import re
from datetime import datetime
from flask import Blueprint, render_template, request, redirect, url_for, flash
from werkzeug.security import generate_password_hash
from models import db, User

register_bp = Blueprint('register', __name__, url_prefix='/register')

@register_bp.route('/', methods=['GET', 'POST'])
def register():
    username = ''
    password = ''
    confirm_password = ''
    username_err = ''
    password_err = ''
    confirm_password_err = ''

    if request.method == 'POST':
        username = request.form.get('username', '').strip()
        password = request.form.get('password', '').strip()
        confirm_password = request.form.get('confirm_password', '').strip()

        # Validate username
        if not username:
            username_err = "Please enter a username."
        elif not re.match(r'^[a-zA-Z0-9_]+$', username):
            username_err = "Username can only contain letters, numbers, and underscores."
        else:
            # Check if username already exists
            if User.query.filter_by(username=username).first():
                username_err = "This username is already taken."

        # Validate password
        if not password:
            password_err = "Please enter a password."
        elif len(password) < 6:
            password_err = "Password must have at least 6 characters."

        # Validate confirm password
        if not confirm_password:
            confirm_password_err = "Please confirm password."
        elif password != confirm_password:
            confirm_password_err = "Password did not match."

        # If no errors, insert new user
        if not username_err and not password_err and not confirm_password_err:
            hashed_password = generate_password_hash(password)
            new_user = User(
                username=username,
                password=hashed_password,
                register_time=datetime.utcnow()
            )
            try:
                db.session.add(new_user)
                db.session.commit()
                flash("Registration successful! Please login.", "success")
                return redirect(url_for('login.login'))
            except Exception as e:
                db.session.rollback()
                flash("Oops! Something went wrong. Please try again.", "danger")

    return render_template('register.html',
                           username=username,
                           password=password,
                           confirm_password=confirm_password,
                           username_err=username_err,
                           password_err=password_err,
                           confirm_password_err=confirm_password_err)