from app.extensions import db
from app.utils.crypto import EncryptedText
from datetime import datetime


class TellerEnrollment(db.Model):
    """
    Represents a Teller enrollment — one per connected bank institution.
    An enrollment contains one or more accounts.
    """
    __tablename__ = 'teller_enrollments'

    id = db.Column(db.Integer, primary_key=True)
    enrollment_id = db.Column(db.String(64), unique=True, nullable=False, index=True)
    access_token = db.Column(EncryptedText, nullable=False)
    institution_name = db.Column(db.String(100), nullable=True)
    user_id = db.Column(db.String(64), nullable=True)  # Teller user ID
    is_active = db.Column(db.Boolean, default=True)
    created_at = db.Column(db.DateTime, default=datetime.utcnow)
    last_synced_at = db.Column(db.DateTime, nullable=True)

    accounts = db.relationship('TellerAccount', back_populates='enrollment',
                               cascade='all, delete-orphan', lazy='dynamic')

    def __repr__(self):
        return f'<TellerEnrollment {self.institution_name} ({self.enrollment_id})>'


class TellerAccount(db.Model):
    """
    Maps a Teller account to a PFM account.
    Tracks the last synced transaction ID for incremental syncs.
    """
    __tablename__ = 'teller_accounts'

    id = db.Column(db.Integer, primary_key=True)
    enrollment_id = db.Column(db.Integer, db.ForeignKey('teller_enrollments.id'), nullable=False)
    teller_account_id = db.Column(db.String(64), unique=True, nullable=False, index=True)
    pfm_account_id = db.Column(db.Integer, db.ForeignKey('accounts.id'), nullable=True)

    account_name = db.Column(db.String(100), nullable=True)
    account_type = db.Column(db.String(50), nullable=True)   # depository / credit
    account_subtype = db.Column(db.String(50), nullable=True) # checking / savings / credit_card
    institution_name = db.Column(db.String(100), nullable=True)
    last_sync_date = db.Column(db.Date, nullable=True)        # date of last successful sync
    last_teller_txn_id = db.Column(db.String(64), nullable=True)  # for from_id pagination
    is_active = db.Column(db.Boolean, default=True)
    created_at = db.Column(db.DateTime, default=datetime.utcnow)

    enrollment = db.relationship('TellerEnrollment', back_populates='accounts')
    pfm_account = db.relationship('Account')

    def __repr__(self):
        return f'<TellerAccount {self.account_name} → PFM #{self.pfm_account_id}>'


class TellerSyncPreview(db.Model):
    """
    Temporary server-side storage for sync preview data.
    Replaces cookie-based session storage which has a 4 KB limit —
    large accounts (100+ transactions) exceeded that limit and caused
    silent data loss on the confirm step.
    One row per teller_account_id; overwritten on each new sync preview.
    """
    __tablename__ = 'teller_sync_previews'

    id              = db.Column(db.Integer, primary_key=True)
    teller_account_id = db.Column(
        db.Integer, db.ForeignKey('teller_accounts.id'),
        nullable=False, unique=True, index=True,
    )
    data_json       = db.Column(db.Text, nullable=False)
    created_at      = db.Column(db.DateTime, default=datetime.utcnow)

    def __repr__(self):
        return f'<TellerSyncPreview account_id={self.teller_account_id}>'