from flask import Blueprint, render_template, redirect, request, url_for, flash
from pytz import timezone, utc
from app.models import Reading, db
from app.forms import ReadingForm
from flask_login import login_required, current_user
from datetime import datetime

reading = Blueprint('reading', __name__)

def get_user_timezone():
    """Fetch the user's timezone, defaulting to UTC."""
    return timezone(current_user.profile.timezone if current_user.profile and current_user.profile.timezone else 'UTC')

def localize_timestamp(timestamp, user_tz):
    """Convert a UTC timestamp to the user's local timezone."""
    return utc.localize(timestamp).astimezone(user_tz)

def save_reading_from_form(reading, form, user_tz):
    """Update a reading with form data and convert the timestamp to UTC."""
    local_timestamp = form.timestamp.data
    reading.timestamp = user_tz.localize(local_timestamp.replace(tzinfo=None)).astimezone(utc)
    reading.systolic = form.systolic.data
    reading.diastolic = form.diastolic.data
    reading.heart_rate = form.heart_rate.data
    db.session.commit()

@reading.route('/add', methods=['GET', 'POST'])
@login_required
def add_reading():
    form = ReadingForm()
    user_tz = get_user_timezone()

    if form.validate_on_submit():
        new_reading = Reading(
            user_id=current_user.id,
            timestamp=user_tz.localize(form.timestamp.data.replace(tzinfo=None)).astimezone(utc),
            systolic=form.systolic.data,
            diastolic=form.diastolic.data,
            heart_rate=form.heart_rate.data,
        )
        db.session.add(new_reading)
        db.session.commit()
        flash("Reading added successfully.", "success")
        return redirect(url_for('main.dashboard'))

    form.timestamp.data = localize_timestamp(datetime.utcnow(), user_tz)
    return render_template('reading/add_reading.html', form=form)

@reading.route('/<int:reading_id>/edit', methods=['GET', 'POST'])
@login_required
def edit_reading(reading_id):
    reading = Reading.query.filter_by(id=reading_id, user_id=current_user.id).first_or_404()
    user_tz = get_user_timezone()

    form = ReadingForm(obj=reading)
    form.timestamp.data = localize_timestamp(reading.timestamp, user_tz)

    if form.validate_on_submit():
        save_reading_from_form(reading, form, user_tz)
        flash('Reading updated successfully!', 'success')
        return redirect(url_for('main.dashboard'))

    return render_template('reading/edit_reading.html', form=form, reading=reading)

@reading.route('/<int:reading_id>/confirm_delete', methods=['GET'])
@login_required
def confirm_delete(reading_id):
    reading = Reading.query.filter_by(id=reading_id, user_id=current_user.id).first_or_404()

    return render_template('reading/confirm_delete.html', reading=reading)

@reading.route('/<int:reading_id>/delete', methods=['POST'])
@login_required
def delete_reading(reading_id):
    reading = Reading.query.filter_by(id=reading_id, user_id=current_user.id).first_or_404()
    db.session.delete(reading)
    db.session.commit()
    flash('Reading deleted successfully!', 'success')
    return redirect(url_for('main.dashboard'))