from flask_wtf import FlaskForm
from wtforms import SelectField, StringField, TextAreaField, IntegerField, SubmitField, DateTimeLocalField
from wtforms.validators import DataRequired, Length, NumberRange, Optional, ValidationError
from flask_babel import lazy_gettext as _l
from datetime import datetime, timedelta

class ReservationForm(FlaskForm):
    classroom_id = SelectField(_l('Classroom'), coerce=int, validators=[DataRequired()])
    commission_id = SelectField(_l('Commission/Subject'), coerce=int, validators=[DataRequired()])
    start_time = DateTimeLocalField(_l('Start Time'), format='%Y-%m-%dT%H:%M', validators=[DataRequired()])
    end_time = DateTimeLocalField(_l('End Time'), format='%Y-%m-%dT%H:%M', validators=[DataRequired()])
    purpose = StringField(_l('Purpose'), validators=[
        DataRequired(),
        Length(min=3, max=500)
    ])
    expected_attendees = IntegerField(_l('Expected Attendees'), validators=[
        DataRequired(),
        NumberRange(min=1, max=500)
    ])
    notes = TextAreaField(_l('Notes'), validators=[
        Optional(),
        Length(max=1000)
    ])
    virtual_link = StringField(_l('Virtual Classroom Link'), validators=[
        Optional(),
        Length(max=500)
    ])
    submit = SubmitField(_l('Make Reservation'))
    
    def __init__(self, *args, is_edit=False, **kwargs):
        super().__init__(*args, **kwargs)
        self.is_edit = is_edit
    
    def validate_end_time(self, field):
        if field.data <= self.start_time.data:
            raise ValidationError('End time must be after start time.')
        
        # Check if duration is reasonable (max 8 hours)
        if field.data > self.start_time.data + timedelta(hours=8):
            raise ValidationError('Reservation cannot exceed 8 hours.')
    
    def validate_start_time(self, field):
        # Don't allow new reservations in the past
        if not self.is_edit and field.data < datetime.now() - timedelta(minutes=10):
            raise ValidationError('Start time cannot be in the past.')
        
        # Don't allow reservations too far in the future (max 3 months)
        if field.data > datetime.now() + timedelta(days=90):
            raise ValidationError('Reservations cannot be made more than 3 months in advance.')