// Package database provides data models and repository interfaces for the Vaultik backup system.
// It includes types for files, chunks, blobs, snapshots, and their relationships.
package database

import "time"

// File represents a file or directory in the backup system.
// It stores metadata about files including timestamps, permissions, ownership,
// and symlink targets. This information is used to restore files with their
// original attributes.
type File struct {
	ID         string // UUID primary key
	Path       string
	MTime      time.Time
	CTime      time.Time
	Size       int64
	Mode       uint32
	UID        uint32
	GID        uint32
	LinkTarget string // empty for regular files, target path for symlinks
}

// IsSymlink returns true if this file is a symbolic link.
// A file is considered a symlink if it has a non-empty LinkTarget.
func (f *File) IsSymlink() bool {
	return f.LinkTarget != ""
}

// FileChunk represents the mapping between files and their constituent chunks.
// Large files are split into multiple chunks for efficient deduplication and storage.
// The Idx field maintains the order of chunks within a file.
type FileChunk struct {
	FileID    string
	Idx       int
	ChunkHash string
}

// Chunk represents a data chunk in the deduplication system.
// Files are split into chunks which are content-addressed by their hash.
// The ChunkHash is the SHA256 hash of the chunk content, used for deduplication.
type Chunk struct {
	ChunkHash string
	Size      int64
}

// Blob represents a blob record in the database.
// A blob is Vaultik's final storage unit - a large file (up to 10GB) containing
// many compressed and encrypted chunks from multiple source files.
// Blobs are content-addressed, meaning their filename in S3 is derived from
// the SHA256 hash of their compressed and encrypted content.
// The blob creation process is: chunks are accumulated -> compressed with zstd
// -> encrypted with age -> hashed -> uploaded to S3 with the hash as filename.
type Blob struct {
	ID               string     // UUID assigned when blob creation starts
	Hash             string     // SHA256 of final compressed+encrypted content (empty until finalized)
	CreatedTS        time.Time  // When blob creation started
	FinishedTS       *time.Time // When blob was finalized (nil if still packing)
	UncompressedSize int64      // Total size of raw chunks before compression
	CompressedSize   int64      // Size after compression and encryption
	UploadedTS       *time.Time // When blob was uploaded to S3 (nil if not uploaded)
}

// BlobChunk represents the mapping between blobs and the chunks they contain.
// This allows tracking which chunks are stored in which blobs, along with
// their position and size within the blob. The offset and length fields
// enable extracting specific chunks from a blob without processing the entire blob.
type BlobChunk struct {
	BlobID    string
	ChunkHash string
	Offset    int64
	Length    int64
}

// ChunkFile represents the reverse mapping showing which files contain a specific chunk.
// This is used during deduplication to identify all files that share a chunk,
// which is important for garbage collection and integrity verification.
type ChunkFile struct {
	ChunkHash  string
	FileID     string
	FileOffset int64
	Length     int64
}

// Snapshot represents a snapshot record in the database
type Snapshot struct {
	ID                   string
	Hostname             string
	VaultikVersion       string
	VaultikGitRevision   string
	StartedAt            time.Time
	CompletedAt          *time.Time // nil if still in progress
	FileCount            int64
	ChunkCount           int64
	BlobCount            int64
	TotalSize            int64   // Total size of all referenced files
	BlobSize             int64   // Total size of all referenced blobs (compressed and encrypted)
	BlobUncompressedSize int64   // Total uncompressed size of all referenced blobs
	CompressionRatio     float64 // Compression ratio (BlobSize / BlobUncompressedSize)
	CompressionLevel     int     // Compression level used for this snapshot
	UploadBytes          int64   // Total bytes uploaded during this snapshot
	UploadDurationMs     int64   // Total milliseconds spent uploading to S3
}

// IsComplete returns true if the snapshot has completed
func (s *Snapshot) IsComplete() bool {
	return s.CompletedAt != nil
}

// SnapshotFile represents the mapping between snapshots and files
type SnapshotFile struct {
	SnapshotID string
	FileID     string
}

// SnapshotBlob represents the mapping between snapshots and blobs
type SnapshotBlob struct {
	SnapshotID string
	BlobID     string
	BlobHash   string // Denormalized for easier manifest generation
}