package bsdaily

import (
	"fmt"
	"log/slog"
	"os"
	"path/filepath"
	"sort"
	"time"
)

func FindLatestDailySnapshot() (dir string, snapshotDate time.Time, err error) {
	entries, err := os.ReadDir(SnapshotBase)
	if err != nil {
		return "", time.Time{}, fmt.Errorf("reading snapshot directory %s: %w", SnapshotBase, err)
	}

	type snapshot struct {
		name string
		date time.Time
	}

	var snapshots []snapshot
	for _, e := range entries {
		if !e.IsDir() {
			continue
		}
		m := snapshotPattern.FindStringSubmatch(e.Name())
		if m == nil {
			continue
		}
		d, err := time.Parse("2006-01-02", m[1])
		if err != nil {
			slog.Warn("skipping snapshot with unparseable date", "name", e.Name(), "error", err)
			continue
		}
		snapshots = append(snapshots, snapshot{name: e.Name(), date: d})
	}

	if len(snapshots) == 0 {
		return "", time.Time{}, fmt.Errorf("no daily snapshots found in %s", SnapshotBase)
	}

	sort.Slice(snapshots, func(i, j int) bool {
		return snapshots[i].date.After(snapshots[j].date)
	})

	latest := snapshots[0]
	dir = filepath.Join(SnapshotBase, latest.name)

	dbPath := filepath.Join(dir, DBFilename)
	if _, err := os.Stat(dbPath); err != nil {
		return "", time.Time{}, fmt.Errorf("database not found in snapshot %s: %w", dir, err)
	}

	return dir, latest.date, nil
}