package cmd

import (
	"fmt"
	"log/slog"
)

// Activate switches the boot target to the passive partition.
// After activation, the next reboot will boot from the new partition
// with boot_counter=3. If health checks fail 3 times, GRUB auto-rolls back.
func Activate(args []string) error {
	opts := parseOpts(args)
	env := opts.NewBootEnv()

	// Get passive slot (the one we want to boot into)
	passiveSlot, err := env.PassiveSlot()
	if err != nil {
		return fmt.Errorf("reading passive slot: %w", err)
	}

	activeSlot, err := env.ActiveSlot()
	if err != nil {
		return fmt.Errorf("reading active slot: %w", err)
	}

	slog.Info("activating slot", "from", activeSlot, "to", passiveSlot)

	// Set the passive slot as active with fresh boot counter
	if err := env.ActivateSlot(passiveSlot); err != nil {
		return fmt.Errorf("activating slot %s: %w", passiveSlot, err)
	}

	fmt.Printf("Slot %s activated (was %s)\n", passiveSlot, activeSlot)
	fmt.Println("Boot counter set to 3. Reboot to start the new version.")
	fmt.Println("The system will automatically roll back if health checks fail 3 times.")

	return nil
}