/*
 * Copyright 1999-2018 Alibaba Group Holding Ltd.
 *
 * 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 com.alibaba.csp.sentinel.dashboard.controller;

import com.alibaba.csp.sentinel.dashboard.auth.AuthAction;
import com.alibaba.csp.sentinel.dashboard.auth.AuthService.PrivilegeType;
import com.alibaba.csp.sentinel.dashboard.client.SentinelApiClient;
import com.alibaba.csp.sentinel.dashboard.datasource.entity.rule.DegradeRuleEntity;
import com.alibaba.csp.sentinel.dashboard.discovery.AppManagement;
import com.alibaba.csp.sentinel.dashboard.discovery.MachineInfo;
import com.alibaba.csp.sentinel.dashboard.domain.Result;
import com.alibaba.csp.sentinel.dashboard.repository.rule.RuleRepository;
import com.alibaba.csp.sentinel.slots.block.RuleConstant;
import com.alibaba.csp.sentinel.slots.block.degrade.circuitbreaker.CircuitBreakerStrategy;
import com.alibaba.csp.sentinel.util.StringUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.Date;
import java.util.List;

/**
 * Controller regarding APIs of degrade rules. Refactored since 1.8.0.
 *
 * @author Carpenter Lee
 * @author Eric Zhao
 */
@RestController
@RequestMapping("/degrade")
public class DegradeController {

    private final Logger logger = LoggerFactory.getLogger(DegradeController.class);

    @Autowired
    private RuleRepository<DegradeRuleEntity, Long> repository;
    @Autowired
    private SentinelApiClient sentinelApiClient;
    @Autowired
    private AppManagement appManagement;

    @GetMapping("/rules.json")
    @AuthAction(PrivilegeType.READ_RULE)
    public Result<List<DegradeRuleEntity>> apiQueryMachineRules(String app, String ip, Integer port) {
        if (StringUtil.isEmpty(app)) {
            return Result.ofFail(-1, "app can't be null or empty");
        }
        if (StringUtil.isEmpty(ip)) {
            return Result.ofFail(-1, "ip can't be null or empty");
        }
        if (port == null) {
            return Result.ofFail(-1, "port can't be null");
        }
        if (!appManagement.isValidMachineOfApp(app, ip)) {
            return Result.ofFail(-1, "given ip does not belong to given app");
        }
        try {
            List<DegradeRuleEntity> rules = sentinelApiClient.fetchDegradeRuleOfMachine(app, ip, port);
            rules = repository.saveAll(rules);
            return Result.ofSuccess(rules);
        } catch (Throwable throwable) {
            logger.error("queryApps error:", throwable);
            return Result.ofThrowable(-1, throwable);
        }
    }

    @PostMapping("/rule")
    @AuthAction(PrivilegeType.WRITE_RULE)
    public Result<DegradeRuleEntity> apiAddRule(@RequestBody DegradeRuleEntity entity) {
        Result<DegradeRuleEntity> checkResult = checkEntityInternal(entity);
        if (checkResult != null) {
            return checkResult;
        }
        Date date = new Date();
        entity.setGmtCreate(date);
        entity.setGmtModified(date);
        try {
            entity = repository.save(entity);
        } catch (Throwable t) {
            logger.error("Failed to add new degrade rule, app={}, ip={}", entity.getApp(), entity.getIp(), t);
            return Result.ofThrowable(-1, t);
        }
        if (!publishRules(entity.getApp(), entity.getIp(), entity.getPort())) {
            logger.warn("Publish degrade rules failed, app={}", entity.getApp());
        }
        return Result.ofSuccess(entity);
    }

    @PutMapping("/rule/{id}")
    @AuthAction(PrivilegeType.WRITE_RULE)
    public Result<DegradeRuleEntity> apiUpdateRule(@PathVariable("id") Long id,
                                                     @RequestBody DegradeRuleEntity entity) {
        if (id == null || id <= 0) {
            return Result.ofFail(-1, "id can't be null or negative");
        }
        DegradeRuleEntity oldEntity = repository.findById(id);
        if (oldEntity == null) {
            return Result.ofFail(-1, "Degrade rule does not exist, id=" + id);
        }
        entity.setApp(oldEntity.getApp());
        entity.setIp(oldEntity.getIp());
        entity.setPort(oldEntity.getPort());
        entity.setId(oldEntity.getId());
        Result<DegradeRuleEntity> checkResult = checkEntityInternal(entity);
        if (checkResult != null) {
            return checkResult;
        }

        entity.setGmtCreate(oldEntity.getGmtCreate());
        entity.setGmtModified(new Date());
        try {
            entity = repository.save(entity);
        } catch (Throwable t) {
            logger.error("Failed to save degrade rule, id={}, rule={}", id, entity, t);
            return Result.ofThrowable(-1, t);
        }
        if (!publishRules(entity.getApp(), entity.getIp(), entity.getPort())) {
            logger.warn("Publish degrade rules failed, app={}", entity.getApp());
        }
        return Result.ofSuccess(entity);
    }

    @DeleteMapping("/rule/{id}")
    @AuthAction(PrivilegeType.DELETE_RULE)
    public Result<Long> delete(@PathVariable("id") Long id) {
        if (id == null) {
            return Result.ofFail(-1, "id can't be null");
        }

        DegradeRuleEntity oldEntity = repository.findById(id);
        if (oldEntity == null) {
            return Result.ofSuccess(null);
        }

        try {
            repository.delete(id);
        } catch (Throwable throwable) {
            logger.error("Failed to delete degrade rule, id={}", id, throwable);
            return Result.ofThrowable(-1, throwable);
        }
        if (!publishRules(oldEntity.getApp(), oldEntity.getIp(), oldEntity.getPort())) {
            logger.warn("Publish degrade rules failed, app={}", oldEntity.getApp());
        }
        return Result.ofSuccess(id);
    }

    private boolean publishRules(String app, String ip, Integer port) {
        List<DegradeRuleEntity> rules = repository.findAllByMachine(MachineInfo.of(app, ip, port));
        return sentinelApiClient.setDegradeRuleOfMachine(app, ip, port, rules);
    }

    private <R> Result<R> checkEntityInternal(DegradeRuleEntity entity) {
        if (StringUtil.isBlank(entity.getApp())) {
            return Result.ofFail(-1, "app can't be blank");
        }
        if (StringUtil.isBlank(entity.getIp())) {
            return Result.ofFail(-1, "ip can't be null or empty");
        }
        if (!appManagement.isValidMachineOfApp(entity.getApp(), entity.getIp())) {
            return Result.ofFail(-1, "given ip does not belong to given app");
        }
        if (entity.getPort() == null || entity.getPort() <= 0) {
            return Result.ofFail(-1, "invalid port: " + entity.getPort());
        }
        if (StringUtil.isBlank(entity.getLimitApp())) {
            return Result.ofFail(-1, "limitApp can't be null or empty");
        }
        if (StringUtil.isBlank(entity.getResource())) {
            return Result.ofFail(-1, "resource can't be null or empty");
        }
        Double threshold = entity.getCount();
        if (threshold == null || threshold < 0) {
            return Result.ofFail(-1, "invalid threshold: " + threshold);
        }
        Integer recoveryTimeoutSec = entity.getTimeWindow();
        if (recoveryTimeoutSec == null || recoveryTimeoutSec <= 0) {
            return Result.ofFail(-1, "recoveryTimeout should be positive");
        }
        Integer strategy = entity.getGrade();
        if (strategy == null) {
            return Result.ofFail(-1, "circuit breaker strategy cannot be null");
        }
        if (strategy < CircuitBreakerStrategy.SLOW_REQUEST_RATIO.getType()
            || strategy > RuleConstant.DEGRADE_GRADE_EXCEPTION_COUNT) {
            return Result.ofFail(-1, "Invalid circuit breaker strategy: " + strategy);
        }
        if (entity.getMinRequestAmount()  == null || entity.getMinRequestAmount() <= 0) {
            return Result.ofFail(-1, "Invalid minRequestAmount");
        }
        if (entity.getStatIntervalMs() == null || entity.getStatIntervalMs() <= 0) {
            return Result.ofFail(-1, "Invalid statInterval");
        }
        if (strategy == RuleConstant.DEGRADE_GRADE_RT) {
            Double slowRatio = entity.getSlowRatioThreshold();
            if (slowRatio == null) {
                return Result.ofFail(-1, "SlowRatioThreshold is required for slow request ratio strategy");
            } else if (slowRatio < 0 || slowRatio > 1) {
                return Result.ofFail(-1, "SlowRatioThreshold should be in range: [0.0, 1.0]");
            }
        } else if (strategy == RuleConstant.DEGRADE_GRADE_EXCEPTION_RATIO) {
            if (threshold > 1) {
                return Result.ofFail(-1, "Ratio threshold should be in range: [0.0, 1.0]");
            }
        }
        return null;
    }
}