import { createServerFn } from "@tanstack/react-start";
import { requireSupabaseAuth } from "@/integrations/supabase/auth-middleware";

type Role = "admin" | "teacher" | "parent" | "student";

// Admin-only: create a user account (service-role, server-side), set its role,
// and optionally link it to a student (for parent hand-off).
export const createUserFn = createServerFn({ method: "POST" })
  .middleware([requireSupabaseAuth])
  .validator((d: { fullName: string; email: string; password: string; role: Role; linkStudentId?: string }) => d)
  .handler(async ({ data, context }) => {
    const { supabaseAdmin } = await import("@/integrations/supabase/client.server");
    const callerId = (context as { userId: string }).userId;

    const { data: adminRow } = await supabaseAdmin
      .from("user_roles").select("role").eq("user_id", callerId).eq("role", "admin").maybeSingle();
    if (!adminRow) throw new Error("Only admins can add users.");

    const email = data.email.trim().toLowerCase();
    if (!email || !data.fullName.trim()) throw new Error("Name and email are required.");

    const { data: created, error } = await supabaseAdmin.auth.admin.createUser({
      email,
      password: data.password,
      email_confirm: true,
      user_metadata: { full_name: data.fullName.trim() },
    });
    if (error) throw new Error(error.message);
    const uid = created.user?.id;
    if (!uid) throw new Error("User creation failed.");

    // The on_auth_user_created trigger assigns 'parent' by default; adjust to the chosen role.
    if (data.role !== "parent") {
      await supabaseAdmin.from("user_roles").delete().eq("user_id", uid).eq("role", "parent");
    }
    const { error: rErr } = await supabaseAdmin
      .from("user_roles").upsert({ user_id: uid, role: data.role }, { onConflict: "user_id,role" });
    if (rErr) throw new Error(rErr.message);

    if (data.linkStudentId && data.role === "parent") {
      const { error: lErr } = await supabaseAdmin
        .from("parent_students").upsert({ parent_id: uid, student_id: data.linkStudentId }, { onConflict: "parent_id,student_id" });
      if (lErr) throw new Error(lErr.message);
    }
    if (data.linkStudentId && data.role === "student") {
      const { error: sErr } = await supabaseAdmin
        .from("students").update({ user_id: uid }).eq("id", data.linkStudentId);
      if (sErr) throw new Error(sErr.message);
    }

    return { id: uid, email };
  });