Implement pack importing/exporting for downloaded Curseforge packs

Abstract out hash implementations
Implement file saving/downloading

curseforge/packinterop/manifest.go

@@ -0,0 +1,104 @@
+package packinterop
+
+import "strings"
+
+type cursePackMeta struct {
+	Minecraft struct {
+		Version    string         `json:"version"`
+		ModLoaders []modLoaderDef `json:"modLoaders"`
+	} `json:"minecraft"`
+	ManifestType    string `json:"manifestType"`
+	ManifestVersion int    `json:"manifestVersion"`
+	NameInternal    string `json:"name"`
+	Version         string `json:"version"`
+	Author          string `json:"author"`
+	ProjectID       int    `json:"projectID"`
+	Files           []struct {
+		ProjectID int  `json:"projectID"`
+		FileID    int  `json:"fileID"`
+		Required  bool `json:"required"`
+	} `json:"files"`
+	Overrides string `json:"overrides"`
+	importSrc ImportPackSource
+}
+
+type modLoaderDef struct {
+	ID      string `json:"id"`
+	Primary bool   `json:"primary"`
+}
+
+func (c cursePackMeta) Name() string {
+	return c.NameInternal
+}
+
+func (c cursePackMeta) Versions() map[string]string {
+	vers := make(map[string]string)
+	vers["minecraft"] = c.Minecraft.Version
+	for _, v := range c.Minecraft.ModLoaders {
+		// Seperate dash-separated modloader/version pairs
+		parts := strings.SplitN(v.ID, "-", 2)
+		if len(parts) == 2 {
+			vers[parts[0]] = parts[1]
+		}
+	}
+	if val, ok := vers["forge"]; ok {
+		// Remove the minecraft version prefix, if it exists
+		vers["forge"] = strings.TrimPrefix(val, c.Minecraft.Version+"-")
+	}
+	return vers
+}
+
+func (c cursePackMeta) Mods() []struct {
+	ModID  int
+	FileID int
+} {
+	list := make([]struct {
+		ModID  int
+		FileID int
+	}, len(c.Files))
+	for i, v := range c.Files {
+		list[i] = struct {
+			ModID  int
+			FileID int
+		}{
+			ModID:  v.ProjectID,
+			FileID: v.FileID,
+		}
+	}
+	return list
+}
+
+type cursePackOverrideWrapper struct {
+	name string
+	ImportPackFile
+}
+
+func (w cursePackOverrideWrapper) Name() string {
+	return w.name
+}
+
+func (c cursePackMeta) GetFiles() ([]ImportPackFile, error) {
+	// Only import files from overrides directory
+	if len(c.Overrides) > 0 {
+		fullList, err := c.importSrc.GetFileList()
+		if err != nil {
+			return nil, err
+		}
+		overridesList := make([]ImportPackFile, 0, len(fullList))
+		overridesPath := c.Overrides
+		if !strings.HasSuffix(overridesPath, "/") {
+			overridesPath = c.Overrides + "/"
+		}
+		// Wrap files, removing overrides/ from the start
+		for _, v := range fullList {
+			if strings.HasPrefix(v.Name(), overridesPath) {
+				overridesList = append(overridesList, cursePackOverrideWrapper{
+					name:           strings.TrimPrefix(v.Name(), overridesPath),
+					ImportPackFile: v,
+				})
+			}
+		}
+		return overridesList, nil
+	}
+	return []ImportPackFile{}, nil
+}