/*
 * Copyright 2014 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package io.netty.util.internal;

import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.util.Locale;

/**
 * Helper class to load JNI resources.
 *
 */
public final class NativeLibraryLoader {

    private static final InternalLogger logger = InternalLoggerFactory.getInstance(NativeLibraryLoader.class);

    private static final String NATIVE_RESOURCE_HOME = "META-INF/native/";
    private static final String OSNAME;
    private static final File WORKDIR;

    static {
        OSNAME = SystemPropertyUtil.get("os.name", "").toLowerCase(Locale.US).replaceAll("[^a-z0-9]+", "");

        String workdir = SystemPropertyUtil.get("io.netty.native.workdir");
        if (workdir != null) {
            File f = new File(workdir);
            f.mkdirs();

            try {
                f = f.getAbsoluteFile();
            } catch (Exception ignored) {
                // Good to have an absolute path, but it's OK.
            }

            WORKDIR = f;
            logger.debug("-Dio.netty.netty.workdir: " + WORKDIR);
        } else {
            WORKDIR = tmpdir();
            logger.debug("-Dio.netty.netty.workdir: " + WORKDIR + " (io.netty.tmpdir)");
        }
    }

    private static File tmpdir() {
        File f;
        try {
            f = toDirectory(SystemPropertyUtil.get("io.netty.tmpdir"));
            if (f != null) {
                logger.debug("-Dio.netty.tmpdir: " + f);
                return f;
            }

            f = toDirectory(SystemPropertyUtil.get("java.io.tmpdir"));
            if (f != null) {
                logger.debug("-Dio.netty.tmpdir: " + f + " (java.io.tmpdir)");
                return f;
            }

            // This shouldn't happen, but just in case ..
            if (isWindows()) {
                f = toDirectory(System.getenv("TEMP"));
                if (f != null) {
                    logger.debug("-Dio.netty.tmpdir: " + f + " (%TEMP%)");
                    return f;
                }

                String userprofile = System.getenv("USERPROFILE");
                if (userprofile != null) {
                    f = toDirectory(userprofile + "\\AppData\\Local\\Temp");
                    if (f != null) {
                        logger.debug("-Dio.netty.tmpdir: " + f + " (%USERPROFILE%\\AppData\\Local\\Temp)");
                        return f;
                    }

                    f = toDirectory(userprofile + "\\Local Settings\\Temp");
                    if (f != null) {
                        logger.debug("-Dio.netty.tmpdir: " + f + " (%USERPROFILE%\\Local Settings\\Temp)");
                        return f;
                    }
                }
            } else {
                f = toDirectory(System.getenv("TMPDIR"));
                if (f != null) {
                    logger.debug("-Dio.netty.tmpdir: " + f + " ($TMPDIR)");
                    return f;
                }
            }
        } catch (Exception ignored) {
            // Environment variable inaccessible
        }

        // Last resort.
        if (isWindows()) {
            f = new File("C:\\Windows\\Temp");
        } else {
            f = new File("/tmp");
        }

        logger.warn("Failed to get the temporary directory; falling back to: " + f);
        return f;
    }

    @SuppressWarnings("ResultOfMethodCallIgnored")
    private static File toDirectory(String path) {
        if (path == null) {
            return null;
        }

        File f = new File(path);
        f.mkdirs();

        if (!f.isDirectory()) {
            return null;
        }

        try {
            return f.getAbsoluteFile();
        } catch (Exception ignored) {
            return f;
        }
    }

    private static boolean isWindows() {
        return OSNAME.startsWith("windows");
    }

    private static boolean isOSX() {
        return OSNAME.startsWith("macosx") || OSNAME.startsWith("osx");
    }

    /**
     * Load the given library with the specified {@link java.lang.ClassLoader}
     */
    public static void load(String name, ClassLoader loader) {
        String libname = System.mapLibraryName(name);
        String path = NATIVE_RESOURCE_HOME + libname;

        URL url = loader.getResource(path);
        if (url == null && isOSX()) {
            if (path.endsWith(".jnilib")) {
                url = loader.getResource(NATIVE_RESOURCE_HOME + "lib" + name + ".dynlib");
            } else {
                url = loader.getResource(NATIVE_RESOURCE_HOME + "lib" + name + ".jnilib");
            }
        }

        if (url == null) {
            // Fall back to normal loading of JNI stuff
            System.loadLibrary(name);
            return;
        }

        int index = libname.lastIndexOf('.');
        String prefix = libname.substring(0, index);
        String suffix = libname.substring(index, libname.length());
        InputStream in = null;
        OutputStream out = null;
        File tmpFile = null;
        boolean loaded = false;
        try {
            tmpFile = File.createTempFile(prefix, suffix, WORKDIR);
            in = url.openStream();
            out = new FileOutputStream(tmpFile);

            byte[] buffer = new byte[8192];
            int length;
            while ((length = in.read(buffer)) > 0) {
                out.write(buffer, 0, length);
            }
            out.flush();
            out.close();
            out = null;

            System.load(tmpFile.getPath());
            loaded = true;
        } catch (Exception e) {
            throw (UnsatisfiedLinkError) new UnsatisfiedLinkError(
                    "could not load a native library: " + name).initCause(e);
        } finally {
            if (in != null) {
                try {
                    in.close();
                } catch (IOException ignore) {
                    // ignore
                }
            }
            if (out != null) {
                try {
                    out.close();
                } catch (IOException ignore) {
                    // ignore
                }
            }
            if (tmpFile != null) {
                if (loaded) {
                    tmpFile.deleteOnExit();
                } else {
                    if (!tmpFile.delete()) {
                        tmpFile.deleteOnExit();
                    }
                }
            }
        }
    }

    private NativeLibraryLoader() {
        // Utility
    }
}
