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

#include <AK/LexicalPath.h>
#include <LibCore/ArgsParser.h>
#include <LibCore/System.h>
#include <LibFileSystem/FileSystem.h>
#include <LibMain/Main.h>
#include <stdio.h>
#include <unistd.h>

ErrorOr<int> serenity_main(Main::Arguments arguments)
{
    TRY(Core::System::pledge("stdio rpath wpath cpath fattr chown"));

    bool link = false;
    auto preserve = FileSystem::PreserveMode::Nothing;
    bool recursion_allowed = false;
    bool verbose = false;
    bool interactive = false;
    Vector<StringView> sources;
    ByteString destination;

    Core::ArgsParser args_parser;
    args_parser.add_option(link, "Link files instead of copying", "link", 'l');
    args_parser.add_option({
        Core::ArgsParser::OptionArgumentMode::Optional,
        "Preserve a selection of mode, ownership and timestamps. Defaults to all three if the option is present but no list is given.",
        "preserve",
        'p',
        "attributes",
        [&preserve](StringView s) {
            if (s.is_empty()) {
                preserve = FileSystem::PreserveMode::Permissions | FileSystem::PreserveMode::Ownership | FileSystem::PreserveMode::Timestamps;
                return true;
            }

            bool values_ok = true;

            s.for_each_split_view(',', SplitBehavior::Nothing, [&](StringView value) {
                if (value == "mode"sv) {
                    preserve |= FileSystem::PreserveMode::Permissions;
                } else if (value == "ownership"sv) {
                    preserve |= FileSystem::PreserveMode::Ownership;
                } else if (value == "timestamps"sv) {
                    preserve |= FileSystem::PreserveMode::Timestamps;
                } else {
                    warnln("cp: Unknown or unimplemented --preserve attribute: '{}'", value);
                    values_ok = false;
                }
            });

            return values_ok;
        },
        Core::ArgsParser::OptionHideMode::None,
    });
    args_parser.add_option(interactive, "Prompt before overwriting files", "interactive", 'i');
    args_parser.add_option(recursion_allowed, "Copy directories recursively", "recursive", 'R');
    args_parser.add_option(recursion_allowed, "Same as -R", nullptr, 'r');
    args_parser.add_option(verbose, "Verbose", "verbose", 'v');
    args_parser.add_positional_argument(sources, "Source file paths", "source");
    args_parser.add_positional_argument(destination, "Destination file path", "destination");
    args_parser.parse(arguments);

    if (has_flag(preserve, FileSystem::PreserveMode::Permissions)) {
        umask(0);
    } else {
        TRY(Core::System::pledge("stdio rpath wpath cpath fattr"));
    }

    bool destination_is_existing_dir = FileSystem::is_directory(destination);

    for (auto& source : sources) {
        // FIXME: May be formatted wrong if destination is a directory with a trailing slash, e.g. if called as such:
        // cp source dest/
        // ... `destination_path` may be formatted as `dest//source`, which isn't strictly correct.
        auto destination_path = destination_is_existing_dir
            ? ByteString::formatted("{}/{}", destination, LexicalPath::basename(source))
            : destination;

        if (interactive && FileSystem::exists(destination_path)) {
            bool overwrite = false;
            while (true) {
                warn("cp: overwrite '{}'? ", destination_path);
                fflush(stdout);

                char* line = nullptr;

                size_t n = 0;
                ssize_t size = getline(&line, &n, stdin);
                ScopeGuard guard([line] { free(line); });

                // Strip trailing newline.
                if (line[size - 1] == '\n') {
                    --size;
                }

                if (size == 1) {
                    if (*line == 'y') {
                        overwrite = true;
                        break;
                    }
                    if (*line == 'n') {
                        break;
                    }
                } else if (size == 2) {
                    if ("no"sv.compare(StringView { line, static_cast<unsigned long>(size) }) == 0) {
                        break;
                    }
                } else if (size == 3) {
                    if ("yes"sv.compare(StringView { line, static_cast<unsigned long>(size) }) == 0) {
                        overwrite = true;
                        break;
                    }
                }
            }

            if (verbose) {
                if (!overwrite) {
                    warnln("cp: skipping {}", destination_path);
                    continue;
                }
                warnln("cp: overwriting {}", destination_path);
            }

            if (!overwrite) {
                continue;
            }
        }

        auto result = FileSystem::copy_file_or_directory(
            destination_path, source,
            recursion_allowed ? FileSystem::RecursionMode::Allowed : FileSystem::RecursionMode::Disallowed,
            link ? FileSystem::LinkMode::Allowed : FileSystem::LinkMode::Disallowed,
            FileSystem::AddDuplicateFileMarker::No,
            preserve);

        if (result.is_error()) {
            if (result.error().code() == EISDIR)
                warnln("cp: -R not specified; omitting directory '{}'", source);
            else
                warnln("cp: unable to copy '{}' to '{}': {}", source, destination_path, strerror(result.error().code()));
            return 1;
        }

        if (verbose)
            outln("'{}' -> '{}'", source, destination_path);
    }
    return 0;
}