# pylint: disable=C0114
import os
import re
import datetime
from flask import Flask, request, jsonify, send_from_directory, render_template
from flasgger import Swagger

app = Flask(__name__, template_folder='templates')
swagger = Swagger(app)
app.config['UPLOAD_DIRECTORY'] = os.environ.get('UPLOAD_DIRECTORY', '/uploads')
app.config['MAX_CONTENT_LENGTH'] = int(os.environ.get('MAX_CONTENT_LENGTH', '5')) * 1024 * 1024  # in MB # pylint: disable=C0301
app.config['ENABLE_WEBSERVER'] = os.getenv('ENABLE_WEBSERVER', 'True').lower() == 'true'


VALID_FILENAME_REGEX = r'^[a-zA-Z0-9\-_\.]+$'

AUTH_TOKEN = os.environ.get('AUTH_TOKEN', 'myuploadtoken')

def is_valid_filename(filename): # pylint: disable=C0116
    return bool(re.match(VALID_FILENAME_REGEX, filename))

if app.config['ENABLE_WEBSERVER']:
    @app.route('/', methods=['GET'])
    def file_list():
        """
        Endpoint for displaying a list of files in the upload directory.
        """
        files = []
        for filename in os.listdir(app.config['UPLOAD_DIRECTORY']):
            file_path = os.path.join(app.config['UPLOAD_DIRECTORY'], filename)
            if os.path.isfile(file_path):
                stats = os.stat(file_path)
                size = stats.st_size
                last_modified = datetime.datetime.fromtimestamp(stats.st_mtime).strftime('%Y-%m-%d %H:%M:%S') # pylint: disable=C0301
                files.append({
                    'name': filename,
                    'size': size,
                    'last_modified': last_modified
                })

        return render_template('file_list.html', files=files)

@app.route('/health', methods=['GET'])
def health_check():
    """
    Endpoint for health check.
    ---
    responses:
        200:
            description: OK
    """
    return 'OK'

@app.route('/upload', methods=['POST'])
def upload_file():
    """
    Endpoint for uploading files.
    Filename can only contain alphanumeric characters, hyphens, underscores, and periods.
    If the filename is the same as an existing file, this file will be overwritten.
    ---
    parameters:
        - name: file
          in: formData
          type: file
          required: true
          description: The file to upload.
        - name: token
          in: header
          type: string
          required: true
          description: Authentication token.
    responses:
        200:
            description: File uploaded successfully.
        400:
            description: Bad request.
        401:
            description: Unauthorized.
    """
    if 'file' not in request.files:
        return jsonify({'error': 'No file part in the request'}), 400

    if 'token' not in request.headers:
        return jsonify({'error': 'No token supplied'}), 401

    if request.headers['token'] != AUTH_TOKEN:
        return jsonify({'error': 'Invalid token supplied'}), 401

    file = request.files['file']
    if file.filename == '':
        return jsonify({'error': 'No file selected for upload'}), 400

    if not is_valid_filename(file.filename):
        return jsonify({'error': 'Invalid filename. Only alphanumeric characters, hyphens, underscores, and periods are allowed.'}), 400 # pylint: disable=C0301

    filename = file.filename
    file.save(os.path.join(app.config['UPLOAD_DIRECTORY'], filename))
    return jsonify({'success': 'File \'{}\' successfully uploaded'.format(filename)}) # pylint: disable=C0209

@app.route('/download/<filename>', methods=['GET'])
def download_file(filename):
    """
    Endpoint for downloading files.
    ---
    parameters:
        - name: filename
          in: path
          type: string
          required: true
          description: The name of the file to download.
    responses:
        200:
            description: File downloaded successfully.
        404:
            description: File not found.
    """
    try:
        return send_from_directory(app.config['UPLOAD_DIRECTORY'], filename)
    except FileNotFoundError:
        return jsonify({'error': 'File \'{}\' not found'}), 404

@app.route('/delete/<filename>', methods=['DELETE'])
def delete_file(filename):
    """
    Endpoint for deleting files.
    ---
    parameters:
        - name: filename
          in: path
          type: string
          required: true
          description: The name of the file to delete.
        - name: token
          in: header
          type: string
          required: true
          description: Authentication token.
    responses:
        200:
            description: File deleted successfully.
        401:
            description: Unauthorized.
        404:
            description: File not found.
    """
    if 'token' not in request.headers:
        return jsonify({'error': 'No token supplied'}), 401

    if request.headers['token'] != AUTH_TOKEN:
        return jsonify({'error': 'Invalid token supplied'}), 401

    file_path = os.path.join(app.config['UPLOAD_DIRECTORY'], filename)
    if not os.path.isfile(file_path):
        return jsonify({'error': 'File not found'}), 404

    os.remove(file_path)
    return jsonify({'success': 'File \'{}\' successfully deleted'.format(filename)}) # pylint: disable=C0209


@app.route('/list', methods=['GET'])
def list_files():
    """
    Endpoint for listing  files.
    ---
    parameters:
        - name: token
          in: header
          type: string
          required: true
          description: Authentication token.
    responses:
        200:
            description: Listed files successfully.
        400:
            description: Bad request.
        401:
            description: Unauthorized.
    """
    if 'token' not in request.headers:
        return jsonify({'error': 'No token supplied'}), 401

    if request.headers['token'] != AUTH_TOKEN:
        return jsonify({'error': 'Invalid token supplied'}), 401

    files = []
    for filename in os.listdir(app.config['UPLOAD_DIRECTORY']):
        file_path = os.path.join(app.config['UPLOAD_DIRECTORY'], filename)
        if os.path.isfile(file_path):
            stats = os.stat(file_path)
            size = stats.st_size
            last_modified = datetime.datetime.fromtimestamp(stats.st_mtime).strftime('%Y-%m-%d %H:%M:%S') # pylint: disable=C0301
            files.append({
                'name': filename,
                'size': size,
                'last_modified': last_modified
            })

    return jsonify({'files': files})

if __name__ == '__main__':
    app.run(debug=True, host='0.0.0.0', port=int(os.environ.get('PORT', 5000)))