import NextAuth, { NextAuthOptions } from "next-auth";
import KeycloakProvider from "next-auth/providers/keycloak";

declare module "next-auth" {
  interface Session {
    user: {
      id: string;
      name?: string | null;
      email?: string | null;
      image?: string | null;
      username: string;
      first_name: string;
      last_name: string;
      role: string[];
    };
    accessToken: string;
  }

  interface JWT {
    accessToken: string;
    refreshToken: string;
    accessTokenExpires: number;
    role: string[];
    username: string;
    first_name: string;
    last_name: string;
  }
}

export const authOptions: NextAuthOptions = {
  providers: [
    KeycloakProvider({
      clientId: process.env.KEYCLOAK_CLIENT_ID!,
      clientSecret: process.env.KEYCLOAK_CLIENT_SECRET!,
      issuer: process.env.KEYCLOAK_ISSUER!,
      profile(profile) {
        return {
          id: profile.sub,
          name: profile.name ?? profile.preferred_username,
          email: profile.email,
          first_name: profile.given_name ?? '',
          last_name: profile.family_name ?? '',
          username: profile.preferred_username ?? profile.email?.split('@')[0] ?? '',
          role: profile.groups ?? [],
        }
      },
    }),
  ],
  callbacks: {
    async jwt({ token, account, profile }) {
      if (account && profile) {
        token.accessToken = account.access_token;
        token.refreshToken = account.refresh_token;
        token.accessTokenExpires = account.expires_at! * 1000;
        token.role = (profile as any).groups ?? [];
        token.username = (profile as any).preferred_username ?? profile.email?.split('@')[0] ?? '';
        token.first_name = (profile as any).given_name ?? '';
        token.last_name = (profile as any).family_name ?? '';
        return token;
      }

      // Return previous token if not expired
      if (Date.now() < (token.accessTokenExpires as number)) {
        return token;
      }

      try {
        // Token has expired, try to refresh it
        function isNonEmptyString(value: string | undefined): value is string {
          return typeof value === 'string' && value.length > 0;
        }

        const clientId = process.env.KEYCLOAK_CLIENT_ID;
        const clientSecret = process.env.KEYCLOAK_CLIENT_SECRET;

        if (!isNonEmptyString(clientId) || !isNonEmptyString(clientSecret)) {
          throw new Error("Missing required environment variables for token refresh");
        }

        // After the type guard check, we can safely assert these as strings
        const validClientId = clientId as string;
        const validClientSecret = clientSecret as string;

        const response = await fetch(
          `${process.env.KEYCLOAK_BASE_URL}/realms/${process.env.KEYCLOAK_REALM}/protocol/openid-connect/token`,
          {
            method: "POST",
            headers: {
              "Content-Type": "application/x-www-form-urlencoded",
            },
            body: new URLSearchParams({
              grant_type: "refresh_token",
              client_id: validClientId,
              client_secret: validClientSecret,
              refresh_token: token.refreshToken as string,
            }),
          }
        );

        const tokens = await response.json();

        if (!response.ok) {
          console.error("Token refresh failed:", tokens);
          throw new Error("RefreshAccessTokenError");
        }

        return {
          ...token,
          accessToken: tokens.access_token,
          refreshToken: tokens.refresh_token ?? token.refreshToken,
          accessTokenExpires: Date.now() + tokens.expires_in * 1000,
        };
      } catch (error) {
        console.error("Error refreshing token:", error);
        
        // Return token with error flag - this will trigger a redirect to sign-in
        return {
          ...token,
          error: "RefreshAccessTokenError",
        };
      }
    },

    async session({ session, token }) {
      if (token.error) {
        // Force sign out if there was a refresh error
        throw new Error("RefreshAccessTokenError");
      }

      session.accessToken = token.accessToken;
      session.user = {
        ...session.user,
        id: token.sub as string,
        first_name: token.first_name ?? '',
        last_name: token.last_name ?? '',
        username: token.username ?? '',
        role: token.role ?? [],
      };
      return session;
    },
  },
  events: {
    async signOut({ token }) {
      if (token.refreshToken) {
        try {
          await fetch(
            `${process.env.KEYCLOAK_BASE_URL}/realms/${process.env.KEYCLOAK_REALM}/protocol/openid-connect/logout`,
            {
              method: "POST",
              headers: {
                "Content-Type": "application/x-www-form-urlencoded",
              },
              body: new URLSearchParams({
                client_id: process.env.KEYCLOAK_CLIENT_ID!,
                client_secret: process.env.KEYCLOAK_CLIENT_SECRET!,
                refresh_token: token.refreshToken as string,
              }),
            }
          );
        } catch (error) {
          console.error("Error during logout:", error);
        }
      }
    },
  },
};

const handler = NextAuth(authOptions);
export { handler as GET, handler as POST };