namespace ZA.CoreService.ESBCertificateManager.Services;

/// <summary>
/// Findet eine nutzbare Java-8-Runtime für Sonic MfApi.
/// </summary>
public static class JavaRuntimeLocator
{
    public static string? Resolve(
        string? configuredPath = null)
    {
        foreach (string? candidate in EnumerateCandidates(configuredPath))
        {
            if (string.IsNullOrWhiteSpace(candidate))
            {
                continue;
            }

            string? resolved = TryResolveExisting(candidate);

            if (resolved is not null)
            {
                return resolved;
            }
        }

        return null;
    }

    private static IEnumerable<string?> EnumerateCandidates(
        string? configuredPath)
    {
        if (!string.IsNullOrWhiteSpace(configuredPath))
        {
            yield return configuredPath.Trim();
        }

        yield return
            @"C:\Program Files (x86)\Java\jre1.8.0_481\bin\java.exe";

        yield return
            @"C:\Program Files (x86)\Java\jre1.8.0_501\bin\java.exe";

        yield return
            @"C:\Program Files\Java\jre1.8.0_481\bin\java.exe";

        yield return
            @"C:\Program Files (x86)\Common Files\Oracle\Java\java8path\java.exe";

        foreach (string root in new[]
                 {
                     @"C:\Program Files (x86)\Java",
                     @"C:\Program Files\Java"
                 })
        {
            if (!Directory.Exists(root))
            {
                continue;
            }

            foreach (string directory in Directory
                         .EnumerateDirectories(root, "jre1.8*")
                         .OrderByDescending(path => path, StringComparer.OrdinalIgnoreCase))
            {
                yield return Path.Combine(directory, "bin", "java.exe");
            }

            foreach (string directory in Directory
                         .EnumerateDirectories(root, "jdk1.8*")
                         .OrderByDescending(path => path, StringComparer.OrdinalIgnoreCase))
            {
                yield return Path.Combine(directory, "bin", "java.exe");
            }
        }

        string? javaHome =
            Environment.GetEnvironmentVariable("JAVA_HOME");

        if (!string.IsNullOrWhiteSpace(javaHome))
        {
            yield return Path.Combine(
                javaHome.Trim(),
                "bin",
                "java.exe");
        }

        string? jreHome =
            Environment.GetEnvironmentVariable("JRE_HOME");

        if (!string.IsNullOrWhiteSpace(jreHome))
        {
            yield return Path.Combine(
                jreHome.Trim(),
                "bin",
                "java.exe");
        }

        yield return "java.exe";
    }

    private static string? TryResolveExisting(string candidate)
    {
        try
        {
            string resolved =
                Path.IsPathRooted(candidate)
                    ? Path.GetFullPath(candidate)
                    : Path.GetFullPath(
                        Path.Combine(
                            AppContext.BaseDirectory,
                            candidate));

            return File.Exists(resolved)
                ? resolved
                : null;
        }
        catch
        {
            return null;
        }
    }
}