/* SPDX-License-Identifier: GPL-3.0-only */
/* Authenticated, bounded wolfSSH transport for the serial session broker. */

#pragma once

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

#include "esp_err.h"
#include "session_broker.h"
#include "user_database.h"

#ifdef __cplusplus
extern "C" {
#endif

#define SSH_TRANSPORT_PORT 22U
#define SSH_TRANSPORT_MAX_SESSIONS 2U
#define SSH_TRANSPORT_IO_BUFFER_SIZE 512U
#define SSH_TRANSPORT_HANDSHAKE_TIMEOUT_SECONDS 15U

typedef enum {
    SSH_TRANSPORT_SESSION_FREE = 0,
    SSH_TRANSPORT_SESSION_HANDSHAKE,
    SSH_TRANSPORT_SESSION_ACTIVE,
    SSH_TRANSPORT_SESSION_CLOSING,
} ssh_transport_session_state_t;

typedef enum {
    SSH_TRANSPORT_ROUTE_NONE = 0,
    SSH_TRANSPORT_ROUTE_BROKER,
    SSH_TRANSPORT_ROUTE_ADMIN_CONSOLE,
} ssh_transport_session_route_t;

typedef struct {
    uint64_t starts;
    uint64_t start_failures;
    uint64_t stops;
    uint64_t tcp_connections;
    uint64_t capacity_rejections;
    uint64_t handshake_successes;
    uint64_t handshake_failures;
    uint64_t handshake_timeouts;
    uint64_t authentication_attempts;
    uint64_t authentication_failures;
    uint64_t request_rejections;
    uint64_t broker_connections;
    uint64_t broker_failures;
    uint64_t disconnections;
    uint64_t writer_requests;
    uint64_t writer_grants;
    uint64_t writer_denials;
    uint64_t writer_revocations;
    uint64_t rx_bytes;
    uint64_t rx_accepted_bytes;
    uint64_t rx_rejected_bytes;
    uint64_t tx_bytes;
    uint64_t io_failures;
    uint64_t session_revocations;
    uint64_t admin_console_admissions;
    uint64_t admin_console_admission_failures;
    uint64_t admin_console_input_rejections;
} ssh_transport_counters_t;

typedef struct {
    bool active;
    bool authenticated;
    bool principal_valid;
    bool writer;
    bool close_requested;
    bool rx_pending;
    bool tx_pending;
    bool admin_command_pending;
    uint32_t admin_output_pending;
    uint32_t session_id;
    uint32_t generation;
    int socket_fd;
    session_broker_client_id_t broker_client_id;
    ssh_transport_session_state_t state;
    ssh_transport_session_route_t route;
    user_role_t user_role;
    user_auth_method_t auth_method;
    char username[USER_DATABASE_USERNAME_CAPACITY + 1U];
    char peer[48];
} ssh_transport_session_snapshot_t;

typedef struct {
    bool initialized;
    bool running;
    bool transitioning;
    uint16_t port;
    esp_err_t last_error;
    uint32_t active_sessions;
    int32_t task_core_id;
    uint32_t task_stack_size;
    uint32_t task_stack_free_minimum;
    ssh_transport_session_snapshot_t sessions[SSH_TRANSPORT_MAX_SESSIONS];
    ssh_transport_counters_t counters;
} ssh_transport_snapshot_t;

/* Installs wolfCrypt RNG/PSRAM hooks and starts the sole wolfSSH owner task. */
esp_err_t ssh_transport_init(void);
esp_err_t ssh_transport_start(void);
esp_err_t ssh_transport_stop(void);

/* Serialize stop, persistent host-key replacement, and conditional restart. */
esp_err_t ssh_transport_replace_host_key(bool reset);

esp_err_t ssh_transport_get_snapshot(ssh_transport_snapshot_t *snapshot);
esp_err_t ssh_transport_clear_counters(void);

/* Close one session, one account's sessions, or every transport session. */
esp_err_t ssh_transport_disconnect(uint32_t session_id);
esp_err_t ssh_transport_revoke_user(const uint8_t *username,
                                    size_t username_length);
esp_err_t ssh_transport_revoke_sessions(void);

#ifdef __cplusplus
}
#endif