// server/api/auth/session.get.ts
import type { SessionResponse } from '~/types/auth'

// Helper function to safely decode the JWT payload (Access Token or ID Token)
const decodeTokenPayload = (token: string | undefined): any | null => {
  if (!token) return null;
  try {
    // Tokens are base64 encoded and separated by '.'
    const parts = token.split(".");
    if (parts.length < 2) return null; // Not a valid JWT format

    const payloadBase64 = parts[1];

    // Decode from base64 and parse the JSON
    // Note: Using Buffer.from is standard in Node.js server environments (like Nitro/H3)
    return JSON.parse(Buffer.from(payloadBase64, "base64").toString());
  } catch (e) {
    console.error("❌ Failed to decode token payload:", e);
    return null;
  }
};

// --- START OF THE SINGLE EXPORT DEFAULT HANDLER ---
export default defineEventHandler(async (event) => {
  console.log("🔍 Session endpoint called");

  const sessionId = getCookie(event, "user_session");
  console.log("🍪 Session cookie exists:", !!sessionId);

  if (!sessionId) {
    console.log("❌ No session cookie found");
    throw createError({
      statusCode: 401,
      statusMessage: "No session cookie found",
    });
  }

  try {
    // Get session from server-side store using session ID
    const { getSession } = await import('~/server/utils/sessionStore');
    const session = getSession(sessionId);
    
    if (!session) {
      console.log("❌ Session not found or expired");
      deleteCookie(event, "user_session");
      throw createError({
        statusCode: 401,
        statusMessage: "Session expired or invalid",
      });
    }
    
    console.log("📋 Session retrieved from store successfully");

    const isExpired = Date.now() > session.expiresAt;
    console.log("   Is Expired:", isExpired);

    // Check if the token has expired
    if (isExpired) {
      console.log("⏰ Session has expired, clearing cookie");
      deleteCookie(event, "user_session");
      throw createError({
        statusCode: 401,
        statusMessage: "Session expired",
      });
    }

    // Decode tokens and prepare the enhanced response data
    const idTokenPayload = decodeTokenPayload(session.idToken);
    const accessTokenPayload = decodeTokenPayload(session.accessToken);

    // Final response object - ensure it matches SessionResponse interface
    const sessionResponse: SessionResponse & { 
      idToken?: any
      idTokenPayload?: any
      accessTokenPayload?: any
      fullSessionObject?: any
      status?: string
    } = {
      success: true,
      // Basic User Info
      user: session.user,

      // Raw Tokens (optional in SessionResponse)
      accessToken: session.accessToken,
      refreshToken: session.refreshToken,

      // Session Timestamps (optional in SessionResponse)
      expiresAt: session.expiresAt,

      // Additional debug fields (not in SessionResponse interface)
      idToken: session.idToken,
      idTokenPayload: idTokenPayload,
      accessTokenPayload: accessTokenPayload,
      fullSessionObject: session,
      status: "authenticated",
    };

    console.log("✅ Session is valid, returning full session data");
    return sessionResponse;
  } catch (parseError) {
    console.error("❌ Failed to parse session cookie:", parseError);
    // If JSON parsing fails or any other error occurs, the session is invalid
    deleteCookie(event, "user_session");
    throw createError({
      statusCode: 401,
      statusMessage: "Invalid session data",
    });
  }
});
// --- END OF THE SINGLE EXPORT DEFAULT HANDLER ---