package backup

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"
)

// R-474 (v0.240.0) — "delete backups" on removal deletes the app's Tier-2 mirror too.
//
// Measured three times on 2026-09-13: removing an app with `remove_backups:true` deleted only its
// db-dumps directory; the recovery unit, the volume tars and the Tier-2 mirror all survived, and a
// later reinstall of the same app then leaned on the old install's unit as its "fresh" restore point
// (R-478). The unit is inside the app's own backups base and RemoveStack deletes it; the MIRROR lives
// on another drive, outside that base, so it is removed here, with its own path check.

func validMirrorStackName(n string) bool {
	return n != "" && n != "." && n != ".." && n != SharesPseudoStack && !strings.ContainsAny(n, `/\`)
}

// tier2MirrorRoots are the namespace roots a Tier-2 mirror of this app can live under: the recorded
// destination, every registered drive, and the system data path (a mirror outlives a changed target).
func (m *Manager) tier2MirrorRoots(stackName string) []string {
	seen := map[string]bool{}
	var roots []string
	add := func(r string) {
		if r == "" {
			return
		}
		r = filepath.Clean(r)
		if filepath.IsAbs(r) && !seen[r] {
			seen[r] = true
			roots = append(roots, r)
		}
	}
	if m.settings != nil {
		if cfg := m.settings.GetCrossDriveConfig(stackName); cfg != nil {
			add(cfg.DestinationPath)
		}
		for _, sp := range m.settings.GetStoragePaths() {
			if sp.Path != "" {
				add(NamespaceRootFor(sp.Path, m.systemDataPath))
			}
		}
	}
	if m.systemDataPath != "" {
		add(NamespaceRootFor(m.systemDataPath, m.systemDataPath))
	}
	return roots
}

// Tier2MirrorDirsForApp lists the app's Tier-2 mirror directories that exist now. Call it BEFORE the
// removal clears the app's cross-drive record, which is one of the places it looks.
func (m *Manager) Tier2MirrorDirsForApp(stackName string) []string {
	if m == nil || !validMirrorStackName(stackName) {
		return nil
	}
	var out []string
	for _, root := range m.tier2MirrorRoots(stackName) {
		d := filepath.Join(root, "backups", "secondary", stackName)
		if fi, err := os.Stat(d); err == nil && fi.IsDir() {
			out = append(out, d)
		}
	}
	return out
}

// RemoveTier2Mirrors deletes the given mirror directories, each only if it is exactly
// <root>/backups/secondary/<stackName> for one of the app's mirror roots — never another app's mirror,
// never the shares mirror, never a path that merely cleans to one. Returns "path (size)" per removal.
func (m *Manager) RemoveTier2Mirrors(stackName string, dirs []string) []string {
	if m == nil || !validMirrorStackName(stackName) {
		return nil
	}
	allowed := map[string]bool{}
	for _, root := range m.tier2MirrorRoots(stackName) {
		allowed[filepath.Join(root, "backups", "secondary", stackName)] = true
	}
	var removed []string
	for _, d := range dirs {
		if !allowed[d] {
			m.logger.Printf("[WARN] [backup] remove %s: refusing to delete %q — not this app's Tier-2 mirror", stackName, d)
			continue
		}
		size := humanizeBytes(dirSizeBytes(d))
		if err := os.RemoveAll(d); err != nil {
			m.logger.Printf("[ERROR] [backup] remove %s: deleting the Tier-2 mirror %s failed: %v", stackName, d, err)
			continue
		}
		m.logger.Printf("[INFO] [backup] remove %s: Tier-2 mirror deleted: %s (%s)", stackName, d, size)
		removed = append(removed, fmt.Sprintf("%s (%s)", d, size))
	}
	return removed
}