/*
 * 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 org.apache.ranger.biz;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.commons.collections.CollectionUtils;
import org.apache.commons.collections.MapUtils;
import org.apache.commons.lang.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.ranger.authorization.hadoop.config.RangerPluginConfig;
import org.apache.ranger.plugin.model.RangerPolicy;
import org.apache.ranger.plugin.model.RangerPolicyDelta;
import org.apache.ranger.plugin.model.RangerSecurityZone;
import org.apache.ranger.plugin.model.RangerServiceDef;
import org.apache.ranger.plugin.store.RoleStore;
import org.apache.ranger.plugin.policyengine.RangerPluginContext;
import org.apache.ranger.plugin.policyengine.RangerPolicyEngineOptions;
import org.apache.ranger.plugin.store.SecurityZoneStore;
import org.apache.ranger.plugin.store.ServiceStore;
import org.apache.ranger.plugin.util.RangerPolicyDeltaUtil;
import org.apache.ranger.plugin.util.RangerRoles;
import org.apache.ranger.plugin.util.ServicePolicies;

public class RangerPolicyAdminCache {
	private static final Log LOG = LogFactory.getLog(RangerPolicyAdminCache.class);

	private final Map<String, RangerPolicyAdmin> policyAdminCache = Collections.synchronizedMap(new HashMap<>());

	final RangerPolicyAdmin getServicePoliciesAdmin(String serviceName, ServiceStore svcStore, RoleStore roleStore, SecurityZoneStore zoneStore, RangerPolicyEngineOptions options) {
		RangerPolicyAdmin ret = null;

		if (serviceName == null || svcStore == null || roleStore == null || zoneStore == null) {
			LOG.warn("Cannot get policy-admin for null serviceName or serviceStore or roleStore or zoneStore");

			return ret;
		}

		ret = policyAdminCache.get(serviceName);

		long        policyVersion;
		long        roleVersion;
		RangerRoles roles;
		boolean     isRolesUpdated = true;

		try {
			if (ret == null) {
				policyVersion = -1L;
				roleVersion   = -1L;
				roles         = roleStore.getRoles(serviceName, roleVersion);

				if (roles == null) {
					if (LOG.isDebugEnabled()) {
						LOG.debug("There are no roles in ranger-admin for service:" + serviceName + "]");
					}
				}
			} else {
				policyVersion = ret.getPolicyVersion();
				roleVersion   = ret.getRoleVersion();
				roles         = roleStore.getRoles(serviceName, roleVersion);

				if (roles == null) { // No changes to roles
					roles          = roleStore.getRoles(serviceName, -1L);
					isRolesUpdated = false;
				}
			}

			ServicePolicies policies = svcStore.getServicePoliciesIfUpdated(serviceName, policyVersion, false);

			if (policies != null) {
				if (policies.getPolicyVersion() != null && !policies.getPolicyVersion().equals(policyVersion)) {
					ServicePolicies updatedServicePolicies = getUpdatedServicePolicies(serviceName, policies, svcStore, zoneStore);

					ret = addOrUpdatePolicyAdmin(ret, updatedServicePolicies, roles, options);
				} else {
					LOG.error("policies object is null or its version is null for getPolicyAdmin(" + serviceName + ") !!");
					LOG.error("Returning old policy admin");
				}
			} else {
				if (ret == null) {
					LOG.error("getPolicyAdmin(" + serviceName + "): failed to get any policies from service-store");
				} else {
					if (isRolesUpdated) {
						ret.setRoles(roles);
					}
				}
			}
		} catch (Exception excp) {
			LOG.error("getPolicyAdmin(" + serviceName + "): failed to get latest policies from service-store", excp);
		}
		if (ret == null) {
			LOG.error("Policy-engine is not built! Returning null policy-engine!");
		}

		return ret;
	}

	private RangerPolicyAdmin addOrUpdatePolicyAdmin(RangerPolicyAdmin policyAdmin, ServicePolicies policies, RangerRoles roles, RangerPolicyEngineOptions options) {
		final RangerPolicyAdmin ret;
		RangerPolicyAdminImpl   oldPolicyAdmin = (RangerPolicyAdminImpl) policyAdmin;

		synchronized(this) {
			Boolean hasPolicyDeltas = RangerPolicyDeltaUtil.hasPolicyDeltas(policies);

			if (hasPolicyDeltas != null) {
				if (hasPolicyDeltas.equals(Boolean.TRUE)) {
					if (oldPolicyAdmin != null) {
						ret = RangerPolicyAdminImpl.getPolicyAdmin(oldPolicyAdmin, policies);
						if (ret != null) {
							ret.setRoles(roles);
						}
					} else {
						LOG.error("Old policy engine is null! Cannot apply deltas without old policy engine!");
						ret = null;
					}
				} else {
					ret = addPolicyAdmin(policies, roles, options);
				}
			} else {
				LOG.warn("ServicePolicies contain neither policies nor policy-deltas !");
				ret = null;
			}

			if (ret != null) {
				if (LOG.isDebugEnabled()) {
					if (oldPolicyAdmin == null) {
						LOG.debug("Adding policy-engine to cache with serviceName:[" + policies.getServiceName() + "] as key");
					} else {
						LOG.debug("Replacing policy-engine in cache with serviceName:[" + policies.getServiceName() + "] as key");
					}
				}
				policyAdminCache.put(policies.getServiceName(), ret);
				if (oldPolicyAdmin != null) {
					oldPolicyAdmin.releaseResources();
				}
			} else {
				LOG.warn("Could not build new policy-engine. Continuing with the old policy-engine, if any");
			}
		}

		return ret != null ? ret : oldPolicyAdmin;
	}

	private RangerPolicyAdmin addPolicyAdmin(ServicePolicies policies, RangerRoles roles, RangerPolicyEngineOptions options) {
		RangerServiceDef    serviceDef          = policies.getServiceDef();
		String              serviceType         = (serviceDef != null) ? serviceDef.getName() : "";
		RangerPluginContext rangerPluginContext = new RangerPluginContext(new RangerPluginConfig(serviceType, null, "ranger-admin", null, null, options));
		RangerPolicyAdmin   ret                 = new RangerPolicyAdminImpl(policies, rangerPluginContext, roles);

		return ret;
	}

	private ServicePolicies getUpdatedServicePolicies(String serviceName, ServicePolicies policies, ServiceStore svcStore, SecurityZoneStore zoneStore) throws  Exception{
		ServicePolicies ret = policies;

		if (ret == null) {
			ret = svcStore.getServicePoliciesIfUpdated(serviceName, -1L, false);
		}

		if (zoneStore != null) {
			Map<String, RangerSecurityZone.RangerSecurityZoneService> securityZones = zoneStore.getSecurityZonesForService(serviceName);

			if (MapUtils.isNotEmpty(securityZones)) {
				ret = getUpdatedServicePoliciesForZones(ret, securityZones);
			}
		}

		return ret;
	}

	public static ServicePolicies getUpdatedServicePoliciesForZones(ServicePolicies servicePolicies, Map<String, RangerSecurityZone.RangerSecurityZoneService> securityZones) {
		final ServicePolicies ret;

		if (MapUtils.isNotEmpty(securityZones)) {
			ret = new ServicePolicies();

			ret.setServiceDef(servicePolicies.getServiceDef());
			ret.setServiceId(servicePolicies.getServiceId());
			ret.setServiceName(servicePolicies.getServiceName());
			ret.setAuditMode(servicePolicies.getAuditMode());
			ret.setPolicyVersion(servicePolicies.getPolicyVersion());
			ret.setPolicyUpdateTime(servicePolicies.getPolicyUpdateTime());

			Map<String, ServicePolicies.SecurityZoneInfo> securityZonesInfo = new HashMap<>();

			if (CollectionUtils.isEmpty(servicePolicies.getPolicyDeltas())) {
				List<RangerPolicy> allPolicies = new ArrayList<>(servicePolicies.getPolicies());

				for (Map.Entry<String, RangerSecurityZone.RangerSecurityZoneService> entry : securityZones.entrySet()) {
					List<RangerPolicy> zonePolicies = extractZonePolicies(allPolicies, entry.getKey());

					if (CollectionUtils.isNotEmpty(zonePolicies)) {
						allPolicies.removeAll(zonePolicies);
					}

					ServicePolicies.SecurityZoneInfo securityZoneInfo = new ServicePolicies.SecurityZoneInfo();

					securityZoneInfo.setZoneName(entry.getKey());
					securityZoneInfo.setPolicies(zonePolicies);
					securityZoneInfo.setResources(entry.getValue().getResources());
					securityZoneInfo.setContainsAssociatedTagService(false);
					securityZonesInfo.put(entry.getKey(), securityZoneInfo);
				}

				ret.setPolicies(allPolicies);
				ret.setTagPolicies(servicePolicies.getTagPolicies());
			} else {
				List<RangerPolicyDelta> allPolicyDeltas = new ArrayList<>(servicePolicies.getPolicyDeltas());

				for (Map.Entry<String, RangerSecurityZone.RangerSecurityZoneService> entry : securityZones.entrySet()) {
					List<RangerPolicyDelta> zonePolicyDeltas = extractZonePolicyDeltas(allPolicyDeltas, entry.getKey());

					if (CollectionUtils.isNotEmpty(zonePolicyDeltas)) {
						allPolicyDeltas.removeAll(zonePolicyDeltas);
					}

					ServicePolicies.SecurityZoneInfo securityZoneInfo = new ServicePolicies.SecurityZoneInfo();

					securityZoneInfo.setZoneName(entry.getKey());
					securityZoneInfo.setPolicyDeltas(zonePolicyDeltas);
					securityZoneInfo.setResources(entry.getValue().getResources());
					securityZoneInfo.setContainsAssociatedTagService(false);
					securityZonesInfo.put(entry.getKey(), securityZoneInfo);
				}

				ret.setPolicyDeltas(allPolicyDeltas);
			}

			ret.setSecurityZones(securityZonesInfo);
		} else {
			ret = servicePolicies;
		}

		return ret;
	}

	private static List<RangerPolicy> extractZonePolicies(final List<RangerPolicy> allPolicies, final String zoneName) {
		final List<RangerPolicy> ret = new ArrayList<>();

		for (RangerPolicy policy : allPolicies) {
			if (policy.getIsEnabled() && StringUtils.equals(policy.getZoneName(), zoneName)) {
				ret.add(policy);
			}
		}

		return ret;
	}

	private static List<RangerPolicyDelta> extractZonePolicyDeltas(final List<RangerPolicyDelta> allPolicyDeltas, final String zoneName) {
		final List<RangerPolicyDelta> ret = new ArrayList<>();

		for (RangerPolicyDelta delta : allPolicyDeltas) {
			if (StringUtils.equals(delta.getZoneName(), zoneName)) {
				ret.add(delta);
			}
		}

		return ret;
	}
}