/*
 * Copyright (c) FIRST and other WPILib contributors.
 * Open Source Software; you can modify and/or share it under the terms of
 * the WPILib BSD license below:
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * Neither the name of FIRST, WPILib, nor the names of other WPILib
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 */

package org.photonvision.jni;

import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;

/** Loads dynamic libraries for all platforms. */
public final class CombinedRuntimeLoader {
    private CombinedRuntimeLoader() {}

    private static String extractionDirectory;

    /**
     * Returns library extraction directory.
     *
     * @return Library extraction directory.
     */
    public static synchronized String getExtractionDirectory() {
        return extractionDirectory;
    }

    private static synchronized void setExtractionDirectory(String directory) {
        extractionDirectory = directory;
    }

    private static String defaultExtractionRoot;

    /**
     * Gets the default extraction root location (~/.wpilib/nativecache) for use if
     * setExtractionDirectory is not set.
     *
     * @return The default extraction root location.
     */
    public static synchronized String getDefaultExtractionRoot() {
        if (defaultExtractionRoot != null) {
            return defaultExtractionRoot;
        }
        String home = System.getProperty("user.home");
        defaultExtractionRoot = Paths.get(home, ".wpilib", "nativecache").toString();
        return defaultExtractionRoot;
    }

    /**
     * Returns platform path.
     *
     * @return The current platform path.
     * @throws IllegalStateException Thrown if the operating system is unknown.
     */
    public static String getPlatformPath() {
        String filePath;
        String arch = System.getProperty("os.arch");

        boolean intel32 = "x86".equals(arch) || "i386".equals(arch);
        boolean intel64 = "amd64".equals(arch) || "x86_64".equals(arch);

        if (System.getProperty("os.name").startsWith("Windows")) {
            if (intel32) {
                filePath = "/windows/x86/";
            } else {
                filePath = "/windows/x86-64/";
            }
        } else if (System.getProperty("os.name").startsWith("Mac")) {
            filePath = "/osx/universal/";
        } else if (System.getProperty("os.name").startsWith("Linux")) {
            if (intel32) {
                filePath = "/linux/x86/";
            } else if (intel64) {
                filePath = "/linux/x86-64/";
            } else if (new File("/usr/local/frc/bin/frcRunRobot.sh").exists()) {
                filePath = "/linux/athena/";
            } else if ("arm".equals(arch) || "arm32".equals(arch)) {
                filePath = "/linux/arm32/";
            } else if ("aarch64".equals(arch) || "arm64".equals(arch)) {
                filePath = "/linux/arm64/";
            } else {
                filePath = "/linux/nativearm/";
            }
        } else {
            throw new IllegalStateException();
        }

        return filePath;
    }

    private static String getLoadErrorMessage(String libraryName, UnsatisfiedLinkError ule) {
        StringBuilder msg = new StringBuilder(512);
        msg.append(libraryName)
                .append(" could not be loaded from path\n" + "\tattempted to load for platform ")
                .append(getPlatformPath())
                .append("\nLast Load Error: \n")
                .append(ule.getMessage())
                .append('\n');
        if (System.getProperty("os.name").startsWith("Windows")) {
            msg.append(
                    "A common cause of this error is missing the C++ runtime.\n"
                            + "Download the latest at https://support.microsoft.com/en-us/help/2977003/the-latest-supported-visual-c-downloads\n");
        }
        return msg.toString();
    }

    /**
     * Extract a list of native libraries.
     *
     * @param <T> The class where the resources would be located
     * @param clazz The actual class object
     * @param resourceName The resource name on the classpath to use for file lookup
     * @return List of all libraries that were extracted
     * @throws IOException Thrown if resource not found or file could not be extracted
     */
    @SuppressWarnings("unchecked")
    public static <T> List<String> extractLibraries(Class<T> clazz, String resourceName)
            throws IOException {
        TypeReference<HashMap<String, Object>> typeRef = new TypeReference<>() {};
        ObjectMapper mapper = new ObjectMapper();
        Map<String, Object> map;
        try (var stream = clazz.getResourceAsStream(resourceName)) {
            map = mapper.readValue(stream, typeRef);
        }

        var platformPath = Paths.get(getPlatformPath());
        var platform = platformPath.getName(0).toString();
        var arch = platformPath.getName(1).toString();

        var platformMap = (Map<String, List<String>>) map.get(platform);

        var fileList = platformMap.get(arch);

        var extractionPathString = getExtractionDirectory();

        if (extractionPathString == null) {
            String hash = (String) map.get("hash");

            var defaultExtractionRoot = getDefaultExtractionRoot();
            var extractionPath = Paths.get(defaultExtractionRoot, platform, arch, hash);
            extractionPathString = extractionPath.toString();

            setExtractionDirectory(extractionPathString);
        }

        List<String> extractedFiles = new ArrayList<>();

        byte[] buffer = new byte[0x10000]; // 64K copy buffer

        for (var file : fileList) {
            try (var stream = clazz.getResourceAsStream(file)) {
                Objects.requireNonNull(stream);

                var outputFile = Paths.get(extractionPathString, new File(file).getName());
                extractedFiles.add(outputFile.toString());
                if (outputFile.toFile().exists()) {
                    continue;
                }
                var parent = outputFile.getParent();
                if (parent == null) {
                    throw new IOException("Output file has no parent");
                }
                parent.toFile().mkdirs();

                try (var os = Files.newOutputStream(outputFile)) {
                    int readBytes;
                    while ((readBytes = stream.read(buffer)) != -1) { // NOPMD
                        os.write(buffer, 0, readBytes);
                    }
                }
            }
        }

        return extractedFiles;
    }

    /**
     * Load a single library from a list of extracted files.
     *
     * @param libraryName The library name to load
     * @param extractedFiles The extracted files to search
     * @throws IOException If library was not found
     */
    public static void loadLibrary(String libraryName, List<String> extractedFiles)
            throws IOException {
        String currentPath = null;
        try {
            for (var extractedFile : extractedFiles) {
                if (extractedFile.contains(libraryName)) {
                    // Load it
                    currentPath = extractedFile;
                    System.load(extractedFile);
                    return;
                }
            }
            throw new IOException("Could not find library " + libraryName);
        } catch (UnsatisfiedLinkError ule) {
            throw new IOException(getLoadErrorMessage(currentPath, ule));
        }
    }

    /**
     * Load a list of native libraries out of a single directory.
     *
     * @param <T> The class where the resources would be located
     * @param clazz The actual class object
     * @param librariesToLoad List of libraries to load
     * @throws IOException Throws an IOException if not found
     */
    public static <T> void loadLibraries(Class<T> clazz, String... librariesToLoad)
            throws IOException {
        // Extract everything

        var extractedFiles = extractLibraries(clazz, "/ResourceInformation.json");

        for (var library : librariesToLoad) {
            loadLibrary(library, extractedFiles);
        }
    }
}