/*
 * Copyright (c) 2018-2020, Andreas Kling <andreas@ladybird.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#pragma once

#include <AK/Badge.h>
#include <AK/ByteString.h>
#include <AK/Function.h>
#include <AK/MemoryStream.h>
#include <AK/OwnPtr.h>
#include <AK/RefCounted.h>
#include <AK/WeakPtr.h>
#include <LibCore/ImmutableBytes.h>
#include <LibCore/Notifier.h>
#include <LibHTTP/HeaderList.h>
#include <LibRequests/NetworkError.h>
#include <LibRequests/RequestTimingInfo.h>

namespace Requests {

class RequestClient;

class ResponseData {
public:
    static ResponseData from_bytes(ReadonlyBytes bytes) { return ResponseData { bytes }; }
    static ResponseData from_immutable_bytes(Core::ImmutableBytes bytes) { return ResponseData { move(bytes) }; }

    [[nodiscard]] ReadonlyBytes bytes() const
    {
        if (m_immutable_bytes.has_value())
            return m_immutable_bytes->bytes();
        return m_bytes;
    }
    [[nodiscard]] Optional<Core::ImmutableBytes> const& immutable_bytes() const { return m_immutable_bytes; }

private:
    explicit ResponseData(ReadonlyBytes bytes)
        : m_bytes(bytes)
    {
    }

    explicit ResponseData(Core::ImmutableBytes bytes)
        : m_immutable_bytes(move(bytes))
    {
    }

    ReadonlyBytes m_bytes;
    Optional<Core::ImmutableBytes> m_immutable_bytes;
};

class ReadStream {
public:
    static ErrorOr<NonnullOwnPtr<ReadStream>> create(int reader_fd);

    NonnullRefPtr<Core::Notifier> const& notifier() const { return m_notifier; }

    bool is_eof() const { return m_stream->is_eof(); }

    ErrorOr<Bytes> read_some(Bytes bytes) { return m_stream->read_some(bytes); }

private:
    ReadStream(NonnullOwnPtr<Stream> stream, NonnullRefPtr<Core::Notifier> notifier)
        : m_stream(move(stream))
        , m_notifier(move(notifier))
    {
    }

    NonnullOwnPtr<Stream> m_stream;
    NonnullRefPtr<Core::Notifier> m_notifier;
};

class Request : public RefCounted<Request>
    , public Weakable<Request> {
public:
    struct CertificateAndKey {
        ByteString certificate;
        ByteString key;
    };

    static NonnullRefPtr<Request> create_from_id(Badge<RequestClient>, RequestClient& client, u64 request_id)
    {
        return adopt_ref(*new Request(client, request_id));
    }

    ~Request();

    u64 id() const { return m_request_id; }
    int request_server_client_id() const;
    int fd() const { return m_fd; }
    bool stop();
    void set_body_delivery_paused(bool);
    void resume_body_delivery();
    void resume_body_delivery_up_to(size_t);
    void release_for_transfer();
    [[nodiscard]] bool has_file_backed_response_body() const;

    using BufferedRequestFinished = Function<void(u64 total_size, RequestTimingInfo const& timing_info, Optional<NetworkError> const& network_error, NonnullRefPtr<HTTP::HeaderList> response_headers, Optional<u32> response_code, Optional<String> reason_phrase, Optional<Core::ImmutableBytes> javascript_bytecode, Optional<u64> javascript_bytecode_cache_vary_key, Core::ImmutableBytes payload)>;

    // Configure the request such that the entirety of the response data is buffered. The callback receives that data and
    // the response headers all at once. Using this method is mutually exclusive with `set_unbuffered_data_received_callback`.
    void set_buffered_request_finished_callback(BufferedRequestFinished);

    using HeadersReceived = Function<void(NonnullRefPtr<HTTP::HeaderList> response_headers, Optional<u32> response_code, Optional<String> const& reason_phrase, Optional<Core::ImmutableBytes> javascript_bytecode, Optional<u64> javascript_bytecode_cache_vary_key)>;
    using DataReceived = Function<void(ResponseData data)>;
    using CachedBodyAvailable = Function<void(Core::ImmutableBytes data)>;
    using RequestFinished = Function<void(u64 total_size, RequestTimingInfo const& timing_info, Optional<NetworkError> network_error)>;
    using RequestStopped = Function<void()>;

    // Configure the request such that the response data is provided unbuffered as it is received. Using this method is
    // mutually exclusive with `set_buffered_request_finished_callback`.
    void set_unbuffered_request_callbacks(HeadersReceived, DataReceived, CachedBodyAvailable, RequestFinished);
    void set_stop_callback(RequestStopped);

    Function<CertificateAndKey()> on_certificate_requested;

    void did_finish(Badge<RequestClient>, u64 total_size, RequestTimingInfo const& timing_info, Optional<NetworkError> const& network_error);
    void did_receive_headers(Badge<RequestClient>, NonnullRefPtr<HTTP::HeaderList> response_headers, Optional<u32> response_code, Optional<String> const& reason_phrase, Optional<Core::ImmutableBytes> javascript_bytecode, Optional<u64> javascript_bytecode_cache_vary_key);
    void did_request_certificates(Badge<RequestClient>);
    void did_transfer(Badge<RequestClient>);

    RefPtr<Core::Notifier>& write_notifier(Badge<RequestClient>) { return m_write_notifier; }
    void set_request_fd(Badge<RequestClient>, int fd);
    void set_request_body_file(Badge<RequestClient>, int fd, u64 offset, u64 size);
    void set_request_cached_body_file(Badge<RequestClient>, int fd, u64 offset, u64 size);

private:
    Request(RequestClient&, u64 request_id);

    void attach_read_stream();
    void set_up_internal_stream_data(DataReceived on_data_available);
    void defer_teardown();

    WeakPtr<RequestClient> m_client;
    u64 m_request_id { 0 };
    RefPtr<Core::Notifier> m_write_notifier;
    int m_fd { -1 };
    bool m_fd_is_owned_by_read_stream { false };

    enum class Mode {
        Buffered,
        Unbuffered,
        Unknown,
    };
    Mode m_mode { Mode::Unknown };

    HeadersReceived on_headers_received;
    RequestFinished on_finish;
    RequestStopped m_on_stop;

    struct InternalBufferedData {
        InternalBufferedData();

        AllocatingMemoryStream payload_stream;
        NonnullRefPtr<HTTP::HeaderList> response_headers;
        Optional<u32> response_code;
        Optional<String> reason_phrase;
        Optional<Core::ImmutableBytes> javascript_bytecode;
        Optional<u64> javascript_bytecode_cache_vary_key;
        Optional<Core::ImmutableBytes> payload;
    };

    struct InternalStreamData {
        InternalStreamData() { }

        OwnPtr<ReadStream> read_stream;
        RefPtr<Core::Notifier> read_notifier;
        u64 total_size { 0 };
        u64 delivered_size { 0 };
        Optional<NetworkError> network_error;
        bool request_done { false };
        RequestTimingInfo timing_info;
        DataReceived on_data_available;
        CachedBodyAvailable on_cached_body_available;
        Function<void()> on_finish {};
        bool user_finish_called { false };
        Optional<Core::ImmutableBytes> file_backed_payload;
        Optional<Core::ImmutableBytes> cached_payload;
        Optional<size_t> body_delivery_remaining_byte_count;
    };

    OwnPtr<InternalBufferedData> m_internal_buffered_data;
    OwnPtr<InternalStreamData> m_internal_stream_data;
    Optional<NetworkError> m_body_delivery_error;
    bool m_body_delivery_paused { false };
};

}