package git

import (
	"context"
	"fmt"
	"strings"
)

func snapshotPrefix(taskID string) string {
	return "refs/byre/tasks/" + taskID + "/snap/"
}

func SnapshotRef(taskID string, n int) string {
	return fmt.Sprintf("%s%d", snapshotPrefix(taskID), n)
}

func CommitSnapshot(ctx context.Context, dir, tree, ref, message string, env []string) (string, error) {
	head, err := Head(ctx, dir)
	if err != nil {
		return "", err
	}
	commit, err := runEnv(ctx, dir, env, "commit-tree", tree, "-p", head, "-m", message)
	if err != nil {
		return "", err
	}
	_, err = run(ctx, dir, "update-ref", ref, commit, "")
	if err != nil {
		return "", err
	}
	return commit, nil
}

func SnapshotRefs(ctx context.Context, repo, taskID string) ([]string, error) {
	out, err := run(ctx, repo, "for-each-ref", "--format=%(refname)", snapshotPrefix(taskID))
	if err != nil {
		return nil, err
	}
	if out == "" {
		return []string{}, nil
	}
	return strings.Split(out, "\n"), nil
}

func DeleteSnapshotRefs(ctx context.Context, repo, taskID string) error {
	refs, err := SnapshotRefs(ctx, repo, taskID)
	if err != nil {
		return err
	}
	if len(refs) == 0 {
		return nil
	}

	b := &strings.Builder{}
	for _, ref := range refs {
		fmt.Fprintf(b, "delete %s\n", ref)
	}
	_, err = runInput(ctx, repo, nil, b.String(), "update-ref", "--stdin")
	return err
}