package net.gdface.sdk;

import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.ServiceLoader;

import net.gdface.utils.Judge;
import static net.gdface.utils.SimpleLog.log;
import static net.gdface.sdk.CapacityFieldConstant.C_SDK_VERSION;

/**
 * FaceApi应用上下文SPIåŠ è½½å·¥å…·ç±»
 * @author guyadong
 *
 */
public class ContextLoader {
        private static final Map<GlobalContextField, Object> globalContext = new HashMap<>();
        private final LinkedHashMap<String, FaceApiContext> classMap = new LinkedHashMap<>();
        private final LinkedHashMap<String, FaceApiContext> versionMap= new LinkedHashMap<>();
        /** 所有找到的 FaceApi 上下文实例 */
        public final List<FaceApiContext> CONTEXTS ;
        // å»¶è¿ŸåŠ è½½çš„å•å®žä¾‹
        private static class Singleton{
                static final ContextLoader INSTANCE = new ContextLoader();
        }
        /**
         * 全局上下文字段定义
         */
        public static enum GlobalContextField{
                /** 并发限制 [int]*/CONCURRENCY,
                /** 人脸检测倾向, [boolean] true:多人脸检测,false:用于帧相关单人脸检测 */MULIT_FACE_DETECT_TREND
        }
        /**
         * 上下文字段定义
         */
        public static enum ContextField{
                /** {@link FaceApi}实例 */INSTANCE,
                /** 授权管理器(LicenceManager)实例 */LICENCE_MANAGER;
                @SuppressWarnings("unchecked")
                public <T>T from(FaceApiContext context){
                        return (T) context.getContext().get(this);
                }
        }
        public  static final ContextLoader getInstance(){
                return Singleton.INSTANCE;
        }
        private ContextLoader() {
                // SPI åŠ è½½æ‰€æœ‰ FaceApi 上下文实例
                ServiceLoader<FaceApiContext> providers = ServiceLoader.load(FaceApiContext.class);
                LinkedList<FaceApiContext> list = new LinkedList<>();
                for(Iterator<FaceApiContext> itor = providers.iterator();itor.hasNext();){
                        FaceApiContext context = itor.next();
                        list.add(context);
                        FaceApi instance = ContextLoader.ContextField.INSTANCE.<FaceApi>from(context);
                        if(instance == null){
                                // 跳过接口实例为空的并报错
                                log("ERROR:FaceApi instance of {} is null",context.getClass().getName());
                                continue;
                        }
                        classMap.put(instance.getClass().getName(), context);
                        String sdkVersion = instance.sdkCapacity().get(C_SDK_VERSION);
                        if(!Judge.isEmpty(sdkVersion)){
                                versionMap.put(sdkVersion, context);
                        }
                }
                CONTEXTS =  Collections.unmodifiableList(list);
        }
        /**
         * 返回找到的第一个FaceApi应用上下文实例
         * @return FaceApi应用上下文实例,找不到返回{@code null}
         */
        public FaceApiContext getContext(){
                try {
                        return CONTEXTS.get(0);
                } catch (IndexOutOfBoundsException e) {
                        return null;
                }
        }
        /**
         * 返回找到的第一个FaceApi应用上下文实例
         * @return FaceApi应用上下文实例
         * @throws IllegalStateException 找不到FaceApi应用上下文实例
         */
        public FaceApiContext getContextChecked(){
                try {
                        return CONTEXTS.get(0);
                } catch (IndexOutOfBoundsException e) {
                        throw new IllegalStateException("NOT FOUND any " + FaceApiContext.class.getSimpleName() + " instance");
                }
        }
        /**
         * 返回包含指定FaceApi实例类名的应用上下文
         * @param className FaceApi实例类名(全名)
         * @return FaceApi应用上下文实例,找不到返回{@code null}
         */
        public FaceApiContext getContextByInstnaceClass(String className){
                return classMap.get(className);
        }
        /**
         * 返回包含指定FaceApi实例类名的应用上下文
         * @param className FaceApi实例类名(全名)
         * @return FaceApi应用上下文实例
         * @throws IllegalArgumentException 找不到指定的上下文实例
         */
        public FaceApiContext getContextByInstnaceClassChecked(String className){
                FaceApiContext context = classMap.get(className);
                if(context == null){
                        throw new IllegalArgumentException("INVALID instance class name: " + className);
                }
                return context;
        }
        /**
         * 返回支持指定SDK版本号的应用上下文
         * @param className SDK版本号
         * @return FaceApi应用上下文实例,找不到返回{@code null}
         */
        public FaceApiContext getContextBySdkVersion(String sdkVersion){
                return versionMap.get(sdkVersion);
        }
        /**
         * 返回支持指定SDK版本号的应用上下文
         * @param className SDK版本号
         * @return FaceApi应用上下文实例,找不到返回{@code null}
         * @throws IllegalArgumentException 找不到指定的上下文实例
         */
        public FaceApiContext getContextBySdkVersionChecked(String sdkVersion){
                FaceApiContext context = versionMap.get(sdkVersion);
                if(context == null){
                        throw new IllegalArgumentException("INVALID sdkVersion: " + sdkVersion);
                }
                return context;
        }
        /**
         * 设置全局上下文,用于应用层在SDK初始化前指定初始化参数<br>
         * @param field
         * @param value
         */
        public static void setGlobalContext(GlobalContextField field,Object value){
                if(field != null && value != null){
                        globalContext.put(field, value);
                }
        }
        @SuppressWarnings("unchecked")
        public static <T>T getGlobalcontext(GlobalContextField field) {
                if(field != null ){
                        return (T) globalContext.get(field);
                }
                return null;
        }
}