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

#include <AK/DeprecatedString.h>
#include <LibCore/ArgsParser.h>
#include <LibCore/ProcessStatisticsReader.h>
#include <LibCore/System.h>
#include <LibMain/Main.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

static ErrorOr<int> pid_of(DeprecatedString const& process_name, bool single_shot, bool omit_pid, pid_t pid)
{
    bool displayed_at_least_one = false;

    auto all_processes = TRY(Core::ProcessStatisticsReader::get_all());

    for (auto& it : all_processes.processes) {
        if (it.name == process_name) {
            if (!omit_pid || it.pid != pid) {
                out(displayed_at_least_one ? " {}"sv : "{}"sv, it.pid);
                displayed_at_least_one = true;

                if (single_shot)
                    break;
            }
        }
    }

    if (displayed_at_least_one)
        outln();

    return 0;
}

ErrorOr<int> serenity_main(Main::Arguments args)
{
    TRY(Core::System::pledge("stdio rpath"));
    TRY(Core::System::unveil("/sys/kernel/processes", "r"));
    TRY(Core::System::unveil("/etc/passwd", "r"));
    TRY(Core::System::unveil(nullptr, nullptr));

    bool single_shot = false;
    StringView omit_pid_value;
    StringView process_name;

    Core::ArgsParser args_parser;
    args_parser.add_option(single_shot, "Only return one pid", nullptr, 's');
    args_parser.add_option(omit_pid_value, "Omit the given PID, or the parent process if the special value %PPID is passed", nullptr, 'o', "pid");
    args_parser.add_positional_argument(process_name, "Process name to search for", "process-name");

    args_parser.parse(args);

    pid_t pid_to_omit = 0;
    if (!omit_pid_value.is_empty()) {
        if (omit_pid_value == "%PPID"sv) {
            pid_to_omit = getppid();
        } else {
            auto number = omit_pid_value.to_uint();
            if (!number.has_value()) {
                warnln("Invalid value for -o");
                args_parser.print_usage(stderr, args.strings[0]);
                return 1;
            }
            pid_to_omit = number.value();
        }
    }
    return pid_of(process_name, single_shot, !omit_pid_value.is_empty(), pid_to_omit);
}