from os import path, mkdir, getcwd
from time import time
from uuid import uuid1

from eventlet import tpool
from flask import Flask, request, make_response, send_from_directory

from pycs.ApplicationStatus import ApplicationStatus


class FileProvider(Flask):
    def __init__(self, app_status: ApplicationStatus, cors=False):
        super().__init__(__name__)

        # add download handler
        @self.route('/media/<identifier>', methods=['GET'])
        def media(identifier):
            # get current project
            opened_projects = list(filter(lambda x: x['status'] == 'open', app_status['projects']))
            if len(opened_projects) == 0:
                return make_response('no open project available', 500)

            current_project = opened_projects[0]
            file_directory = path.join(getcwd(), 'projects', current_project['id'], 'data')

            # get object
            data_objects = list(filter(lambda x: x['id'] == identifier, current_project['data']))
            if len(data_objects) == 0:
                return make_response('data object not avilable', 500)

            target_object = data_objects[0]

            # return data
            file_name = target_object['id'] + target_object['extension']
            return send_from_directory(file_directory, file_name)

        # add upload handler
        @self.route('/upload', methods=['POST'])
        def upload():
            file_uuid = str(uuid1())

            # get current project path
            opened_projects = list(filter(lambda x: x['status'] == 'open', app_status['projects']))
            if len(opened_projects) == 0:
                return make_response('no open project available', 500)

            current_project = opened_projects[0]
            upload_path = path.join('projects', current_project['id'], 'data')

            # get file object
            # TODO read stream and parse data
            # TODO update progress correctly
            files = request.files

            if 'file' not in files.keys():
                return make_response('no file uploaded', 500)

            file = files['file']
            file_name = file.filename

            # add job to app status
            job = app_status['jobs'].append({
                'id': file_uuid,
                'type': 'upload',
                'progress': 0,
                'filename': file_name,
                'created': int(time()),
                'finished': None
            })

            if not path.exists(upload_path):
                mkdir(upload_path)

            # open file handler
            file_name, file_extension = path.splitext(file_name)
            file_path = path.join(upload_path, f'{file_uuid}{file_extension}')

            with open(file_path, 'wb') as file_handler:
                # prepare some properties
                file_size = int(request.form['size']) if 'size' in request.form.keys() else None
                file_stream = file.stream

                # define handler function
                def file_write():
                    data = file_stream.read(262144)  # 256 kiB
                    file_handler.write(data)
                    return len(data)

                # transfer blocks to storage and update progress
                progress = 0
                while True:
                    read_bytes = tpool.execute(file_write)
                    progress += read_bytes

                    if file_size is not None:
                        job['progress'] = progress / file_size

                    if read_bytes == 0:
                        break

            # set progress to 1 after upload is done
            job['progress'] = 1
            job['finished'] = int(time())

            # add to project files
            if 'data' not in current_project:
                current_project['data'] = []

            current_project['data'].append({
                'id': file_uuid,
                'name': file_name,
                'extension': file_extension,
                'size': progress,
                'created': job['created']
            })

            # create response and allow cors if needed
            response = make_response()
            if cors:
                response.headers['Access-Control-Allow-Origin'] = '*'

            return response