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/*
 * Copyright 2016-2019 the original author or 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
 *
 * https://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 demo.eventservice;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.messaging.support.MessageBuilder;
import org.springframework.statemachine.StateMachine;
import org.springframework.statemachine.persist.StateMachinePersister;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseStatus;

import demo.eventservice.StateMachineConfig.Events;
import demo.eventservice.StateMachineConfig.States;
import reactor.core.publisher.Mono;

@Controller
public class StateMachineController {

//tag::snippetA[]
	@Autowired
	private StateMachine stateMachine;

	@Autowired
	private StateMachinePersister stateMachinePersister;
//end::snippetA[]

	@Autowired
	private String stateChartModel;

	@RequestMapping("/")
	public String home() {
		return "redirect:/state";
	}

//tag::snippetB[]
	@RequestMapping("/state")
	public String feedAndGetState(@RequestParam(value = "user", required = false) String user,
			@RequestParam(value = "id", required = false) Events id, Model model) throws Exception {
		model.addAttribute("user", user);
		model.addAttribute("allTypes", Events.values());
		model.addAttribute("stateChartModel", stateChartModel);
		// we may get into this page without a user so
		// do nothing with a state machine
		if (StringUtils.hasText(user)) {
			resetStateMachineFromStore(user);
			if (id != null) {
				feedMachine(user, id);
			}
			model.addAttribute("states", stateMachine.getState().getIds());
			model.addAttribute("extendedState", stateMachine.getExtendedState().getVariables());
		}
		return "states";
	}
//end::snippetB[]

//tag::snippetC[]
	@RequestMapping(value = "/feed",method= RequestMethod.POST)
	@ResponseStatus(HttpStatus.OK)
	public void feedPageview(@RequestBody(required = true) Pageview event) throws Exception {
		Assert.notNull(event.getUser(), "User must be set");
		Assert.notNull(event.getId(), "Id must be set");
		resetStateMachineFromStore(event.getUser());
		feedMachine(event.getUser(), event.getId());
	}
//end::snippetC[]

//tag::snippetD[]
	private void feedMachine(String user, Events id) throws Exception {
		stateMachine
			.sendEvent(Mono.just(MessageBuilder
				.withPayload(id).build()))
			.blockLast();
		stateMachinePersister.persist(stateMachine, "testprefix:" + user);
	}
//end::snippetD[]

//tag::snippetE[]
	private StateMachine resetStateMachineFromStore(String user) throws Exception {
		return stateMachinePersister.restore(stateMachine, "testprefix:" + user);
	}
//end::snippetE[]
}