package util

import (
	"fmt"
	"strconv"
	"strings"

	"golang.org/x/sys/windows/registry"
)

const legacyJavaRegPath = "SOFTWARE\\JavaSoft\\Java Runtime Environment"
const jdkRegPath = "SOFTWARE\\JavaSoft\\JDK"

func LocateJavaHome(component string, majorVersion int) (string, error) {
	if component == "jre-legacy" {
		jre, err := registry.OpenKey(registry.LOCAL_MACHINE, legacyJavaRegPath, registry.QUERY_VALUE)
		if err != nil {
			return "", err
		}
		curVer, _, err := jre.GetStringValue("CurrentVersion")
		if err != nil {
			return "", nil
		}
		mVer, err := strconv.ParseInt(strings.Split(curVer, ".")[1], 10, 64)
		if err != nil {
			return "", nil
		}
		if mVer < int64(majorVersion) {
			return "", fmt.Errorf("installed JRE version %s is older than allowed 1.%d", curVer, majorVersion)
		}
		jre, err = registry.OpenKey(registry.LOCAL_MACHINE, fmt.Sprintf("%s\\%s", legacyJavaRegPath, curVer), registry.QUERY_VALUE)
		if err != nil {
			return "", err
		}
		javaHome, _, err := jre.GetStringValue("JavaHome")
		if err != nil {
			return "", err
		}
		return javaHome, nil
	} else {
		jdk, err := registry.OpenKey(registry.LOCAL_MACHINE, jdkRegPath, registry.QUERY_VALUE)
		if err != nil {
			return "", err
		}
		curVer, _, err := jdk.GetStringValue("CurrentVersion")
		if err != nil {
			return "", nil
		}
		mVer, err := strconv.ParseInt(strings.Split(curVer, ".")[0], 10, 64)
		if err != nil {
			return "", nil
		}
		if mVer < int64(majorVersion) {
			return "", fmt.Errorf("installed JDK version %d is older than allowed %d", mVer, majorVersion)
		}
		jdk, err = registry.OpenKey(registry.LOCAL_MACHINE, fmt.Sprintf("%s\\%s", jdkRegPath, curVer), registry.QUERY_VALUE)
		if err != nil {
			return "", err
		}
		javaHome, _, err := jdk.GetStringValue("JavaHome")
		if err != nil {
			return "", err
		}
		return javaHome, nil
	}

	return "", nil
}