package hasher

import (
	"crypto/md5"
	"crypto/sha256"
	"hash"
	"io"
	"os"
)

type Hasher struct {
	HashSupplier func() hash.Hash
}

func NewSha256Hasher() *Hasher {
	return NewHasher(func() hash.Hash {
		return sha256.New()
	},
	)
}

func NewMd5Hasher() *Hasher {
	return NewHasher(func() hash.Hash {
		return md5.New()
	},
	)
}

func NewHasher(hashSupplier func() hash.Hash) *Hasher {
	return &Hasher{
		HashSupplier: hashSupplier,
	}
}

func (self *Hasher) GetFileHashString(fileLocation string) (string, error) {
	bytes, err := self.GetFileHashBytes(fileLocation)
	if err != nil {
		return "", err
	}

	return string(bytes), nil
}

func (self *Hasher) GetFileHashBytes(fileLocation string) ([]byte, error) {
	file, err := os.Open(fileLocation)
	if err != nil {
		return nil, err
	}
	defer file.Close()

	return self.GetHashBytes(file)
}

func (self *Hasher) GetHashString(reader io.Reader) (string, error) {
	bytes, err := self.GetHashBytes(reader)
	if err != nil {
		return "", err
	}

	return string(bytes), nil
}

func (self *Hasher) GetHashBytes(reader io.Reader) ([]byte, error) {
	hasher := self.HashSupplier()
	_, err := io.Copy(hasher, reader)

	if err != nil {
		return nil, err
	}

	return hasher.Sum(nil), nil
}