"""
app/models.py
─────────────
SQLAlchemy ORM models (database schema) and Pydantic v2 schemas
(request/response validation) for every PMDI domain entity.
"""
from __future__ import annotations

from datetime import date, datetime
from typing import Any, Dict, List, Optional

from pydantic import BaseModel, ConfigDict, EmailStr
from sqlalchemy import (
    Boolean, Column, Date, DateTime, ForeignKey,
    Integer, String, Text,
)
from sqlalchemy.dialects.postgresql import ARRAY, JSONB
from sqlalchemy.orm import relationship

from app.database import Base


# ═══════════════════════════════════════════════════════════════════════════════
#  Notification delivery-status constants
# ═══════════════════════════════════════════════════════════════════════════════

STATUS_DELIVERED = "Delivered from Server"
STATUS_RELAY     = "Sent to Mail Relay"
STATUS_FAILED    = "Failed"


# ═══════════════════════════════════════════════════════════════════════════════
#  SQLAlchemy ORM Models
# ═══════════════════════════════════════════════════════════════════════════════

class AdminUser(Base):
    """Internal administrator account with optional TOTP MFA."""
    __tablename__ = "admin_users"

    id              = Column(Integer, primary_key=True, index=True)
    username        = Column(String(64),  unique=True, nullable=False, index=True)
    hashed_password = Column(String(256), nullable=False)
    totp_secret     = Column(String(64),  nullable=True)   # base32 TOTP secret
    mfa_enabled     = Column(Boolean, default=False, nullable=False)
    created_at      = Column(DateTime, default=datetime.utcnow, nullable=False)


class Client(Base):
    """Customer record referenced by invoices."""
    __tablename__ = "clients"

    id             = Column(Integer, primary_key=True, index=True)
    client_id_name = Column(String(64),  unique=True, nullable=False)  # short slug
    client_name    = Column(String(256), nullable=False)
    client_email   = Column(String(256), nullable=False)
    created_at     = Column(DateTime, default=datetime.utcnow)

    invoices = relationship("Invoice", back_populates="client")


class EmailTemplate(Base):
    """Jinja2 email template with a human-readable name, subject, and body."""
    __tablename__ = "email_templates"

    id            = Column(Integer, primary_key=True, index=True)
    name          = Column(String(128), nullable=False)          # dropdown label
    template_type = Column(String(32),  nullable=False)          # "Notification" | "Overdue"
    subject       = Column(String(256), nullable=False)          # Jinja2 subject line
    template_body = Column(Text, nullable=False)                 # Jinja2 body
    created_at    = Column(DateTime, default=datetime.utcnow)

    invoices = relationship("Invoice", back_populates="template")


class Invoice(Base):
    """Open receivable with scheduling metadata for automated reminders."""
    __tablename__ = "invoices"

    id                      = Column(Integer, primary_key=True, index=True)
    invoice_number          = Column(String(64), nullable=False, unique=True)
    client_id               = Column(Integer, ForeignKey("clients.id",  ondelete="RESTRICT"), nullable=False)
    pay_date                = Column(Date, nullable=False)
    template_id             = Column(Integer, ForeignKey("email_templates.id", ondelete="RESTRICT"), nullable=False)
    # Days-before-pay_date triggers, e.g. [30, 14, 7, 1]
    notification_dates      = Column(ARRAY(Integer), nullable=True, default=[])
    # Send recurring overdue alert every N days past due (0 = disabled)
    overdue_recurring_days  = Column(Integer, default=0, nullable=False)
    paid                    = Column(Boolean, default=False, nullable=False)
    created_at              = Column(DateTime, default=datetime.utcnow)

    client   = relationship("Client",        back_populates="invoices")
    template = relationship("EmailTemplate", back_populates="invoices")
    logs     = relationship(
        "NotificationLog",
        back_populates="invoice",
        cascade="all, delete-orphan",
    )


class NotificationLog(Base):
    """Immutable audit record for every email dispatch attempt."""
    __tablename__ = "notification_logs"

    id            = Column(Integer, primary_key=True, index=True)
    invoice_id    = Column(Integer, ForeignKey("invoices.id", ondelete="CASCADE"), nullable=False)
    status        = Column(String(64), nullable=False)   # STATUS_* constants
    sent_at       = Column(DateTime, default=datetime.utcnow, nullable=False)
    context       = Column(JSONB, nullable=True)          # runtime snapshot for UI display
    error_message = Column(Text, nullable=True)

    invoice = relationship("Invoice", back_populates="logs")


# ═══════════════════════════════════════════════════════════════════════════════
#  Pydantic v2 Schemas
# ═══════════════════════════════════════════════════════════════════════════════

_orm = ConfigDict(from_attributes=True)


# ── Auth / JWT ─────────────────────────────────────────────────────────────────

class LoginRequest(BaseModel):
    username: str
    password: str


class TokenResponse(BaseModel):
    access_token: str
    token_type:   str  = "bearer"
    mfa_required: bool = False


class MFAVerifyRequest(BaseModel):
    username:  str
    totp_code: str


class MFASetupResponse(BaseModel):
    secret: str
    qr_uri: str


class UserRead(BaseModel):
    model_config = _orm
    id:          int
    username:    str
    mfa_enabled: bool


# ── Client ─────────────────────────────────────────────────────────────────────

class ClientCreate(BaseModel):
    client_id_name: str
    client_name:    str
    client_email:   EmailStr


class ClientUpdate(ClientCreate):
    pass


class ClientRead(BaseModel):
    model_config = _orm
    id:             int
    client_id_name: str
    client_name:    str
    client_email:   str


# ── EmailTemplate ──────────────────────────────────────────────────────────────

class TemplateCreate(BaseModel):
    name:          str
    template_type: str    # "Notification" | "Overdue"
    subject:       str
    template_body: str


class TemplateUpdate(TemplateCreate):
    pass


class TemplateRead(BaseModel):
    model_config = _orm
    id:            int
    name:          str
    template_type: str
    subject:       str
    template_body: str


# ── Invoice ────────────────────────────────────────────────────────────────────

class InvoiceCreate(BaseModel):
    invoice_number:         str
    client_id:              int
    pay_date:               date
    template_id:            int
    notification_dates:     Optional[List[int]] = []
    overdue_recurring_days: int = 0
    paid:                   bool = False


class InvoiceUpdate(InvoiceCreate):
    pass


class InvoiceRead(BaseModel):
    model_config = _orm
    id:                     int
    invoice_number:         str
    client_id:              int
    pay_date:               date
    template_id:            int
    notification_dates:     Optional[List[int]] = []
    overdue_recurring_days: int
    paid:                   bool
    # Eagerly joined for the dashboard display
    client:   Optional[ClientRead]   = None
    template: Optional[TemplateRead] = None


# ── Notification Log ───────────────────────────────────────────────────────────

class NotificationLogRead(BaseModel):
    model_config = _orm
    id:            int
    invoice_id:    int
    status:        str
    sent_at:       datetime
    context:       Optional[Dict[str, Any]] = None
    error_message: Optional[str] = None


# ── Config ─────────────────────────────────────────────────────────────────────

class ConfigEntry(BaseModel):
    key:    str
    value:  str
    masked: bool