package cmd

import (
	"fmt"

	"github.com/spf13/cobra"
	"github.com/david/knox/internal/db"
	"github.com/david/knox/internal/watch"
)

// NewReconcileCmd rebuilds all derived state (entries cache, threads) from the
// append-only observation log. With --dry-run it reports what would change
// without writing.
func NewReconcileCmd(kdb *db.KnoxDB) *cobra.Command {
	var dryRun bool
	cmd := &cobra.Command{
		Use:   "reconcile",
		Short: "Rebuild entries and threads from the observation log",
		Long: `Reconcile makes derived state converge on the append-only observation log.

Entries are dropped and rebuilt via deterministic SQL aggregation; the
auto-threader then re-links/create threads idempotently by cluster_key. After a
gossip pull, reconcile brings a node's materialized view in line with whatever
observations it now holds.`,
		RunE: func(c *cobra.Command, args []string) error {
			if dryRun {
				return dryRunReconcile(kdb)
			}
			created, linked, err := watch.Reconcile(kdb)
			if err != nil {
				return err
			}
			fmt.Printf("reconciled: entries rebuilt, %d threads created, %d observations linked\n", created, linked)
			return nil
		},
	}
	cmd.Flags().BoolVar(&dryRun, "dry-run", false, "report drift without writing")
	return cmd
}

func dryRunReconcile(kdb *db.KnoxDB) error {
	// Ground truth from the log (computed in a throwaway way via a count of
	// what rebuild would produce) vs the current materialized cache.
	current, _ := kdb.EntryCount()
	logCount := kdb.ObservationEntryEstimate()

	threader := watch.NewAutoThreader(kdb)
	threader.DryRun = true
	created, linked, _ := threader.AutoThread()

	fmt.Printf("drift: %d entries current, %d from log (%+d), %d threads would be created, %d obs would be linked\n",
		current, logCount, logCount-current, created, linked)
	return nil
}