from os.path import isfile, join, relpath
from glob import glob

from tfw.components.mixins import SupervisorMixin
from tfw.event_handler_base import TriggerlessEventHandler
from tfw.components.directory_monitor import DirectoryMonitor

from tfw.config.logs import logging
log = logging.getLogger(__name__)


class FileManager:
    def __init__(self, working_directory, selected_file=None):
        self.exclude = ['__pycache__']
        self._workdir = working_directory
        self.filename = selected_file or self.files[0]

    def select_file(self, filename):
        if not filename in self.files:
           raise EnvironmentError('No such file in workdir!')
        self.filename = filename

    @property
    def files(self):
        return [self._relpath(file) for file in glob(join(self._workdir, '**/*'), recursive=True)
                if isfile(file) and
                not any(word in file for word in self.exclude)]

    @property
    def file_contents(self):
        with open(self._filepath(self.filename), 'r', errors='surrogateescape') as ifile:
            return ifile.read()

    @file_contents.setter
    def file_contents(self, value):
        with open(self._filepath(self.filename), 'w', errors='surrogateescape') as ofile:
            ofile.write(value)

    def _filepath(self, filename):
        return join(self._workdir, filename)

    def _relpath(self, filename):
        return relpath(self._filepath(filename), start=self._workdir)


class SourceCodeEventHandler(TriggerlessEventHandler, SupervisorMixin):
    def __init__(self, key, directory, process_name, selected_file=None):
        super().__init__(key)
        self.filemanager = FileManager(directory, selected_file=selected_file)
        self.process_name = process_name

        self.commands = {
            'read': self.read,
            'write': self.write,
            'select': self.select
        }

        self.monitor = DirectoryMonitor(directory)
        self.monitor.watch()    # This runs on a separate thread

    def read(self, data):
        try: data['content'] = self.filemanager.file_contents
        except PermissionError: data['content'] = 'You have no permission to open that file :('
        except FileNotFoundError: data['content'] = 'This file was removed :('
        except Exception: data['content'] = 'Failed to read file :('
        return data

    def write(self, data):
        with self.monitor.pauser:
            try: self.filemanager.file_contents = data['content']
            except Exception: log.exception('Error writing file!')
            self.restart_process()
        return data

    def select(self, data):
        try: self.filemanager.select_file(data['filename'])
        except EnvironmentError: log.exception('Failed to select file "{}"'.format(data['filename']))
        return data

    def attach_fileinfo(self, data):
        data['filename'] = self.filemanager.filename
        data['files'] = self.filemanager.files

    def handle_event(self, key, data_json):
        data = data_json['data']
        data_json['data'] = self.commands[data['command']](data)
        self.attach_fileinfo(data)
        return data_json

    def cleanup(self):
        self.monitor.stop()