package moe.nea.modernjava.launch.relaunch;

import moe.nea.modernjava.launch.util.PropertyNames;
import moe.nea.modernjava.launch.util.TextIoUtils;
import org.apache.commons.io.IOUtils;
import org.apache.commons.lang3.SystemUtils;

import java.io.File;
import java.util.ArrayList;
import java.util.List;

public class JavaScanner {

    public static final String JAVA_BINARY_PATH = "bin/java" + (SystemUtils.IS_OS_WINDOWS ? ".exe" : "");
    public static final String JAVA_COMPILER_PATH = "bin/javac" + (SystemUtils.IS_OS_WINDOWS ? ".exe" : "");

    public boolean isJavaHome(File potential) {
        if (new File(potential, JAVA_BINARY_PATH).exists()) {
            return true;
        }
        return false;
    }

    private List<LocalJavaVersion> versionList = new ArrayList<>();

    public void scanDirectory(File file) {
        scanDirectory(file, 1);
    }

    public void scanDirectory(File file, int depthLimit) {
        if (depthLimit < 0) return;
        if (isJavaHome(file)) {
            versionList.add(new LocalJavaVersion(file));
        } else {
            for (File listFile : file.listFiles()) {
                if (listFile.isDirectory()) {
                    scanDirectory(listFile, depthLimit - 1);
                }
            }
        }
    }

    public void prettyPrint() {
        String s = "Fun fact these are the found Java Runtime Environments:\n";
        for (LocalJavaVersion localJavaVersion : versionList) {
            s += localJavaVersion.prettyPrint();
        }
        System.out.println(s);
    }

    public void scanDefaultPaths() {
        File home = new File(System.getProperty("user.home"));
        scanDirectory(new File(home, ".sdkman/candidates/java"));
        scanDirectory(new File(home, ".jdks"));
        scanDirectory(new File("/usr"), 0);
        String[] paths = System.getProperty(PropertyNames.JAVA_SCAN_PATH, "").split(File.pathSeparator);
        for (String path : paths) {
            if (!path.isEmpty()) {
                scanDirectory(new File(path).getParentFile(), 3);
            }
        }
    }

    public LocalJavaVersion findCandidate() {
        LocalJavaVersion bestFit = null;
        for (LocalJavaVersion localJavaVersion : versionList) {
            if (localJavaVersion.isJdk() && localJavaVersion.getMajorVersion() == 16) {
                bestFit = localJavaVersion;
            }
        }
        return bestFit;
    }

    public static class LocalJavaVersion {
        private final File javaHome;
        private String versionString;

        public LocalJavaVersion(File javaHome) {
            this.javaHome = javaHome;
        }

        public File getJavaHome() {
            return javaHome;
        }

        public File getJavaBinary() {
            return new File(javaHome, JAVA_BINARY_PATH);
        }

        public boolean isJdk() {
            return new File(javaHome, JAVA_COMPILER_PATH).exists();
        }

        public String getVersionString() {
            if (versionString == null) {
                ProcessBuilder processBuilder = new ProcessBuilder();
                processBuilder.command(getJavaBinary().getAbsolutePath(), "-version");
                processBuilder.redirectInput(ProcessBuilder.Redirect.PIPE);
                processBuilder.redirectOutput(ProcessBuilder.Redirect.PIPE);
                processBuilder.redirectError(ProcessBuilder.Redirect.PIPE);
                try {
                    Process process = processBuilder.start();
                    process.waitFor();
                    versionString = IOUtils.toString(process.getInputStream()) + IOUtils.toString(process.getErrorStream());
                } catch (Exception e) {
                    e.printStackTrace();
                    versionString = "<invalid>";
                }
            }
            return versionString;
        }

        public String prettyPrint() {
            return javaHome.getAbsolutePath() + ":\n"
                    + "\tJava Binary: " + getJavaBinary().getAbsolutePath() + "\n"
                    + "\tMajor Version: " + getMajorVersion() + "\n"
                    + "\tFull Version: " + getVersion() + "\n"
                    + "\tIs Jdk: " + isJdk() + "\n"
                    ;
        }

        public String getVersion() {
            String v = getVersionString();
            String[] s = v.split("\"");
            if (s.length < 2) return null;
            return s[1];
        }

        public int getMajorVersion() {
            try {
                return Integer.parseInt(getVersion().split("\\.")[0]);
            } catch (Exception e) {
                return -1;
            }
        }
    }
}