hashutil

type Hash interface {
	// HashFromFile calculate the hash value of the file
	// If you reuse the file reader, please set its offset to start position first, like os.File.Seek
	HashFromFile(file io.Reader) (hashString string, err error)
	// HashFromFileName calculate the hash value of the file
	HashFromFileName(path string) (hash string, err error)
	// HashFromFileChunk calculate the hash value of the file chunk
	HashFromFileChunk(path string, offset int64, chunkSize int64) (hash string, err error)
	// Hash calculate the hash value of the bytes
	Hash(bytes []byte) (hashString string)
	// HashFromString calculate the hash value of the string
	HashFromString(s string) (hash string)
	// CheckpointsHashFromFileName calculate the hash value of the entire file and first chunk and some checkpoints
	// the first chunk hash is optional
	// the checkpoint hash is optional
	// the entire file hash is required
	CheckpointsHashFromFileName(path string, chunkSize int64, checkpointCount int) (hvs HashValues, err error)
	// CheckpointsHashFromFile calculate the hash value of the entire file and first chunk and some checkpoints
	CheckpointsHashFromFile(f *os.File, chunkSize int64, checkpointCount int) (hvs HashValues, err error)
	// GetFileSizeAndHashCheckpoints get the file size and hash checkpoints from the specified file
	GetFileSizeAndHashCheckpoints(path string, chunkSize int64, checkpointCount int) (size int64, hash string, hvs HashValues, err error)
	// Compare whether the source file is equal to the destination file
	Compare(chunkSize int64, checkpointCount int, sourceFile *os.File, sourceSize int64, dest string, destSize int64, offset *int64) (equal bool)
	// QuickCompare if the forceChecksum is false, check whether the size and time are both equal, otherwise return false
	QuickCompare(forceChecksum bool, sourceSize, destSize int64, sourceModTime, destModTime time.Time) (equal bool)
	// CompareHashValues compare the HashValues from source file with the destination file
	CompareHashValues(dstPath string, sourceSize int64, sourceHash string, chunkSize int64, hvs HashValues) (equal bool, hv *HashValue)
	// CompareHashValuesWithFileName calculate the file hashes and return the last continuous hit HashValue.
	// The offset in the HashValues must equal chunkSize * N, and N greater than zero
	CompareHashValuesWithFileName(path string, chunkSize int64, hvs HashValues) (eq *HashValue, err error)
}

type HashValue struct {
	// Offset the file data to calculate the hash value from zero to offset
	Offset int64 `json:"offset"`
	// Hash the file checkpoint hash value
	Hash string `json:"hash"`
}

type HashValues []*HashValue