package org.openautonomousconnection.webserver.api;

import org.openautonomousconnection.protocol.side.server.CustomConnectedClient;
import org.openautonomousconnection.protocol.side.web.ProtocolWebServer;
import org.openautonomousconnection.protocol.side.web.managers.SessionManager;

import java.io.IOException;
import java.util.Locale;
import java.util.Map;

/**
 * Provides session-related information for Java WebPages.
 * Reads session id primarily from Cookie header ("session=...").
 */
public final class SessionContext {

    private static final String COOKIE_NAME = "session";

    private final String sessionId;
    private final String user;
    private final boolean valid;

    private SessionContext(String sessionId, String user, boolean valid) {
        this.sessionId = sessionId;
        this.user = user;
        this.valid = valid;
    }

    /**
     * Creates a SessionContext from request headers (case-insensitive).
     *
     * @param client  connected client
     * @param server  web server
     * @param headers request headers
     * @return session context
     * @throws IOException on errors
     */
    public static SessionContext from(CustomConnectedClient client, ProtocolWebServer server, Map<String, String> headers) throws IOException {
        if (headers == null || headers.isEmpty()) return new SessionContext(null, null, false);

        String sessionId = extractSessionId(headers);
        if (sessionId == null || sessionId.isBlank()) return new SessionContext(null, null, false);

        String ip = (client != null
                && client.getConnection() != null
                && client.getConnection().getTcpSocket() != null
                && client.getConnection().getTcpSocket().getInetAddress() != null)
                ? client.getConnection().getTcpSocket().getInetAddress().getHostAddress()
                : "";

        String userAgent = getHeaderIgnoreCase(headers, "user-agent");
        if (userAgent == null) userAgent = "";

        boolean valid = SessionManager.isValid(sessionId, ip, userAgent, server);
        if (!valid) return new SessionContext(sessionId, null, false);

        String user = SessionManager.getUser(sessionId);
        return new SessionContext(sessionId, user, true);
    }

    private static String extractSessionId(Map<String, String> headers) {
        String cookie = getHeaderIgnoreCase(headers, "cookie");
        String fromCookie = parseCookie(cookie, COOKIE_NAME);
        if (fromCookie != null && !fromCookie.isBlank()) return fromCookie;

        // Fallback
        String session = getHeaderIgnoreCase(headers, "session");
        return (session == null || session.isBlank()) ? null : session.trim();
    }

    private static String parseCookie(String cookieHeader, String name) {
        if (cookieHeader == null || cookieHeader.isBlank() || name == null || name.isBlank()) return null;

        String[] parts = cookieHeader.split(";");
        for (String p : parts) {
            String t = p.trim();
            int eq = t.indexOf('=');
            if (eq <= 0) continue;

            String k = t.substring(0, eq).trim();
            if (!k.equalsIgnoreCase(name)) continue;

            String v = t.substring(eq + 1).trim();
            return v.isEmpty() ? null : v;
        }
        return null;
    }

    private static String getHeaderIgnoreCase(Map<String, String> headers, String key) {
        if (key == null) return null;
        String needle = key.trim().toLowerCase(Locale.ROOT);
        for (Map.Entry<String, String> e : headers.entrySet()) {
            if (e.getKey() == null) continue;
            if (e.getKey().trim().toLowerCase(Locale.ROOT).equals(needle)) {
                return e.getValue();
            }
        }
        return null;
    }

    /**
     * @return whether session is valid
     */
    public boolean isValid() {
        return valid;
    }

    /**
     * @return session id
     */
    public String getSessionId() {
        return sessionId;
    }

    /**
     * @return user id stored in session (string)
     */
    public String getUser() {
        return user;
    }
}