From 55ce2fb581dfb5346c69e2ea89a7a39c93994398 Mon Sep 17 00:00:00 2001
From: comp500 <comp500@users.noreply.github.com>
Date: Mon, 14 Feb 2022 18:21:22 +0000
Subject: [PATCH] Use new SHA1/MD5 hashes from CurseForge API

---
 curseforge/curseforge.go | 19 +++++++++----------
 curseforge/request.go    | 37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+), 10 deletions(-)

diff --git a/curseforge/curseforge.go b/curseforge/curseforge.go
index 3ad39b8..d5fc01f 100644
--- a/curseforge/curseforge.go
+++ b/curseforge/curseforge.go
@@ -179,16 +179,16 @@ func createModFile(modInfo modInfo, fileInfo modFileInfo, index *core.Index) err
 		return err
 	}
 
+	hash, hashFormat := fileInfo.getBestHash()
+
 	modMeta := core.Mod{
 		Name:     modInfo.Name,
 		FileName: fileInfo.FileName,
 		Side:     core.UniversalSide,
 		Download: core.ModDownload{
-			URL: u,
-			// TODO: murmur2 hashing may be unstable in curse api, calculate the hash manually?
-			// TODO: check if the hash is invalid (e.g. 0)
-			HashFormat: "murmur2",
-			Hash:       strconv.Itoa(fileInfo.Fingerprint),
+			URL:        u,
+			HashFormat: hashFormat,
+			Hash:       hash,
 		},
 		Update: updateMap,
 	}
@@ -421,12 +421,11 @@ func (u cfUpdater) DoUpdate(mods []*core.Mod, cachedState []interface{}) error {
 
 		v.FileName = fileInfoData.FileName
 		v.Name = modState.Name
+		hash, hashFormat := fileInfoData.getBestHash()
 		v.Download = core.ModDownload{
-			URL: u,
-			// TODO: murmur2 hashing may be unstable in curse api, calculate the hash manually?
-			// TODO: check if the hash is invalid (e.g. 0)
-			HashFormat: "murmur2",
-			Hash:       strconv.Itoa(fileInfoData.Fingerprint),
+			URL:        u,
+			HashFormat: hashFormat,
+			Hash:       hash,
 		}
 
 		v.Update["curseforge"]["project-id"] = modState.ID
diff --git a/curseforge/request.go b/curseforge/request.go
index 23c91eb..116d8f9 100644
--- a/curseforge/request.go
+++ b/curseforge/request.go
@@ -124,6 +124,12 @@ const (
 	modloaderTypeFabric
 )
 
+//noinspection GoUnusedConst
+const (
+	hashAlgoSHA1 int = iota + 1
+	hashAlgoMD5
+)
+
 // modInfo is a subset of the deserialised JSON response from the Curse API for mods (addons)
 type modInfo struct {
 	Name                   string        `json:"name"`
@@ -244,6 +250,37 @@ type modFileInfo struct {
 		ModID int `json:"addonId"`
 		Type  int `json:"type"`
 	} `json:"dependencies"`
+
+	Hashes []struct {
+		Value     string `json:"value"`
+		Algorithm int    `json:"algorithm"`
+	} `json:"hashes"`
+}
+
+func (i modFileInfo) getBestHash() (hash string, hashFormat string) {
+	// TODO: check if the hash is invalid (e.g. 0)
+	hash = strconv.Itoa(i.Fingerprint)
+	hashFormat = "murmur2"
+	hashPreferred := 0
+
+	// Prefer SHA1, then MD5 if found:
+	if i.Hashes != nil {
+		for _, v := range i.Hashes {
+			if v.Algorithm == hashAlgoMD5 && hashPreferred < 1 {
+				hashPreferred = 1
+
+				hash = v.Value
+				hashFormat = "md5"
+			} else if v.Algorithm == hashAlgoSHA1 && hashPreferred < 2 {
+				hashPreferred = 2
+
+				hash = v.Value
+				hashFormat = "sha1"
+			}
+		}
+	}
+
+	return
 }
 
 func getFileInfo(modID int, fileID int) (modFileInfo, error) {