package org.reflections.util;

import org.reflections.Configuration;
import org.reflections.Reflections;
import org.reflections.ReflectionsException;
import org.reflections.adapters.JavaReflectionAdapter;
import org.reflections.adapters.JavassistAdapter;
import org.reflections.adapters.MetadataAdapter;
import org.reflections.scanners.Scanner;
import org.reflections.scanners.SubTypesScanner;
import org.reflections.scanners.TypeAnnotationsScanner;
import org.reflections.serializers.Serializer;
import org.reflections.serializers.XmlSerializer;

import java.net.URL;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.function.Predicate;
import java.util.stream.Stream;

a fluent builder for Configuration, to be used for constructing a Reflections instance 
usage:
     new Reflections(
         new ConfigurationBuilder()
             .filterInputsBy(new FilterBuilder().include("your project's common package prefix here..."))
             .setUrls(ClasspathHelper.forClassLoader())
             .setScanners(new SubTypesScanner(), new TypeAnnotationsScanner().filterResultsBy(myClassAnnotationsFilter)));


executorService is used optionally used for parallel scanning. if value is null then scanning is done in a simple for loop 
defaults: accept all for inputsFilter, executorService is null, serializer is XmlSerializer /**
 * a fluent builder for {@link org.reflections.Configuration}, to be used for constructing a {@link org.reflections.Reflections} instance
 * <p>usage:
 * <pre>
 *      new Reflections(
 *          new ConfigurationBuilder()
 *              .filterInputsBy(new FilterBuilder().include("your project's common package prefix here..."))
 *              .setUrls(ClasspathHelper.forClassLoader())
 *              .setScanners(new SubTypesScanner(), new TypeAnnotationsScanner().filterResultsBy(myClassAnnotationsFilter)));
 * </pre>
 * <br>{@link #executorService} is used optionally used for parallel scanning. if value is null then scanning is done in a simple for loop
 * <p>defaults: accept all for {@link #inputsFilter},
 * {@link #executorService} is null,
 * {@link #serializer} is {@link org.reflections.serializers.XmlSerializer}
 */
public class ConfigurationBuilder implements Configuration {
    private Set<Scanner> scanners;
    private Set<URL> urls;
    /*lazy*/ protected MetadataAdapter metadataAdapter;
    private Predicate<String> inputsFilter;
    /*lazy*/ private Serializer serializer;
    private ExecutorService executorService;
    private ClassLoader[] classLoaders;
    private boolean expandSuperTypes = true;

    public ConfigurationBuilder() {
        scanners = new HashSet<>(Arrays.asList(new TypeAnnotationsScanner(), new SubTypesScanner()));
        urls = new HashSet<>();
    }

    
constructs a ConfigurationBuilder using the given parameters, in a non statically typed way. that is, each element in params is guessed by it's type and populated into the configuration. 

    
String - add urls using ClasspathHelper.forPackage(String, ClassLoader...) ()}
    
Class - add urls using ClasspathHelper.forClass(Class<?>, ClassLoader...) 
    
ClassLoader - use these classloaders in order to find urls in ClasspathHelper.forPackage(), ClasspathHelper.forClass() and for resolving types
    
Scanner - use given scanner, overriding the default scanners
    
URL - add the given url for scanning
    
Object[] - flatten and use each element as above
 an input FilterBuilder will be set according to given packages. 
use any parameter type in any order. this constructor uses instanceof on each param and instantiate a ConfigurationBuilder appropriately. /** constructs a {@link ConfigurationBuilder} using the given parameters, in a non statically typed way.
     * that is, each element in {@code params} is guessed by it's type and populated into the configuration.
     * <ul>
     *     <li>{@link String} - add urls using {@link ClasspathHelper#forPackage(String, ClassLoader...)} ()}</li>
     *     <li>{@link Class} - add urls using {@link ClasspathHelper#forClass(Class, ClassLoader...)} </li>
     *     <li>{@link ClassLoader} - use these classloaders in order to find urls in ClasspathHelper.forPackage(), ClasspathHelper.forClass() and for resolving types</li>
     *     <li>{@link Scanner} - use given scanner, overriding the default scanners</li>
     *     <li>{@link URL} - add the given url for scanning</li>
     *     <li>{@code Object[]} - flatten and use each element as above</li>
     * </ul>
     *
     * an input {@link FilterBuilder} will be set according to given packages.
     * <p>use any parameter type in any order. this constructor uses instanceof on each param and instantiate a {@link ConfigurationBuilder} appropriately.
     * */
    @SuppressWarnings("unchecked")
    public static ConfigurationBuilder build(final Object... params) {
        ConfigurationBuilder builder = new ConfigurationBuilder();

        //flatten
        List<Object> parameters = new ArrayList<>();
        if (params != null) {
            for (Object param : params) {
                if (param != null) {
                    if (param.getClass().isArray()) { for (Object p : (Object[]) param) if (p != null) parameters.add(p); }
                    else if (param instanceof Iterable) { for (Object p : (Iterable) param) if (p != null) parameters.add(p); }
                    else parameters.add(param);
                }
            }
        }

        List<ClassLoader> loaders = new ArrayList<>();
        for (Object param : parameters) if (param instanceof ClassLoader) loaders.add((ClassLoader) param);

        ClassLoader[] classLoaders = loaders.isEmpty() ? null : loaders.toArray(new ClassLoader[loaders.size()]);
        FilterBuilder filter = new FilterBuilder();
        List<Scanner> scanners = new ArrayList<>();

        for (Object param : parameters) {
            if (param instanceof String) {
                builder.addUrls(ClasspathHelper.forPackage((String) param, classLoaders));
                filter.includePackage((String) param);
            }
            else if (param instanceof Class) {
                if (Scanner.class.isAssignableFrom((Class) param)) {
                    try { builder.addScanners(((Scanner) ((Class) param).newInstance())); } catch (Exception e) { /*fallback*/ }
                }
                builder.addUrls(ClasspathHelper.forClass((Class) param, classLoaders));
                filter.includePackage(((Class) param));
            }
            else if (param instanceof Scanner) { scanners.add((Scanner) param); }
            else if (param instanceof URL) { builder.addUrls((URL) param); }
            else if (param instanceof ClassLoader) { /* already taken care */ }
            else if (param instanceof Predicate) { filter.add((Predicate<String>) param); }
            else if (param instanceof ExecutorService) { builder.setExecutorService((ExecutorService) param); }
            else if (Reflections.log != null) { throw new ReflectionsException("could not use param " + param); }
        }

        if (builder.getUrls().isEmpty()) {
            if (classLoaders != null) {
                builder.addUrls(ClasspathHelper.forClassLoader(classLoaders)); //default urls getResources("")
            } else {
                builder.addUrls(ClasspathHelper.forClassLoader()); //default urls getResources("")
            }
        }

        builder.filterInputsBy(filter);
        if (!scanners.isEmpty()) { builder.setScanners(scanners.toArray(new Scanner[scanners.size()])); }
        if (!loaders.isEmpty()) { builder.addClassLoaders(loaders); }

        return builder;
    }

    public ConfigurationBuilder forPackages(String... packages) {
        for (String pkg : packages) {
            addUrls(ClasspathHelper.forPackage(pkg));
        }
        return this;
    }

    public Set<Scanner> getScanners() {
		return scanners;
	}

    
set the scanners instances for scanning different metadata /** set the scanners instances for scanning different metadata */
    public ConfigurationBuilder setScanners(final Scanner... scanners) {
        this.scanners.clear();
        return addScanners(scanners);
    }

    
set the scanners instances for scanning different metadata /** set the scanners instances for scanning different metadata */
    public ConfigurationBuilder addScanners(final Scanner... scanners) {
        this.scanners.addAll(Arrays.asList(scanners));
        return this;
    }

    public Set<URL> getUrls() {
        return urls;
    }

    
set the urls to be scanned
use ClasspathHelper convenient methods to get the relevant urls /** set the urls to be scanned
     * <p>use {@link org.reflections.util.ClasspathHelper} convenient methods to get the relevant urls
     * */
    public ConfigurationBuilder setUrls(final Collection<URL> urls) {
		this.urls = new HashSet<>(urls);
        return this;
	}

    
set the urls to be scanned
use ClasspathHelper convenient methods to get the relevant urls /** set the urls to be scanned
     * <p>use {@link org.reflections.util.ClasspathHelper} convenient methods to get the relevant urls
     * */
    public ConfigurationBuilder setUrls(final URL... urls) {
        this.urls = new HashSet<>(Arrays.asList(urls));
        return this;
	}

    
add urls to be scanned
use ClasspathHelper convenient methods to get the relevant urls /** add urls to be scanned
     * <p>use {@link org.reflections.util.ClasspathHelper} convenient methods to get the relevant urls
     * */
    public ConfigurationBuilder addUrls(final Collection<URL> urls) {
        this.urls.addAll(urls);
        return this;
    }

    
add urls to be scanned
use ClasspathHelper convenient methods to get the relevant urls /** add urls to be scanned
     * <p>use {@link org.reflections.util.ClasspathHelper} convenient methods to get the relevant urls
     * */
    public ConfigurationBuilder addUrls(final URL... urls) {
        this.urls.addAll(new HashSet<>(Arrays.asList(urls)));
        return this;
    }

    
returns the metadata adapter. if javassist library exists in the classpath, this method returns JavassistAdapter otherwise defaults to JavaReflectionAdapter. 
the JavassistAdapter is preferred in terms of performance and class loading. /** returns the metadata adapter.
     * if javassist library exists in the classpath, this method returns {@link JavassistAdapter} otherwise defaults to {@link JavaReflectionAdapter}.
     * <p>the {@link JavassistAdapter} is preferred in terms of performance and class loading. */
    public MetadataAdapter getMetadataAdapter() {
        if (metadataAdapter != null) return metadataAdapter;
        else {
            try {
                return (metadataAdapter = new JavassistAdapter());
            } catch (Throwable e) {
                if (Reflections.log != null)
                    Reflections.log.warn("could not create JavassistAdapter, using JavaReflectionAdapter", e);
                return (metadataAdapter = new JavaReflectionAdapter());
            }
        }
    }

    
sets the metadata adapter used to fetch metadata from classes /** sets the metadata adapter used to fetch metadata from classes */
    public ConfigurationBuilder setMetadataAdapter(final MetadataAdapter metadataAdapter) {
        this.metadataAdapter = metadataAdapter;
        return this;
    }

    public Predicate<String> getInputsFilter() {
        return inputsFilter;
    }

    
sets the input filter for all resources to be scanned.
 supply a Predicate or use the FilterBuilder/** sets the input filter for all resources to be scanned.
     * <p> supply a {@link Predicate} or use the {@link FilterBuilder}*/
    public void setInputsFilter(Predicate<String> inputsFilter) {
        this.inputsFilter = inputsFilter;
    }

    
sets the input filter for all resources to be scanned.
 supply a Predicate or use the FilterBuilder/** sets the input filter for all resources to be scanned.
     * <p> supply a {@link Predicate} or use the {@link FilterBuilder}*/
    public ConfigurationBuilder filterInputsBy(Predicate<String> inputsFilter) {
        this.inputsFilter = inputsFilter;
        return this;
    }

    public ExecutorService getExecutorService() {
        return executorService;
    }

    
sets the executor service used for scanning. /** sets the executor service used for scanning. */
    public ConfigurationBuilder setExecutorService(ExecutorService executorService) {
        this.executorService = executorService;
        return this;
    }

    
sets the executor service used for scanning to ThreadPoolExecutor with core size as Runtime.availableProcessors() 
default is ThreadPoolExecutor with a single core /** sets the executor service used for scanning to ThreadPoolExecutor with core size as {@link java.lang.Runtime#availableProcessors()}
     * <p>default is ThreadPoolExecutor with a single core */
    public ConfigurationBuilder useParallelExecutor() {
        return useParallelExecutor(Runtime.getRuntime().availableProcessors());
    }

    
sets the executor service used for scanning to ThreadPoolExecutor with core size as the given availableProcessors parameter.
the executor service spawns daemon threads by default.
default is ThreadPoolExecutor with a single core /** sets the executor service used for scanning to ThreadPoolExecutor with core size as the given availableProcessors parameter.
     * the executor service spawns daemon threads by default.
     * <p>default is ThreadPoolExecutor with a single core */
    public ConfigurationBuilder useParallelExecutor(final int availableProcessors) {
        ThreadFactory threadFactory = new ThreadFactory() {
            private final AtomicInteger threadNumber = new AtomicInteger(1);

            public Thread newThread(Runnable r) {
                Thread t = new Thread(r);
                t.setName("org.reflections-scanner-" + threadNumber.getAndIncrement());
                t.setDaemon(true);
                return t;
            }
        };
        setExecutorService(Executors.newFixedThreadPool(availableProcessors, threadFactory));
        return this;
    }

    public Serializer getSerializer() {
        return serializer != null ? serializer : (serializer = new XmlSerializer()); //lazily defaults to XmlSerializer
    }

    
sets the serializer used when issuing Reflections.save /** sets the serializer used when issuing {@link org.reflections.Reflections#save} */
    public ConfigurationBuilder setSerializer(Serializer serializer) {
        this.serializer = serializer;
        return this;
    }

    
get class loader, might be used for scanning or resolving methods/fields /** get class loader, might be used for scanning or resolving methods/fields */
    public ClassLoader[] getClassLoaders() {
        return classLoaders;
    }

    @Override
    public boolean shouldExpandSuperTypes() {
        return expandSuperTypes;
    }

    
if set to true, Reflections will expand super types after scanning.
see Reflections.expandSuperTypes() /**
     * if set to true, Reflections will expand super types after scanning.
     * <p>see {@link org.reflections.Reflections#expandSuperTypes()}
     */
    public ConfigurationBuilder setExpandSuperTypes(boolean expandSuperTypes) {
        this.expandSuperTypes = expandSuperTypes;
        return this;
    }

    
set class loader, might be used for resolving methods/fields /** set class loader, might be used for resolving methods/fields */
    public void setClassLoaders(ClassLoader[] classLoaders) {
        this.classLoaders = classLoaders;
    }

    
add class loader, might be used for resolving methods/fields /** add class loader, might be used for resolving methods/fields */
    public ConfigurationBuilder addClassLoader(ClassLoader classLoader) {
        return addClassLoaders(classLoader);
    }

    
add class loader, might be used for resolving methods/fields /** add class loader, might be used for resolving methods/fields */
    public ConfigurationBuilder addClassLoaders(ClassLoader... classLoaders) {
        this.classLoaders = this.classLoaders == null ? classLoaders :
                Stream.concat(Stream.concat(Arrays.stream(this.classLoaders), Arrays.stream(classLoaders)), Stream.of(ClassLoader.class))
                        .distinct().toArray(ClassLoader[]::new);
        return this;
    }

    
add class loader, might be used for resolving methods/fields /** add class loader, might be used for resolving methods/fields */
    public ConfigurationBuilder addClassLoaders(Collection<ClassLoader> classLoaders) {
        return addClassLoaders(classLoaders.toArray(new ClassLoader[classLoaders.size()]));
    }
}