Implement pack importing/exporting for downloaded Curseforge packs

Abstract out hash implementations
Implement file saving/downloading

curseforge/packinterop/minecraftinstance.go

@@ -0,0 +1,85 @@
+package packinterop
+
+import (
+	"path/filepath"
+	"strings"
+)
+
+type twitchInstalledPackMeta struct {
+	NameInternal string `json:"name"`
+	Path         string `json:"installPath"`
+	// TODO: javaArgsOverride?
+	// TODO: allocatedMemory?
+	MCVersion string `json:"gameVersion"`
+	Modloader struct {
+		Name               string `json:"name"`
+		MavenVersionString string `json:"mavenVersionString"`
+	} `json:"baseModLoader"`
+	ModpackOverrides []string `json:"modpackOverrides"`
+	ModsInternal     []struct {
+		ID   int `json:"addonID"`
+		File struct {
+			// I've given up on using this cached data, just going to re-request it
+			ID int `json:"id"`
+		} `json:"installedFile"`
+	} `json:"installedAddons"`
+	// Used to determine if modpackOverrides should be used or not
+	IsUnlocked bool `json:"isUnlocked"`
+	importSrc  ImportPackSource
+}
+
+func (m twitchInstalledPackMeta) Name() string {
+	return m.NameInternal
+}
+
+func (m twitchInstalledPackMeta) Versions() map[string]string {
+	vers := make(map[string]string)
+	vers["minecraft"] = m.MCVersion
+	if strings.HasPrefix(m.Modloader.Name, "forge") {
+		if len(m.Modloader.MavenVersionString) > 0 {
+			vers["forge"] = strings.TrimPrefix(m.Modloader.MavenVersionString, "net.minecraftforge:forge:")
+		} else {
+			vers["forge"] = strings.TrimPrefix(m.Modloader.Name, "forge-")
+		}
+		// Remove the minecraft version prefix, if it exists
+		vers["forge"] = strings.TrimPrefix(vers["forge"], m.MCVersion+"-")
+	}
+	return vers
+}
+
+func (m twitchInstalledPackMeta) Mods() []struct {
+	ModID  int
+	FileID int
+} {
+	list := make([]struct {
+		ModID  int
+		FileID int
+	}, len(m.ModsInternal))
+	for i, v := range m.ModsInternal {
+		list[i] = struct {
+			ModID  int
+			FileID int
+		}{
+			ModID:  v.ID,
+			FileID: v.File.ID,
+		}
+	}
+	return list
+}
+
+func (m twitchInstalledPackMeta) GetFiles() ([]ImportPackFile, error) {
+	// If the modpack is unlocked, import all the files
+	// Otherwise import just the modpack overrides
+	if m.IsUnlocked {
+		return m.importSrc.GetFileList()
+	}
+	list := make([]ImportPackFile, len(m.ModpackOverrides))
+	var err error
+	for i, v := range m.ModpackOverrides {
+		list[i], err = m.importSrc.GetFile(filepath.ToSlash(v))
+		if err != nil {
+			return nil, err
+		}
+	}
+	return list, nil
+}