// Implementation of the cd builtin.
#include "config.h"  // IWYU pragma: keep

#include "builtin_cd.h"

#include <fcntl.h>
#include <sys/stat.h>

#include <cerrno>

#include "builtin.h"
#include "common.h"
#include "env.h"
#include "fallback.h"  // IWYU pragma: keep
#include "io.h"
#include "parser.h"
#include "path.h"
#include "proc.h"
#include "wutil.h"  // IWYU pragma: keep

/// The cd builtin. Changes the current directory to the one specified or to $HOME if none is
/// specified. The directory can be relative to any directory in the CDPATH variable.
maybe_t<int> builtin_cd(parser_t &parser, io_streams_t &streams, wchar_t **argv) {
    const wchar_t *cmd = argv[0];
    int argc = builtin_count_args(argv);
    help_only_cmd_opts_t opts;

    int optind;
    int retval = parse_help_only_cmd_opts(opts, &optind, argc, argv, parser, streams);
    if (retval != STATUS_CMD_OK) return retval;

    if (opts.print_help) {
        builtin_print_help(parser, streams, cmd);
        return STATUS_CMD_OK;
    }

    wcstring dir_in;
    if (argv[optind]) {
        dir_in = argv[optind];
    } else {
        auto maybe_dir_in = parser.vars().get(L"HOME");
        if (maybe_dir_in.missing_or_empty()) {
            streams.err.append_format(_(L"%ls: Could not find home directory\n"), cmd);
            return STATUS_CMD_ERROR;
        }
        dir_in = maybe_dir_in->as_string();
    }

    wcstring pwd = parser.vars().get_pwd_slash();
    maybe_t<wcstring> mdir = path_get_cdpath(dir_in, pwd, parser.vars());
    if (!mdir) {
        if (errno == ENOTDIR) {
            streams.err.append_format(_(L"%ls: '%ls' is not a directory\n"), cmd, dir_in.c_str());
        } else if (errno == ENOENT) {
            streams.err.append_format(_(L"%ls: The directory '%ls' does not exist\n"), cmd,
                                      dir_in.c_str());
        } else if (errno == EROTTEN) {
            streams.err.append_format(_(L"%ls: '%ls' is a rotten symlink\n"), cmd, dir_in.c_str());
        } else {
            streams.err.append_format(_(L"%ls: Unknown error trying to locate directory '%ls'\n"),
                                      cmd, dir_in.c_str());
        }

        if (!parser.is_interactive()) streams.err.append(parser.current_line());

        return STATUS_CMD_ERROR;
    }
    const wcstring &dir = *mdir;

    wcstring norm_dir = normalize_path(dir);

    // We need to keep around the fd for this directory, in the parser.
    autoclose_fd_t dir_fd(wopen_cloexec(norm_dir, O_RDONLY));
    bool success = dir_fd.valid() && fchdir(dir_fd.fd()) == 0;

    if (!success) {
        struct stat buffer;
        int status;

        status = wstat(dir, &buffer);
        if (!status && S_ISDIR(buffer.st_mode)) {
            streams.err.append_format(_(L"%ls: Permission denied: '%ls'\n"), cmd, dir_in.c_str());
        } else {
            streams.err.append_format(_(L"%ls: '%ls' is not a directory\n"), cmd, dir_in.c_str());
        }

        if (!parser.is_interactive()) {
            streams.err.append(parser.current_line());
        }

        return STATUS_CMD_ERROR;
    }

    parser.libdata().cwd_fd = std::make_shared<const autoclose_fd_t>(std::move(dir_fd));
    std::vector<event_t> evts;
    parser.vars().set_one(L"PWD", ENV_EXPORT | ENV_GLOBAL, std::move(norm_dir), &evts);
    for (const auto &evt : evts) {
        event_fire(parser, evt);
    }
    return STATUS_CMD_OK;
}