#ifndef AWS_HTTP_CONNECTION_MANAGER_H
#define AWS_HTTP_CONNECTION_MANAGER_H

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

#include <aws/http/http.h>

#include <aws/common/byte_buf.h>

struct aws_client_bootstrap;
struct aws_http_connection;
struct aws_http_connection_manager;
struct aws_socket_options;
struct aws_tls_connection_options;

typedef void(aws_http_connection_manager_on_connection_setup_fn)(
    struct aws_http_connection *connection,
    int error_code,
    void *user_data);

typedef void(aws_http_connection_manager_shutdown_complete_fn)(void *user_data);

/*
 * Connection manager configuration struct.
 *
 * Contains all of the configuration needed to create an http connection as well as
 * the maximum number of connections to ever have in existence.
 */
struct aws_http_connection_manager_options {
    /*
     * http connection configuration
     */
    struct aws_client_bootstrap *bootstrap;
    size_t initial_window_size;
    const struct aws_socket_options *socket_options;
    const struct aws_tls_connection_options *tls_connection_options;
    const struct aws_http_proxy_options *proxy_options;
    const struct aws_http_connection_monitoring_options *monitoring_options;
    struct aws_byte_cursor host;
    uint16_t port;

    /*
     * Maximum number of connections this manager is allowed to contain
     */
    size_t max_connections;

    /*
     * Callback and associated user data to invoke when the connection manager has
     * completely shutdown and has finished deleting itself.
     * Technically optional, but correctness may be impossible without it.
     */
    void *shutdown_complete_user_data;
    aws_http_connection_manager_shutdown_complete_fn *shutdown_complete_callback;

    /**
     * If set to true, the read back pressure mechanism will be enabled.
     */
    bool enable_read_back_pressure;

    /**
     * If set to a non-zero value, then connections that stay in the pool longer than the specified
     * timeout will be closed automatically.
     */
    uint64_t max_connection_idle_in_milliseconds;
};

AWS_EXTERN_C_BEGIN

/*
 * Connection managers are ref counted.  Adds one external ref to the manager.
 */
AWS_HTTP_API
void aws_http_connection_manager_acquire(struct aws_http_connection_manager *manager);

/*
 * Connection managers are ref counted.  Removes one external ref from the manager.
 *
 * When the ref count goes to zero, the connection manager begins its shut down
 * process.  All pending connection acquisitions are failed (with callbacks
 * invoked) and any (erroneous) subsequent attempts to acquire a connection
 * fail immediately.  The connection manager destroys itself once all pending
 * asynchronous activities have resolved.
 */
AWS_HTTP_API
void aws_http_connection_manager_release(struct aws_http_connection_manager *manager);

/*
 * Creates a new connection manager with the supplied configuration options.
 *
 * The returned connection manager begins with a ref count of 1.
 */
AWS_HTTP_API
struct aws_http_connection_manager *aws_http_connection_manager_new(
    struct aws_allocator *allocator,
    struct aws_http_connection_manager_options *options);

/*
 * Requests a connection from the manager.  The requester is notified of
 * an acquired connection (or failure to acquire) via the supplied callback.
 *
 * Once a connection has been successfully acquired from the manager it
 * must be released back (via aws_http_connection_manager_release_connection)
 * at some point.  Failure to do so will cause a resource leak.
 */
AWS_HTTP_API
void aws_http_connection_manager_acquire_connection(
    struct aws_http_connection_manager *manager,
    aws_http_connection_manager_on_connection_setup_fn *callback,
    void *user_data);

/*
 * Returns a connection back to the manager.  All acquired connections must
 * eventually be released back to the manager in order to avoid a resource leak.
 */
AWS_HTTP_API
int aws_http_connection_manager_release_connection(
    struct aws_http_connection_manager *manager,
    struct aws_http_connection *connection);

AWS_EXTERN_C_END

#endif /* AWS_HTTP_CONNECTION_MANAGER_H */