from datetime import datetime, timezone
import uuid
from sqlalchemy import (
    Column, String, Integer, BigInteger, Boolean, DateTime,
    ForeignKey, Text, Index
)
from sqlalchemy.orm import relationship
from app.core.database import Base

def utc_now():
    return datetime.now(timezone.utc)

class User(Base):
    __tablename__ = "users"

    id = Column(Integer, primary_key=True, index=True)
    email = Column(String(255), unique=True, index=True, nullable=False)
    hashed_password = Column(String(255), nullable=False)
    full_name = Column(String(255), nullable=True)
    role = Column(String(50), default="ADMIN", nullable=False)  # ADMIN, OPERATOR, VIEWER
    is_active = Column(Boolean, default=True, nullable=False)
    created_at = Column(DateTime(timezone=True), default=utc_now, nullable=False)

class Client(Base):
    __tablename__ = "clients"

    id = Column(Integer, primary_key=True, index=True)
    client_code = Column(String(50), unique=True, index=True, nullable=False)  # e.g., CLIENT-0001
    name = Column(String(255), nullable=False)
    alias = Column(String(255), nullable=True)
    hostname = Column(String(255), nullable=True)
    os_info = Column(String(255), nullable=True)
    ip_address = Column(String(100), nullable=True)
    agent_version = Column(String(50), default="1.0.0", nullable=False)
    status = Column(String(50), default="OFFLINE", nullable=False)  # ONLINE, OFFLINE, SYNCING, ERROR
    storage_used_bytes = Column(BigInteger, default=0, nullable=False)
    storage_quota_bytes = Column(BigInteger, default=100 * 1024 * 1024 * 1024, nullable=False)  # 100 GB default
    last_seen_at = Column(DateTime(timezone=True), nullable=True)
    last_backup_at = Column(DateTime(timezone=True), nullable=True)
    is_active = Column(Boolean, default=True, nullable=False)
    created_at = Column(DateTime(timezone=True), default=utc_now, nullable=False)

    credentials = relationship("ClientCredential", back_populates="client", cascade="all, delete-orphan")
    jobs = relationship("BackupJob", back_populates="client", cascade="all, delete-orphan")
    backup_files = relationship("BackupFile", back_populates="client", cascade="all, delete-orphan")
    backup_sessions = relationship("BackupSession", back_populates="client", cascade="all, delete-orphan")

class ClientCredential(Base):
    __tablename__ = "client_credentials"

    id = Column(Integer, primary_key=True, index=True)
    client_id = Column(Integer, ForeignKey("clients.id", ondelete="CASCADE"), nullable=False)
    device_id = Column(String(100), unique=True, index=True, nullable=False)  # Unique UUID
    token_hash = Column(String(255), unique=True, index=True, nullable=False)
    name = Column(String(255), default="Primary Windows Agent", nullable=False)
    is_revoked = Column(Boolean, default=False, nullable=False)
    created_at = Column(DateTime(timezone=True), default=utc_now, nullable=False)
    last_used_at = Column(DateTime(timezone=True), nullable=True)

    client = relationship("Client", back_populates="credentials")

class RegistrationCode(Base):
    __tablename__ = "registration_codes"

    id = Column(Integer, primary_key=True, index=True)
    code = Column(String(50), unique=True, index=True, nullable=False)  # e.g., OED-A1B2-C3D4
    is_used = Column(Boolean, default=False, nullable=False)
    client_name_hint = Column(String(255), nullable=True)
    client_id = Column(Integer, ForeignKey("clients.id"), nullable=True)
    expires_at = Column(DateTime(timezone=True), nullable=False)
    created_at = Column(DateTime(timezone=True), default=utc_now, nullable=False)

class BackupJob(Base):
    __tablename__ = "backup_jobs"

    id = Column(Integer, primary_key=True, index=True)
    job_code = Column(String(50), unique=True, index=True, nullable=False)  # e.g., JOB-001
    client_id = Column(Integer, ForeignKey("clients.id", ondelete="CASCADE"), nullable=False)
    name = Column(String(255), nullable=False)
    source_path = Column(String(1024), nullable=False)  # e.g., C:\SQLBackups
    file_patterns = Column(String(255), default="*.bak,*.mdf", nullable=False)
    schedule_cron = Column(String(100), default="0 2 * * *", nullable=False)  # default 02:00 AM daily
    is_active = Column(Boolean, default=True, nullable=False)
    
    # Retention policies
    keep_daily = Column(Integer, default=7, nullable=False)
    keep_weekly = Column(Integer, default=4, nullable=False)
    keep_monthly = Column(Integer, default=12, nullable=False)
    min_stable_time_seconds = Column(Integer, default=60, nullable=False)
    
    status = Column(String(50), default="IDLE", nullable=False)  # IDLE, RUNNING, ERROR, SUCCESS
    last_run_at = Column(DateTime(timezone=True), nullable=True)
    next_run_at = Column(DateTime(timezone=True), nullable=True)
    created_at = Column(DateTime(timezone=True), default=utc_now, nullable=False)

    client = relationship("Client", back_populates="jobs")
    backup_files = relationship("BackupFile", back_populates="job", cascade="all, delete-orphan")
    backup_sessions = relationship("BackupSession", back_populates="job", cascade="all, delete-orphan")

class BackupSession(Base):
    __tablename__ = "backup_sessions"

    id = Column(Integer, primary_key=True, index=True)
    session_code = Column(String(100), unique=True, index=True, default=lambda: str(uuid.uuid4()), nullable=False)
    client_id = Column(Integer, ForeignKey("clients.id", ondelete="CASCADE"), nullable=False)
    job_id = Column(Integer, ForeignKey("backup_jobs.id", ondelete="CASCADE"), nullable=True)
    
    filename = Column(String(512), nullable=False)
    file_size = Column(BigInteger, nullable=False)
    chunk_size = Column(Integer, default=4 * 1024 * 1024, nullable=False)
    total_chunks = Column(Integer, nullable=False)
    received_chunks_count = Column(Integer, default=0, nullable=False)
    sha256_full = Column(String(64), nullable=False)
    
    status = Column(String(50), default="PENDING", nullable=False)  # PENDING, UPLOADING, ASSEMBLING, VERIFYING, SUCCESS, FAILED, CANCELLED
    error_message = Column(Text, nullable=True)
    started_at = Column(DateTime(timezone=True), default=utc_now, nullable=False)
    completed_at = Column(DateTime(timezone=True), nullable=True)

    client = relationship("Client", back_populates="backup_sessions")
    job = relationship("BackupJob", back_populates="backup_sessions")
    chunks = relationship("BackupChunk", back_populates="session", cascade="all, delete-orphan")

    __table_args__ = (
        Index("idx_session_client_status", "client_id", "status"),
    )

class BackupChunk(Base):
    __tablename__ = "backup_chunks"

    id = Column(Integer, primary_key=True, index=True)
    session_id = Column(Integer, ForeignKey("backup_sessions.id", ondelete="CASCADE"), nullable=False)
    chunk_index = Column(Integer, nullable=False)
    chunk_size = Column(Integer, nullable=False)
    sha256 = Column(String(64), nullable=False)
    is_received = Column(Boolean, default=False, nullable=False)
    received_at = Column(DateTime(timezone=True), nullable=True)

    session = relationship("BackupSession", back_populates="chunks")

    __table_args__ = (
        Index("idx_chunk_session_idx", "session_id", "chunk_index", unique=True),
    )

class BackupFile(Base):
    __tablename__ = "backup_files"

    id = Column(Integer, primary_key=True, index=True)
    client_id = Column(Integer, ForeignKey("clients.id", ondelete="CASCADE"), nullable=False)
    job_id = Column(Integer, ForeignKey("backup_jobs.id", ondelete="CASCADE"), nullable=True)
    session_id = Column(Integer, ForeignKey("backup_sessions.id", ondelete="SET NULL"), nullable=True)
    
    filename = Column(String(512), nullable=False)
    relative_path = Column(String(1024), nullable=False)
    file_size = Column(BigInteger, nullable=False)
    sha256 = Column(String(64), nullable=False)
    retention_tag = Column(String(50), default="DAILY", nullable=False)  # DAILY, WEEKLY, MONTHLY, MANUAL
    is_active = Column(Boolean, default=True, nullable=False)
    created_at = Column(DateTime(timezone=True), default=utc_now, nullable=False)

    client = relationship("Client", back_populates="backup_files")
    job = relationship("BackupJob", back_populates="backup_files")

class EventLog(Base):
    __tablename__ = "event_logs"

    id = Column(Integer, primary_key=True, index=True)
    timestamp = Column(DateTime(timezone=True), default=utc_now, nullable=False, index=True)
    event_type = Column(String(100), nullable=False, index=True)  # LOGIN, CLIENT_REGISTERED, BACKUP_STARTED, BACKUP_COMPLETED, BACKUP_FAILED, etc.
    severity = Column(String(50), default="INFO", nullable=False)  # INFO, WARNING, ERROR, CRITICAL
    client_id = Column(Integer, nullable=True, index=True)
    job_id = Column(Integer, nullable=True, index=True)
    user_email = Column(String(255), nullable=True)
    ip_address = Column(String(100), nullable=True)
    message = Column(Text, nullable=False)
    details_json = Column(Text, nullable=True)

class SystemSetting(Base):
    __tablename__ = "system_settings"

    key = Column(String(100), primary_key=True, index=True)
    value = Column(String(1024), nullable=False)