from django.db import models
from django.contrib.auth.models import User

class File(models.Model):
    owner = models.ForeignKey(User, on_delete=models.CASCADE, related_name='files')
    file = models.FileField(upload_to='uploads/')
    shared_with = models.ManyToManyField(User, related_name='shared_files', blank=True)
    created_at = models.DateTimeField(auto_now_add=True)
    description = models.TextField(blank=True)

    def __str__(self):
        return f"{self.file.name}（{self.owner.username}）"

class Message(models.Model):
    sender = models.ForeignKey(User, on_delete=models.CASCADE, related_name='sent_messages')
    recipients = models.ManyToManyField(User, related_name='received_messages')
    content = models.TextField()
    created_at = models.DateTimeField(auto_now_add=True)
    file = models.ForeignKey(File, on_delete=models.SET_NULL, null=True, blank=True)

    def __str__(self):
        return f"来自 {self.sender.username} 的消息"

    class Meta:
        ordering = ['-created_at']

class PublicMessage(models.Model):
    name = models.CharField(max_length=100, default="公共", editable=False)
    content = models.TextField()
    created_at = models.DateTimeField(auto_now_add=True)
    ip_address = models.GenericIPAddressField(null=True, blank=True)

    def __str__(self):
        return f"来自 {self.name or '匿名用户'} 的公开留言"

class PublicFile(models.Model):
    name = models.CharField(max_length=100, default="公共", editable=False)
    file = models.FileField(upload_to='public_uploads/')
    description = models.TextField(blank=True)
    created_at = models.DateTimeField(auto_now_add=True)
    ip_address = models.GenericIPAddressField(null=True, blank=True)

    def __str__(self):
        return f"来自 {self.name or '匿名用户'} 的公开文件"

class Friendship(models.Model):
    STATUS_CHOICES = [
        ('pending', '等待中'),
        ('accepted', '已接受'),
        ('rejected', '已拒绝'),
    ]

    from_user = models.ForeignKey(User, on_delete=models.CASCADE, related_name='friendship_requests_sent')
    to_user = models.ForeignKey(User, on_delete=models.CASCADE, related_name='friendship_requests_received')
    status = models.CharField(max_length=10, choices=STATUS_CHOICES, default='pending')
    created_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        unique_together = ('from_user', 'to_user')
        ordering = ['-created_at']

    def __str__(self):
        return f"{self.from_user.username} -> {self.to_user.username} ({self.status})"