"""SQLAlchemy models for config backup tables."""

import uuid
from datetime import datetime

from sqlalchemy import Boolean, DateTime, ForeignKey, Integer, LargeBinary, SmallInteger, String, Text, UniqueConstraint, func
from sqlalchemy.dialects.postgresql import UUID
from sqlalchemy.orm import Mapped, mapped_column, relationship

from app.database import Base


class ConfigBackupRun(Base):
    """Metadata for a single config backup run.

    The actual config content (export.rsc and backup.bin) lives in the tenant's
    bare git repository at GIT_STORE_PATH/{tenant_id}.git. This table provides
    the timeline view and per-run metadata without duplicating file content in
    PostgreSQL.
    """

    __tablename__ = "config_backup_runs"

    id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        primary_key=True,
        default=uuid.uuid4,
        server_default=func.gen_random_uuid(),
    )
    device_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("devices.id", ondelete="CASCADE"),
        nullable=False,
        index=True,
    )
    tenant_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("tenants.id", ondelete="CASCADE"),
        nullable=False,
        index=True,
    )
    # Git commit hash in the tenant's bare repo where this backup is stored.
    commit_sha: Mapped[str] = mapped_column(Text, nullable=False)
    # Trigger type: 'scheduled' | 'manual' | 'pre-restore' | 'checkpoint' | 'config-change'
    trigger_type: Mapped[str] = mapped_column(String(20), nullable=False)
    # Lines added/removed vs the prior export.rsc for this device.
    # NULL for the first backup (no prior version to diff against).
    lines_added: Mapped[int | None] = mapped_column(Integer, nullable=True)
    lines_removed: Mapped[int | None] = mapped_column(Integer, nullable=True)
    # Encryption metadata: NULL=plaintext, 1=client-side AES-GCM, 2=OpenBao Transit
    encryption_tier: Mapped[int | None] = mapped_column(SmallInteger, nullable=True)
    # 12-byte AES-GCM nonce for Tier 1 (client-side) backups; NULL for plaintext/Transit
    encryption_nonce: Mapped[bytes | None] = mapped_column(LargeBinary, nullable=True)
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        server_default=func.now(),
        nullable=False,
    )

    def __repr__(self) -> str:
        return (
            f"<ConfigBackupRun id={self.id} device_id={self.device_id} "
            f"trigger={self.trigger_type!r} sha={self.commit_sha[:8]!r}>"
        )


class ConfigBackupSchedule(Base):
    """Per-tenant default and per-device override backup schedule config.

    A row with device_id=NULL is the tenant-level default (daily at 2am).
    A row with a specific device_id overrides the tenant default for that device.
    """

    __tablename__ = "config_backup_schedules"
    __table_args__ = (
        UniqueConstraint("tenant_id", "device_id", name="uq_backup_schedule_tenant_device"),
    )

    id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        primary_key=True,
        default=uuid.uuid4,
        server_default=func.gen_random_uuid(),
    )
    tenant_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("tenants.id", ondelete="CASCADE"),
        nullable=False,
        index=True,
    )
    # NULL = tenant-level default schedule; non-NULL = device-specific override.
    device_id: Mapped[uuid.UUID | None] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("devices.id", ondelete="CASCADE"),
        nullable=True,
    )
    # Standard cron expression (5 fields). Default: daily at 2am UTC.
    cron_expression: Mapped[str] = mapped_column(
        String(100),
        nullable=False,
        default="0 2 * * *",
        server_default="0 2 * * *",
    )
    enabled: Mapped[bool] = mapped_column(
        Boolean,
        nullable=False,
        default=True,
        server_default="TRUE",
    )
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        server_default=func.now(),
        nullable=False,
    )

    def __repr__(self) -> str:
        scope = f"device={self.device_id}" if self.device_id else f"tenant={self.tenant_id}"
        return f"<ConfigBackupSchedule {scope} cron={self.cron_expression!r} enabled={self.enabled}>"


class ConfigPushOperation(Base):
    """Tracks pending two-phase config push operations for panic-revert recovery.

    Before pushing a config, a row is inserted with status='pending_verification'.
    If the API pod restarts during the 60-second verification window, the startup
    handler checks this table and either commits (deletes the RouterOS scheduler
    job) or marks the operation as 'failed'. This prevents the panic-revert
    scheduler from firing and reverting a successful push after an API restart.

    See Pitfall 6 in 04-RESEARCH.md for the full failure scenario.
    """

    __tablename__ = "config_push_operations"

    id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        primary_key=True,
        default=uuid.uuid4,
        server_default=func.gen_random_uuid(),
    )
    device_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("devices.id", ondelete="CASCADE"),
        nullable=False,
        index=True,
    )
    tenant_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("tenants.id", ondelete="CASCADE"),
        nullable=False,
        index=True,
    )
    # Git commit SHA we'd revert to if the push fails.
    pre_push_commit_sha: Mapped[str] = mapped_column(Text, nullable=False)
    # RouterOS scheduler job name created on the device for panic-revert.
    scheduler_name: Mapped[str] = mapped_column(String(255), nullable=False)
    # 'pending_verification' | 'committed' | 'reverted' | 'failed'
    status: Mapped[str] = mapped_column(
        String(30),
        nullable=False,
        default="pending_verification",
        server_default="pending_verification",
    )
    started_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        server_default=func.now(),
        nullable=False,
    )
    completed_at: Mapped[datetime | None] = mapped_column(
        DateTime(timezone=True),
        nullable=True,
    )

    def __repr__(self) -> str:
        return (
            f"<ConfigPushOperation id={self.id} device_id={self.device_id} "
            f"status={self.status!r}>"
        )


class RouterConfigSnapshot(Base):
    """A point-in-time router configuration snapshot.

    The config_text column stores OpenBao Transit ciphertext (vault:v1:...).
    Plaintext router config is NEVER stored in PostgreSQL -- it is encrypted
    via Transit before insertion and decrypted on read.

    The sha256_hash column stores the SHA-256 hex digest of the PLAINTEXT
    config (computed before encryption). This enables deduplication: if
    the hash matches the latest snapshot for a device, no new row is created.
    """

    __tablename__ = "router_config_snapshots"

    id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        primary_key=True,
        default=uuid.uuid4,
        server_default=func.gen_random_uuid(),
    )
    device_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("devices.id", ondelete="CASCADE"),
        nullable=False,
        index=True,
    )
    tenant_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("tenants.id", ondelete="CASCADE"),
        nullable=False,
        index=True,
    )
    # OpenBao Transit ciphertext (vault:v1:...). Plaintext NEVER stored.
    config_text: Mapped[str] = mapped_column(Text, nullable=False)
    # SHA-256 hex digest of the PLAINTEXT config, for deduplication.
    sha256_hash: Mapped[str] = mapped_column(String(64), nullable=False)
    collected_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        server_default=func.now(),
        nullable=False,
    )
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        server_default=func.now(),
        nullable=False,
    )

    def __repr__(self) -> str:
        return (
            f"<RouterConfigSnapshot id={self.id} device_id={self.device_id} "
            f"hash={self.sha256_hash[:8]!r}>"
        )


class RouterConfigDiff(Base):
    """Unified diff between two consecutive router config snapshots.

    Stores the diff_text (unified diff output) along with line counts
    for quick display without re-parsing. References both the old and
    new snapshot by foreign key.
    """

    __tablename__ = "router_config_diffs"

    id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        primary_key=True,
        default=uuid.uuid4,
        server_default=func.gen_random_uuid(),
    )
    device_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("devices.id", ondelete="CASCADE"),
        nullable=False,
        index=True,
    )
    tenant_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("tenants.id", ondelete="CASCADE"),
        nullable=False,
        index=True,
    )
    old_snapshot_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("router_config_snapshots.id", ondelete="CASCADE"),
        nullable=False,
    )
    new_snapshot_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("router_config_snapshots.id", ondelete="CASCADE"),
        nullable=False,
    )
    diff_text: Mapped[str] = mapped_column(Text, nullable=False)
    lines_added: Mapped[int] = mapped_column(Integer, nullable=False, default=0, server_default="0")
    lines_removed: Mapped[int] = mapped_column(Integer, nullable=False, default=0, server_default="0")
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        server_default=func.now(),
        nullable=False,
    )

    def __repr__(self) -> str:
        return (
            f"<RouterConfigDiff id={self.id} device_id={self.device_id} "
            f"+{self.lines_added}/-{self.lines_removed}>"
        )


class RouterConfigChange(Base):
    """A parsed change extracted from a router config diff.

    Each change represents a semantic modification (e.g., firewall rule
    added, IP address changed) parsed from the unified diff. The component
    field identifies the RouterOS section (e.g., 'ip/firewall/filter').
    """

    __tablename__ = "router_config_changes"

    id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        primary_key=True,
        default=uuid.uuid4,
        server_default=func.gen_random_uuid(),
    )
    diff_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("router_config_diffs.id", ondelete="CASCADE"),
        nullable=False,
        index=True,
    )
    device_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("devices.id", ondelete="CASCADE"),
        nullable=False,
        index=True,
    )
    tenant_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("tenants.id", ondelete="CASCADE"),
        nullable=False,
        index=True,
    )
    # RouterOS config section path (e.g., 'ip/firewall/filter')
    component: Mapped[str] = mapped_column(Text, nullable=False)
    # Human-readable description of the change
    summary: Mapped[str] = mapped_column(Text, nullable=False)
    # Raw diff line(s), nullable for synthesized changes
    raw_line: Mapped[str | None] = mapped_column(Text, nullable=True)
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        server_default=func.now(),
        nullable=False,
    )

    def __repr__(self) -> str:
        return (
            f"<RouterConfigChange id={self.id} diff_id={self.diff_id} "
            f"component={self.component!r}>"
        )