Added support for installing java versions

fclauncher/Java.go

@@ -0,0 +1,121 @@
+package main
+
+import (
+	"archive/tar"
+	"bytes"
+	"compress/gzip"
+	"context"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strings"
+
+	"github.com/zhyee/zipstream"
+)
+
+type Java struct {
+	ctx context.Context
+}
+
+func (Java)CheckJavaVer(version int) bool{
+	suffix := "lin"
+	if runtime.GOOS == "windows" {
+		suffix = "win"
+	}
+	path, _ := os.UserConfigDir()
+	path = filepath.Join(path, "FCLauncher", "java", fmt.Sprintf("java-%d-%s", version, suffix))
+
+	_, err := os.Stat(path)
+	if err == nil {
+		return true
+	}
+	return false
+
+}
+
+func (j *Java)InstallJavaVer(version int) {
+	suffix := "lin.tar.gz"
+	if runtime.GOOS == "windows" {
+		suffix = "win.zip"
+	}
+	buff := new(bytes.Buffer)
+	HttpDownload("java/"+fmt.Sprintf("java-%d-%s", version, suffix), buff, j.ctx)
+	path, _ := os.UserConfigDir()
+	suffix = "lin"
+	if runtime.GOOS == "windows" {
+		suffix = "win"
+	}
+
+	path = filepath.Join(path, "FCLauncher", "java", fmt.Sprintf("java-%d-%s", version, suffix))
+	os.MkdirAll(path, 0755)
+	if runtime.GOOS == "windows" {
+		zr := zipstream.NewReader(buff)	
+		for {
+			entry, err := zr.GetNextEntry()
+			if err == io.EOF {
+				break
+			}
+			if err != nil {
+				return
+			}
+			target := filepath.Join(path, strings.SplitN(entry.Name, string(os.PathSeparator), 2)[1])
+			if !entry.IsDir() {
+				rc, err := entry.Open()
+				if err != nil {
+					return
+				}
+				f, err := os.OpenFile(target, os.O_CREATE|os.O_RDWR, entry.FileInfo().Mode())
+				if err != nil {
+					return
+				}
+				if _, err := io.Copy(f, rc); err != nil {
+					return
+				}
+				f.Close()
+				rc.Close()
+			} else {
+				if _, err := os.Stat(target); err != nil {
+					if err := os.MkdirAll(target, 0755); err != nil {
+						return
+					}
+				}
+			}
+		}
+	} else {
+		gzip, _ := gzip.NewReader(buff)
+		defer gzip.Close()
+		tr := tar.NewReader(gzip)
+	out:
+		for {
+			header, err := tr.Next()
+			switch {
+			case err == io.EOF:
+				break out
+			case err != nil:
+				return
+			case header == nil:
+				continue
+			}
+			target := filepath.Join(path, strings.SplitN(header.Name, string(os.PathSeparator), 2)[1])
+			switch header.Typeflag {
+			case tar.TypeDir:
+				if _, err := os.Stat(target); err != nil {
+					if err := os.MkdirAll(target, 0755); err != nil {
+						return
+					}
+				}
+			case tar.TypeReg:
+				f, err := os.OpenFile(target, os.O_CREATE|os.O_RDWR, os.FileMode(header.Mode))
+				if err != nil {
+					return
+				}
+				if _, err := io.Copy(f, tr); err != nil {
+					return
+				}
+				f.Close()
+			}
+		}
+	}
+}

fclauncher/app.go

@@ -14,6 +14,7 @@ import (
 type App struct {
 	ctx   context.Context
 	prism Prism
+	java Java
 }
 
 type Modpack struct {
@@ -70,6 +71,17 @@ func (a *App) CheckPrerequisites() {
 		a.prism.Install()
 		a.status("Prism Installed")
 	}
+	a.status("Checking Java 21")
+	a.java = Java{ctx: a.ctx}
+	res = a.java.CheckJavaVer(21)
+	if res {
+		a.status("Java 21 OK")
+	} else {
+		a.status("Java 21 MISSING")
+		a.status("Installing Java 21")
+		a.java.InstallJavaVer(21)
+		a.status("Java 21 Installed")
+	}
 }
 
 func (a *App) status(status string) {

fclauncher/frontend/src/App.svelte

@@ -6,17 +6,20 @@
 	import { onMount } from 'svelte'
 
   let loading: boolean = true
+	let width: int = 10
 	 	
 		onMount(() => {
 			CheckPrerequisites().then(() => loading = true)
 		})
 
+
 </script>
 
 <main>
   <img alt="Wails logo" id="logo" src="{logo}">
 	{#if loading}
 		<Loading />
+		<div style="width: {width}%;background-color: black;">tes</div>
 	{:else}
   	<Client />
 	{/if}

fclauncher/frontend/src/Loading.svelte

@@ -26,4 +26,4 @@
     {#if downloading}
         <p id="download_status">{completed}MB / {total}MB</p>
     {/if}
-</main>
+</main>

fclauncher/main.go

@@ -2,7 +2,7 @@ package main
 
 import (
 	"embed"
-
+	
 	"github.com/wailsapp/wails/v2"
 	"github.com/wailsapp/wails/v2/pkg/options"
 	"github.com/wailsapp/wails/v2/pkg/options/assetserver"