/*
 * Author: Sven Gothel <sgothel@jausoft.com>
 * Copyright (c) 2021 Gothel Software e.K.
 * Copyright (c) 2021 ZAFENA AB
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#ifndef JAU_IO_UTIL_HPP_
#define JAU_IO_UTIL_HPP_

#include <string>
#include <cstdint>
#include <functional>
#include <thread>
#include <vector>

#include <jau/basic_types.hpp>
#include <jau/callocator_sec.hpp>
#include <jau/ringbuffer.hpp>

// Include Botan header files before this one to be integrated w/ Botan!
// #include <botan_all.h>

namespace jau::io {
    /** @defgroup IOUtils IO Utilities
     *  Input and Output (IO) types and functionality.
     *
     *  @{
     */

#ifdef BOTAN_VERSION_MAJOR
    template<typename T> using secure_vector = std::vector<T, Botan::secure_allocator<T>>;
#else
    template<typename T> using secure_vector = std::vector<T, jau::callocator_sec<T>>;
#endif

    typedef std::basic_string<char, std::char_traits<char>, jau::callocator_sec<char>> secure_string;

    typedef jau::ringbuffer<uint8_t, size_t> ByteRingbuffer;

    extern const size_t BEST_URLSTREAM_RINGBUFFER_SIZE;

    /**
     * I/O direction, read or write
     */
    enum class io_dir_t : int8_t {
        /** Read Operation */
        READ  = 0,

        /** Write Operation */
        WRITE =  1
    };

    /**
     * Asynchronous I/O operation result value
     */
    enum class async_io_result_t : int8_t {
        /** Operation failed. */
        FAILED  = -1,

        /** Operation still in progress. */
        NONE    =  0,

        /** Operation succeeded. */
        SUCCESS =  1
    };
    typedef jau::ordered_atomic<async_io_result_t, std::memory_order::memory_order_relaxed> relaxed_atomic_async_io_result_t;

    /**
     * Stream consumer function
     * - `bool consumer(secure_vector<uint8_t>& data, bool is_final)`
     *
     * Returns true to signal continuation, false to end streaming.
     */
    typedef std::function<bool (secure_vector<uint8_t>& /* data */, bool /* is_final */)> StreamConsumerFunc;

    /**
     * Synchronous byte input stream reader from given file path using the given StreamConsumerFunc consumer_fn.
     *
     * To abort streaming, user may return `false` from the given `consumer_func`.
     *
     * @param input_file input file name path, `-` denotes std::stdin.
     * @param buffer secure std::vector buffer, passed down to consumer_fn
     * @param consumer_fn StreamConsumerFunc consumer for each received heap of bytes, returning true to continue stream of false to abort.
     * @return total bytes read or 0 if error
     */
    uint64_t read_file(const std::string& input_file,
            secure_vector<uint8_t>& buffer,
            StreamConsumerFunc consumer_fn) noexcept;

    class ByteInStream; // fwd

    /**
     * Synchronous byte input stream reader using the given StreamConsumerFunc consumer_fn.
     *
     * To abort streaming, user may return `false` from the given `consumer_func`.
     *
     * @param in the input byte stream to read from
     * @param buffer secure std::vector buffer, passed down to consumer_fn
     * @param consumer_fn StreamConsumerFunc consumer for each received heap of bytes, returning true to continue stream of false to abort.
     * @return total bytes read or 0 if error
     */
    uint64_t read_stream(ByteInStream& in,
            secure_vector<uint8_t>& buffer,
            StreamConsumerFunc consumer_fn) noexcept;

    /**
     * Synchronous double-buffered byte input stream reader using the given StreamConsumerFunc consumer_fn.
     *
     * To abort streaming, user may return `false` from the given `consumer_func`.
     *
     * Implementation reads one buffer ahead in respect to consumer_fn(). <br/>
     * If reading zero bytes on the next buffer,
     * it propagates the end-of-file (EOF) to the previous buffer which will be send via consumer_fn() next.<br/>
     *
     * This way, the consumer_fn() will always receive its `is_final` flag on the last sent bytes (size > 0)
     * even if the content-size is unknown (pipe). <br/>
     * Hence it allows e.g. decryption to work where the final data chunck must be processed as such.
     *
     * @param in the input byte stream to read from
     * @param buffer1 secure std::vector buffer, passed down to consumer_fn
     * @param buffer2 secure std::vector buffer, passed down to consumer_fn
     * @param consumer_fn StreamConsumerFunc consumer for each received heap of bytes, returning true to continue stream of false to abort.
     * @return total bytes read or 0 if error
     */
    uint64_t read_stream(ByteInStream& in,
            secure_vector<uint8_t>& buffer1, secure_vector<uint8_t>& buffer2,
            StreamConsumerFunc consumer_fn) noexcept;

    /**
     * Synchronous URL stream reader using the given StreamConsumerFunc consumer_fn.
     *
     * To abort streaming, user may return `false` from the given `consumer_func`.
     *
     * Standard implementation uses [curl](https://curl.se/),
     * hence all [*libcurl* network protocols](https://curl.se/docs/url-syntax.html) are supported,
     * see jau::io::uri::supported_protocols().
     *
     * If the uri-sheme doesn't match a supported protocol, see jau::io::uri::protocol_supported(),
     * function returns immediately with zero bytes.
     *
     * @param url the URL to open a connection to and stream bytes from
     * @param buffer secure std::vector buffer, passed down to consumer_fn
     * @param consumer_fn StreamConsumerFunc consumer for each received heap of bytes, returning true to continue stream of false to abort.
     * @return total bytes read or 0 if transmission error or protocol of given url is not supported
     */
    uint64_t read_url_stream(const std::string& url,
            secure_vector<uint8_t>& buffer,
            StreamConsumerFunc consumer_fn) noexcept;

    /**
     * Asynchronous URL read content using the given byte jau::ringbuffer, allowing parallel reading.
     *
     * To abort streaming, user may set given reference `results` to a value other than async_io_result_t::NONE.
     *
     * Standard implementation uses [curl](https://curl.se/),
     * hence all [*libcurl* network protocols](https://curl.se/docs/url-syntax.html) are supported,
     * see jau::io::uri::supported_protocols().
     *
     * If the uri-sheme doesn't match a supported protocol, see jau::io::uri::protocol_supported(),
     * function returns with nullptr.
     *
     * @param url the URL to open a connection to and stream bytes from
     * @param buffer the ringbuffer destination to write into
     * @param has_content_length indicating whether content_length is known from server
     * @param content_length tracking the content_length
     * @param total_read tracking the total_read
     * @param result reference to tracking async_io_result_t. If set to other than async_io_result_t::NONE while streaming, streaming is aborted.
     * @return the url background reading thread unique-pointer or nullptr if protocol of given url is not supported
     */
    std::unique_ptr<std::thread> read_url_stream(const std::string& url,
            ByteRingbuffer& buffer,
            jau::relaxed_atomic_bool& has_content_length,
            jau::relaxed_atomic_uint64& content_length,
            jau::relaxed_atomic_uint64& total_read,
            relaxed_atomic_async_io_result_t& result) noexcept;

    void print_stats(const std::string& prefix, const uint64_t& out_bytes_total, const jau::fraction_i64& td) noexcept;

    /**@}*/

    /**
     * Limited URI toolkit to query handled protocols by the IO implementation.
     *
     * The URI scheme functionality exposed here is limited and only provided to decide whether the used implementation
     * is able to handle the protocol. This is not a replacement for a proper URI class.
     */
    namespace uri_tk {
        /** \addtogroup IOUtils
         *
         *  @{
         */

        /**
         * Returns a list of supported protocol supported by [*libcurl* network protocols](https://curl.se/docs/url-syntax.html),
         * queried at runtime.
         * @see protocol_supported()
         */
        std::vector<std::string_view> supported_protocols() noexcept;

        /**
         * Returns the valid uri-scheme from given uri,
         * which is empty if no valid scheme is included.
         *
         * The given uri must included at least a colon after the uri-scheme part.
         *
         * @param uri an uri
         * @return valid uri-scheme, empty if non found
         */
        std::string_view get_scheme(const std::string_view& uri) noexcept;

        /**
         * Returns true if the uri-scheme of given uri matches a supported by [*libcurl* network protocols](https://curl.se/docs/url-syntax.html) otherwise false.
         *
         * The uri-scheme is retrieved via get_scheme() passing given uri, hence must included at least a colon after the uri-scheme part.
         *
         * The *libcurl* supported protocols is queried at runtime, see supported_protocols().
         *
         * @param uri an uri to test
         * @return true if the uri-scheme of given uri is supported, otherwise false.
         * @see supported_protocols()
         * @see get_scheme()
         */
        bool protocol_supported(const std::string_view& uri) noexcept;

        /**
         * Returns true if the uri-scheme of given uri matches the local `file` protocol, i.e. starts with `file://`.
         * @param uri an uri to test
         */
        bool is_local_file_protocol(const std::string_view& uri) noexcept;

        /**@}*/
    }

} // namespace elevator::io

#endif /* JAU_IO_UTIL_HPP_ */