import os
import datetime
from dotenv import load_dotenv
from sqlalchemy import create_engine, Column, Integer, String, Numeric, Boolean, DateTime, ForeignKey, CheckConstraint
from sqlalchemy.orm import declarative_base, sessionmaker

# Load environment variables from .env file
load_dotenv()

DATABASE_URL = os.getenv("DATABASE_URL")

if not DATABASE_URL:
    DATABASE_URL = "postgresql://postgres:postgres@localhost:5432/postgres"

# For Supabase, pool_pre_ping=True is highly recommended to handle stale connections
engine = create_engine(
    DATABASE_URL,
    pool_pre_ping=True,
    pool_recycle=3600
)

SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

Base = declarative_base()


# =============================================================================
# DIMENSIONES — mapeadas exactamente al DDL de Supabase
# =============================================================================

class DimTiempo(Base):
    __tablename__ = "dim_tiempo"
    id_tiempo   = Column(Integer, primary_key=True)
    gestion     = Column(Integer, nullable=False, default=2026)
    semestre    = Column(Integer, default=1)
    mes         = Column(String(20), default="Mayo")


class DimEstudiante(Base):
    __tablename__ = "dim_estudiante"
    id_estudiante     = Column(Integer, primary_key=True, index=True)
    nombre_completo   = Column(String(200), nullable=False)
    codigo_estudiante = Column(String(50))


class DimDocente(Base):
    __tablename__ = "dim_docente"
    id_docente        = Column(Integer, primary_key=True)
    nombre_completo   = Column(String(200), nullable=False, default="Docente Generico")
    area_especialidad = Column(String(200), default="Generico")


class DimModulo(Base):
    __tablename__ = "dim_modulo"
    id_modulo           = Column(Integer, primary_key=True)
    nombre_modulo       = Column(String(200), nullable=False, default="Modulo Generico")
    nombre_institucion  = Column(String(200), nullable=False, default="GiraGroup")
    programa            = Column(String(200), default="General")


class DimOrigenDocumental(Base):
    """Mapeada a la tabla dim_origen_documental en Supabase."""
    __tablename__ = "dim_origen_documental"
    id_documento        = Column(Integer, primary_key=True)
    tipo_documento      = Column(String(10), default="SHEET")
    nombre_archivo      = Column(String(500), default="archivo_generico")
    fecha_procesamiento = Column(DateTime, default=datetime.datetime.utcnow)


class Users(Base):
    """Tabla de usuarios/autenticación en Supabase."""
    __tablename__ = "users"
    id              = Column(Integer, primary_key=True)
    username        = Column(String(100), unique=True, nullable=False, default="sistema")
    hashed_password = Column(String(255), nullable=False, default="$placeholder$")
    role            = Column(String(20), default="admin")
    created_at      = Column(DateTime, default=datetime.datetime.utcnow)


# =============================================================================
# TABLAS DE HECHOS
# =============================================================================

class FactRendimientoAcademico(Base):
    __tablename__ = "fact_rendimiento_academico"
    id_hecho_aca                   = Column(Integer, primary_key=True, index=True)
    id_estudiante                  = Column(Integer, ForeignKey("dim_estudiante.id_estudiante"))
    id_docente                     = Column(Integer, ForeignKey("dim_docente.id_docente"))
    id_modulo                      = Column(Integer, ForeignKey("dim_modulo.id_modulo"))
    id_tiempo                      = Column(Integer, ForeignKey("dim_tiempo.id_tiempo"))
    id_documento                   = Column(Integer, ForeignKey("dim_origen_documental.id_documento"))
    id_usuario_carga               = Column(Integer, ForeignKey("users.id"))
    nota_final                     = Column(Numeric(5, 2))
    asistencia_pct                 = Column(Numeric(5, 2))
    incumplimiento_actividades_pct = Column(Numeric(5, 2), default=0.00)
    nivel_confianza_ia             = Column(Numeric(5, 4))
    requiere_revision              = Column(Boolean, default=False)
    created_at                     = Column(DateTime, default=datetime.datetime.utcnow)


class FactSituacionFinanciera(Base):
    __tablename__ = "fact_situacion_financiera"
    id_hecho_fin   = Column(Integer, primary_key=True)
    id_estudiante  = Column(Integer, ForeignKey("dim_estudiante.id_estudiante"))
    id_tiempo      = Column(Integer, ForeignKey("dim_tiempo.id_tiempo"))
    monto_deuda    = Column(Numeric(10, 2))
    cuotas_impagas = Column(Integer)
    estado_cartera = Column(String(20))
    tipo_alerta    = Column(String(20))
    fecha_registro = Column(DateTime, default=datetime.datetime.utcnow)


def get_db():
    """
    Dependency injection helper to yield a database session.
    Guarantees that the session is closed after the request completes.
    """
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()