package com.github.streamshub.console.api.service;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Optional;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CompletionStage;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import jakarta.enterprise.context.ApplicationScoped;
import jakarta.inject.Inject;
import jakarta.ws.rs.NotFoundException;

import org.eclipse.microprofile.config.inject.ConfigProperty;
import org.jboss.logging.Logger;

import com.github.streamshub.console.api.model.FetchParams;
import com.github.streamshub.console.api.model.connect.ConnectCluster;
import com.github.streamshub.console.api.model.connect.Connector;
import com.github.streamshub.console.api.model.connect.ConnectorPlugin;
import com.github.streamshub.console.api.model.connect.ConnectorTask;
import com.github.streamshub.console.api.support.ContextualExecutorProvider;
import com.github.streamshub.console.api.support.FieldFilter;
import com.github.streamshub.console.api.support.KafkaConnectAPI;
import com.github.streamshub.console.api.support.KafkaConnectAPI.ConnectorOffsets;
import com.github.streamshub.console.api.support.KafkaContext;
import com.github.streamshub.console.api.support.ListRequestContext;
import com.github.streamshub.console.api.support.Promises;
import com.github.streamshub.console.config.ConsoleConfig;
import com.github.streamshub.console.config.KafkaConnectConfig;
import com.github.streamshub.console.support.Identifiers;

import io.fabric8.kubernetes.client.CustomResource;
import io.strimzi.api.kafka.model.connect.KafkaConnect;
import io.strimzi.api.kafka.model.connect.KafkaConnectStatus;
import io.strimzi.api.kafka.model.mirrormaker2.KafkaMirrorMaker2;
import io.strimzi.api.kafka.model.mirrormaker2.KafkaMirrorMaker2Status;

import static java.util.Collections.emptyList;
import static java.util.Collections.emptyMap;
import static java.util.concurrent.CompletableFuture.completedStage;

@ApplicationScoped
public class KafkaConnectService {

    static final CompletionStage<ConnectCluster> PROMISE_NULL_CLUSTER = completedStage(null);
    static final CompletionStage<Map<Integer, Map<String, String>>> PROMISE_EMPTY_CONFIG = completedStage(emptyMap());
    static final CompletionStage<List<String>> PROMISE_NULL_TOPICS = completedStage(null);
    static final CompletionStage<List<Connector.ConnectorOffset>> PROMISE_NULL_OFFSETS = completedStage(null);
    static final CompletionStage<List<ConnectorPlugin>> PROMISE_NULL_PLUGINS = completedStage(null);
    static final CompletionStage<List<Connector>> PROMISE_EMPTY_CONNECTORS = completedStage(emptyList());

    @Inject
    Logger logger;

    @Inject
    ContextualExecutorProvider threadContext;

    @Inject
    ConsoleConfig consoleConfig;

    @Inject
    /**
     * All Kafka contexts known to the application
     */
    Map<String, KafkaContext> kafkaContexts;

    @Inject
    KafkaConnectAPI.Client connectClient;

    @Inject
    StrimziResourceService strimziService;

    @Inject
    @ConfigProperty(name = "console.connect.mirror.classes.checkpoints")
    List<String> mmCheckpoints;

    @Inject
    @ConfigProperty(name = "console.connect.mirror.classes.heartbeats")
    List<String> mmHeartbeats;

    @Inject
    @ConfigProperty(name = "console.connect.mirror.classes.sources")
    List<String> mmSources;

    public CompletionStage<List<ConnectCluster>> listClusters(FieldFilter fields, ListRequestContext<ConnectCluster> listSupport) {
        var pendingServerInfo = consoleConfig.getKafkaConnectClusters()
                .stream()
                .filter(listSupport.filter(KafkaConnectConfig.class))
                .map(config -> describeCluster(config, fields, listSupport.getFetchParams(), true))
                .toList();

        return Promises.joinStages(pendingServerInfo)
                .thenApply(results -> results.stream()
                        .filter(listSupport.filter(ConnectCluster.class))
                        .map(listSupport::tally)
                        .filter(listSupport::betweenCursors)
                        .sorted(listSupport.getSortComparator())
                        .dropWhile(listSupport::beforePageBegin)
                        .takeWhile(listSupport::pageCapacityAvailable)
                        .toList());
    }

    public CompletionStage<ConnectCluster> describeCluster(String clusterId, FieldFilter fields, FetchParams fetchParams) {
        String[] idParts = Identifiers.decode(clusterId);
        KafkaConnectConfig clusterConfig = consoleConfig.getKafkaConnectCluster(idParts[0])
                .orElseThrow(() -> new NotFoundException("Unknown Kafka Connect cluster"));
        return describeCluster(clusterConfig, fields, fetchParams, true);
    }

    private CompletionStage<ConnectCluster> describeCluster(KafkaConnectConfig clusterConfig, FieldFilter fields, FetchParams fetchParams, boolean primaryResource) {
        var clusterKey = clusterConfig.clusterKey();
        var includePlugins = fields.isIncluded(ConnectCluster.FIELDS_PARAM, ConnectCluster.Fields.PLUGINS.toString());
        var pluginPromise = includePlugins
            ? describeConnectorPlugins(clusterConfig)
            : PROMISE_NULL_PLUGINS;

        var includeConnectors = fetchParams.includes(ConnectCluster.Fields.CONNECTORS.toString());
        var fetchConnectors = includeConnectors || fields.isIncluded(ConnectCluster.FIELDS_PARAM, ConnectCluster.Fields.CONNECTORS.toString());
        var connectorPromise = primaryResource && fetchConnectors
            ? listConnectors(clusterConfig, fields, fetchParams)
            : PROMISE_EMPTY_CONNECTORS;
        var kafkaIdentifiers = mapKafkaIdentifiers(clusterConfig);

        var customResourcePromise = getConnectResource(clusterConfig);

        return connectClient.getWorkerDetails(clusterKey)
                .thenApply(server -> {
                    var cluster = new ConnectCluster(Identifiers.encode("", clusterConfig.clusterKey()));
                    cluster.name(clusterConfig.getName());
                    cluster.namespace(clusterConfig.getNamespace());
                    cluster.commit(server.commit());
                    cluster.kafkaClusterId(server.kafkaClusterId());
                    cluster.version(server.version());
                    cluster.kafkaClusters(kafkaIdentifiers);
                    return cluster;
                })
                .thenCombine(pluginPromise, ConnectCluster::plugins)
                .thenCombine(connectorPromise, (cluster, connectors) -> cluster.connectors(connectors, includeConnectors))
                .thenCombine(customResourcePromise, (cluster, customResource) -> {
                    if (clusterConfig.isMirrorMaker().booleanValue()) {
                        var mmCR = customResource.map(KafkaMirrorMaker2.class::cast);
                        cluster.setManaged(Boolean.valueOf(mmCR.isPresent()));
                        mmCR.map(KafkaMirrorMaker2::getStatus)
                            .map(KafkaConnectStatus::getReplicas)
                            .ifPresent(cluster::replicas);
                    } else {
                        var connectCR = customResource.map(KafkaConnect.class::cast);
                        cluster.setManaged(Boolean.valueOf(connectCR.isPresent()));
                        connectCR.map(KafkaConnect::getStatus)
                            .map(KafkaConnectStatus::getReplicas)
                            .ifPresent(cluster::replicas);
                    }
                    return cluster;
                });
    }

    public List<String> mapKafkaIdentifiers(KafkaConnectConfig clusterConfig) {
        return clusterConfig.getKafkaClusters()
                .stream()
                .map(consoleConfig.getKafka()::getCluster)
                .filter(Optional::isPresent)
                .map(Optional::get)
                .map(kafkaConfig -> kafkaContexts.values()
                        .stream()
                        .filter(ctx -> ctx.clusterConfig().clusterKey().equals(kafkaConfig.clusterKey()))
                        .findFirst()
                        .orElse(null))
                .filter(Objects::nonNull)
                .map(ctx -> ctx.clusterId())
                .toList();
    }

    public CompletionStage<List<Connector>> listConnectors(FieldFilter fields, ListRequestContext<Connector> listSupport) {
        var pendingClusterResults = consoleConfig.getKafkaConnectClusters()
                .stream()
                .filter(listSupport.filter(KafkaConnectConfig.class))
                .map(clusterConfig -> listConnectors(clusterConfig, fields, listSupport.getFetchParams()))
                .toList();

        return Promises.joinStages(pendingClusterResults)
                .thenApply(clusterResults -> clusterResults.stream().flatMap(Collection::stream))
                .thenApply(results -> results
                        .filter(listSupport.filter(Connector.class))
                        .map(listSupport::tally)
                        .filter(listSupport::betweenCursors)
                        .sorted(listSupport.getSortComparator())
                        .dropWhile(listSupport::beforePageBegin)
                        .takeWhile(listSupport::pageCapacityAvailable)
                        .toList());
    }

    public CompletionStage<Connector> describeConnector(
            String connectorId,
            FieldFilter fields,
            FetchParams fetchParams) {
        String[] idParts = Identifiers.decode(connectorId);
        KafkaConnectConfig clusterConfig = consoleConfig.getKafkaConnectCluster(idParts[0])
                .orElseThrow(() -> new NotFoundException("Unknown Kafka Connect connector"));
        return describeConnector(clusterConfig, idParts[1], fields, fetchParams);
    }

    private CompletionStage<List<Connector>> listConnectors(
            KafkaConnectConfig clusterConfig,
            FieldFilter fields,
            FetchParams fetchParams) {

        return connectClient.getConnectors(clusterConfig.clusterKey())
                .thenApplyAsync(names -> names.stream()
                        .map(name -> describeConnector(clusterConfig, name, fields, fetchParams)),
                        threadContext.currentContextExecutor())
                .thenCompose(Promises::joinStages);
    }

    private CompletionStage<Connector> describeConnector(
            KafkaConnectConfig clusterConfig,
            String connectorName,
            FieldFilter fields,
            FetchParams fetchParams) {

        var includeTopics = fields.isIncluded(Connector.FIELDS_PARAM, Connector.Fields.TOPICS.toString());
        var includeOffsets = fields.isIncluded(Connector.FIELDS_PARAM, Connector.Fields.OFFSETS.toString());

        var includeTasks = fetchParams.includes(Connector.Fields.TASKS.toString());
        var fetchTasks = includeTasks || fields.isIncluded(Connector.FIELDS_PARAM, Connector.Fields.TASKS.toString());
        var includeTaskConfigs = includeTasks && fields.isIncluded(ConnectorTask.FIELDS_PARAM, ConnectorTask.Fields.CONFIG.toString());

        var includeCluster = fetchParams.includes(Connector.Fields.CONNECT_CLUSTER.toString());
        var clusterPromise = includeCluster ? describeCluster(clusterConfig, fields, fetchParams, false) : PROMISE_NULL_CLUSTER;

        var topicsPromise = includeTopics
            ? describeConnectorTopics(clusterConfig, connectorName)
            : PROMISE_NULL_TOPICS;

        var offsetPromise = includeOffsets
            ? describeConnectorOffsets(clusterConfig, connectorName)
            : PROMISE_NULL_OFFSETS;

        var taskConfigPromise = includeTaskConfigs
            ? describeConnectorTasks(clusterConfig, connectorName)
            : PROMISE_EMPTY_CONFIG;

        var customResourcePromise = getConnectorResource(clusterConfig);

        return connectClient.getConnector(clusterConfig.clusterKey(), connectorName)
            .thenCombine(
                connectClient.getConnectorStatus(clusterConfig.clusterKey(), connectorName),
                (info, state) -> {
                    Connector connector = new Connector(Identifiers.encode("", clusterConfig.clusterKey(), connectorName));
                    connector.name(connectorName);
                    connector.namespace(clusterConfig.getNamespace());
                    connector.type(mapType(info));
                    connector.config(info.config());
                    connector.state(state.connector().state());
                    connector.trace(state.connector().trace());
                    connector.workerId(state.connector().workerId());

                    if (fetchTasks) {
                        mapTasks(connector, info, state, includeTasks);
                    }

                    return connector;
                }
            )
            .thenCombine(topicsPromise, Connector::topics)
            .thenCombine(offsetPromise, Connector::offsets)
            .thenCombine(taskConfigPromise, this::mapTaskConfigs)
            .thenCombine(
                clusterPromise,
                (connector, cluster) -> connector.connectCluster(cluster, includeCluster)
            )
            .thenCombine(customResourcePromise, (connector, customResource) -> {
                if (clusterConfig.isMirrorMaker().booleanValue()) {
                    customResource.map(KafkaMirrorMaker2.class::cast)
                        .map(KafkaMirrorMaker2::getStatus)
                        .map(KafkaMirrorMaker2Status::getConnectors)
                        .map(Collection::stream)
                        .orElseGet(Stream::empty)
                        .filter(entry -> connectorName.equals(entry.get("name")))
                        .findFirst()
                        .ifPresentOrElse(
                            entry -> connector.setManaged(Boolean.TRUE),
                            () -> connector.setManaged(Boolean.FALSE)
                        );
                } else {
                    connector.setManaged(Boolean.valueOf(customResource.isPresent()));
                }
                return connector;
            });
    }

    private String mapType(KafkaConnectAPI.ConnectorInfo info) {
        var config = Optional.ofNullable(info.config()).orElseGet(Collections::emptyMap);
        var className = config.getOrDefault("connector.class", "");
        return mapType(info.type(), className);
    }

    private String mapType(String type, String className) {
        if (mmCheckpoints.contains(className)) {
            type += ":mm-checkpoint";
        } else if (mmHeartbeats.contains(className)) {
            type += ":mm-heartbeat";
        } else if (mmSources.contains(className)) {
            type += ":mm";
        }

        return type;
    }

    private void mapTasks(Connector connector, KafkaConnectAPI.ConnectorInfo info, KafkaConnectAPI.ConnectorStateInfo state, boolean include) {
        List<ConnectorTask> tasks = new ArrayList<>();

        for (var taskInfo : info.tasks()) {
            var taskState = state.tasks().stream()
                    .filter(t -> Objects.equals(t.id(), taskInfo.task()))
                    .findFirst();
            var taskId = Identifiers.encode(connector.getId(), String.valueOf(taskInfo.task()));
            ConnectorTask task = new ConnectorTask(taskId);

            task.taskId(taskInfo.task());
            taskState.ifPresent(ts -> {
                task.state(ts.state());
                task.trace(ts.trace());
                task.workerId(ts.workerId());
            });
            task.connector(connector, include);
            tasks.add(task);
        }

        connector.tasks(tasks, true);
    }

    private Connector mapTaskConfigs(Connector connector, Map<Integer, Map<String, String>> configs) {
        for (var config : configs.entrySet()) {
            for (var task : connector.taskResources()) {
                if (task.taskId().equals(config.getKey())) {
                    task.config(config.getValue());
                    break;
                }
            }
        }

        return connector;
    }

    private CompletionStage<List<ConnectorPlugin>> describeConnectorPlugins(KafkaConnectConfig clusterConfig) {
        return connectClient.getConnectorPlugins(clusterConfig.clusterKey())
                .thenApply(plugins -> plugins.stream()
                        .map(plugin -> new ConnectorPlugin(
                                plugin.className(),
                                mapType(plugin.type(), plugin.className()),
                                plugin.version()))
                        .toList());
    }

    private CompletionStage<List<String>> describeConnectorTopics(KafkaConnectConfig clusterConfig, String connectorName) {
        return connectClient.getConnectorTopics(clusterConfig.clusterKey(), connectorName)
                .thenApply(topics -> Optional.ofNullable(topics.get(connectorName))
                        .map(KafkaConnectAPI.TopicInfo::topics)
                        .orElse(null));
    }

    private CompletionStage<List<Connector.ConnectorOffset>> describeConnectorOffsets(KafkaConnectConfig clusterConfig, String connectorName) {
        return connectClient.getConnectorOffsets(clusterConfig.clusterKey(), connectorName)
                .thenApply(ConnectorOffsets::offsets)
                .thenApply(offsets -> offsets.stream()
                        .map(o -> new Connector.ConnectorOffset(o.offset(), o.partition()))
                        .toList());
    }

    private CompletionStage<Map<Integer, Map<String, String>>> describeConnectorTasks(KafkaConnectConfig clusterConfig, String connectorName) {
        return connectClient.getConnectorTasks(clusterConfig.clusterKey(), connectorName)
                .thenApply(tasks -> tasks.stream()
                        .map(t -> Map.entry(t.id().task(), t.config()))
                        .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue)));
    }

    private CompletionStage<Optional<? extends CustomResource<?, ?>>> getConnectResource(KafkaConnectConfig clusterConfig) {
        String namespace = clusterConfig.getNamespace();
        String name = clusterConfig.getName();
        CompletableFuture<Optional<? extends CustomResource<?, ?>>> promise = new CompletableFuture<>();

        if (clusterConfig.isMirrorMaker().booleanValue()) {
            strimziService.getKafkaMirrorMaker2(namespace, name).thenApply(promise::complete);
        } else {
            strimziService.getKafkaConnect(namespace, name).thenApply(promise::complete);
        }

        return promise;
    }

    private CompletionStage<Optional<? extends CustomResource<?, ?>>> getConnectorResource(KafkaConnectConfig clusterConfig) {
        String namespace = clusterConfig.getNamespace();
        String name = clusterConfig.getName();
        CompletableFuture<Optional<? extends CustomResource<?, ?>>> promise = new CompletableFuture<>();

        if (clusterConfig.isMirrorMaker().booleanValue()) {
            strimziService.getKafkaMirrorMaker2(namespace, name).thenApply(promise::complete);
        } else {
            strimziService.getKafkaConnector(namespace, name).thenApply(promise::complete);
        }

        return promise;
    }
}
