import { NextRequest, NextResponse } from "next/server";
import { loadConfig } from "@/lib/config";

export const dynamic = "force-dynamic";
export const maxDuration = 10;

const DEFAULT_SCOPES = [
  "https://graph.microsoft.com/Mail.Read",
  "https://graph.microsoft.com/Mail.ReadWrite",
  "https://graph.microsoft.com/Files.Read",
  "https://graph.microsoft.com/Files.Read.All",
  "offline_access",
  "openid",
  "profile",
];

/**
 * POST /api/microsoft/token
 *
 * Polls for the token after the user completes the device code flow.
 * Body: { device_code: string, client_id?: string, tenant_id?: string, scopes?: string[] }
 *
 * Returns:
 *   access_token, refresh_token, id_token — on success
 *   { error: "authorization_pending" } — user hasn't logged in yet (keep polling)
 *   { error: "authorization_declined" } — user declined
 *   { error: "expired_token" } — code expired
 */
export async function POST(request: NextRequest) {
  let config;
  try {
    config = loadConfig();
  } catch (e) {
    console.error("[microsoft/token] loadConfig error:", e);
    config = { graph: {} };
  }

  const defaultClientId =
    process.env.AZURE_AD_CLIENT_ID ||
    process.env.AZURE_CLIENT_ID ||
    process.env.MICROSOFT_CLIENT_ID ||
    config.graph?.clientId ||
    "";

  const defaultTenantId =
    process.env.AZURE_AD_TENANT_ID ||
    process.env.AZURE_TENANT_ID ||
    process.env.MICROSOFT_TENANT_ID ||
    config.graph?.tenantId ||
    "common";

  const body = await request.json().catch(() => ({}));
  const deviceCode = body.device_code;
  const clientId = body.client_id || defaultClientId;
  const tenantId = body.tenant_id || defaultTenantId;
  const scopes = body.scopes || DEFAULT_SCOPES;

  if (!deviceCode) {
    return NextResponse.json({ error: "device_code is required" }, { status: 400 });
  }
  if (!clientId) {
    return NextResponse.json(
      { error: "client_id is required. Configure AZURE_AD_CLIENT_ID or AZURE_CLIENT_ID." },
      { status: 400 }
    );
  }

  try {
    const controller = new AbortController();
    const timeout = setTimeout(() => controller.abort(), 9000);
    try {
      const res = await fetch(
        `https://login.microsoftonline.com/${tenantId}/oauth2/v2.0/token`,
        {
          method: "POST",
          headers: { "Content-Type": "application/x-www-form-urlencoded" },
          body: new URLSearchParams({
            grant_type: "urn:ietf:params:oauth:grant-type:device_code",
            client_id: clientId,
            device_code: deviceCode,
            scope: scopes.join(" "),
          }),
          signal: controller.signal,
        }
      );

      const text = await res.text();
      const data = text ? JSON.parse(text) : {};

      if (!res.ok) {
        // Return the specific error so the client can handle polling
        return NextResponse.json({
          error: data.error || "token_request_failed",
          error_description: data.error_description || "",
          interval: data.interval || 5,
        }, { status: 400 });
      }

      return NextResponse.json({
        access_token: data.access_token,
        refresh_token: data.refresh_token,
        id_token: data.id_token,
        expires_in: data.expires_in,
        token_type: data.token_type,
        scope: data.scope,
      });
    } finally {
      clearTimeout(timeout);
    }
  } catch (e: any) {
    return NextResponse.json({ error: e.name === "AbortError" ? "Token request timed out" : e.message }, { status: 504 });
  }
}