# -*- coding: utf-8 -*-
##########################################################################
#
# pgAdmin 4 - PostgreSQL Tools
#
# Copyright (C) 2013 - 2021, The pgAdmin Development Team
# This software is released under the PostgreSQL License
#
##########################################################################

"""
Introduce a function to run the process executor in detached mode.
"""
import csv
import os
import sys
import psutil
from abc import ABCMeta, abstractproperty, abstractmethod
from datetime import datetime
from pickle import dumps, loads
from subprocess import Popen, PIPE
import logging

from pgadmin.utils import u_encode, file_quote, fs_encoding, \
    get_complete_file_path, get_storage_directory, IS_WIN
from pgadmin.browser.server_groups.servers.utils import does_server_exists
from pgadmin.utils.constants import KERBEROS

import pytz
from dateutil import parser
from flask import current_app, session
from flask_babel import gettext as _
from flask_security import current_user

import config
from pgadmin.model import Process, db
from io import StringIO

PROCESS_NOT_STARTED = 0
PROCESS_STARTED = 1
PROCESS_FINISHED = 2
PROCESS_TERMINATED = 3
PROCESS_NOT_FOUND = _("Could not find a process with the specified ID.")


def get_current_time(format='%Y-%m-%d %H:%M:%S.%f %z'):
    """
    Generate the current time string in the given format.
    """
    return datetime.utcnow().replace(
        tzinfo=pytz.utc
    ).strftime(format)


class IProcessDesc(object, metaclass=ABCMeta):
    @abstractproperty
    def message(self):
        pass

    @abstractmethod
    def details(self, cmd, args):
        pass

    @property
    def current_storage_dir(self):

        if config.SERVER_MODE:

            file = self.bfile
            try:
                # check if file name is encoded with UTF-8
                file = self.bfile.decode('utf-8')
            except Exception:
                # do nothing if bfile is not encoded.
                pass

            path = get_complete_file_path(file)
            path = file if path is None else path

            if IS_WIN:
                path = os.path.realpath(path)

            storage_directory = os.path.basename(get_storage_directory())

            if storage_directory in path:
                start = path.index(storage_directory)
                end = start + (len(storage_directory))
                last_dir = os.path.dirname(path[end:])
            else:
                last_dir = file

            last_dir = replace_path_for_win(last_dir)

            return None if hasattr(self, 'is_import') and self.is_import \
                else last_dir

        return None


def replace_path_for_win(last_dir=None):
    if IS_WIN:
        if '\\' in last_dir and len(last_dir) == 1:
            last_dir = last_dir.replace('\\', '\\\\')
        else:
            last_dir = last_dir.replace('\\', '/')

    return last_dir


class BatchProcess(object):
    def __init__(self, **kwargs):

        self.id = self.desc = self.cmd = self.args = self.log_dir = \
            self.stdout = self.stderr = self.stime = self.etime = \
            self.ecode = None
        self.env = dict()

        if 'id' in kwargs:
            self._retrieve_process(kwargs['id'])
        else:
            self._create_process(
                kwargs['desc'], kwargs['cmd'], kwargs['args']
            )

    def _retrieve_process(self, _id):
        p = Process.query.filter_by(pid=_id, user_id=current_user.id).first()

        if p is None:
            raise LookupError(PROCESS_NOT_FOUND)

        tmp_desc = loads(p.desc)

        # ID
        self.id = _id
        # Description
        self.desc = tmp_desc
        # Status Acknowledged time
        self.atime = p.acknowledge
        # Command
        self.cmd = p.command
        # Arguments
        self.args = p.arguments
        # Log Directory
        self.log_dir = p.logdir
        # Standard ouput log file
        self.stdout = os.path.join(p.logdir, 'out')
        # Standard error log file
        self.stderr = os.path.join(p.logdir, 'err')
        # Start time
        self.stime = p.start_time
        # End time
        self.etime = p.end_time
        # Exit code
        self.ecode = p.exit_code
        # Process State
        self.process_state = p.process_state

    def _create_process(self, _desc, _cmd, _args):
        ctime = get_current_time(format='%y%m%d%H%M%S%f')
        log_dir = os.path.join(
            config.SESSION_DB_PATH, 'process_logs'
        )

        def random_number(size):
            import random
            import string

            return ''.join(
                random.choice(
                    string.ascii_uppercase + string.digits
                ) for _ in range(size)
            )

        created = False
        size = 0
        uid = ctime
        while not created:
            try:
                uid += random_number(size)
                log_dir = os.path.join(log_dir, uid)
                size += 1
                if not os.path.exists(log_dir):
                    os.makedirs(log_dir, int('700', 8))
                    created = True
            except OSError as oe:
                import errno
                if oe.errno != errno.EEXIST:
                    raise

        # ID
        self.id = ctime
        # Description
        self.desc = _desc
        # Status Acknowledged time
        self.atime = None
        # Command
        self.cmd = _cmd
        # Log Directory
        self.log_dir = log_dir
        # Standard ouput log file
        self.stdout = os.path.join(log_dir, 'out')
        # Standard error log file
        self.stderr = os.path.join(log_dir, 'err')
        # Start time
        self.stime = None
        # End time
        self.etime = None
        # Exit code
        self.ecode = None
        # Process State
        self.process_state = PROCESS_NOT_STARTED

        # Arguments
        self.args = _args
        args_csv_io = StringIO()
        csv_writer = csv.writer(
            args_csv_io, delimiter=str(','), quoting=csv.QUOTE_MINIMAL
        )
        csv_writer.writerow(_args)

        args_val = args_csv_io.getvalue().strip(str('\r\n'))
        tmp_desc = dumps(self.desc)

        j = Process(
            pid=int(uid),
            command=_cmd,
            arguments=args_val,
            logdir=log_dir,
            desc=tmp_desc,
            user_id=current_user.id
        )
        db.session.add(j)
        db.session.commit()

    def check_start_end_time(self):
        """
        Check start and end time to check process is still executing or not.
        :return:
        """
        if self.stime is not None:
            if self.etime is None:
                raise RuntimeError(_('The process has already been started.'))
            raise RuntimeError(
                _('The process has already finished and cannot be restarted.')
            )

    def start(self, cb=None):
        self.check_start_end_time()

        executor = file_quote(os.path.join(
            os.path.dirname(u_encode(__file__)), 'process_executor.py'
        ))

        if os.name == 'nt':
            paths = os.environ['PATH'].split(os.pathsep)

            current_app.logger.info(
                "Process Executor: Operating System Path %s",
                str(paths)
            )

            interpreter = self.get_interpreter(paths)
        else:
            interpreter = sys.executable

        cmd = [
            interpreter if interpreter is not None else 'python',
            executor, self.cmd
        ]
        cmd.extend(self.args)

        current_app.logger.info(
            "Executing the process executor with the arguments: %s",
            str(cmd)
        )

        # Make a copy of environment, and add new variables to support
        env = os.environ.copy()
        env['PROCID'] = self.id
        env['OUTDIR'] = self.log_dir
        env['PGA_BGP_FOREGROUND'] = "1"
        if config.SERVER_MODE and session and \
                session['auth_source_manager']['current_source'] == \
                KERBEROS:
            env['KRB5CCNAME'] = session['KRB5CCNAME']

        if self.env:
            env.update(self.env)

        if cb is not None:
            cb(env)
        if os.name == 'nt':
            DETACHED_PROCESS = 0x00000008
            from subprocess import CREATE_NEW_PROCESS_GROUP

            # We need to redirect the standard input, standard output, and
            # standard error to devnull in order to allow it start in detached
            # mode on
            stdout = os.devnull
            stderr = stdout
            stdin = open(os.devnull, "r")
            stdout = open(stdout, "a")
            stderr = open(stderr, "a")

            p = Popen(
                cmd,
                close_fds=False,
                env=env,
                stdout=stdout.fileno(),
                stderr=stderr.fileno(),
                stdin=stdin.fileno(),
                creationflags=(CREATE_NEW_PROCESS_GROUP | DETACHED_PROCESS)
            )
        else:
            # if in debug mode, wait for process to complete and
            # get the stdout and stderr of popen.
            if config.CONSOLE_LOG_LEVEL <= logging.DEBUG:
                p = self.get_process_output(cmd, env)
            else:
                p = Popen(
                    cmd, close_fds=True, stdout=None, stderr=None, stdin=None,
                    preexec_fn=self.preexec_function, env=env
                )

        self.ecode = p.poll()

        # Execution completed immediately.
        # Process executor cannot update the status, if it was not able to
        # start properly.
        if self.ecode is not None and self.ecode != 0:
            # There is no way to find out the error message from this process
            # as standard output, and standard error were redirected to
            # devnull.
            p = Process.query.filter_by(
                pid=self.id, user_id=current_user.id
            ).first()
            p.start_time = p.end_time = get_current_time()
            if not p.exit_code:
                p.exit_code = self.ecode
            p.process_state = PROCESS_FINISHED
            db.session.commit()
        else:
            # Update the process state to "Started"
            p = Process.query.filter_by(
                pid=self.id, user_id=current_user.id
            ).first()
            p.process_state = PROCESS_STARTED
            db.session.commit()

    def get_process_output(self, cmd, env):
        """
        :param cmd:
        :param env:
        :return:
        """
        p = Popen(
            cmd, close_fds=True, stdout=PIPE, stderr=PIPE, stdin=None,
            preexec_fn=self.preexec_function, env=env
        )

        output, errors = p.communicate()
        output = output.decode() \
            if hasattr(output, 'decode') else output
        errors = errors.decode() \
            if hasattr(errors, 'decode') else errors
        current_app.logger.debug(
            'Process Watcher Out:{0}'.format(output))
        current_app.logger.debug(
            'Process Watcher Err:{0}'.format(errors))

        return p

    def preexec_function(self):
        import signal
        # Detaching from the parent process group
        os.setpgrp()
        # Explicitly ignoring signals in the child process
        signal.signal(signal.SIGINT, signal.SIG_IGN)

    def get_interpreter(self, paths):
        """
        Get interpreter.
        :param paths:
        :return:
        """
        paths.insert(0, os.path.join(u_encode(sys.prefix), 'Scripts'))
        paths.insert(0, u_encode(sys.prefix))

        interpreter = self.which('pythonw.exe', paths)
        if interpreter is None:
            interpreter = self.which('python.exe', paths)

        current_app.logger.info(
            "Process Executor: Interpreter value in path: %s",
            str(interpreter)
        )
        if interpreter is None and current_app.PGADMIN_RUNTIME:
            # We've faced an issue with Windows 2008 R2 (x86) regarding,
            # not honouring the environment variables set under the Qt
            # (e.g. runtime), and also setting PYTHONHOME same as
            # sys.executable (i.e. pgAdmin4.exe).
            #
            # As we know, we're running it under the runtime, we can assume
            # that 'venv' directory will be available outside of 'bin'
            # directory.
            #
            # We would try out luck to find python executable based on that
            # assumptions.
            bin_path = os.path.dirname(sys.executable)

            venv = os.path.realpath(
                os.path.join(bin_path, '..\\venv')
            )

            interpreter = self.which('pythonw.exe', [venv])
            if interpreter is None:
                interpreter = self.which('python.exe', [venv])

            current_app.logger.info(
                "Process Executor: Interpreter value in virtual "
                "environment: %s", str(interpreter)
            )

            if interpreter is not None:
                # Our assumptions are proven right.
                # Let's append the 'bin' directory to the PATH environment
                # variable. And, also set PYTHONHOME environment variable
                # to 'venv' directory.
                os.environ['PATH'] = bin_path + ';' + os.environ['PATH']
                os.environ['PYTHONHOME'] = venv

        return interpreter

    def which(self, program, paths):
        def is_exe(fpath):
            return os.path.exists(fpath) and os.access(fpath, os.X_OK)

        for path in paths:
            if not os.path.isdir(path):
                continue
            exe_file = os.path.join(u_encode(path, fs_encoding), program)
            if is_exe(exe_file):
                return file_quote(exe_file)
        return None

    def read_log(self, logfile, log, pos, ctime, ecode=None, enc='utf-8'):
        import re
        completed = True
        idx = 0
        c = re.compile(r"(\d+),(.*$)")

        if not os.path.isfile(logfile):
            return 0, False

        with open(logfile, 'rb') as f:
            eofs = os.fstat(f.fileno()).st_size
            f.seek(pos, 0)
            if pos == eofs and ecode is None:
                completed = False

            while pos < eofs:
                idx += 1
                line = f.readline()
                line = line.decode(enc, 'replace')
                r = c.split(line)
                if len(r) < 3:
                    # ignore this line
                    pos = f.tell()
                    continue
                if r[1] > ctime:
                    completed = False
                    break
                log.append([r[1], r[2]])
                pos = f.tell()
                if idx >= 1024:
                    completed = False
                    break
                if pos == eofs:
                    if ecode is None:
                        completed = False
                    break

        return pos, completed

    def status(self, out=0, err=0):
        ctime = get_current_time(format='%y%m%d%H%M%S%f')

        stdout = []
        stderr = []
        out_completed = err_completed = False
        process_output = (out != -1 and err != -1)

        j = Process.query.filter_by(
            pid=self.id, user_id=current_user.id
        ).first()
        enc = sys.getdefaultencoding()
        if enc == 'ascii':
            enc = 'utf-8'

        execution_time = None

        if j is not None:
            status, updated = BatchProcess.update_process_info(j)
            if updated:
                db.session.commit()
            self.stime = j.start_time
            self.etime = j.end_time
            self.ecode = j.exit_code

            if self.stime is not None:
                stime = parser.parse(self.stime)
                etime = parser.parse(self.etime or get_current_time())

                execution_time = BatchProcess.total_seconds(etime - stime)

            if process_output:
                out, out_completed = self.read_log(
                    self.stdout, stdout, out, ctime, self.ecode, enc
                )
                err, err_completed = self.read_log(
                    self.stderr, stderr, err, ctime, self.ecode, enc
                )
        else:
            out_completed = err_completed = False

        if out == -1 or err == -1:
            return {
                'start_time': self.stime,
                'exit_code': self.ecode,
                'execution_time': execution_time,
                'process_state': self.process_state
            }

        return {
            'out': {
                'pos': out,
                'lines': stdout,
                'done': out_completed
            },
            'err': {
                'pos': err,
                'lines': stderr,
                'done': err_completed
            },
            'start_time': self.stime,
            'exit_code': self.ecode,
            'execution_time': execution_time,
            'process_state': self.process_state
        }

    @staticmethod
    def _check_start_time(p, data):
        """
        Check start time and its related other timing checks.
        :param p: Process.
        :param data: Data
        :return:
        """
        if 'start_time' in data and data['start_time']:
            p.start_time = data['start_time']

            # We can't have 'exit_code' without the 'start_time'
            if 'exit_code' in data and \
                    data['exit_code'] is not None:
                p.exit_code = data['exit_code']

                # We can't have 'end_time' without the 'exit_code'.
                if 'end_time' in data and data['end_time']:
                    p.end_time = data['end_time']

    @staticmethod
    def update_process_info(p):
        if p.start_time is None or p.end_time is None:
            status = os.path.join(p.logdir, 'status')
            if not os.path.isfile(status):
                return False, False

            with open(status, 'r') as fp:
                import json
                try:
                    data = json.load(fp)

                    #  First - check for the existance of 'start_time'.
                    BatchProcess._check_start_time(p, data)
                    # get the pid of the utility.
                    if 'pid' in data:
                        p.utility_pid = data['pid']

                    return True, True

                except ValueError as e:
                    current_app.logger.warning(
                        _("Status for the background process '{0}' could "
                          "not be loaded.").format(p.pid)
                    )
                    current_app.logger.exception(e)
                    return False, False
        return True, False

    @staticmethod
    def _check_process_desc(p):
        """
        Check process desc instance and return data according to process.
        :param p: process
        :return: return value for details, type_desc and desc related
        to process
        """
        desc = loads(p.desc)
        details = desc
        type_desc = ''
        current_storage_dir = None

        if isinstance(desc, IProcessDesc):

            from pgadmin.tools.backup import BackupMessage
            from pgadmin.tools.import_export import IEMessage
            args = []
            args_csv = StringIO(
                p.arguments.encode('utf-8')
                if hasattr(p.arguments, 'decode') else p.arguments
            )
            args_reader = csv.reader(args_csv, delimiter=str(','))
            for arg in args_reader:
                args = args + arg
            details = desc.details(p.command, args)
            type_desc = desc.type_desc
            if isinstance(desc, (BackupMessage, IEMessage)):
                current_storage_dir = desc.current_storage_dir
            desc = desc.message

        return desc, details, type_desc, current_storage_dir

    @staticmethod
    def list():
        processes = Process.query.filter_by(user_id=current_user.id)
        changed = False

        res = []
        for p in processes:
            status, updated = BatchProcess.update_process_info(p)
            if not status:
                continue
            elif not changed:
                changed = updated

            if p.start_time is None or (
                p.acknowledge is not None and p.end_time is None
            ):
                continue

            if BatchProcess._operate_orphan_process(p):
                continue

            execution_time = None

            stime = parser.parse(p.start_time)
            etime = parser.parse(p.end_time or get_current_time())

            execution_time = BatchProcess.total_seconds(etime - stime)

            desc, details, type_desc, current_storage_dir = BatchProcess.\
                _check_process_desc(p)

            res.append({
                'id': p.pid,
                'desc': desc,
                'type_desc': type_desc,
                'details': details,
                'stime': stime,
                'etime': p.end_time,
                'exit_code': p.exit_code,
                'acknowledge': p.acknowledge,
                'execution_time': execution_time,
                'process_state': p.process_state,
                'current_storage_dir': current_storage_dir,
            })

        if changed:
            db.session.commit()

        return res

    @staticmethod
    def _operate_orphan_process(p):

        if p and p.desc:
            desc = loads(p.desc)
            if does_server_exists(desc.sid, current_user.id) is False:
                current_app.logger.warning(
                    _("Server with id '{0}' is either removed or does "
                      "not exists for the background process "
                      "'{1}'").format(desc.sid, p.pid)
                )
                try:
                    BatchProcess.acknowledge(p.pid)
                except LookupError as lerr:
                    current_app.logger.warning(
                        _("Status for the background process '{0}' could "
                          "not be loaded.").format(p.pid)
                    )
                    current_app.logger.exception(lerr)
                return True

        return False

    @staticmethod
    def total_seconds(dt):
        return round(dt.total_seconds(), 2)

    @staticmethod
    def acknowledge(_pid):
        """
        Acknowledge from the user, he/she has alredy watched the status.

        Update the acknowledgement status, if the process is still running.
        And, delete the process information from the configuration, and the log
        files related to the process, if it has already been completed.
        """
        p = Process.query.filter_by(
            user_id=current_user.id, pid=_pid
        ).first()

        if p is None:
            raise LookupError(PROCESS_NOT_FOUND)

        if p.end_time is not None:
            logdir = p.logdir
            db.session.delete(p)
            import shutil
            shutil.rmtree(logdir, True)
        else:
            p.acknowledge = get_current_time()

        db.session.commit()

    def set_env_variables(self, server, **kwargs):
        """Set environment variables"""
        if server:
            # Set SSL related ENV variables
            if server.sslcert and server.sslkey and server.sslrootcert:
                # SSL environment variables
                self.env['PGSSLMODE'] = server.ssl_mode
                self.env['PGSSLCERT'] = get_complete_file_path(server.sslcert)
                self.env['PGSSLKEY'] = get_complete_file_path(server.sslkey)
                self.env['PGSSLROOTCERT'] = get_complete_file_path(
                    server.sslrootcert
                )

            # Set service name related ENV variable
            if server.service:
                self.env['PGSERVICE'] = server.service

        if 'env' in kwargs:
            self.env.update(kwargs['env'])

    @staticmethod
    def stop_process(_pid):
        """
        """
        p = Process.query.filter_by(
            user_id=current_user.id, pid=_pid
        ).first()

        if p is None:
            raise LookupError(PROCESS_NOT_FOUND)

        try:
            process = psutil.Process(p.utility_pid)
            process.terminate()
            # Update the process state to "Terminated"
            p.process_state = PROCESS_TERMINATED
            db.session.commit()
        except psutil.Error as e:
            current_app.logger.warning(
                _("Unable to kill the background process '{0}'").format(
                    p.utility_pid)
            )
            current_app.logger.exception(e)