/**
 * Copyright © 2016 The Thingsboard Authors
 *
 * Licensed 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 org.thingsboard.server.service.component;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.common.base.Charsets;
import com.google.common.io.Resources;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider;
import org.springframework.core.type.filter.AnnotationTypeFilter;
import org.springframework.stereotype.Service;
import org.thingsboard.server.common.data.plugin.ComponentDescriptor;
import org.thingsboard.server.common.data.plugin.ComponentType;
import org.thingsboard.server.dao.component.ComponentDescriptorService;
import org.thingsboard.server.extensions.api.component.*;

import javax.annotation.PostConstruct;
import java.io.IOException;
import java.lang.annotation.Annotation;
import java.util.*;
import java.util.stream.Collectors;

@Service
@Slf4j
public class AnnotationComponentDiscoveryService implements ComponentDiscoveryService {

    @Value("${plugins.scan_packages}")
    private String[] scanPackages;

    @Autowired
    private ComponentDescriptorService componentDescriptorService;

    private Map<String, ComponentDescriptor> components = new HashMap<>();

    private Map<ComponentType, List<ComponentDescriptor>> componentsMap = new HashMap<>();

    private ObjectMapper mapper = new ObjectMapper();

    @PostConstruct
    public void init() {
        registerComponents(ComponentType.FILTER, Filter.class);

        registerComponents(ComponentType.PROCESSOR, Processor.class);

        registerComponents(ComponentType.ACTION, Action.class);

        registerComponents(ComponentType.PLUGIN, Plugin.class);

        log.info("Found following definitions: {}", components.values());
    }

    private void registerComponents(ComponentType type, Class<? extends Annotation> annotation) {
        List<ComponentDescriptor> components = persist(getBeanDefinitions(annotation), type);
        componentsMap.put(type, components);
        registerComponents(components);
    }

    private void registerComponents(Collection<ComponentDescriptor> comps) {
        comps.stream().forEach(c -> components.put(c.getClazz(), c));
    }

    private List<ComponentDescriptor> persist(Set<BeanDefinition> filterDefs, ComponentType type) {
        List<ComponentDescriptor> result = new ArrayList<>();
        for (BeanDefinition def : filterDefs) {
            ComponentDescriptor scannedComponent = new ComponentDescriptor();
            String clazzName = def.getBeanClassName();
            try {
                scannedComponent.setType(type);
                Class<?> clazz = Class.forName(clazzName);
                String descriptorResourceName;
                switch (type) {
                    case FILTER:
                        Filter filterAnnotation = clazz.getAnnotation(Filter.class);
                        scannedComponent.setName(filterAnnotation.name());
                        scannedComponent.setScope(filterAnnotation.scope());
                        descriptorResourceName = filterAnnotation.descriptor();
                        break;
                    case PROCESSOR:
                        Processor processorAnnotation = clazz.getAnnotation(Processor.class);
                        scannedComponent.setName(processorAnnotation.name());
                        scannedComponent.setScope(processorAnnotation.scope());
                        descriptorResourceName = processorAnnotation.descriptor();
                        break;
                    case ACTION:
                        Action actionAnnotation = clazz.getAnnotation(Action.class);
                        scannedComponent.setName(actionAnnotation.name());
                        scannedComponent.setScope(actionAnnotation.scope());
                        descriptorResourceName = actionAnnotation.descriptor();
                        break;
                    case PLUGIN:
                        Plugin pluginAnnotation = clazz.getAnnotation(Plugin.class);
                        scannedComponent.setName(pluginAnnotation.name());
                        scannedComponent.setScope(pluginAnnotation.scope());
                        descriptorResourceName = pluginAnnotation.descriptor();
                        for (Class<?> actionClazz : pluginAnnotation.actions()) {
                            ComponentDescriptor actionComponent = getComponent(actionClazz.getName())
                                    .orElseThrow(() -> {
                                        log.error("Can't initialize plugin {}, due to missing action {}!", def.getBeanClassName(), actionClazz.getName());
                                        return new ClassNotFoundException("Action: " + actionClazz.getName() + "is missing!");
                                    });
                            if (actionComponent.getType() != ComponentType.ACTION) {
                                log.error("Plugin {} action {} has wrong component type!", def.getBeanClassName(), actionClazz.getName(), actionComponent.getType());
                                throw new RuntimeException("Plugin " + def.getBeanClassName() + "action " + actionClazz.getName() + " has wrong component type!");
                            }
                        }
                        scannedComponent.setActions(Arrays.asList(pluginAnnotation.actions()).stream().map(action -> action.getName()).collect(Collectors.joining(",")));
                        break;
                    default:
                        throw new RuntimeException(type + " is not supported yet!");
                }
                scannedComponent.setConfigurationDescriptor(mapper.readTree(
                        Resources.toString(Resources.getResource(descriptorResourceName), Charsets.UTF_8)));
                scannedComponent.setClazz(clazzName);
                log.info("Processing scanned component: {}", scannedComponent);
            } catch (Exception e) {
                log.error("Can't initialize component {}, due to {}", def.getBeanClassName(), e.getMessage(), e);
                throw new RuntimeException(e);
            }
            ComponentDescriptor persistedComponent = componentDescriptorService.findByClazz(clazzName);
            if (persistedComponent == null) {
                log.info("Persisting new component: {}", scannedComponent);
                scannedComponent = componentDescriptorService.saveComponent(scannedComponent);
            } else if (scannedComponent.equals(persistedComponent)) {
                log.info("Component is already persisted: {}", persistedComponent);
                scannedComponent = persistedComponent;
            } else {
                log.info("Component {} will be updated to {}", persistedComponent, scannedComponent);
                componentDescriptorService.deleteByClazz(persistedComponent.getClazz());
                scannedComponent.setId(persistedComponent.getId());
                scannedComponent = componentDescriptorService.saveComponent(scannedComponent);
            }
            result.add(scannedComponent);
        }
        return result;
    }

    private Set<BeanDefinition> getBeanDefinitions(Class<? extends Annotation> componentType) {
        ClassPathScanningCandidateComponentProvider scanner = new ClassPathScanningCandidateComponentProvider(false);
        scanner.addIncludeFilter(new AnnotationTypeFilter(componentType));
        Set<BeanDefinition> defs = new HashSet<>();
        for (String scanPackage : scanPackages) {
            defs.addAll(scanner.findCandidateComponents(scanPackage));
        }
        return defs;
    }

    @Override
    public List<ComponentDescriptor> getComponents(ComponentType type) {
        return Collections.unmodifiableList(componentsMap.get(type));
    }

    @Override
    public Optional<ComponentDescriptor> getComponent(String clazz) {
        return Optional.ofNullable(components.get(clazz));
    }

    @Override
    public List<ComponentDescriptor> getPluginActions(String pluginClazz) {
        Optional<ComponentDescriptor> pluginOpt = getComponent(pluginClazz);
        if (pluginOpt.isPresent()) {
            ComponentDescriptor plugin = pluginOpt.get();
            if (ComponentType.PLUGIN != plugin.getType()) {
                throw new IllegalArgumentException(pluginClazz + " is not a plugin!");
            }
            List<ComponentDescriptor> result = new ArrayList<>();
            for (String action : plugin.getActions().split(",")) {
                getComponent(action).ifPresent(v -> result.add(v));
            }
            return result;
        } else {
            throw new IllegalArgumentException(pluginClazz + " is not a component!");
        }
    }
}
