import uuid
from django.db import models
from django.conf import settings
from apps.profiles.models import Institution


class MeetingStatus(models.TextChoices):
    PENDING = 'pending', 'Pending'
    SCHEDULED = 'scheduled', 'Scheduled'
    COMPLETED = 'completed', 'Completed'
    CANCELLED = 'cancelled', 'Cancelled'
    DECLINED = 'declined', 'Declined'


class MeetingRequest(models.Model):
    title = models.CharField(max_length=255, verbose_name="Meeting Title / Subject")
    requester_institution = models.ForeignKey(
        Institution,
        on_delete=models.CASCADE,
        related_name='requested_meetings',
        verbose_name="Requester Institution"
    )
    recipient_institution = models.ForeignKey(
        Institution,
        on_delete=models.CASCADE,
        related_name='received_meetings',
        verbose_name="Recipient Institution"
    )
    created_by = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        on_delete=models.CASCADE,
        related_name='created_meetings',
        verbose_name="Initiated By"
    )
    status = models.CharField(
        max_length=20,
        choices=MeetingStatus.choices,
        default=MeetingStatus.PENDING,
        verbose_name="Status"
    )
    meeting_date = models.DateField(verbose_name="Proposed / Confirmed Date")
    meeting_time = models.TimeField(verbose_name="Proposed / Confirmed Time")
    duration_minutes = models.PositiveIntegerField(default=60, verbose_name="Duration (Minutes)")
    meeting_url = models.URLField(max_length=500, blank=True, verbose_name="Video Meeting Link")
    agenda = models.TextField(blank=True, verbose_name="Meeting Agenda & Topics")
    admin_notes = models.TextField(blank=True, verbose_name="Internal / Admin Notes")
    rejection_reason = models.TextField(blank=True, verbose_name="Rejection / Decline Reason")
    
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        ordering = ['-meeting_date', '-meeting_time']
        verbose_name = "Meeting Request"
        verbose_name_plural = "Meeting Requests"
        indexes = [
            models.Index(fields=['requester_institution', 'status']),
            models.Index(fields=['recipient_institution', 'status']),
            models.Index(fields=['meeting_date', 'status']),
        ]

    def __str__(self):
        return f"{self.title} ({self.requester_institution.name} -> {self.recipient_institution.name}) [{self.status}]"

    def save(self, *args, **kwargs):
        # Auto-generate video meeting room if missing
        if not self.meeting_url and self.status in [MeetingStatus.PENDING, MeetingStatus.SCHEDULED]:
            room_id = f"mch-meet-{uuid.uuid4().hex[:12]}"
            self.meeting_url = f"https://meet.jit.si/{room_id}"
        super().save(*args, **kwargs)