/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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 com.epam.dlab;

import com.epam.dlab.core.BillingUtils;
import com.epam.dlab.core.ModuleType;
import com.epam.dlab.exceptions.InitializationException;
import com.fasterxml.jackson.annotation.JsonClassDescription;
import com.fasterxml.jackson.annotation.JsonTypeName;
import org.apache.commons.lang3.StringUtils;

import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/** Print help for billing tool.
 */
public class Help {

	private Help() {
	}

	/** Print help to console.
	 * @param resourceName the name of resource.
	 * @param substitute - map for substitution in help content.
	 * @throws InitializationException
	 */
	private static void printHelp(String resourceName, Map<String, String> substitute) throws InitializationException {
		List<String> list = BillingUtils.getResourceAsList("/" + Help.class.getName() + "." + resourceName + ".txt");
		String help = StringUtils.join(list, System.lineSeparator());

		if (substitute == null) {
			substitute = new HashMap<>();
		}
		substitute.put("classname", BillingServiceImpl.class.getName());

		for (String key : substitute.keySet()) {
			help = StringUtils.replace(help, "${" + key.toUpperCase() + "}", substitute.get(key));
		}
		System.out.println(help);
	}

	/** Create and return substitutions for names of modules.
	 * @return
	 * @throws InitializationException
	 */
	private static Map<String, String> findModules() throws InitializationException {
		List<Class<?>> modules = BillingUtils.getModuleClassList();
		Map<String, String> substitute = new HashMap<>();
		
		for (Class<?> module : modules) {
			ModuleType type = BillingUtils.getModuleType(module);
			JsonTypeName typeName = module.getAnnotation(JsonTypeName.class);
			if (typeName != null) {
				String typeNames = substitute.get(type.toString() + "s");
				typeNames = (typeNames == null ? typeName.value() : typeNames + ", " + typeName.value());
				substitute.put(type.toString() + "s", typeNames);
			}
		}
		
		return substitute;
	}

	/** Find and return help for module.
	 * @param type the type of module.
	 * @param name the name of module.
	 * @throws InitializationException
	 */
	private static String findModuleHelp(ModuleType type, String name) throws InitializationException {
		List<Class<?>> modules = BillingUtils.getModuleClassList();
		String typeNames = null;
		for (Class<?> module : modules) {
			ModuleType t = BillingUtils.getModuleType(module);
			if (t == type) {
				JsonTypeName typeName = module.getAnnotation(JsonTypeName.class);
				if (typeName != null ) {
					if (name.equals(typeName.value())) {
						JsonClassDescription description = module.getAnnotation(JsonClassDescription.class);
						if (description != null) {
							return description.value();
						}
						throw new InitializationException("Help for " + type + " " + name + " not found");
					} else {
						typeNames = (typeNames == null ? typeName.value() : typeNames + ", " + typeName.value());
					}
				}
			}
		}
		throw new InitializationException("Module for " + type + " " + name + " not found." +
				(typeNames == null ? "" : " Module type must be one of next: " + typeNames));
	}

	/** Print help screen for billing tool. 
	 * @throws InitializationException */
	public static void usage(String ... args) throws InitializationException {
		if (args == null || args.length == 0) {
			printHelp("usage", null);
		} else if (args[0].equalsIgnoreCase("conf")) {
			printHelp("conf", findModules());
		} else {
			ModuleType type = ModuleType.of(args[0]);
			if (type == null) {
				System.out.println("Unknown --help " + args[0] + " command.");
			} else if (args.length < 2) {
				System.out.println("Missing the type of module.");
				String typeNames = findModules().get(type.toString() + "s");
				if (typeNames != null) {
					System.out.println("Must be one of next: " + typeNames);
				}
			} else if (args.length > 2) {
				System.out.println("Extra arguments in command: " +
					StringUtils.join(Arrays.copyOfRange(args, 2, args.length), " "));
			} else {
				System.out.println(findModuleHelp(type, args[1]));
			}
		}
	}
}