package settings

import (
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"time"
)

// KeptCopy is one second-drive copy whose source is gone (D25, operator ruling 2026-10-21). The record is what the
// backups page lists and what „Eltávolítás" removes — by Path, identity-checked against Dev/Ino, never by size or a
// name pattern (07 §8.2 as amended by D25).
type KeptCopy struct {
	ID        string `json:"id"`         // stable: sha256 of Path, first 16 hex
	Kind      string `json:"kind"`       // "share" | "app"
	Source    string `json:"source"`     // the share's name, or "<app>: <folder>"
	Drive     string `json:"drive"`      // the SOURCE drive's label (or its path when the drive is no longer registered)
	Reason    string `json:"reason"`     // "drive_away" | "drive_gone" | "folder_missing"
	DestBase  string `json:"dest_base"`  // the copy tree it lives in; Path must stay inside it
	Path      string `json:"path"`       // the copy's absolute directory
	Dev       uint64 `json:"dev"`        // identity at record time
	Ino       uint64 `json:"ino"`        // identity at record time
	SizeBytes int64  `json:"size_bytes"` // at the latest run
	Since     string `json:"since"`      // RFC3339, first time it was kept
}

// KeptCopyID is the record's id for a copy path.
func KeptCopyID(path string) string {
	h := sha256.Sum256([]byte(path))
	return hex.EncodeToString(h[:8])
}

// GetKeptCopies returns a copy of the kept-copy records.
func (s *Settings) GetKeptCopies() []KeptCopy {
	s.mu.RLock()
	defer s.mu.RUnlock()
	return append([]KeptCopy(nil), s.KeptCopies...)
}

// UpsertKeptCopy records a kept copy (or refreshes its size and identity), keeping the first Since.
func (s *Settings) UpsertKeptCopy(k KeptCopy) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	if k.Path == "" || k.DestBase == "" {
		return fmt.Errorf("kept copy: empty path or dest base")
	}
	k.ID = KeptCopyID(k.Path)
	for i := range s.KeptCopies {
		if s.KeptCopies[i].ID == k.ID {
			since := s.KeptCopies[i].Since
			k.Since = since
			if s.KeptCopies[i] == k {
				return nil // nothing changed — no write
			}
			s.KeptCopies[i] = k
			return s.save()
		}
	}
	if k.Since == "" {
		k.Since = time.Now().UTC().Format(time.RFC3339)
	}
	s.KeptCopies = append(s.KeptCopies, k)
	if s.log != nil {
		s.log.Printf("[INFO] [settings] kept copy recorded: kind=%s source=%q reason=%s path=%s", k.Kind, k.Source, k.Reason, k.Path)
	}
	return s.save()
}

// DropKeptCopy forgets the record of a copy path (the source came back, or the household removed the copy). The
// copy's data is not touched here.
func (s *Settings) DropKeptCopy(id string) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	for i := range s.KeptCopies {
		if s.KeptCopies[i].ID == id {
			s.KeptCopies = append(s.KeptCopies[:i], s.KeptCopies[i+1:]...)
			return s.save()
		}
	}
	return nil
}