# Source code for searx.engines.command

    # SPDX-License-Identifier: AGPL-3.0-or-later
    """With *command engines* administrators can run engines to integrate arbitrary
    shell commands.

    .. attention::

       When creating and enabling a ``command`` engine on a public instance, you
       must be careful to avoid leaking private data.

    The easiest solution is to limit the access by setting ``tokens`` as described
    in section :ref:`private engines`.  The engine base is flexible.  Only your
    imagination can limit the power of this engine (and maybe security concerns).

    Configuration
    =============

    The following options are available:

    ``command``:
      A comma separated list of the elements of the command.  A special token
      ``{{QUERY}}`` tells where to put the search terms of the user. Example:

      .. code:: yaml

         ['ls', '-l', '-h', '{{QUERY}}']

    ``delimiter``:
      A mapping containing a delimiter ``char`` and the *titles* of each element in
      ``keys``.

    ``parse_regex``:
      A dict containing the regular expressions for each result key.

    ``query_type``:

      The expected type of user search terms.  Possible values: ``path`` and
      ``enum``.

      ``path``:
        Checks if the user provided path is inside the working directory.  If not,
        the query is not executed.

      ``enum``:
        Is a list of allowed search terms.  If the user submits something which is
        not included in the list, the query returns an error.

    ``query_enum``:
      A list containing allowed search terms if ``query_type`` is set to ``enum``.

    ``working_dir``:
      The directory where the command has to be executed.  Default: ``./``.

    ``result_separator``:
      The character that separates results. Default: ``\\n``.

    Example
    =======

    The example engine below can be used to find files with a specific name in the
    configured working directory:

    .. code:: yaml

      - name: find
        engine: command
        command: ['find', '.', '-name', '{{QUERY}}']
        query_type: path
        shortcut: fnd
        delimiter:
            chars: ' '
            keys: ['line']

    Implementations
    ===============
    """

    import re
    from os.path import expanduser, isabs, realpath, commonprefix
    from shlex import split as shlex_split
    from subprocess import Popen, PIPE
    from threading import Thread

    from searx import logger

    engine_type = 'offline'
    paging = True
    command = []
    delimiter = {}
    parse_regex = {}
    query_type = ''
    query_enum = []
    environment_variables = {}
    working_dir = realpath('.')
    result_separator = '\n'
    result_template = 'key-value.html'
    timeout = 4.0

    _command_logger = logger.getChild('command')
    _compiled_parse_regex = {}

    def init(engine_settings):
        check_parsing_options(engine_settings)

        if 'command' not in engine_settings:
            raise ValueError('engine command : missing configuration key: command')

        global command, working_dir, delimiter, parse_regex, environment_variables  # pylint: disable=global-statement

        command = engine_settings['command']

        if 'working_dir' in engine_settings:
            working_dir = engine_settings['working_dir']
            if not isabs(engine_settings['working_dir']):
                working_dir = realpath(working_dir)

        if 'parse_regex' in engine_settings:
            parse_regex = engine_settings['parse_regex']
            for result_key, regex in parse_regex.items():
                _compiled_parse_regex[result_key] = re.compile(regex, flags=re.MULTILINE)
        if 'delimiter' in engine_settings:
            delimiter = engine_settings['delimiter']

        if 'environment_variables' in engine_settings:
            environment_variables = engine_settings['environment_variables']

    def search(query, params):
        cmd = _get_command_to_run(query)
        if not cmd:
            return []

        results = []
        reader_thread = Thread(target=_get_results_from_process, args=(results, cmd, params['pageno']))
        reader_thread.start()
        reader_thread.join(timeout=timeout)

        return results

    def _get_command_to_run(query):
        params = shlex_split(query)
        __check_query_params(params)

        cmd = []
        for c in command:
            if c == '{{QUERY}}':
                cmd.extend(params)
            else:
                cmd.append(c)

        return cmd

    def _get_results_from_process(results, cmd, pageno):
        leftover = ''
        count = 0
        start, end = __get_results_limits(pageno)
        with Popen(cmd, stdout=PIPE, stderr=PIPE, env=environment_variables) as process:
            line = process.stdout.readline()
            while line:
                buf = leftover + line.decode('utf-8')
                raw_results = buf.split(result_separator)
                if raw_results[-1]:
                    leftover = raw_results[-1]
                raw_results = raw_results[:-1]

                for raw_result in raw_results:
                    result = __parse_single_result(raw_result)
                    if result is None:
                        _command_logger.debug('skipped result:', raw_result)
                        continue

                    if start <= count and count <= end:  # pylint: disable=chained-comparison
                        result['template'] = result_template
                        results.append(result)

                    count += 1
                    if end < count:
                        return results

                line = process.stdout.readline()

            return_code = process.wait(timeout=timeout)
            if return_code != 0:
                raise RuntimeError('non-zero return code when running command', cmd, return_code)
            return None

    def __get_results_limits(pageno):
        start = (pageno - 1) * 10
        end = start + 9
        return start, end

    def __check_query_params(params):
        if not query_type:
            return

        if query_type == 'path':
            query_path = params[-1]
            query_path = expanduser(query_path)
            if commonprefix([realpath(query_path), working_dir]) != working_dir:
                raise ValueError('requested path is outside of configured working directory')
        elif query_type == 'enum' and len(query_enum) > 0:
            for param in params:
                if param not in query_enum:
                    raise ValueError('submitted query params is not allowed', param, 'allowed params:', query_enum)

    def check_parsing_options(engine_settings):
        """Checks if delimiter based parsing or regex parsing is configured correctly"""

        if 'delimiter' not in engine_settings and 'parse_regex' not in engine_settings:
            raise ValueError('failed to init settings for parsing lines: missing delimiter or parse_regex')
        if 'delimiter' in engine_settings and 'parse_regex' in engine_settings:
            raise ValueError('failed to init settings for parsing lines: too many settings')

        if 'delimiter' in engine_settings:
            if 'chars' not in engine_settings['delimiter'] or 'keys' not in engine_settings['delimiter']:
                raise ValueError

    def __parse_single_result(raw_result):
        """Parses command line output based on configuration"""

        result = {}

        if delimiter:
            elements = raw_result.split(delimiter['chars'], maxsplit=len(delimiter['keys']) - 1)
            if len(elements) != len(delimiter['keys']):
                return {}
            for i in range(len(elements)):  # pylint: disable=consider-using-enumerate
                result[delimiter['keys'][i]] = elements[i]

        if parse_regex:
            for result_key, regex in _compiled_parse_regex.items():
                found = regex.search(raw_result)
                if not found:
                    return {}
                result[result_key] = raw_result[found.start() : found.end()]

        return result