src/database.py

# File: src/database.py
# Purpose: SQLAlchemy ORM models and session factory for PostgreSQL storage

from datetime import datetime
from sqlalchemy import (
    create_engine, Column, Integer, String, Float, Text,
    DateTime, ForeignKey, JSON
)
from sqlalchemy.orm import declarative_base, relationship, sessionmaker
from config import DATABASE_URL

engine = create_engine(DATABASE_URL, pool_pre_ping=True)
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
Base = declarative_base()


class Candidate(Base):
    __tablename__ = "candidates"

    id = Column(Integer, primary_key=True, index=True)
    name = Column(String(200), nullable=False)
    phone = Column(String(30), nullable=False)
    email = Column(String(200))
    resume_text = Column(Text)
    created_at = Column(DateTime, default=datetime.utcnow)

    sessions = relationship("InterviewSession", back_populates="candidate")


class InterviewSession(Base):
    __tablename__ = "interview_sessions"

    id = Column(Integer, primary_key=True, index=True)
    candidate_id = Column(Integer, ForeignKey("candidates.id"), nullable=False)
    call_sid = Column(String(60), unique=True)          # Twilio CallSid
    status = Column(String(30), default="initiated")   # initiated|active|completed|failed
    started_at = Column(DateTime, default=datetime.utcnow)
    ended_at = Column(DateTime)

    communication_score = Column(Float)
    technical_score = Column(Float)
    confidence_score = Column(Float)
    overall_score = Column(Float)
    recommendation = Column(String(100))
    report_text = Column(Text)
    extracted_skills = Column(JSON)

    candidate = relationship("Candidate", back_populates="sessions")
    turns = relationship("ConversationTurn", back_populates="session")


class ConversationTurn(Base):
    __tablename__ = "conversation_turns"

    id = Column(Integer, primary_key=True, index=True)
    session_id = Column(Integer, ForeignKey("interview_sessions.id"), nullable=False)
    turn_index = Column(Integer, nullable=False)
    speaker = Column(String(10), nullable=False)        # "ai" | "candidate"
    text = Column(Text, nullable=False)
    audio_url = Column(String(500))                     # S3/GCS path if stored
    timestamp = Column(DateTime, default=datetime.utcnow)

    session = relationship("InterviewSession", back_populates="turns")


def init_db():
    Base.metadata.create_all(bind=engine)


def get_db():
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()