from datetime import datetime, timedelta

from sqlalchemy.dialects.mysql import INTEGER

from app import db


class EmergencyAccess(db.Model):
    """
    Emergency access grant from a vault owner (grantor) to a trusted contact (grantee).

    Status flow:
      invited  → grantee calls /accept      → accepted
      accepted → grantor calls /provide     → ready   (enc_vault stored)
      ready    → grantee calls /request     → pending (wait timer starts)
      pending  → grantor calls /deny        → ready   (reset, grantee can request again)
      pending  (wait_days elapsed)          → grantable  (grantee fetches vault)

    Zero-knowledge: enc_vault is a JSON array of vault items re-encrypted by the grantor
    using the ECDH shared secret (grantor private key + grantee public key).
    """
    __tablename__ = 'emergency_access'

    id = db.Column(INTEGER(unsigned=True), autoincrement=True, primary_key=True)
    grantor_id = db.Column(
        INTEGER(unsigned=True),
        db.ForeignKey('users.id', ondelete='CASCADE'),
        nullable=False,
    )
    grantee_email = db.Column(db.String(255), nullable=False)
    grantee_id = db.Column(
        INTEGER(unsigned=True),
        db.ForeignKey('users.id', ondelete='SET NULL'),
        nullable=True,
    )
    wait_days = db.Column(db.Integer, default=7, nullable=False)
    # invited | accepted | ready | pending | denied
    status = db.Column(db.String(20), default='invited', nullable=False)
    request_initiated_at = db.Column(db.DateTime, nullable=True)
    # JSON string: [{ id, name, item_type, enc_data, iv }, ...]
    enc_vault = db.Column(db.Text, nullable=True)
    created_at = db.Column(db.DateTime, default=datetime.utcnow, nullable=False)

    @property
    def wait_elapsed(self):
        """True if the wait period has passed since the access request."""
        if self.status != 'pending' or not self.request_initiated_at:
            return False
        return datetime.utcnow() >= self.request_initiated_at + timedelta(days=self.wait_days)

    def to_dict(self, grantor_email=None):
        return {
            'id': self.id,
            'grantor_id': self.grantor_id,
            'grantor_email': grantor_email,
            'grantee_email': self.grantee_email,
            'grantee_id': self.grantee_id,
            'wait_days': self.wait_days,
            'status': self.status,
            'wait_elapsed': self.wait_elapsed,
            'request_initiated_at': (
                self.request_initiated_at.isoformat() if self.request_initiated_at else None
            ),
            'created_at': self.created_at.isoformat() if self.created_at else None,
        }