#ifndef SESSION_H
#define SESSION_H

#include <libwebsockets.h>
#include <stdbool.h>
#include <stdint.h>

// Includes terminating null.
#define SESSION_USERNAME_MAX_LEN 32
#define SESSION_CHAT_BUF_SIZE 1024

/**
 * session_t
 * Represents a single WebSocket client session in the chat server.
 */
typedef struct SESSION {
    struct lws* wsi;                     // Libwebsockets connection handle.
    uint64_t id;                         // Unique session ID.
    struct SESSION* next;                // Next session in the internal list.
    char name[SESSION_USERNAME_MAX_LEN]; // Stored username.
    bool named;                          // True once username is set.
    unsigned char buf[LWS_PRE + SESSION_CHAT_BUF_SIZE]; // Outgoing buffer per session
    size_t buf_len;                      // Length of data in buf
} Session;

/**
 * session_create
 * Allocate and initialize a new session, adding it to the internal list.
 *
 * @param wsi   The libwebsockets connection handle.
 * @return      Pointer to the new session, or NULL on failure.
 */
Session* session_create(struct lws* wsi);

/**
 * session_destroy
 * Remove the given session from the internal list and free its memory.
 *
 * @param sess  The session to destroy.
 */
void session_destroy(Session* sess);

/**
 * session_get_head
 * Retrieve the head of the internal session linked list.
 *
 * @return The first session in the list, or NULL if none.
 */
Session* session_get_head(void);

/**
 * session_broadcast
 * Iterate every session in the internal list and invoke the callback.
 *
 * @param cb   Function to call for each session.
 * @param user Arbitrary user data passed through to each callback.
 */
void session_broadcast(void (*cb)(Session* sess, void* user), void* user);

/**
 * session_set_username
 * Store a username in the given session.
 *
 * @param sess      The session to update.
 * @param username  Null-terminated string to copy into the session.
 */
void session_set_username(Session* sess, const char* username);

/**
 * session_get_username
 * Fetch the username stored in the session.
 *
 * @param sess  The session to query.
 * @return      Pointer to the stored username (readonly).
 */
const char* session_get_username(const Session* sess);

/**
 * session_has_username
 * Check whether a session has already set a username.
 *
 * @param sess  The session to query.
 * @return      True if a username is set, false otherwise.
 */
bool session_has_username(const Session* sess);

/**
 * session_get_id
 * Fetch the session ID.
 *
 * @param sess  The session to query.
 * @return      The session's unique ID.
 */
uint64_t session_get_id(const Session* sess);

#endif // SESSION_H