package chuankou;

import java.io.File;
import java.net.URISyntaxException;
import java.nio.file.Path;
import java.nio.file.Paths;

/**
 * Ensures the correct jSerialComm native library is available on Windows/x86_64 systems.
 */
public final class SerialPortNativeLoader {
    private static final String LIB_PROPERTY = "com.fazecast.jSerialComm.library.path";
    private static final String EXPECTED_DLL = "jSerialComm.dll";

    private SerialPortNativeLoader() {
        // utility class
    }

    public static void ensureLibraryPresent() {
        if (System.getProperty(LIB_PROPERTY) != null) {
            return;
        }

        String osName = System.getProperty("os.name", "").toLowerCase();
        if (!osName.contains("win")) {
            return;
        }

        String arch = System.getProperty("os.arch", "").toLowerCase();
        if (!arch.contains("64")) {
            return;
        }

        Path candidateDir = Paths.get("lib", "native", "windows", "x86_64").toAbsolutePath();
        File dllFile = candidateDir.resolve(EXPECTED_DLL).toFile();
        if (!dllFile.isFile()) {
            candidateDir = resolveFromCodeSource();
            if (candidateDir != null) {
                dllFile = candidateDir.resolve(EXPECTED_DLL).toFile();
            }
        }

        if (dllFile.isFile()) {
            System.setProperty(LIB_PROPERTY, candidateDir.toString());
        } else {
            System.err.println("Expected jSerialComm native library not found. Checked " + dllFile);
        }
    }

    private static Path resolveFromCodeSource() {
        try {
            java.security.CodeSource codeSource = SerialPortNativeLoader.class.getProtectionDomain().getCodeSource();
            if (codeSource == null) {
                return null;
            }

            Path location = Paths.get(codeSource.getLocation().toURI()).toAbsolutePath();
            Path baseDir = location.getParent();
            if (baseDir == null) {
                return null;
            }

            Path siblingLibDir = baseDir.resolveSibling("lib").resolve("native").resolve("windows").resolve("x86_64");
            if (siblingLibDir.toFile().isDirectory()) {
                return siblingLibDir;
            }

            Path relativeLibDir = baseDir.resolve("lib").resolve("native").resolve("windows").resolve("x86_64");
            if (relativeLibDir.toFile().isDirectory()) {
                return relativeLibDir;
            }
        } catch (URISyntaxException | SecurityException ignored) {
            // ignore
        }
        return null;
    }
}