Swap Postgres version via Homebrew

swap_pg_version.sh

swap_pg_version() {
    if [ $# -ne 1 ]; then
        echo "Usage: swap_pg_version <version>"
        return 1
    fi

    TARGET_VERSION="postgresql@$1"
    
    # List all installed PostgreSQL versions
    INSTALLED_VERSIONS=$(brew list --formula | grep 'postgresql@')
    
    # Find the currently running version
    RUNNING_VERSION=$(brew services list | grep 'postgresql@' | grep 'started' | awk '{print $1}')
    
    # Check if the target version is installed
    if echo "$INSTALLED_VERSIONS" | grep -q "^$TARGET_VERSION\$"; then
        # Stop the currently running version if it's different from the target version
        if [ -n "$RUNNING_VERSION" ] && [ "$RUNNING_VERSION" != "$TARGET_VERSION" ]; then
            echo "Stopping the currently running $RUNNING_VERSION..."
            brew services stop $RUNNING_VERSION
        fi

        # Unlink the current version
        if [ -n "$RUNNING_VERSION" ]; then
            brew unlink $RUNNING_VERSION
        fi

        # Link the target version
        brew link $TARGET_VERSION --force --overwrite
        
        # Start the new version
        brew services start $TARGET_VERSION
        echo "Switched to $TARGET_VERSION"
    else
        echo "PostgreSQL version $1 is not installed."
        return 1
    fi
}