#ifndef AWS_IO_SOCKET_H
#define AWS_IO_SOCKET_H
/**
 * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 * SPDX-License-Identifier: Apache-2.0.
 */

#include <aws/io/channel.h>
#include <aws/io/io.h>

AWS_PUSH_SANE_WARNING_LEVEL

enum aws_socket_domain {
    AWS_SOCKET_IPV4,
    AWS_SOCKET_IPV6,
    /* Unix domain sockets (or at least something like them) */
    AWS_SOCKET_LOCAL,
    /* VSOCK used in inter-VM communication */
    AWS_SOCKET_VSOCK,
};

enum aws_socket_type {
    /* A streaming socket sends reliable messages over a two-way connection.
     * This means TCP when used with IPV4/6, and Unix domain sockets, when used with
     * AWS_SOCKET_LOCAL*/
    AWS_SOCKET_STREAM,
    /* A datagram socket is connectionless and sends unreliable messages.
     * This means UDP when used with IPV4/6.
     * LOCAL and VSOCK sockets are not compatible with DGRAM.*/
    AWS_SOCKET_DGRAM,
};

/**
 * Socket Implementation type. Decides which socket implementation is used. If set to
 * `AWS_SOCKET_IMPL_PLATFORM_DEFAULT`, it will automatically use the platform’s default.
 *
 * PLATFORM DEFAULT SOCKET IMPLEMENTATION TYPE
 * Linux       | AWS_SOCKET_IMPL_POSIX
 * Windows     | AWS_SOCKET_IMPL_WINSOCK
 * BSD Variants| AWS_SOCKET_IMPL_POSIX
 * MacOS       | AWS_SOCKET_IMPL_POSIX
 * iOS         | AWS_SOCKET_IMPL_APPLE_NETWORK_FRAMEWORK
 */
enum aws_socket_impl_type {
    AWS_SOCKET_IMPL_PLATFORM_DEFAULT = 0,
    AWS_SOCKET_IMPL_POSIX,
    AWS_SOCKET_IMPL_WINSOCK,
    AWS_SOCKET_IMPL_APPLE_NETWORK_FRAMEWORK,
};

#define AWS_NETWORK_INTERFACE_NAME_MAX 16

typedef void(aws_socket_on_shutdown_complete_fn)(void *user_data);

struct aws_socket_options {
    enum aws_socket_type type;
    enum aws_socket_domain domain;
    enum aws_socket_impl_type impl_type;
    uint32_t connect_timeout_ms;
    /* Keepalive properties are TCP only.
     * Set keepalive true to periodically transmit messages for detecting a disconnected peer.
     * If interval or timeout are zero, then default values are used. */
    uint16_t keep_alive_interval_sec;
    uint16_t keep_alive_timeout_sec;
    /* If set, sets the number of keep alive probes allowed to fail before the connection is considered
     * lost. If zero OS defaults are used. On Windows, this option is meaningless until Windows 10 1703.*/
    uint16_t keep_alive_max_failed_probes;
    bool keepalive;

    /**
     * THIS IS AN EXPERIMENTAL AND UNSTABLE API
     * (Optional)
     * This property is used to bind the socket to a particular network interface by name, such as eth0 and ens32.
     * If this is empty, the socket will not be bound to any interface and will use OS defaults. If the provided name
     * is invalid, `aws_socket_init()` will error out with AWS_IO_SOCKET_INVALID_OPTIONS. This option is only
     * supported on Linux, macOS(bsd socket), and platforms that have either SO_BINDTODEVICE or IP_BOUND_IF. It is not
     * supported on Windows and Apple Network Framework. `AWS_ERROR_PLATFORM_NOT_SUPPORTED` will be raised on
     * unsupported platforms.
     */
    char network_interface_name[AWS_NETWORK_INTERFACE_NAME_MAX];
};

struct aws_socket;

/**
 * Called in client mode when an outgoing connection has succeeded or an error has occurred.
 * If the connection was successful error_code will be AWS_ERROR_SUCCESS and the socket has already been assigned
 * to the event loop specified in aws_socket_connect().
 *
 * If an error occurred error_code will be non-zero.
 */
typedef void(aws_socket_on_connection_result_fn)(struct aws_socket *socket, int error_code, void *user_data);

/**
 * Called by a listening socket when a listener accept has successfully initialized or an error has occurred.
 * If the listener was successful error_code will be AWS_ERROR_SUCCESS and the socket has already been assigned
 * to the event loop specified in aws_socket_start_accept().
 *
 * If an error occurred error_code will be non-zero.
 */
typedef void(aws_socket_on_accept_started_fn)(struct aws_socket *socket, int error_code, void *user_data);

/**
 * Called by a listening socket when either an incoming connection has been received or an error occurred.
 *
 * In the normal use-case, this function will be called multiple times over the lifetime of a single listening socket.
 * new_socket is already connected and initialized, and is using the same options and allocator as the listening socket.
 * A user may want to call aws_socket_set_options() on the new socket if different options are desired.
 *
 * new_socket is not yet assigned to an event-loop. The user should call aws_socket_assign_to_event_loop() before
 * performing IO operations. The user must call `aws_socket_clean_up()` and "aws_mem_release()" when they're done with
 * the new_socket, to free it.
 *
 * When error_code is AWS_ERROR_SUCCESS, new_socket is the recently accepted connection.
 * If error_code is non-zero, an error occurred and you should aws_socket_close() the socket.
 *
 * Do not call aws_socket_clean_up() from this callback.
 */
typedef void(aws_socket_on_accept_result_fn)(
    struct aws_socket *socket,
    int error_code,
    struct aws_socket *new_socket,
    void *user_data);

/**
 * Callback for when the data passed to a call to aws_socket_write() has either completed or failed.
 * On success, error_code will be AWS_ERROR_SUCCESS.
 *
 * `socket` may be NULL in the callback if the socket is released and cleaned up before the callback is triggered.
 */
typedef void(
    aws_socket_on_write_completed_fn)(struct aws_socket *socket, int error_code, size_t bytes_written, void *user_data);
/**
 * Callback for when socket is either readable (edge-triggered) or when an error has occurred. If the socket is
 * readable, error_code will be AWS_ERROR_SUCCESS.
 *
 * `socket` may be NULL in the callback if the socket is released and cleaned up before the callback is triggered.
 */
typedef void(aws_socket_on_readable_fn)(struct aws_socket *socket, int error_code, void *user_data);

#ifdef _WIN32
#    define AWS_ADDRESS_MAX_LEN 256
#else
#    include <sys/un.h>
#    define AWS_ADDRESS_MAX_LEN sizeof(((struct sockaddr_un *)0)->sun_path)
#endif
struct aws_socket_endpoint {
    char address[AWS_ADDRESS_MAX_LEN];
    uint32_t port;
};

struct aws_socket {
    struct aws_socket_vtable *vtable;
    struct aws_allocator *allocator;
    struct aws_socket_endpoint local_endpoint;
    struct aws_socket_endpoint remote_endpoint;
    struct aws_socket_options options;
    struct aws_io_handle io_handle;
    struct aws_event_loop *event_loop;
    struct aws_channel_handler *handler;
    int state;
    aws_socket_on_readable_fn *readable_fn;
    void *readable_user_data;
    aws_socket_on_connection_result_fn *connection_result_fn;
    aws_socket_on_accept_result_fn *accept_result_fn;
    void *connect_accept_user_data;
    void *impl;
};

struct aws_socket_connect_options {
    const struct aws_socket_endpoint *remote_endpoint;
    struct aws_event_loop *event_loop;
    aws_socket_on_connection_result_fn *on_connection_result;
    void *user_data;

    /*
     * This is only set when using Apple SecItem for TLS negotiation.
     * Apple Network Connections using SecItem require all TLS configuration options at the point of
     * creating the socket slot as it handles both the TCP and TLS negotiation before returning a
     * valid socket for use.
     */
    struct aws_tls_connection_options *tls_connection_options;
};

struct aws_socket_listener_options {
    aws_socket_on_accept_result_fn *on_accept_result;
    void *on_accept_result_user_data;

    // This callback is invoked when the listener starts accepting incoming connections.
    // If the callback set, the socket must not be released before the callback invoked.
    aws_socket_on_accept_started_fn *on_accept_start;
    void *on_accept_start_user_data;
};

struct aws_socket_bind_options {
    const struct aws_socket_endpoint *local_endpoint;
    void *user_data;

    /*
     * This is only set when using Apple SecItem for TLS negotiation.
     * Apple Network Connections using SecItem require all TLS configuration options at the point of
     * creating the socket slot as it handles both the TCP and TLS negotiation before returning a
     * valid socket for use.
     * Socket bind also needs an event loop to run its verification block.
     */
    struct aws_event_loop *event_loop;
    struct aws_tls_connection_options *tls_connection_options;
};

struct aws_byte_buf;
struct aws_byte_cursor;
struct aws_string;

AWS_EXTERN_C_BEGIN

/**
 * Initializes a socket object with socket options. options will be copied.
 */
AWS_IO_API int aws_socket_init(
    struct aws_socket *socket,
    struct aws_allocator *alloc,
    const struct aws_socket_options *options);

/**
 * Shuts down any pending operations on the socket, and cleans up state. The socket object can be re-initialized after
 * this operation. This function calls aws_socket_close. If you have not already called aws_socket_close() on the
 * socket, all of the rules for aws_socket_close() apply here. In this case it will not fail if you use the function
 * improperly, but on some platforms you will certainly leak memory.
 *
 * If the socket has already been closed, you can safely, call this from any thread.
 */
AWS_IO_API void aws_socket_clean_up(struct aws_socket *socket);

/**
 * Connects to a remote endpoint. In UDP, this simply binds the socket to a remote address for use with
 * `aws_socket_write()`, and if the operation is successful, the socket can immediately be used for write operations.
 *
 * In TCP, LOCAL and VSOCK this function will not block. If the return value is successful, then you must wait on the
 * `on_connection_result()` callback to be invoked before using the socket.
 *
 * If an event_loop is provided for UDP sockets, a notification will be sent on
 * on_connection_result in the event-loop's thread. Upon completion, the socket will already be assigned
 * an event loop. If NULL is passed for UDP, it will immediately return upon success, but you must call
 * aws_socket_assign_to_event_loop before use.
 */
AWS_IO_API int aws_socket_connect(struct aws_socket *socket, struct aws_socket_connect_options *socket_connect_options);

/**
 * Binds the socket to a local address. In UDP mode, the socket is ready for `aws_socket_read()` operations. In
 * connection oriented modes, you still must call `aws_socket_listen()` and `aws_socket_start_accept()` before using the
 * socket. local_endpoint is copied.
 */
AWS_IO_API int aws_socket_bind(struct aws_socket *socket, struct aws_socket_bind_options *socket_bind_options);

/**
 * Get the local address which the socket is bound to.
 * Raises an error if no address is bound.
 */
AWS_IO_API int aws_socket_get_bound_address(const struct aws_socket *socket, struct aws_socket_endpoint *out_address);

/**
 * TCP, LOCAL and VSOCK only. Sets up the socket to listen on the address bound to in `aws_socket_bind()`.
 */
AWS_IO_API int aws_socket_listen(struct aws_socket *socket, int backlog_size);

/**
 * TCP, LOCAL and VSOCK only. The socket will begin accepting new connections. This is an asynchronous operation. New
 * connections or errors will arrive via the `on_accept_result` callback.
 *
 * aws_socket_bind() and aws_socket_listen() must be called before calling this function.
 *
 */
AWS_IO_API int aws_socket_start_accept(
    struct aws_socket *socket,
    struct aws_event_loop *accept_loop,
    struct aws_socket_listener_options options);

/**
 * TCP, LOCAL and VSOCK only. The listening socket will stop accepting new connections.
 * It is safe to call `aws_socket_start_accept()` again after
 * this operation. This can be called from any thread but be aware,
 * on some platforms, if you call this from outside of the current event loop's thread, it will block
 * until the event loop finishes processing the request for unsubscribe in it's own thread.
 */
AWS_IO_API int aws_socket_stop_accept(struct aws_socket *socket);

/**
 * Calls `close()` on the socket and unregisters all io operations from the event loop. This function must be called
 * from the event-loop's thread unless this is a listening socket. If it's a listening socket it can be called from any
 * non-event-loop thread or the event-loop the socket is currently assigned to. If called from outside the event-loop,
 * this function will block waiting on the socket to close. If this is called from an event-loop thread other than
 * the one it's assigned to, it presents the possibility of a deadlock, so don't do it.
 *
 * If you are using Apple Network Framework, you should always call this function from an event-loop thread regardless
 * it is a server or client socket.
 */
AWS_IO_API int aws_socket_close(struct aws_socket *socket);

/**
 * Calls `shutdown()` on the socket based on direction.
 */
AWS_IO_API int aws_socket_shutdown_dir(struct aws_socket *socket, enum aws_channel_direction dir);

/**
 * Sets new socket options on the underlying socket.
 */
AWS_IO_API int aws_socket_set_options(struct aws_socket *socket, const struct aws_socket_options *options);

/**
 * Assigns the socket to the event-loop. The socket will begin receiving read/write/error notifications after this call.
 *
 * Note: If you called connect for TCP or Unix Domain Sockets and received a connection_success callback, this has
 * already happened. You only need to call this function when:
 *
 * a.) This socket is a server socket (e.g. a result of a call to start_accept())
 * b.) This socket is a UDP socket.
 */
AWS_IO_API int aws_socket_assign_to_event_loop(struct aws_socket *socket, struct aws_event_loop *event_loop);

/**
 * Gets the event-loop the socket is assigned to.
 */
AWS_IO_API struct aws_event_loop *aws_socket_get_event_loop(struct aws_socket *socket);

/**
 * Subscribes on_readable to notifications when the socket goes readable (edge-triggered). Errors will also be received
 * in the callback.
 *
 * Note! This function is technically not thread safe, but we do not enforce which thread you call from.
 * It's your responsibility to either call this in safely (e.g. just don't call it in parallel from multiple threads) or
 * schedule a task to call it. If you call it before your first call to read, it will be fine.
 */
AWS_IO_API int aws_socket_subscribe_to_readable_events(
    struct aws_socket *socket,
    aws_socket_on_readable_fn *on_readable,
    void *user_data);

/**
 * Reads from the socket. This call is non-blocking and will return `AWS_IO_SOCKET_READ_WOULD_BLOCK` if no data is
 * available. `read` is the amount of data read into `buffer`.
 *
 * Attempts to read enough to fill all remaining space in the buffer, from `buffer->len` to `buffer->capacity`.
 * `buffer->len` is updated to reflect the buffer's new length.
 *
 *
 * Use aws_socket_subscribe_to_readable_events() to receive notifications of when the socket goes readable.
 *
 * NOTE! This function must be called from the event-loop used in aws_socket_assign_to_event_loop
 */
AWS_IO_API int aws_socket_read(struct aws_socket *socket, struct aws_byte_buf *buffer, size_t *amount_read);

/**
 * Writes to the socket. This call is non-blocking and will attempt to write as much as it can, but will queue any
 * remaining portion of the data for write when available. written_fn will be invoked once the entire cursor has been
 * written, or the write failed or was cancelled.
 *
 * NOTE! This function must be called from the event-loop used in aws_socket_assign_to_event_loop
 *
 * For client sockets, connect() and aws_socket_assign_to_event_loop() must be called before calling this.
 *
 * For incoming sockets from a listener, aws_socket_assign_to_event_loop() must be called first.
 */
AWS_IO_API int aws_socket_write(
    struct aws_socket *socket,
    const struct aws_byte_cursor *cursor,
    aws_socket_on_write_completed_fn *written_fn,
    void *user_data);

/**
 * Apple Network Framework only. The callback that will triggered when aws_socket_close() finished. The callback
 * will be called from the socket event loop.
 */
AWS_IO_API int aws_socket_set_close_complete_callback(
    struct aws_socket *socket,
    aws_socket_on_shutdown_complete_fn fn,
    void *user_data);

/**
 * Apple Network Framework only. The callback that will triggered when aws_socket_cleanup() finished. And
 * it is only safe to release the socket afterwards. The callback will be called from the socket event loop.
 */
AWS_IO_API int aws_socket_set_cleanup_complete_callback(
    struct aws_socket *socket,
    aws_socket_on_shutdown_complete_fn fn,
    void *user_data);

/**
 * Gets the latest error from the socket. If no error has occurred AWS_OP_SUCCESS will be returned. This function does
 * not raise any errors to the installed error handlers.
 */
AWS_IO_API int aws_socket_get_error(struct aws_socket *socket);

/**
 * Returns true if the socket is still open (doesn't mean connected or listening, only that it hasn't had close()
 * called.
 */
AWS_IO_API bool aws_socket_is_open(struct aws_socket *socket);

/**
 * Raises AWS_IO_SOCKET_INVALID_ADDRESS and logs an error if connecting to this port is illegal.
 * For example, port must be in range 1-65535 to connect with IPv4.
 * These port values would fail eventually in aws_socket_connect(),
 * but you can use this function to validate earlier.
 */
AWS_IO_API int aws_socket_validate_port_for_connect(uint32_t port, enum aws_socket_domain domain);

/**
 * Raises AWS_IO_SOCKET_INVALID_ADDRESS and logs an error if binding to this port is illegal.
 * For example, port must in range 0-65535 to bind with IPv4.
 * These port values would fail eventually in aws_socket_bind(),
 * but you can use this function to validate earlier.
 */
AWS_IO_API int aws_socket_validate_port_for_bind(uint32_t port, enum aws_socket_domain domain);

/**
 * Assigns a random address (UUID) for use with AWS_SOCKET_LOCAL (Unix Domain Sockets).
 * For use in internal tests only.
 */
AWS_IO_API void aws_socket_endpoint_init_local_address_for_test(struct aws_socket_endpoint *endpoint);

/**
 * Validates whether the network interface name is valid. On Windows, it will always return false since we don't support
 * network_interface_name on Windows */
AWS_IO_API bool aws_is_network_interface_name_valid(const char *interface_name);

/**
 * Get default impl type based on the platform.
 * For user in internal tests only.
 */
AWS_IO_API enum aws_socket_impl_type aws_socket_get_default_impl_type(void);

/**
 * Parse an IPv4 address string and convert it to binary representation.
 *
 * This function converts a string representation of an IPv4 address
 * into its binary network byte order (big-endian) representation.
 *
 * @param src The IPv4 address string to parse. Must be a valid IPv4 address in dotted decimal notation.
 * @param dst Pointer to a uint32_t where the parsed address will be stored in network byte order.
 *
 * @return AWS_OP_SUCCESS on success, or AWS_OP_ERR on failure.
 *         On failure, aws_last_error() will be set to:
 *         - AWS_IO_SOCKET_INVALID_ADDRESS if the input string is not a valid IPv4 address
 */
AWS_IO_API int aws_parse_ipv4_address(const struct aws_string *src, uint32_t *dst);

/**
 * Parse an IPv6 address string and convert it to binary representation.
 *
 * This function converts a string representation of an IPv6 address
 * into its binary network byte order(big-endian) representation.
 *
 * @param src The IPv6 address string to parse. Must be a valid IPv6 address in standard notation.
 * @param dst Pointer to an aws_byte_buf where the parsed address will be appended.
 *            The buffer must have at least 16 bytes of available capacity.
 *            The parsed 16-byte IPv6 address will be appended to the buffer and
 *            the buffer's length will be increased by 16.
 *
 * @return AWS_OP_SUCCESS on success, or AWS_OP_ERR on failure.
 *         On failure, aws_last_error() will be set to:
 *         - AWS_IO_SOCKET_INVALID_ADDRESS if the input string is not a valid IPv6 address
 *         - AWS_ERROR_SHORT_BUFFER if the destination buffer doesn't have enough capacity
 */
AWS_IO_API int aws_parse_ipv6_address(const struct aws_string *src, struct aws_byte_buf *dst);

AWS_EXTERN_C_END
AWS_POP_SANE_WARNING_LEVEL

#endif /* AWS_IO_SOCKET_H */