/*-
 * ========================LICENSE_START=================================
 * O-RAN-SC
 * %%
 * Copyright (C) 2019 Nordix Foundation
 * %%
 * 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.
 * ========================LICENSE_END===================================
 */
package org.oransc.ric.portal.dashboard.controller;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;

import io.swagger.annotations.ApiOperation;

import java.lang.invoke.MethodHandles;
import java.util.Collection;

import javax.servlet.http.HttpServletResponse;

import org.oransc.ric.portal.dashboard.DashboardConstants;
import org.oransc.ric.portal.dashboard.exceptions.HttpBadRequestException;
import org.oransc.ric.portal.dashboard.exceptions.HttpInternalServerErrorException;
import org.oransc.ric.portal.dashboard.exceptions.HttpNotFoundException;
import org.oransc.ric.portal.dashboard.exceptions.HttpNotImplementedException;
import org.oransc.ric.portal.dashboard.model.PolicyInstances;
import org.oransc.ric.portal.dashboard.model.PolicyTypes;
import org.oransc.ric.portal.dashboard.policyagentapi.PolicyAgentApi;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.security.access.annotation.Secured;
import org.springframework.util.Assert;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

/**
 * Proxies calls from the front end to the Policy agent API.
 *
 * If a method throws RestClientResponseException, it is handled by
 * {@link CustomResponseEntityExceptionHandler#handleProxyMethodException(Exception, org.springframework.web.context.request.WebRequest)}
 * which returns status 502. All other exceptions are handled by Spring which
 * returns status 500.
 */
@RestController
@RequestMapping(value = PolicyController.CONTROLLER_PATH, produces = MediaType.APPLICATION_JSON_VALUE)
public class PolicyController {

    private static final Logger logger = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
    private static Gson gson = new GsonBuilder() //
        .serializeNulls() //
        .create(); //

    // Publish paths in constants so tests are easy to write
    public static final String CONTROLLER_PATH = DashboardConstants.ENDPOINT_PREFIX + "/policy";
    // Endpoints
    public static final String VERSION_METHOD = DashboardConstants.VERSION_METHOD;
    public static final String POLICY_TYPES_METHOD = "policytypes";
    public static final String POLICY_TYPE_ID_NAME = "policy_type_id";
    public static final String POLICIES_NAME = "policies";
    public static final String POLICY_INSTANCE_ID_NAME = "policy_instance_id";

    // Populated by the autowired constructor
    private final PolicyAgentApi policyAgentApi;

    @Autowired
    public PolicyController(final PolicyAgentApi policyAgentApi) {
        Assert.notNull(policyAgentApi, "API must not be null");
        this.policyAgentApi = policyAgentApi;
        logger.debug("ctor: configured with client type {}", policyAgentApi.getClass().getName());
    }

    /*
     * The fields are defined in the Policy Control Typescript interface.
     */
    @ApiOperation(value = "Gets the policy types from Near Realtime-RIC")
    @GetMapping(POLICY_TYPES_METHOD)
    @Secured({DashboardConstants.ROLE_ADMIN, DashboardConstants.ROLE_STANDARD})
    public ResponseEntity<PolicyTypes> getAllPolicyTypes(HttpServletResponse response) {
        logger.debug("getAllPolicyTypes");
        return this.policyAgentApi.getAllPolicyTypes();
    }

    @ApiOperation(value = "Returns the policy instances for the given policy type.")
    @GetMapping(POLICY_TYPES_METHOD + "/{" + POLICY_TYPE_ID_NAME + "}/" + POLICIES_NAME)
    @Secured({DashboardConstants.ROLE_ADMIN, DashboardConstants.ROLE_STANDARD})
    public ResponseEntity<String> getPolicyInstances(@PathVariable(POLICY_TYPE_ID_NAME) String policyTypeIdString) {
        logger.debug("getPolicyInstances {}", policyTypeIdString);

        ResponseEntity<PolicyInstances> response = this.policyAgentApi.getPolicyInstancesForType(policyTypeIdString);
        if (!response.getStatusCode().is2xxSuccessful()) {
            return new ResponseEntity<>(response.getStatusCode());
        }
        String json = gson.toJson(response.getBody());
        return new ResponseEntity<>(json, response.getStatusCode());
    }

    @ApiOperation(value = "Returns a policy instance of a type")
    @GetMapping(POLICY_TYPES_METHOD + "/{" + POLICY_TYPE_ID_NAME + "}/" + POLICIES_NAME + "/{" + POLICY_INSTANCE_ID_NAME
        + "}")
    @Secured({DashboardConstants.ROLE_ADMIN, DashboardConstants.ROLE_STANDARD})
    public ResponseEntity<String> getPolicyInstance(@PathVariable(POLICY_TYPE_ID_NAME) String policyTypeIdString,
        @PathVariable(POLICY_INSTANCE_ID_NAME) String policyInstanceId) {
        logger.debug("getPolicyInstance {}:{}", policyTypeIdString, policyInstanceId);
        return this.policyAgentApi.getPolicyInstance(policyInstanceId);
    }

    @ApiOperation(value = "Creates the policy instances for the given policy type.")
    @PutMapping(POLICY_TYPES_METHOD + "/{" + POLICY_TYPE_ID_NAME + "}/" + POLICIES_NAME + "/{" + POLICY_INSTANCE_ID_NAME
        + "}")
    @Secured({DashboardConstants.ROLE_ADMIN})
    public ResponseEntity<String> putPolicyInstance(@PathVariable(POLICY_TYPE_ID_NAME) String policyTypeIdString,
        @RequestParam(name = "ric", required = true) String ric,
        @PathVariable(POLICY_INSTANCE_ID_NAME) String policyInstanceId, @RequestBody String instance) {
        logger.debug("putPolicyInstance typeId: {}, instanceId: {}, instance: {}", policyTypeIdString, policyInstanceId,
            instance);
        return this.policyAgentApi.putPolicy(policyTypeIdString, policyInstanceId, instance, ric);
    }

    @ApiOperation(value = "Deletes the policy instances for the given policy type.")
    @DeleteMapping(POLICY_TYPES_METHOD + "/{" + POLICY_TYPE_ID_NAME + "}/" + POLICIES_NAME + "/{"
        + POLICY_INSTANCE_ID_NAME + "}")
    @Secured({DashboardConstants.ROLE_ADMIN})
    public void deletePolicyInstance(@PathVariable(POLICY_TYPE_ID_NAME) String policyTypeIdString,
        @PathVariable(POLICY_INSTANCE_ID_NAME) String policyInstanceId) {
        logger.debug("deletePolicyInstance typeId: {}, instanceId: {}", policyTypeIdString, policyInstanceId);
        this.policyAgentApi.deletePolicy(policyInstanceId);
    }

    private void checkHttpError(String httpCode) {
        logger.debug("Http Response Code: {}", httpCode);
        if (httpCode.equals(String.valueOf(HttpStatus.NOT_FOUND.value()))) {
            logger.error("Caught HttpNotFoundException");
            throw new HttpNotFoundException("Not Found Exception");
        } else if (httpCode.equals(String.valueOf(HttpStatus.BAD_REQUEST.value()))) {
            logger.error("Caught HttpBadRequestException");
            throw new HttpBadRequestException("Bad Request Exception");
        } else if (httpCode.equals(String.valueOf(HttpStatus.INTERNAL_SERVER_ERROR.value()))) {
            logger.error("Caught HttpInternalServerErrorException");
            throw new HttpInternalServerErrorException("Internal Server Error Exception");
        } else if (httpCode.equals(String.valueOf(HttpStatus.NOT_IMPLEMENTED.value()))) {
            logger.error("Caught HttpNotImplementedException");
            throw new HttpNotImplementedException("Not Implemented Exception");
        }
    }

    @ApiOperation(value = "Returns the rics supporting the given policy type.")
    @GetMapping("/rics")
    @Secured({DashboardConstants.ROLE_ADMIN, DashboardConstants.ROLE_STANDARD})
    public ResponseEntity<String> getRicsSupportingType(
        @RequestParam(name = "policyType", required = true) String supportingPolicyType) {
        logger.debug("getRicsSupportingType {}", supportingPolicyType);

        ResponseEntity<Collection<String>> result = this.policyAgentApi.getRicsSupportingType(supportingPolicyType);
        if (!result.getStatusCode().is2xxSuccessful()) {
            return new ResponseEntity<>(result.getStatusCode());
        }
        String json = gson.toJson(result.getBody());
        return new ResponseEntity<>(json, result.getStatusCode());
    }

};