"""Add terminal_command_logs table for command history

Revision ID: 0014
Revises: 0013_add_terminal_sessions_table
Create Date: 2024-12-18

This migration creates the terminal_command_logs table to store
validated terminal commands for history and audit purposes.
"""
from alembic import op
import sqlalchemy as sa
from sqlalchemy import inspect


# revision identifiers, used by Alembic.
revision = '0014'
down_revision = '0013'
branch_labels = None
depends_on = None


def table_exists(table_name: str) -> bool:
    """Check if a table exists in the database."""
    bind = op.get_bind()
    inspector = inspect(bind)
    return table_name in inspector.get_table_names()


def index_exists(index_name: str, table_name: str) -> bool:
    """Check if an index exists on a table."""
    bind = op.get_bind()
    inspector = inspect(bind)
    indexes = inspector.get_indexes(table_name)
    return any(idx['name'] == index_name for idx in indexes)


def upgrade() -> None:
    # Check if table already exists (idempotent migration)
    if table_exists('terminal_command_logs'):
        print("Table 'terminal_command_logs' already exists, skipping creation.")
    else:
        op.create_table(
            'terminal_command_logs',
            sa.Column('id', sa.Integer(), autoincrement=True, nullable=False),
            sa.Column('created_at', sa.DateTime(timezone=True), server_default=sa.func.now(), nullable=False),
            sa.Column('host_id', sa.String(), nullable=False),
            sa.Column('user_id', sa.String(), nullable=True),
            sa.Column('terminal_session_id', sa.String(64), nullable=True),
            sa.Column('command', sa.Text(), nullable=False),
            sa.Column('command_hash', sa.String(64), nullable=False),
            sa.Column('source', sa.String(20), server_default='terminal', nullable=False),
            sa.Column('is_blocked', sa.Boolean(), server_default='0', nullable=False),
            sa.Column('blocked_reason', sa.String(255), nullable=True),
            sa.Column('username', sa.String(100), nullable=True),
            sa.Column('host_name', sa.String(100), nullable=True),
            sa.PrimaryKeyConstraint('id'),
            sa.ForeignKeyConstraint(['host_id'], ['hosts.id'], ondelete='CASCADE'),
            sa.ForeignKeyConstraint(['user_id'], ['users.id'], ondelete='SET NULL'),
        )
    
    # Create indexes for efficient querying (only if they don't exist)
    if not index_exists('ix_terminal_command_logs_created_at', 'terminal_command_logs'):
        op.create_index('ix_terminal_command_logs_created_at', 'terminal_command_logs', ['created_at'])
    if not index_exists('ix_terminal_command_logs_host_id', 'terminal_command_logs'):
        op.create_index('ix_terminal_command_logs_host_id', 'terminal_command_logs', ['host_id'])
    if not index_exists('ix_terminal_command_logs_user_id', 'terminal_command_logs'):
        op.create_index('ix_terminal_command_logs_user_id', 'terminal_command_logs', ['user_id'])
    if not index_exists('ix_terminal_command_logs_terminal_session_id', 'terminal_command_logs'):
        op.create_index('ix_terminal_command_logs_terminal_session_id', 'terminal_command_logs', ['terminal_session_id'])
    if not index_exists('ix_terminal_command_logs_command_hash', 'terminal_command_logs'):
        op.create_index('ix_terminal_command_logs_command_hash', 'terminal_command_logs', ['command_hash'])
    
    # Composite indexes for common query patterns
    if not index_exists('ix_terminal_cmd_host_created', 'terminal_command_logs'):
        op.create_index('ix_terminal_cmd_host_created', 'terminal_command_logs', ['host_id', 'created_at'])
    if not index_exists('ix_terminal_cmd_user_created', 'terminal_command_logs'):
        op.create_index('ix_terminal_cmd_user_created', 'terminal_command_logs', ['user_id', 'created_at'])
    if not index_exists('ix_terminal_cmd_host_hash', 'terminal_command_logs'):
        op.create_index('ix_terminal_cmd_host_hash', 'terminal_command_logs', ['host_id', 'command_hash'])


def downgrade() -> None:
    # Drop indexes
    op.drop_index('ix_terminal_cmd_host_hash', table_name='terminal_command_logs')
    op.drop_index('ix_terminal_cmd_user_created', table_name='terminal_command_logs')
    op.drop_index('ix_terminal_cmd_host_created', table_name='terminal_command_logs')
    op.drop_index('ix_terminal_command_logs_command_hash', table_name='terminal_command_logs')
    op.drop_index('ix_terminal_command_logs_terminal_session_id', table_name='terminal_command_logs')
    op.drop_index('ix_terminal_command_logs_user_id', table_name='terminal_command_logs')
    op.drop_index('ix_terminal_command_logs_host_id', table_name='terminal_command_logs')
    op.drop_index('ix_terminal_command_logs_created_at', table_name='terminal_command_logs')
    
    # Drop table
    op.drop_table('terminal_command_logs')