package cli

import (
	"fmt"

	"github.com/spf13/cobra"

	"gitea.mynodes.xyz/ilker/llmgw/internal/store"
)

// newMoveStoreCmd copies a store into another one.
//
// Written because keys are stored hashed. Moving to PostgreSQL without this
// means every person and every script needs a new key issued, and the old ones
// cannot even be looked up to say which they were.
//
// It reads and writes, and nothing else runs while it does: run it with the
// gateway stopped. A copy taken while requests are landing would miss whatever
// arrived after the table it had already passed.
func newMoveStoreCmd() *cobra.Command {
	var from, to string

	cmd := &cobra.Command{
		Use:   "move-store",
		Short: "Copy a store into another one, for moving SQLite to PostgreSQL",
		Long: "Copies every table, parents first, into an empty destination.\n\n" +
			"Stop the gateway first. This makes no attempt to copy a store that is\n" +
			"being written to: rows landing after the table they belong to has been\n" +
			"passed would simply be absent, and nothing would say so.\n\n" +
			"The destination must be empty. Merging two stores means deciding which\n" +
			"of two projects with the same id was meant, and there is no answer to\n" +
			"that which is not a guess.",
		Args: cobra.NoArgs,
		RunE: func(cmd *cobra.Command, _ []string) error {
			if from == "" || to == "" {
				return fmt.Errorf("--from and --to are both required")
			}
			src, err := store.Open(cmd.Context(), from)
			if err != nil {
				return fmt.Errorf("opening the source: %w", err)
			}
			defer src.Close()

			dst, err := store.Open(cmd.Context(), to)
			if err != nil {
				return fmt.Errorf("opening the destination: %w", err)
			}
			defer dst.Close()

			res, err := src.CopyTo(cmd.Context(), dst)
			// Printed even on failure: a partial copy is the one case where
			// knowing how far it got decides what to do next.
			out := cmd.OutOrStdout()
			var total int64
			for _, r := range res {
				if r.Rows > 0 {
					fmt.Fprintf(out, "  %-16s %d\n", r.Table, r.Rows)
				}
				total += r.Rows
			}
			if err != nil {
				return err
			}
			fmt.Fprintf(out, "\n%d rows copied. Point the gateway at the new store and start it.\n", total)
			return nil
		},
	}
	cmd.Flags().StringVar(&from, "from", "", "source: a SQLite path, a postgres:// URL, or @file holding one")
	cmd.Flags().StringVar(&to, "to", "", "destination, same forms")
	return cmd
}