLES.has(v)) {
    return { ok: false, error: `"${v}" is reserved. Pick a different one.` };
  }
  return { ok: true, value: v };
};

export const handleUpdateHandle = async (c: AppContext): Promise<Response> => {
  const session = requireSession(c);
  const logger = c.var.log.child({ component: "account" });
  const body = await readJsonBody<UpdateHandleBody>(c);

  if (typeof body.preferredUsername !== "string") {
    throw new HttpError(400, "invalid_body", "preferredUsername (string) required.");
  }

  const result = validateHandle(body.preferredUsername);
  if (!result.ok) {
    throw new HttpError(400, "invalid_username", result.error);
  }

  await c.var.db
    .update(users)
    .set({ preferredUsername: result.value, updatedAt: new Date() })
    .where(eq(users.id, session.user.id));

  logger.info("handle_updated", { userId: session.user.id, preferredUsername: result.value });
  return c.json({ preferredUsername: result.value });
};