export async function resolveRequirements()

in src/java-runtime/utils/upstreamApi.ts [15:108]
73 lines of code
17 McCabe index (conditional complexity)

export async function resolveRequirements(): Promise<{
    tooling_jre: string | undefined;  // Used to launch Java extension.
    tooling_jre_version: number;
    java_home: string | undefined; // Used as default project JDK.
    java_version: number;
}> {
    const javaExtPath: string | undefined = vscode.extensions.getExtension("redhat.java")?.extensionPath
    let toolingJre: string | undefined = await findEmbeddedJRE(javaExtPath);
    let toolingJreVersion: number = await getMajorVersion(toolingJre);
    return new Promise(async (resolve, reject) => {
        let source: string;
        const javaPreferences = checkJavaPreferences();
        let preferenceName = javaPreferences.preference;
        let javaVersion: number = 0;
        let javaHome = javaPreferences.javaHome;
        if (javaHome) { // java.jdt.ls.java.home or java.home setting has highest priority.
            source = `java.home variable defined in ${env.appName} settings`;
            javaHome = expandHomeDir(javaHome);
            if (!await fse.pathExists(javaHome!)) {
                invalidJavaHome(reject, `The ${source} points to a missing or inaccessible folder (${javaHome})`);
            } else if (!await fse.pathExists(path.resolve(javaHome!, 'bin', JAVAC_FILENAME))) {
                let msg: string;
                if (await fse.pathExists(path.resolve(javaHome!, JAVAC_FILENAME))) {
                    msg = `'bin' should be removed from the ${source} (${javaHome})`;
                } else {
                    msg = `The ${source} (${javaHome}) does not point to a JDK.`;
                }
                invalidJavaHome(reject, msg);
            }
            javaVersion = await getMajorVersion(javaHome);
            if (preferenceName === "java.jdt.ls.java.home" || !toolingJre) {
                toolingJre = javaHome;
                toolingJreVersion = javaVersion;
            }
        }

        // java.home not specified, search valid JDKs from env.JAVA_HOME, env.PATH, SDKMAN, jEnv, jabba, Common directories
        const javaRuntimes = await findRuntimes({checkJavac: true, withVersion: true, withTags: true});
        if (!toolingJre) { // universal version
            // as latest version as possible.
            sortJdksByVersion(javaRuntimes);
            const validJdks = javaRuntimes.filter(r => r.version && r.version.major >= REQUIRED_JDK_VERSION);
            if (validJdks.length > 0) {
                sortJdksBySource(validJdks);
                javaHome = validJdks[0].homedir;
                javaVersion = validJdks[0].version?.major ?? 0;
                toolingJre = javaHome;
                toolingJreVersion = javaVersion;
            }
        } else { // pick a default project JDK/JRE
            /**
             * For legacy users, we implicitly following the order below to
             * set a default project JDK during initialization:
             * java.home > env.JDK_HOME > env.JAVA_HOME > env.PATH
             *
             * We'll keep it for compatibility.
             */
            if (javaHome && (await getRuntime(javaHome) !== undefined)) {
                const runtime = await getRuntime(javaHome, {withVersion: true});
                if (runtime) {
                    javaHome = runtime.homedir;
                    javaVersion = runtime.version?.major ?? 0;
                }
            } else if (javaRuntimes.length) {
                sortJdksBySource(javaRuntimes);
                javaHome = javaRuntimes[0].homedir;
                javaVersion = javaRuntimes[0].version?.major ?? 0;
            } else if (javaHome = (await findDefaultRuntimeFromSettings() ?? "")) {
                javaVersion = await getMajorVersion(javaHome);
            } else {
                /**
                 * Originally it was:
                 * invalidJavaHome(reject, "Please download and install a JDK to compile your project. You can configure your projects with different JDKs by the setting ['java.configuration.runtimes'](https://github.com/redhat-developer/vscode-java/wiki/JDK-Requirements#java.configuration.runtimes)");
                 * 
                 * here we focus on tooling jre, so we swallow the error.
                 * 
                 */
            }
        }
        

        if (!toolingJre || toolingJreVersion < REQUIRED_JDK_VERSION) {
            // For universal version, we still require users to install a qualified JDK to run Java extension.
            invalidJavaHome(reject, `Java ${REQUIRED_JDK_VERSION} or more recent is required to run the Java extension. Please download and install a recent JDK. You can still compile your projects with older JDKs by configuring ['java.configuration.runtimes'](https://github.com/redhat-developer/vscode-java/wiki/JDK-Requirements#java.configuration.runtimes)`);
        }

        resolve({
            tooling_jre: toolingJre,  // Used to launch Java extension.
            tooling_jre_version: toolingJreVersion,
            java_home: javaHome, // Used as default project JDK.
            java_version: javaVersion,
        });
    });
}