/*
 * Copyright (c) 2021, Idan Horowitz <idan.horowitz@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <LibCompress/Gzip.h>
#include <LibCore/ArgsParser.h>
#include <LibCore/FileStream.h>
#include <LibCore/MappedFile.h>
#include <LibCore/System.h>
#include <LibMain/Main.h>
#include <unistd.h>

ErrorOr<int> serenity_main(Main::Arguments arguments)
{
    Vector<StringView> filenames;
    bool keep_input_files { false };
    bool write_to_stdout { false };
    bool decompress { false };

    Core::ArgsParser args_parser;
    args_parser.add_option(keep_input_files, "Keep (don't delete) input files", "keep", 'k');
    args_parser.add_option(write_to_stdout, "Write to stdout, keep original files unchanged", "stdout", 'c');
    args_parser.add_option(decompress, "Decompress", "decompress", 'd');
    args_parser.add_positional_argument(filenames, "Files", "FILES");
    args_parser.parse(arguments);

    if (write_to_stdout)
        keep_input_files = true;

    for (auto const& input_filename : filenames) {
        String output_filename;
        if (decompress) {
            if (!input_filename.ends_with(".gz"sv)) {
                warnln("unknown suffix for: {}, skipping", input_filename);
                continue;
            }
            output_filename = input_filename.substring_view(0, input_filename.length() - ".gz"sv.length());
        } else {
            output_filename = String::formatted("{}.gz", input_filename);
        }

        // We map the whole file instead of streaming to reduce size overhead (gzip header) and increase the deflate block size (better compression)
        // TODO: automatically fallback to buffered streaming for very large files
        RefPtr<Core::MappedFile> file;
        ReadonlyBytes input_bytes;
        if (TRY(Core::System::stat(input_filename)).st_size > 0) {
            file = TRY(Core::MappedFile::map(input_filename));
            input_bytes = file->bytes();
        }

        AK::Optional<ByteBuffer> output_bytes;
        if (decompress)
            output_bytes = Compress::GzipDecompressor::decompress_all(input_bytes);
        else
            output_bytes = Compress::GzipCompressor::compress_all(input_bytes);

        if (!output_bytes.has_value()) {
            warnln("Failed gzip {} input file", decompress ? "decompressing"sv : "compressing"sv);
            return 1;
        }

        auto success = false;
        if (write_to_stdout) {
            auto stdout = Core::OutputFileStream { Core::File::standard_output() };
            success = stdout.write_or_error(output_bytes.value());
        } else {
            auto output_stream_result = Core::OutputFileStream::open(output_filename);
            if (output_stream_result.is_error()) {
                warnln("Failed opening output file for writing: {}", output_stream_result.error());
                return 1;
            }
            success = output_stream_result.value().write_or_error(output_bytes.value());
        }
        if (!success) {
            warnln("Failed writing to output");
            return 1;
        }

        if (!keep_input_files) {
            TRY(Core::System::unlink(input_filename));
        }
    }
    return 0;
}