Implement Modrinth pack exporting (fixes #34)

core/hash.go

@@ -5,23 +5,44 @@ import (
 	"crypto/sha1"
 	"crypto/sha256"
 	"crypto/sha512"
-	"errors"
+	"encoding/binary"
+	"encoding/hex"
+	"fmt"
+	"github.com/packwiz/packwiz/curseforge/murmur2"
 	"hash"
+	"strconv"
 	"strings"
 )
 
 // GetHashImpl gets an implementation of hash.Hash for the given hash type string
-func GetHashImpl(hashType string) (hash.Hash, error) {
+func GetHashImpl(hashType string) (hash.Hash, HashStringer, error) {
 	switch strings.ToLower(hashType) {
 	case "sha1":
-		return sha1.New(), nil
+		return sha1.New(), hexStringer{}, nil
 	case "sha256":
-		return sha256.New(), nil
+		return sha256.New(), hexStringer{}, nil
 	case "sha512":
-		return sha512.New(), nil
+		return sha512.New(), hexStringer{}, nil
 	case "md5":
-		return md5.New(), nil
+		return md5.New(), hexStringer{}, nil
+	case "murmur2":
+		return murmur2.New(), numberStringer{}, nil
 	}
-	// TODO: implement murmur2
-	return nil, errors.New("hash implementation not found")
+	return nil, nil, fmt.Errorf("hash implementation %s not found", hashType)
+}
+
+type HashStringer interface {
+	HashToString([]byte) string
+}
+
+type hexStringer struct{}
+
+func (hexStringer) HashToString(data []byte) string {
+	return hex.EncodeToString(data)
+}
+
+type numberStringer struct{}
+
+func (numberStringer) HashToString(data []byte) string {
+	return strconv.FormatUint(uint64(binary.BigEndian.Uint32(data)), 10)
 }

core/index.go

@@ -1,7 +1,6 @@
 package core
 
 import (
-	"encoding/hex"
 	"errors"
 	"io"
 	"os"
@@ -133,7 +132,7 @@ func (in *Index) updateFile(path string) error {
 		// Hash usage strategy (may change):
 		// Just use SHA256, overwrite existing hash regardless of what it is
 		// May update later to continue using the same hash that was already being used
-		h, err := GetHashImpl("sha256")
+		h, stringer, err := GetHashImpl("sha256")
 		if err != nil {
 			_ = f.Close()
 			return err
@@ -146,7 +145,7 @@ func (in *Index) updateFile(path string) error {
 		if err != nil {
 			return err
 		}
-		hashString = hex.EncodeToString(h.Sum(nil))
+		hashString = stringer.HashToString(h.Sum(nil))
 	}
 
 	mod := false
@@ -348,7 +347,7 @@ func (in Index) SaveFile(f IndexFile, dest io.Writer) error {
 	if err != nil {
 		return err
 	}
-	h, err := GetHashImpl(hashFormat)
+	h, stringer, err := GetHashImpl(hashFormat)
 	if err != nil {
 		return err
 	}
@@ -359,7 +358,7 @@ func (in Index) SaveFile(f IndexFile, dest io.Writer) error {
 		return err
 	}
 
-	calculatedHash := hex.EncodeToString(h.Sum(nil))
+	calculatedHash := stringer.HashToString(h.Sum(nil))
 	if calculatedHash != f.Hash && !viper.GetBool("no-internal-hashes") {
 		return errors.New("hash of saved file is invalid")
 	}

core/mod.go

@@ -1,7 +1,6 @@
 package core
 
 import (
-	"encoding/hex"
 	"errors"
 	"fmt"
 	"io"
@@ -90,7 +89,7 @@ func (m Mod) Write() (string, string, error) {
 		}
 	}
 
-	h, err := GetHashImpl("sha256")
+	h, stringer, err := GetHashImpl("sha256")
 	if err != nil {
 		_ = f.Close()
 		return "", "", err
@@ -101,7 +100,7 @@ func (m Mod) Write() (string, string, error) {
 	// Disable indentation
 	enc.Indent = ""
 	err = enc.Encode(m)
-	hashString := hex.EncodeToString(h.Sum(nil))
+	hashString := stringer.HashToString(h.Sum(nil))
 	if err != nil {
 		_ = f.Close()
 		return "sha256", hashString, err
@@ -135,7 +134,7 @@ func (m Mod) DownloadFile(dest io.Writer) error {
 		_ = resp.Body.Close()
 		return errors.New("invalid status code " + strconv.Itoa(resp.StatusCode))
 	}
-	h, err := GetHashImpl(m.Download.HashFormat)
+	h, stringer, err := GetHashImpl(m.Download.HashFormat)
 	if err != nil {
 		return err
 	}
@@ -146,7 +145,7 @@ func (m Mod) DownloadFile(dest io.Writer) error {
 		return err
 	}
 
-	calculatedHash := hex.EncodeToString(h.Sum(nil))
+	calculatedHash := stringer.HashToString(h.Sum(nil))
 
 	// Check if the hash of the downloaded file matches the expected hash.
 	if calculatedHash != m.Download.Hash {

core/pack.go

@@ -1,7 +1,6 @@
 package core
 
 import (
-	"encoding/hex"
 	"errors"
 	"fmt"
 	"io"
@@ -116,7 +115,7 @@ func (pack *Pack) UpdateIndexHash() error {
 	// Hash usage strategy (may change):
 	// Just use SHA256, overwrite existing hash regardless of what it is
 	// May update later to continue using the same hash that was already being used
-	h, err := GetHashImpl("sha256")
+	h, stringer, err := GetHashImpl("sha256")
 	if err != nil {
 		_ = f.Close()
 		return err
@@ -125,7 +124,7 @@ func (pack *Pack) UpdateIndexHash() error {
 		_ = f.Close()
 		return err
 	}
-	hashString := hex.EncodeToString(h.Sum(nil))
+	hashString := stringer.HashToString(h.Sum(nil))
 
 	pack.Index.HashFormat = "sha256"
 	pack.Index.Hash = hashString