Started work on downloading minecraft

fclauncher/InstanceManager.go

@@ -11,6 +11,7 @@ import (
 	"runtime"
 	"strconv"
 	"strings"
+	"time"
 )
 
 type Instance struct {
@@ -146,6 +147,17 @@ func (i *InstanceManager)InstallModpack(modpack Modpack, instanceName string){
 
 }
 
+func (i *InstanceManager)InstallVanilla(version string, instanceName string) {
+	metadata, err := GetVersionMetadata(version)
+	if err != nil {
+		fmt.Printf("Unable to obtain metadata: %s\n", err)
+	} else {
+		fmt.Printf("Version Metadata: %+v", metadata)
+	}
+	time.Sleep(time.Second * 1)
+	return
+}
+
 func (i *InstanceManager)GetInstances() []Instance{
 	return i.instances
 }

fclauncher/app.go

@@ -61,6 +61,21 @@ func (a *App) CheckPrerequisites() {
 		a.Java.InstallJavaVer(21)
 		a.Status("Java 21 Installed")
 	}
+
+}
+
+func (App) GetVersions() ([]string, error) {
+	manifest, err := GetVersionManifest()
+	if err != nil {
+		fmt.Printf("Manifest Error: %s\n", err)
+		return []string{}, err
+	}
+	versions := []string{}
+	for _, version := range manifest.Versions {
+		versions = append(versions, version.Id)
+	}
+	return versions, nil
+
 }
 
 func (a *App) Status(status string) {

fclauncher/frontend/src/Instances.svelte

@@ -1,12 +1,13 @@
 <script lang="ts">
   import {GetModpacks, GetModpack} from '../wailsjs/go/main/ModpackManager.js'
-	import {InstallModpack, GetInstances, CheckUpdate} from '../wailsjs/go/main/InstanceManager.js'
+	import {InstallVanilla, GetInstances, CheckUpdate} from '../wailsjs/go/main/InstanceManager.js'
 	import {LaunchInstance} from '../wailsjs/go/main/Prism.js'
+	import {GetVersions} from '../wailsjs/go/main/App.js'
 	import {onMount} from 'svelte'
 	import {loading} from './global.ts'
 	import {slide} from 'svelte/transition'
 
-  let modpacks: Modpack[] = []
+  let modpacks: string[] = []
 	let pack: string
 	let instances: Instance[] = []
 	let instance: Instance
@@ -14,10 +15,10 @@
 	let name: string = "New Modpack"
 
 	function updateLists(){
-		GetModpacks().then((result) => {
+		GetVersions().then((result) => {
 				modpacks = result
-				pack = modpacks[0].Id
-				name = modpacks[0].Name
+				pack = modpacks[0]
+				name = modpacks[0]
 		})
 		GetInstances().then((result) => {
 			instances = result
@@ -41,19 +42,15 @@
 
 	function install(){
 		$loading = true
-		GetModpack(pack).then((result) => {
-			InstallModpack(result, name).then(() => {
-				updateLists()
-				addingInstance = false
-				$loading = false
-			})
+		InstallVanilla(pack, name).then(() => {
+			addingInstance = false
+			$loading = false
+			updateLists()
 		})
 	}
 
 	function onchange(event){
-		GetModpack(event.target.value).then((result) => {
-			name = result.Name
-		})
+		name = event.target.value
 	}
 
 
@@ -71,7 +68,7 @@
 		<div transition:slide="{{duration:300}}">
 			<select id="pack" on:change={onchange} bind:value={pack} name="pack">Select a Modpack: 
 				{#each modpacks as pack}
-					<option value={pack.Id}>{pack.Name}</option>
+					<option value={pack}>{pack}</option>
 				{/each}
 			</select>
 			<br/>

fclauncher/frontend/wailsjs/go/main/App.d.ts

@@ -3,4 +3,6 @@
 
 export function CheckPrerequisites():Promise<void>;
 
+export function GetVersions():Promise<Array<string>>;
+
 export function Status(arg1:string):Promise<void>;

fclauncher/frontend/wailsjs/go/main/App.js

@@ -6,6 +6,10 @@ export function CheckPrerequisites() {
   return window['go']['main']['App']['CheckPrerequisites']();
 }
 
+export function GetVersions() {
+  return window['go']['main']['App']['GetVersions']();
+}
+
 export function Status(arg1) {
   return window['go']['main']['App']['Status'](arg1);
 }

fclauncher/frontend/wailsjs/go/main/InstanceManager.d.ts

@@ -8,4 +8,6 @@ export function GetInstances():Promise<Array<main.Instance>>;
 
 export function InstallModpack(arg1:main.Modpack,arg2:string):Promise<void>;
 
+export function InstallVanilla(arg1:string,arg2:string):Promise<void>;
+
 export function SearchInstances():Promise<void>;

fclauncher/frontend/wailsjs/go/main/InstanceManager.js

@@ -14,6 +14,10 @@ export function InstallModpack(arg1, arg2) {
   return window['go']['main']['InstanceManager']['InstallModpack'](arg1, arg2);
 }
 
+export function InstallVanilla(arg1, arg2) {
+  return window['go']['main']['InstanceManager']['InstallVanilla'](arg1, arg2);
+}
+
 export function SearchInstances() {
   return window['go']['main']['InstanceManager']['SearchInstances']();
 }

fclauncher/minecraft.go

@@ -0,0 +1,216 @@
+package main
+
+import (
+	"crypto/sha1"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"path/filepath"
+	"time"
+)
+
+type McVersionManifestEntry struct {
+	Id string
+	Type string
+	Url string
+	Time time.Time
+	ReleaseTime time.Time
+	Sha1 string
+	ComplianceLevel int
+}
+
+type McLatestEntry struct {
+	Release string
+	Snapshot string
+}
+
+type McVersionManifest struct {
+	Latest McLatestEntry
+	Versions []McVersionManifestEntry
+}
+
+type McArguments struct {
+	Game []string
+	Jvm []string
+}
+
+type McAssetIndex struct {
+	Id string
+	Sha1 string
+	Size int
+	TotalSize int
+	Url string
+}
+
+type McJavaVersion struct {
+	Component string
+	MajorVersion int
+}
+
+type McLibraryArtifact struct {
+	Path string
+	Sha1 string
+	Size int
+	Url string
+}
+
+type McLibraryDownload struct {
+	Artifact McLibraryArtifact
+}
+
+type McRuleOs struct {
+	Name string
+	Version string
+	ARch string
+}
+
+type McRule struct {
+	Action string
+	Features map[string]bool
+	Os McRuleOs
+}
+
+type McLibrary struct {
+	Downloads McLibraryDownload
+	Name string
+	Rules []McRule
+}
+
+type McDownload struct {
+	Sha1 string
+	Size int
+	Url string
+}
+
+type McMetadata struct {
+	Arguments McArguments
+	AssetIndex McAssetIndex
+	Assets string
+	ComplianceLevel int
+	Downloads map[string]McDownload
+	Id string
+	JavaVersion	McJavaVersion
+	Libraries []McLibrary
+	Logging interface{}
+	MainClass string
+	MinimumLauncherVersion int
+	ReleaseTime time.Time
+	Time time.Time
+	Type string
+}
+
+func GetVersionManifest() (McVersionManifest, error) {
+	resp, err := http.Get("https://piston-meta.mojang.com/mc/game/version_manifest_v2.json")
+	var returnError error = nil
+	if err == nil {
+		defer resp.Body.Close()
+		data, err := io.ReadAll(resp.Body)
+		if err == nil {
+			versionManifest := McVersionManifest{}	
+			err = json.Unmarshal(data, &versionManifest)
+			if err == nil {
+				dir, err := os.UserConfigDir()
+				if err != nil {
+					return versionManifest, nil
+				}
+				err = os.MkdirAll(filepath.Join(dir, "FCLauncher", "cache"), 0755)
+				f, err := os.OpenFile(filepath.Join(dir, "FCLauncher", "cache", "versionManifest.json"), os.O_CREATE|os.O_RDWR, 0755)
+				defer f.Close()
+				f.Write(data)
+				return versionManifest, nil
+			} else {
+				returnError = fmt.Errorf("Unable to parse Json: %e\n", err)
+			}
+		} else {
+			returnError = fmt.Errorf("Unable to read version manifest: %e\n", err)
+		}
+	} else {
+		returnError = fmt.Errorf("Unable to download version manifest: %e\n", err)
+	}
+
+	dir, err := os.UserConfigDir()
+	if err != nil {
+		return McVersionManifest{}, returnError
+	}
+	path := filepath.Join(dir, "FCLauncher", "cache", "versionManifest.json")
+	if _, err = os.Stat(path); err != nil {
+		return McVersionManifest{}, returnError
+	}
+	f, err := os.OpenFile(path, os.O_RDONLY, 0755)
+	if err != nil {
+		return McVersionManifest{}, returnError
+	}
+	data, _ := io.ReadAll(f)
+	if err != nil {
+		return McVersionManifest{}, returnError
+	}
+	versionManifest := McVersionManifest{}
+	err = json.Unmarshal(data, &versionManifest)
+	if err != nil {
+		return McVersionManifest{}, returnError
+	}
+	return versionManifest, nil
+
+}
+
+func GetVersionMetadata(wantedVersion string) (McMetadata, error) {
+	manifest, err := GetVersionManifest()
+	if err != nil {
+		return McMetadata{}, fmt.Errorf("GetVersionMetadata: %e\n", err)
+	}
+
+	for _, version := range manifest.Versions {
+		if wantedVersion == version.Id {
+			//found it
+			dir, err := os.UserConfigDir()
+			if err == nil {
+				path := filepath.Join(dir, "FCLauncher", "cache", "versionMetadata", wantedVersion+".json")
+				if _, err := os.Stat(path); err == nil {
+					if f, err := os.OpenFile(path, os.O_RDONLY, 0755); err == nil {
+						defer f.Close()
+						if data, err := io.ReadAll(f); err == nil {
+							sha := sha1.Sum(data)
+							if hex.EncodeToString(sha[:20]) == version.Sha1{
+								metadata := McMetadata{}
+								json.Unmarshal(data, &metadata)
+								fmt.Printf("Found cache!\n")
+								return metadata, nil
+							}
+						}
+					}
+				}
+			}
+			resp, err := http.Get(version.Url)
+			if err != nil {
+				return McMetadata{}, fmt.Errorf("Unable to download metadata: %e\n", err)
+			}
+			defer resp.Body.Close()
+			data, err := io.ReadAll(resp.Body)
+			if err != nil {
+				return McMetadata{}, fmt.Errorf("Unable to download metadata: %e\n", err)
+			}
+			sha := sha1.Sum(data)
+			if hex.EncodeToString(sha[:20]) != version.Sha1 {
+				return McMetadata{}, fmt.Errorf("GetMetadata: Sha1 hash does not match\n")
+			}
+			metadata := McMetadata{}
+			err = json.Unmarshal(data, &metadata)
+			dir, err = os.UserConfigDir()
+			if err == nil {
+				path := filepath.Join(dir, "FCLauncher", "cache", "versionMetadata")
+				if os.MkdirAll(path, 0755) == nil {
+					if f, err := os.OpenFile(filepath.Join(path, wantedVersion+".json"), os.O_CREATE|os.O_RDWR, 0755); err == nil {
+						defer f.Close()
+						f.Write(data)
+					}
+				}
+			}
+			return metadata, nil
+			
+		}
+	}
+	return McMetadata{}, fmt.Errorf("Unable to find version %s\n", wantedVersion)
+}