/*
 * Copyright (c) 2020, The SerenityOS developers.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "Shell.h"
#include <AK/LexicalPath.h>
#include <LibCore/ArgsParser.h>
#include <LibCore/File.h>
#include <inttypes.h>
#include <signal.h>
#include <sys/wait.h>
#include <unistd.h>

extern char** environ;
extern RefPtr<Line::Editor> editor;

int Shell::builtin_alias(int argc, const char** argv)
{
    Vector<const char*> arguments;

    Core::ArgsParser parser;
    parser.add_positional_argument(arguments, "List of name[=values]'s", "name[=value]", Core::ArgsParser::Required::No);

    if (!parser.parse(argc, const_cast<char**>(argv), false))
        return 1;

    if (arguments.is_empty()) {
        for (auto& alias : m_aliases)
            printf("%s=%s\n", escape_token(alias.key).characters(), escape_token(alias.value).characters());
        return 0;
    }

    bool fail = false;
    for (auto& argument : arguments) {
        auto parts = String { argument }.split_limit('=', 2, true);
        if (parts.size() == 1) {
            auto alias = m_aliases.get(parts[0]);
            if (alias.has_value()) {
                printf("%s=%s\n", escape_token(parts[0]).characters(), escape_token(alias.value()).characters());
            } else {
                fail = true;
            }
        } else {
            m_aliases.set(parts[0], parts[1]);
            add_entry_to_cache(parts[0]);
        }
    }

    return fail ? 1 : 0;
}

int Shell::builtin_bg(int argc, const char** argv)
{
    int job_id = -1;

    Core::ArgsParser parser;
    parser.add_positional_argument(job_id, "Job ID to run in background", "job-id", Core::ArgsParser::Required::No);

    if (!parser.parse(argc, const_cast<char**>(argv), false))
        return 1;

    if (job_id == -1 && !jobs.is_empty())
        job_id = find_last_job_id();

    auto* job = const_cast<Job*>(find_job(job_id));

    if (!job) {
        if (job_id == -1) {
            fprintf(stderr, "bg: no current job\n");
        } else {
            fprintf(stderr, "bg: job with id %d not found\n", job_id);
        }
        return 1;
    }

    job->set_running_in_background(true);
    job->set_is_suspended(false);

    dbg() << "Resuming " << job->pid() << " (" << job->cmd() << ")";
    fprintf(stderr, "Resuming job %" PRIu64 " - %s\n", job->job_id(), job->cmd().characters());

    if (killpg(job->pgid(), SIGCONT) < 0) {
        perror("killpg");
        return 1;
    }

    return 0;
}

int Shell::builtin_cd(int argc, const char** argv)
{
    const char* arg_path = nullptr;

    Core::ArgsParser parser;
    parser.add_positional_argument(arg_path, "Path to change to", "path", Core::ArgsParser::Required::No);

    if (!parser.parse(argc, const_cast<char**>(argv), false))
        return 1;

    String new_path;

    if (!arg_path) {
        new_path = home;
        if (cd_history.is_empty() || cd_history.last() != home)
            cd_history.enqueue(home);
    } else {
        if (cd_history.is_empty() || cd_history.last() != arg_path)
            cd_history.enqueue(arg_path);
        if (strcmp(arg_path, "-") == 0) {
            char* oldpwd = getenv("OLDPWD");
            if (oldpwd == nullptr)
                return 1;
            new_path = oldpwd;
        } else if (arg_path[0] == '/') {
            new_path = argv[1];
        } else {
            StringBuilder builder;
            builder.append(cwd);
            builder.append('/');
            builder.append(arg_path);
            new_path = builder.to_string();
        }
    }

    auto real_path = Core::File::real_path_for(new_path);
    if (real_path.is_empty()) {
        fprintf(stderr, "Invalid path '%s'\n", new_path.characters());
        return 1;
    }
    const char* path = real_path.characters();

    int rc = chdir(path);
    if (rc < 0) {
        if (errno == ENOTDIR) {
            fprintf(stderr, "Not a directory: %s\n", path);
        } else {
            fprintf(stderr, "chdir(%s) failed: %s\n", path, strerror(errno));
        }
        return 1;
    }
    setenv("OLDPWD", cwd.characters(), 1);
    cwd = real_path;
    setenv("PWD", cwd.characters(), 1);
    return 0;
}

int Shell::builtin_cdh(int argc, const char** argv)
{
    int index = -1;

    Core::ArgsParser parser;
    parser.add_positional_argument(index, "Index of the cd history entry (leave out for a list)", "index", Core::ArgsParser::Required::No);

    if (!parser.parse(argc, const_cast<char**>(argv), false))
        return 1;

    if (index == -1) {
        if (cd_history.is_empty()) {
            fprintf(stderr, "cdh: no history available\n");
            return 0;
        }

        for (ssize_t i = cd_history.size() - 1; i >= 0; --i)
            printf("%lu: %s\n", cd_history.size() - i, cd_history.at(i).characters());
        return 0;
    }

    if (index < 1 || (size_t)index > cd_history.size()) {
        fprintf(stderr, "cdh: history index out of bounds: %d not in (0, %zu)\n", index, cd_history.size());
        return 1;
    }

    const char* path = cd_history.at(cd_history.size() - index).characters();
    const char* cd_args[] = { "cd", path, nullptr };
    return Shell::builtin_cd(2, cd_args);
}

int Shell::builtin_dirs(int argc, const char** argv)
{
    // The first directory in the stack is ALWAYS the current directory
    directory_stack.at(0) = cwd.characters();

    bool clear = false;
    bool print = false;
    bool number_when_printing = false;
    char separator = ' ';

    Vector<const char*> paths;

    Core::ArgsParser parser;
    parser.add_option(clear, "Clear the directory stack", "clear", 'c');
    parser.add_option(print, "Print directory entries one per line", "print", 'p');
    parser.add_option(number_when_printing, "Number the directories in the stack when printing", "number", 'v');
    parser.add_positional_argument(paths, "Extra paths to put on the stack", "path", Core::ArgsParser::Required::No);

    if (!parser.parse(argc, const_cast<char**>(argv), false))
        return 1;

    // -v implies -p
    print = print || number_when_printing;

    if (print) {
        if (!paths.is_empty()) {
            fprintf(stderr, "dirs: 'print' and 'number' are not allowed when any path is specified");
            return 1;
        }
        separator = '\n';
    }

    if (clear) {
        for (size_t i = 1; i < directory_stack.size(); i++)
            directory_stack.remove(i);
    }

    for (auto& path : paths)
        directory_stack.append(path);

    if (print || (!clear && paths.is_empty())) {
        int index = 0;
        for (auto& directory : directory_stack) {
            if (number_when_printing)
                printf("%d ", index++);
            print_path(directory);
            fputc(separator, stdout);
        }
    }

    return 0;
}

int Shell::builtin_exit(int argc, const char** argv)
{
    int exit_code = 0;
    Core::ArgsParser parser;
    parser.add_positional_argument(exit_code, "Exit code", "code", Core::ArgsParser::Required::No);
    if (!parser.parse(argc, const_cast<char**>(argv)))
        return 1;

    if (!jobs.is_empty()) {
        if (!m_should_ignore_jobs_on_next_exit) {
            fprintf(stderr, "Shell: You have %zu active job%s, run 'exit' again to really exit.\n", jobs.size(), jobs.size() > 1 ? "s" : "");
            m_should_ignore_jobs_on_next_exit = true;
            return 1;
        }
    }
    stop_all_jobs();
    save_history();
    if (m_is_interactive)
        printf("Good-bye!\n");
    exit(exit_code);
    return 0;
}

int Shell::builtin_export(int argc, const char** argv)
{
    Vector<const char*> vars;

    Core::ArgsParser parser;
    parser.add_positional_argument(vars, "List of variable[=value]'s", "values", Core::ArgsParser::Required::No);

    if (!parser.parse(argc, const_cast<char**>(argv), false))
        return 1;

    if (vars.is_empty()) {
        for (size_t i = 0; environ[i]; ++i)
            puts(environ[i]);
        return 0;
    }

    for (auto& value : vars) {
        auto parts = String { value }.split_limit('=', 2);

        if (parts.size() == 1) {
            auto value = lookup_local_variable(parts[0]);
            if (value) {
                auto values = value->resolve_as_list(*this);
                StringBuilder builder;
                builder.join(" ", values);
                parts.append(builder.to_string());
            } else {
                // Ignore the export.
                continue;
            }
        }

        int setenv_return = setenv(parts[0].characters(), parts[1].characters(), 1);

        if (setenv_return != 0) {
            perror("setenv");
            return 1;
        }

        if (parts[0] == "PATH")
            cache_path();
    }

    return 0;
}

int Shell::builtin_fg(int argc, const char** argv)
{
    int job_id = -1;

    Core::ArgsParser parser;
    parser.add_positional_argument(job_id, "Job ID to bring to foreground", "job-id", Core::ArgsParser::Required::No);

    if (!parser.parse(argc, const_cast<char**>(argv), false))
        return 1;

    if (job_id == -1 && !jobs.is_empty())
        job_id = find_last_job_id();

    RefPtr<Job> job = find_job(job_id);

    if (!job) {
        if (job_id == -1) {
            fprintf(stderr, "fg: no current job\n");
        } else {
            fprintf(stderr, "fg: job with id %d not found\n", job_id);
        }
        return 1;
    }

    job->set_running_in_background(false);
    job->set_is_suspended(false);

    dbg() << "Resuming " << job->pid() << " (" << job->cmd() << ")";
    fprintf(stderr, "Resuming job %" PRIu64 " - %s\n", job->job_id(), job->cmd().characters());

    tcsetpgrp(STDOUT_FILENO, job->pgid());
    tcsetpgrp(STDIN_FILENO, job->pgid());

    if (killpg(job->pgid(), SIGCONT) < 0) {
        perror("killpg");
        return 1;
    }

    block_on_job(job);

    return job->exit_code();
}

int Shell::builtin_disown(int argc, const char** argv)
{
    Vector<const char*> str_job_ids;

    Core::ArgsParser parser;
    parser.add_positional_argument(str_job_ids, "Id of the jobs to disown (omit for current job)", "job_ids", Core::ArgsParser::Required::No);

    if (!parser.parse(argc, const_cast<char**>(argv), false))
        return 1;

    Vector<size_t> job_ids;
    for (auto& job_id : str_job_ids) {
        auto id = StringView(job_id).to_uint();
        if (id.has_value())
            job_ids.append(id.value());
        else
            fprintf(stderr, "disown: Invalid job id %s\n", job_id);
    }

    if (job_ids.is_empty())
        job_ids.append(find_last_job_id());

    Vector<const Job*> jobs_to_disown;

    for (auto id : job_ids) {
        auto job = find_job(id);
        if (!job)
            fprintf(stderr, "disown: job with id %zu not found\n", id);
        else
            jobs_to_disown.append(job);
    }

    if (jobs_to_disown.is_empty()) {
        if (str_job_ids.is_empty())
            fprintf(stderr, "disown: no current job\n");
        // An error message has already been printed about the nonexistence of each listed job.
        return 1;
    }

    for (auto job : jobs_to_disown) {
        job->deactivate();

        if (!job->is_running_in_background())
            fprintf(stderr, "disown warning: job %" PRIu64 " is currently not running, 'kill -%d %d' to make it continue\n", job->job_id(), SIGCONT, job->pid());

        jobs.remove(job->pid());
    }

    return 0;
}

int Shell::builtin_history(int, const char**)
{
    for (size_t i = 0; i < editor->history().size(); ++i) {
        printf("%6zu  %s\n", i, editor->history()[i].characters());
    }
    return 0;
}

int Shell::builtin_jobs(int argc, const char** argv)
{
    bool list = false, show_pid = false;

    Core::ArgsParser parser;
    parser.add_option(list, "List all information about jobs", "list", 'l');
    parser.add_option(show_pid, "Display the PID of the jobs", "pid", 'p');

    if (!parser.parse(argc, const_cast<char**>(argv), false))
        return 1;

    Job::PrintStatusMode mode = Job::PrintStatusMode::Basic;

    if (show_pid)
        mode = Job::PrintStatusMode::OnlyPID;

    if (list)
        mode = Job::PrintStatusMode::ListAll;

    for (auto& it : jobs) {
        if (!it.value->print_status(mode))
            return 1;
    }

    return 0;
}

int Shell::builtin_popd(int argc, const char** argv)
{
    if (directory_stack.size() <= 1) {
        fprintf(stderr, "Shell: popd: directory stack empty\n");
        return 1;
    }

    bool should_not_switch = false;
    String path = directory_stack.take_last();

    Core::ArgsParser parser;
    parser.add_option(should_not_switch, "Do not switch dirs", "no-switch", 'n');

    if (!parser.parse(argc, const_cast<char**>(argv), false))
        return 1;

    bool should_switch = !should_not_switch;

    // When no arguments are given, popd removes the top directory from the stack and performs a cd to the new top directory.
    if (argc == 1) {
        int rc = chdir(path.characters());
        if (rc < 0) {
            fprintf(stderr, "chdir(%s) failed: %s\n", path.characters(), strerror(errno));
            return 1;
        }

        cwd = path;
        return 0;
    }

    LexicalPath lexical_path(path.characters());
    if (!lexical_path.is_valid()) {
        fprintf(stderr, "LexicalPath failed to canonicalize '%s'\n", path.characters());
        return 1;
    }

    const char* real_path = lexical_path.string().characters();

    struct stat st;
    int rc = stat(real_path, &st);
    if (rc < 0) {
        fprintf(stderr, "stat(%s) failed: %s\n", real_path, strerror(errno));
        return 1;
    }

    if (!S_ISDIR(st.st_mode)) {
        fprintf(stderr, "Not a directory: %s\n", real_path);
        return 1;
    }

    if (should_switch) {
        int rc = chdir(real_path);
        if (rc < 0) {
            fprintf(stderr, "chdir(%s) failed: %s\n", real_path, strerror(errno));
            return 1;
        }

        cwd = lexical_path.string();
    }

    return 0;
}

int Shell::builtin_pushd(int argc, const char** argv)
{
    StringBuilder path_builder;
    bool should_switch = true;

    // From the BASH reference manual: https://www.gnu.org/software/bash/manual/html_node/Directory-Stack-Builtins.html
    // With no arguments, pushd exchanges the top two directories and makes the new top the current directory.
    if (argc == 1) {
        if (directory_stack.size() < 2) {
            fprintf(stderr, "pushd: no other directory\n");
            return 1;
        }

        String dir1 = directory_stack.take_first();
        String dir2 = directory_stack.take_first();
        directory_stack.insert(0, dir2);
        directory_stack.insert(1, dir1);

        int rc = chdir(dir2.characters());
        if (rc < 0) {
            fprintf(stderr, "chdir(%s) failed: %s\n", dir2.characters(), strerror(errno));
            return 1;
        }

        cwd = dir2;

        return 0;
    }

    // Let's assume the user's typed in 'pushd <dir>'
    if (argc == 2) {
        directory_stack.append(cwd.characters());
        if (argv[1][0] == '/') {
            path_builder.append(argv[1]);
        } else {
            path_builder.appendf("%s/%s", cwd.characters(), argv[1]);
        }
    } else if (argc == 3) {
        directory_stack.append(cwd.characters());
        for (int i = 1; i < argc; i++) {
            const char* arg = argv[i];

            if (arg[0] != '-') {
                if (arg[0] == '/') {
                    path_builder.append(arg);
                } else
                    path_builder.appendf("%s/%s", cwd.characters(), arg);
            }

            if (!strcmp(arg, "-n"))
                should_switch = false;
        }
    }

    LexicalPath lexical_path(path_builder.to_string());
    if (!lexical_path.is_valid()) {
        fprintf(stderr, "LexicalPath failed to canonicalize '%s'\n", path_builder.to_string().characters());
        return 1;
    }

    const char* real_path = lexical_path.string().characters();

    struct stat st;
    int rc = stat(real_path, &st);
    if (rc < 0) {
        fprintf(stderr, "stat(%s) failed: %s\n", real_path, strerror(errno));
        return 1;
    }

    if (!S_ISDIR(st.st_mode)) {
        fprintf(stderr, "Not a directory: %s\n", real_path);
        return 1;
    }

    if (should_switch) {
        int rc = chdir(real_path);
        if (rc < 0) {
            fprintf(stderr, "chdir(%s) failed: %s\n", real_path, strerror(errno));
            return 1;
        }

        cwd = lexical_path.string();
    }

    return 0;
}

int Shell::builtin_pwd(int, const char**)
{
    print_path(cwd);
    fputc('\n', stdout);
    return 0;
}

int Shell::builtin_setopt(int argc, const char** argv)
{
    if (argc == 1) {
#define __ENUMERATE_SHELL_OPTION(name, default_, description) \
    if (options.name)                                         \
        fprintf(stderr, #name "\n");

        ENUMERATE_SHELL_OPTIONS();

#undef __ENUMERATE_SHELL_OPTION
    }

    Core::ArgsParser parser;
#define __ENUMERATE_SHELL_OPTION(name, default_, description)     \
    bool name = false;                                            \
    bool not_##name = false;                                      \
    parser.add_option(name, "Enable: " description, #name, '\0'); \
    parser.add_option(not_##name, "Disable: " description, "no_" #name, '\0');

    ENUMERATE_SHELL_OPTIONS();

#undef __ENUMERATE_SHELL_OPTION

    if (!parser.parse(argc, const_cast<char**>(argv), false))
        return 1;

#define __ENUMERATE_SHELL_OPTION(name, default_, description) \
    if (name)                                                 \
        options.name = true;                                  \
    if (not_##name)                                           \
        options.name = false;

    ENUMERATE_SHELL_OPTIONS();

#undef __ENUMERATE_SHELL_OPTION

    return 0;
}

int Shell::builtin_shift(int argc, const char** argv)
{
    int count = 1;

    Core::ArgsParser parser;
    parser.add_positional_argument(count, "Shift count", "count", Core::ArgsParser::Required::No);

    if (!parser.parse(argc, const_cast<char**>(argv), false))
        return 1;

    if (count < 1)
        return 0;

    auto argv_ = lookup_local_variable("ARGV");
    if (!argv_) {
        fprintf(stderr, "shift: ARGV is unset\n");
        return 1;
    }

    if (!argv_->is_list())
        argv_ = adopt(*new AST::ListValue({ argv_.release_nonnull() }));

    auto& values = static_cast<AST::ListValue*>(argv_.ptr())->values();
    if ((size_t)count > values.size()) {
        fprintf(stderr, "shift: shift count must not be greater than %zu\n", values.size());
        return 1;
    }

    for (auto i = 0; i < count; ++i)
        values.take_first();

    return 0;
}

int Shell::builtin_time(int argc, const char** argv)
{
    Vector<const char*> args;

    Core::ArgsParser parser;
    parser.add_positional_argument(args, "Command to execute with arguments", "command", Core::ArgsParser::Required::Yes);

    if (!parser.parse(argc, const_cast<char**>(argv), false))
        return 1;

    AST::Command command;
    for (auto& arg : args)
        command.argv.append(arg);

    auto commands = expand_aliases({ move(command) });

    Core::ElapsedTimer timer;
    int exit_code = 1;
    timer.start();
    for (auto& job : run_commands(commands)) {
        block_on_job(job);
        exit_code = job.exit_code();
    }
    fprintf(stderr, "Time: %d ms\n", timer.elapsed());
    return exit_code;
}

int Shell::builtin_umask(int argc, const char** argv)
{
    const char* mask_text = nullptr;

    Core::ArgsParser parser;
    parser.add_positional_argument(mask_text, "New mask (omit to get current mask)", "octal-mask", Core::ArgsParser::Required::No);

    if (!parser.parse(argc, const_cast<char**>(argv), false))
        return 1;

    if (!mask_text) {
        mode_t old_mask = umask(0);
        printf("%#o\n", old_mask);
        umask(old_mask);
        return 0;
    }

    unsigned mask;
    int matches = sscanf(mask_text, "%o", &mask);
    if (matches == 1) {
        umask(mask);
        return 0;
    }

    fprintf(stderr, "umask: Invalid mask '%s'\n", mask_text);
    return 1;
}

int Shell::builtin_unset(int argc, const char** argv)
{
    Vector<const char*> vars;

    Core::ArgsParser parser;
    parser.add_positional_argument(vars, "List of variables", "variables", Core::ArgsParser::Required::Yes);

    if (!parser.parse(argc, const_cast<char**>(argv), false))
        return 1;

    for (auto& value : vars) {
        if (lookup_local_variable(value)) {
            unset_local_variable(value);
        } else {
            unsetenv(value);
        }
    }

    return 0;
}

bool Shell::run_builtin(int argc, const char** argv, int& retval)
{
    if (argc == 0)
        return false;

    StringView name { argv[0] };

#define __ENUMERATE_SHELL_BUILTIN(builtin)      \
    if (name == #builtin) {                     \
        retval = builtin_##builtin(argc, argv); \
        return true;                            \
    }

    ENUMERATE_SHELL_BUILTINS();

#undef __ENUMERATE_SHELL_BUILTIN

    return false;
}

bool Shell::has_builtin(const StringView& name) const
{
#define __ENUMERATE_SHELL_BUILTIN(builtin) \
    if (name == #builtin) {                \
        return true;                       \
    }

    ENUMERATE_SHELL_BUILTINS();

#undef __ENUMERATE_SHELL_BUILTIN
    return false;
}