import os
from flask import Flask, render_template, request, redirect, abort, url_for, session
import requests
from datetime import datetime

def get_env_variable(var_name):
    value = os.environ.get(var_name)
    if not value:
        raise ValueError(f"Missing required environment variable: {var_name}")
    return value

app = Flask(__name__)

# Read environment variables outside the route function
client_id = get_env_variable('CLIENT_ID')
redirect_uri = get_env_variable('REDIRECT_URI')
optional_scopes = get_env_variable('OPTIONAL_SCOPES')
database_url = get_env_variable('DATABASE_URL')
secret_key = get_env_variable('APP_SECRET_KEY')

# Set secret key to enable sessions
app.secret_key = secret_key

csrf_protection_string = None

@app.route('/')
def home():
    if is_logged_in():
        token_id = session.get('token_id')
        resp = requests.get(f'{database_url}/token/{token_id}')
        raise_for_status(resp)
        resp_json = resp.json()
        token = resp_json['token']

        user_info = requests.get('https://api.github.com/user', headers={
            'Authorization': f'Bearer {token.get("access_token")}'
        }).json()

        last_synced = datetime.fromtimestamp(token.get('timestamp')).strftime('%Y-%m-%d %H:%M:%S')
        next_sync = datetime.fromtimestamp(token.get('timestamp') + token.get('expiration_seconds')).strftime('%Y-%m-%d %H:%M:%S')
        return render_template('home.html', user_info=user_info,
                                readwise_api_key=token.get('readwise_api_key', ''),
                                last_synced=last_synced, next_sync=next_sync)

    # Generate a CSRF protection string
    global csrf_protection_string
    csrf_protection_string = os.urandom(16).hex()

    # Pass dynamic variables to the template
    return render_template('login.html', client_id=client_id, redirect_uri=redirect_uri, 
                           optional_scopes=optional_scopes, csrf_protection_string=csrf_protection_string)

@app.route('/oauth-redirect')
def oauth_redirect():
    auth_code = request.args.get('code')
    csrf_token = request.args.get('state')

    # Verify the CSRF protection string
    if csrf_token != csrf_protection_string:
        abort(400, 'Invalid CSRF token. Please try again.')

    # Exchange authorization code for access and refresh tokens
    # response = requests.post(
    #     'https://www.inoreader.com/oauth2/token',
    #     headers={
    #         'Content-Type': 'application/x-www-form-urlencoded',
    #     },
    #     data={
    #         'code': auth_code,
    #         'redirect_uri': get_env_variable('REDIRECT_URI'),
    #         'client_id': get_env_variable('CLIENT_ID'),
    #         'client_secret': get_env_variable('CLIENT_SECRET'),
    #         'scope': '',
    #         'grant_type': 'authorization_code'
    #     }
    # )

    # TEST: Github OAuth - REMOVE
    response = requests.post(
        'https://github.com/login/oauth/access_token',
        headers={
            'Accept': 'application/json'
        },
        data={
            'code': auth_code,
            'redirect_uri': get_env_variable('REDIRECT_URI'),
            'client_id': get_env_variable('CLIENT_ID'),
            'client_secret': get_env_variable('CLIENT_SECRET')
        }
    )

    raise_for_status(response)

    token = response.json()

    # TEST: Github OAuth - REMOVE
    token['refresh_token'] = 'N/A'
    token['expires_in'] = 3600

    user_info = requests.get('https://api.github.com/user', headers={
        'Authorization': f'Bearer {token.get("access_token")}'
        }).json()

    # Save tokens for later use
    token_id = save_token(
        user_info.get('email'), # for inoreader it's userEmail
        token.get('access_token'),
        token.get('refresh_token'),
        token.get('expires_in')
    )

    set_session_token_id(token_id)
    return redirect(url_for('home'))

# logout
@app.route('/logout', methods=['POST'])
def logout():
    token_id = session.get('token_id')

    if not token_id:
        return redirect(url_for('home'))
    
    # remove token_id from session
    session.pop('token_id', None)

    # response = requests.put(f'{database_url}/token/{token_id}', headers={
    #     'Content-Type': 'application/json'
    # }, json={
    #     'is_logged_in': False
    # })
    # response.raise_for_status()

    return redirect(url_for('home'))

@app.route('/readwise', methods=['POST'])
def submit_readwise_api():
    token_id = session.get('token_id')

    if not token_id:
        return redirect(url_for('home'))

    response = requests.put(f'{database_url}/token/{token_id}', headers={
        'Content-Type': 'application/json'
    }, json={
        'readwise_api_key': request.form.get('readwise_api_key')
    })
    raise_for_status(response)

    return redirect(url_for('home'))

def is_logged_in():
    token_id = session.get('token_id')
    if not token_id:
        return False

    response = requests.get(f'{database_url}/token/{token_id}')
    raise_for_status(response)
    resp_json = response.json()
    token = resp_json['token']

    return token.get('active', False)

def save_token(email, access_token, refresh_token, expiration_seconds):
    response = requests.post(
        f'{database_url}/token',
        headers={
            'Content-Type': 'application/json'
        },
        json={
            'email': email,
            'access_token': access_token,
            'refresh_token': refresh_token,
            'expiration_seconds': expiration_seconds
        }
    )
    raise_for_status(response)

    return response.json().get('id')

def set_session_token_id(token_id):
    session['token_id'] = token_id

def raise_for_status(response):
    if response.status_code not in range(200, 300):
        msg = None
        try:
            msg = response.json().get('error', '')
        except:
            msg = response.text
        raise Exception(f'HTTPError: {response.status_code} \n Message: {msg}')

if __name__ == '__main__':
    app.run(host='0.0.0.0', debug=True, port=5000)