import { collectDefaultMetrics } from 'prom-client';
import memoizee from 'memoizee';
import type EventEmitter from 'events';
import type { Knex } from 'knex';
import * as events from './metric-events';
import {
    DB_POOL_UPDATE,
    FEATURE_ARCHIVED,
    FEATURE_CREATED,
    FEATURE_REVIVED,
    FEATURE_STRATEGY_ADD,
    FEATURE_STRATEGY_REMOVE,
    FEATURE_STRATEGY_UPDATE,
    FEATURE_ENVIRONMENT_ENABLED,
    FEATURE_ENVIRONMENT_DISABLED,
    FEATURE_VARIANTS_UPDATED,
    FEATURE_METADATA_UPDATED,
    FEATURE_UPDATED,
    CLIENT_METRICS,
    CLIENT_REGISTER,
    PROJECT_ENVIRONMENT_REMOVED,
} from './types/events';
import type { IUnleashConfig } from './types/option';
import type { ISettingStore, IUnleashStores } from './types/stores';
import { hoursToMilliseconds, minutesToMilliseconds } from 'date-fns';
import type { InstanceStatsService } from './features/instance-stats/instance-stats-service';
import type { IEnvironment, ISdkHeartbeat } from './types';
import {
    createCounter,
    createGauge,
    createSummary,
    createHistogram,
} from './util/metrics';
import type { SchedulerService } from './services';
import type { IClientMetricsEnv } from './features/metrics/client-metrics/client-metrics-store-v2-type';

export default class MetricsMonitor {
    constructor() {}

    async startMonitoring(
        config: IUnleashConfig,
        stores: IUnleashStores,
        version: string,
        eventBus: EventEmitter,
        instanceStatsService: InstanceStatsService,
        schedulerService: SchedulerService,
        db: Knex,
    ): Promise<void> {
        if (!config.server.serverMetrics) {
            return Promise.resolve();
        }

        const { eventStore, environmentStore } = stores;
        const { flagResolver } = config;

        const cachedEnvironments: () => Promise<IEnvironment[]> = memoizee(
            async () => environmentStore.getAll(),
            {
                promise: true,
                maxAge: hoursToMilliseconds(1),
            },
        );

        collectDefaultMetrics();

        const requestDuration = createSummary({
            name: 'http_request_duration_milliseconds',
            help: 'App response time',
            labelNames: ['path', 'method', 'status', 'appName'],
            percentiles: [0.1, 0.5, 0.9, 0.95, 0.99],
            maxAgeSeconds: 600,
            ageBuckets: 5,
        });
        const schedulerDuration = createSummary({
            name: 'scheduler_duration_seconds',
            help: 'Scheduler duration time',
            labelNames: ['jobId'],
            percentiles: [0.1, 0.5, 0.9, 0.95, 0.99],
            maxAgeSeconds: 600,
            ageBuckets: 5,
        });
        const dbDuration = createSummary({
            name: 'db_query_duration_seconds',
            help: 'DB query duration time',
            labelNames: ['store', 'action'],
            percentiles: [0.1, 0.5, 0.9, 0.95, 0.99],
            maxAgeSeconds: 600,
            ageBuckets: 5,
        });
        const functionDuration = createSummary({
            name: 'function_duration_seconds',
            help: 'Function duration time',
            labelNames: ['functionName', 'className'],
            percentiles: [0.1, 0.5, 0.9, 0.95, 0.99],
            maxAgeSeconds: 600,
            ageBuckets: 5,
        });
        const featureFlagUpdateTotal = createCounter({
            name: 'feature_toggle_update_total',
            help: 'Number of times a toggle has been updated. Environment label would be "n/a" when it is not available, e.g. when a feature flag is created.',
            labelNames: ['toggle', 'project', 'environment', 'environmentType'],
        });
        const featureFlagUsageTotal = createCounter({
            name: 'feature_toggle_usage_total',
            help: 'Number of times a feature flag has been used',
            labelNames: ['toggle', 'active', 'appName'],
        });
        const featureFlagsTotal = createGauge({
            name: 'feature_toggles_total',
            help: 'Number of feature flags',
            labelNames: ['version'],
        });
        const maxFeatureEnvironmentStrategies = createGauge({
            name: 'max_feature_environment_strategies',
            help: 'Maximum number of environment strategies in one feature',
            labelNames: ['feature', 'environment'],
        });
        const maxFeatureStrategies = createGauge({
            name: 'max_feature_strategies',
            help: 'Maximum number of strategies in one feature',
            labelNames: ['feature'],
        });
        const maxConstraintValues = createGauge({
            name: 'max_constraint_values',
            help: 'Maximum number of constraint values used in a single constraint',
            labelNames: ['feature', 'environment'],
        });
        const maxConstraintsPerStrategy = createGauge({
            name: 'max_strategy_constraints',
            help: 'Maximum number of constraints used on a single strategy',
            labelNames: ['feature', 'environment'],
        });
        const largestProjectEnvironment = createGauge({
            name: 'largest_project_environment_size',
            help: 'The largest project environment size (bytes) based on strategies, constraints, variants and parameters',
            labelNames: ['project', 'environment'],
        });
        const largestFeatureEnvironment = createGauge({
            name: 'largest_feature_environment_size',
            help: 'The largest feature environment size (bytes) base on strategies, constraints, variants and parameters',
            labelNames: ['feature', 'environment'],
        });

        const featureTogglesArchivedTotal = createGauge({
            name: 'feature_toggles_archived_total',
            help: 'Number of archived feature flags',
        });
        const usersTotal = createGauge({
            name: 'users_total',
            help: 'Number of users',
        });
        const serviceAccounts = createGauge({
            name: 'service_accounts_total',
            help: 'Number of service accounts',
        });
        const apiTokens = createGauge({
            name: 'api_tokens_total',
            help: 'Number of API tokens',
            labelNames: ['type'],
        });
        const enabledMetricsBucketsPreviousDay = createGauge({
            name: 'enabled_metrics_buckets_previous_day',
            help: 'Number of hourly enabled/disabled metric buckets in the previous day',
        });
        const variantMetricsBucketsPreviousDay = createGauge({
            name: 'variant_metrics_buckets_previous_day',
            help: 'Number of hourly variant metric buckets in the previous day',
        });
        const usersActive7days = createGauge({
            name: 'users_active_7',
            help: 'Number of users active in the last 7 days',
        });
        const usersActive30days = createGauge({
            name: 'users_active_30',
            help: 'Number of users active in the last 30 days',
        });
        const usersActive60days = createGauge({
            name: 'users_active_60',
            help: 'Number of users active in the last 60 days',
        });
        const usersActive90days = createGauge({
            name: 'users_active_90',
            help: 'Number of users active in the last 90 days',
        });
        const projectsTotal = createGauge({
            name: 'projects_total',
            help: 'Number of projects',
            labelNames: ['mode'],
        });
        const environmentsTotal = createGauge({
            name: 'environments_total',
            help: 'Number of environments',
        });
        const groupsTotal = createGauge({
            name: 'groups_total',
            help: 'Number of groups',
        });

        const rolesTotal = createGauge({
            name: 'roles_total',
            help: 'Number of roles',
        });

        const customRootRolesTotal = createGauge({
            name: 'custom_root_roles_total',
            help: 'Number of custom root roles',
        });

        const customRootRolesInUseTotal = createGauge({
            name: 'custom_root_roles_in_use_total',
            help: 'Number of custom root roles in use',
        });

        const segmentsTotal = createGauge({
            name: 'segments_total',
            help: 'Number of segments',
        });

        const contextTotal = createGauge({
            name: 'context_total',
            help: 'Number of context',
        });

        const strategiesTotal = createGauge({
            name: 'strategies_total',
            help: 'Number of strategies',
        });

        const clientAppsTotal = createGauge({
            name: 'client_apps_total',
            help: 'Number of registered client apps aggregated by range by last seen',
            labelNames: ['range'],
        });

        const samlEnabled = createGauge({
            name: 'saml_enabled',
            help: 'Whether SAML is enabled',
        });

        const oidcEnabled = createGauge({
            name: 'oidc_enabled',
            help: 'Whether OIDC is enabled',
        });

        const clientSdkVersionUsage = createCounter({
            name: 'client_sdk_versions',
            help: 'Which sdk versions are being used',
            labelNames: [
                'sdk_name',
                'sdk_version',
                'platform_name',
                'platform_version',
                'yggdrasil_version',
                'spec_version',
            ],
        });

        const productionChanges30 = createGauge({
            name: 'production_changes_30',
            help: 'Changes made to production environment last 30 days',
            labelNames: ['environment'],
        });
        const productionChanges60 = createGauge({
            name: 'production_changes_60',
            help: 'Changes made to production environment last 60 days',
            labelNames: ['environment'],
        });
        const productionChanges90 = createGauge({
            name: 'production_changes_90',
            help: 'Changes made to production environment last 90 days',
            labelNames: ['environment'],
        });

        const rateLimits = createGauge({
            name: 'rate_limits',
            help: 'Rate limits (per minute) for METHOD/ENDPOINT pairs',
            labelNames: ['endpoint', 'method'],
        });
        const featureCreatedByMigration = createCounter({
            name: 'feature_created_by_migration_count',
            help: 'Feature createdBy migration count',
        });
        const eventCreatedByMigration = createCounter({
            name: 'event_created_by_migration_count',
            help: 'Event createdBy migration count',
        });
        const proxyRepositoriesCreated = createCounter({
            name: 'proxy_repositories_created',
            help: 'Proxy repositories created',
        });
        const frontendApiRepositoriesCreated = createCounter({
            name: 'frontend_api_repositories_created',
            help: 'Frontend API repositories created',
        });
        const mapFeaturesForClientDuration = createHistogram({
            name: 'map_features_for_client_duration',
            help: 'Duration of mapFeaturesForClient function',
        });

        const featureLifecycleStageDuration = createGauge({
            name: 'feature_lifecycle_stage_duration',
            labelNames: ['stage', 'project_id'],
            help: 'Duration of feature lifecycle stages',
        });

        const featureLifecycleStageCountByProject = createGauge({
            name: 'feature_lifecycle_stage_count_by_project',
            help: 'Count features in a given stage by project id',
            labelNames: ['stage', 'project_id'],
        });

        const featureLifecycleStageEnteredCounter = createCounter({
            name: 'feature_lifecycle_stage_entered',
            help: 'Count how many features entered a given stage',
            labelNames: ['stage'],
        });

        const projectEnvironmentsDisabled = createCounter({
            name: 'project_environments_disabled',
            help: 'How many "environment disabled" events we have received for each project',
            labelNames: ['project_id'],
        });

        const orphanedTokensTotal = createGauge({
            name: 'orphaned_api_tokens_total',
            help: 'Number of API tokens without a project',
        });

        const orphanedTokensActive = createGauge({
            name: 'orphaned_api_tokens_active',
            help: 'Number of API tokens without a project, last seen within 3 months',
        });

        const legacyTokensTotal = createGauge({
            name: 'legacy_api_tokens_total',
            help: 'Number of API tokens with v1 format',
        });

        const legacyTokensActive = createGauge({
            name: 'legacy_api_tokens_active',
            help: 'Number of API tokens with v1 format, last seen within 3 months',
        });

        const exceedsLimitErrorCounter = createCounter({
            name: 'exceeds_limit_error',
            help: 'The number of exceeds limit errors registered by this instance.',
            labelNames: ['resource', 'limit'],
        });

        async function collectStaticCounters() {
            try {
                const stats = await instanceStatsService.getStats();
                const [
                    maxStrategies,
                    maxEnvironmentStrategies,
                    maxConstraintValuesResult,
                    maxConstraintsPerStrategyResult,
                    stageCountByProjectResult,
                    stageDurationByProject,
                    largestProjectEnvironments,
                    largestFeatureEnvironments,
                    deprecatedTokens,
                ] = await Promise.all([
                    stores.featureStrategiesReadModel.getMaxFeatureStrategies(),
                    stores.featureStrategiesReadModel.getMaxFeatureEnvironmentStrategies(),
                    stores.featureStrategiesReadModel.getMaxConstraintValues(),
                    stores.featureStrategiesReadModel.getMaxConstraintsPerStrategy(),
                    stores.featureLifecycleReadModel.getStageCountByProject(),
                    stores.featureLifecycleReadModel.getAllWithStageDuration(),
                    stores.largestResourcesReadModel.getLargestProjectEnvironments(
                        1,
                    ),
                    stores.largestResourcesReadModel.getLargestFeatureEnvironments(
                        1,
                    ),
                    stores.apiTokenStore.countDeprecatedTokens(),
                ]);

                featureFlagsTotal.reset();
                featureFlagsTotal.labels({ version }).set(stats.featureToggles);

                featureTogglesArchivedTotal.reset();
                featureTogglesArchivedTotal.set(stats.archivedFeatureToggles);

                usersTotal.reset();
                usersTotal.set(stats.users);

                serviceAccounts.reset();
                serviceAccounts.set(stats.serviceAccounts);

                stageDurationByProject.forEach((stage) => {
                    featureLifecycleStageDuration
                        .labels({
                            stage: stage.stage,
                            project_id: stage.project,
                        })
                        .set(stage.duration);
                });

                eventBus.on(
                    events.STAGE_ENTERED,
                    (entered: { stage: string; feature: string }) => {
                        featureLifecycleStageEnteredCounter
                            .labels({ stage: entered.stage })
                            .inc();
                    },
                );

                eventBus.on(
                    events.EXCEEDS_LIMIT,
                    ({
                        resource,
                        limit,
                    }: { resource: string; limit: number }) => {
                        exceedsLimitErrorCounter
                            .labels({ resource, limit })
                            .inc();
                    },
                );

                featureLifecycleStageCountByProject.reset();
                stageCountByProjectResult.forEach((stageResult) =>
                    featureLifecycleStageCountByProject
                        .labels({
                            project_id: stageResult.project,
                            stage: stageResult.stage,
                        })
                        .set(stageResult.count),
                );

                apiTokens.reset();

                for (const [type, value] of stats.apiTokens) {
                    apiTokens.labels({ type }).set(value);
                }

                orphanedTokensTotal.reset();
                orphanedTokensTotal.set(deprecatedTokens.orphanedTokens);

                orphanedTokensActive.reset();
                orphanedTokensActive.set(deprecatedTokens.activeOrphanedTokens);

                legacyTokensTotal.reset();
                legacyTokensTotal.set(deprecatedTokens.legacyTokens);

                legacyTokensActive.reset();
                legacyTokensActive.set(deprecatedTokens.activeLegacyTokens);

                if (maxEnvironmentStrategies) {
                    maxFeatureEnvironmentStrategies.reset();
                    maxFeatureEnvironmentStrategies
                        .labels({
                            environment: maxEnvironmentStrategies.environment,
                            feature: maxEnvironmentStrategies.feature,
                        })
                        .set(maxEnvironmentStrategies.count);
                }
                if (maxStrategies) {
                    maxFeatureStrategies.reset();
                    maxFeatureStrategies
                        .labels({ feature: maxStrategies.feature })
                        .set(maxStrategies.count);
                }
                if (maxConstraintValuesResult) {
                    maxConstraintValues.reset();
                    maxConstraintValues
                        .labels({
                            environment: maxConstraintValuesResult.environment,
                            feature: maxConstraintValuesResult.feature,
                        })
                        .set(maxConstraintValuesResult.count);
                }
                if (maxConstraintsPerStrategyResult) {
                    maxConstraintsPerStrategy.reset();
                    maxConstraintsPerStrategy
                        .labels({
                            environment:
                                maxConstraintsPerStrategyResult.environment,
                            feature: maxConstraintsPerStrategyResult.feature,
                        })
                        .set(maxConstraintsPerStrategyResult.count);
                }

                if (largestProjectEnvironments.length > 0) {
                    const projectEnvironment = largestProjectEnvironments[0];
                    largestProjectEnvironment.reset();
                    largestProjectEnvironment
                        .labels({
                            project: projectEnvironment.project,
                            environment: projectEnvironment.environment,
                        })
                        .set(projectEnvironment.size);
                }

                if (largestFeatureEnvironments.length > 0) {
                    const featureEnvironment = largestFeatureEnvironments[0];
                    largestFeatureEnvironment.reset();
                    largestFeatureEnvironment
                        .labels({
                            feature: featureEnvironment.feature,
                            environment: featureEnvironment.environment,
                        })
                        .set(featureEnvironment.size);
                }

                enabledMetricsBucketsPreviousDay.reset();
                enabledMetricsBucketsPreviousDay.set(
                    stats.previousDayMetricsBucketsCount.enabledCount,
                );
                variantMetricsBucketsPreviousDay.reset();
                variantMetricsBucketsPreviousDay.set(
                    stats.previousDayMetricsBucketsCount.variantCount,
                );

                usersActive7days.reset();
                usersActive7days.set(stats.activeUsers.last7);
                usersActive30days.reset();
                usersActive30days.set(stats.activeUsers.last30);
                usersActive60days.reset();
                usersActive60days.set(stats.activeUsers.last60);
                usersActive90days.reset();
                usersActive90days.set(stats.activeUsers.last90);

                productionChanges30.reset();
                productionChanges30.set(stats.productionChanges.last30);
                productionChanges60.reset();
                productionChanges60.set(stats.productionChanges.last60);
                productionChanges90.reset();
                productionChanges90.set(stats.productionChanges.last90);

                projectsTotal.reset();
                stats.projects.forEach((projectStat) => {
                    projectsTotal
                        .labels({ mode: projectStat.mode })
                        .set(projectStat.count);
                });

                environmentsTotal.reset();
                environmentsTotal.set(stats.environments);

                groupsTotal.reset();
                groupsTotal.set(stats.groups);

                rolesTotal.reset();
                rolesTotal.set(stats.roles);

                customRootRolesTotal.reset();
                customRootRolesTotal.set(stats.customRootRoles);

                customRootRolesInUseTotal.reset();
                customRootRolesInUseTotal.set(stats.customRootRolesInUse);

                segmentsTotal.reset();
                segmentsTotal.set(stats.segments);

                contextTotal.reset();
                contextTotal.set(stats.contextFields);

                strategiesTotal.reset();
                strategiesTotal.set(stats.strategies);

                samlEnabled.reset();
                samlEnabled.set(stats.SAMLenabled ? 1 : 0);

                oidcEnabled.reset();
                oidcEnabled.set(stats.OIDCenabled ? 1 : 0);

                clientAppsTotal.reset();
                stats.clientApps.forEach(({ range, count }) =>
                    clientAppsTotal.labels({ range }).set(count),
                );

                rateLimits.reset();
                rateLimits
                    .labels({
                        endpoint: '/api/client/metrics',
                        method: 'POST',
                    })
                    .set(config.metricsRateLimiting.clientMetricsMaxPerMinute);
                rateLimits
                    .labels({
                        endpoint: '/api/client/register',
                        method: 'POST',
                    })
                    .set(config.metricsRateLimiting.clientRegisterMaxPerMinute);
                rateLimits
                    .labels({
                        endpoint: '/api/frontend/metrics',
                        method: 'POST',
                    })
                    .set(
                        config.metricsRateLimiting.frontendMetricsMaxPerMinute,
                    );
                rateLimits
                    .labels({
                        endpoint: '/api/frontend/register',
                        method: 'POST',
                    })
                    .set(
                        config.metricsRateLimiting.frontendRegisterMaxPerMinute,
                    );
                rateLimits
                    .labels({
                        endpoint: '/api/admin/user-admin',
                        method: 'POST',
                    })
                    .set(config.rateLimiting.createUserMaxPerMinute);
                rateLimits
                    .labels({
                        endpoint: '/auth/simple',
                        method: 'POST',
                    })
                    .set(config.rateLimiting.simpleLoginMaxPerMinute);
                rateLimits
                    .labels({
                        endpoint: '/auth/reset/password-email',
                        method: 'POST',
                    })
                    .set(config.rateLimiting.passwordResetMaxPerMinute);
                rateLimits
                    .labels({
                        endpoint: '/api/signal-endpoint/:name',
                        method: 'POST',
                    })
                    .set(
                        config.rateLimiting.callSignalEndpointMaxPerSecond * 60,
                    );
            } catch (e) {}
        }

        await schedulerService.schedule(
            collectStaticCounters.bind(this),
            hoursToMilliseconds(2),
            'collectStaticCounters',
            0, // no jitter
        );

        eventBus.on(
            events.REQUEST_TIME,
            ({ path, method, time, statusCode, appName }) => {
                requestDuration
                    .labels({
                        path,
                        method,
                        status: statusCode,
                        appName,
                    })
                    .observe(time);
            },
        );

        eventBus.on(events.SCHEDULER_JOB_TIME, ({ jobId, time }) => {
            schedulerDuration.labels(jobId).observe(time);
        });

        eventBus.on(
            events.FUNCTION_TIME,
            ({ functionName, className, time }) => {
                functionDuration
                    .labels({
                        functionName,
                        className,
                    })
                    .observe(time);
            },
        );

        eventBus.on(events.EVENTS_CREATED_BY_PROCESSED, ({ updated }) => {
            eventCreatedByMigration.inc(updated);
        });

        eventBus.on(events.FEATURES_CREATED_BY_PROCESSED, ({ updated }) => {
            featureCreatedByMigration.inc(updated);
        });

        eventBus.on(events.DB_TIME, ({ store, action, time }) => {
            dbDuration
                .labels({
                    store,
                    action,
                })
                .observe(time);
        });

        eventBus.on(events.PROXY_REPOSITORY_CREATED, () => {
            proxyRepositoriesCreated.inc();
        });

        eventBus.on(events.FRONTEND_API_REPOSITORY_CREATED, () => {
            frontendApiRepositoriesCreated.inc();
        });

        eventBus.on(events.PROXY_FEATURES_FOR_TOKEN_TIME, ({ duration }) => {
            mapFeaturesForClientDuration.observe(duration);
        });

        eventStore.on(FEATURE_CREATED, ({ featureName, project }) => {
            featureFlagUpdateTotal.increment({
                toggle: featureName,
                project,
                environment: 'n/a',
                environmentType: 'n/a',
            });
        });
        eventStore.on(FEATURE_VARIANTS_UPDATED, ({ featureName, project }) => {
            featureFlagUpdateTotal.increment({
                toggle: featureName,
                project,
                environment: 'n/a',
                environmentType: 'n/a',
            });
        });
        eventStore.on(FEATURE_METADATA_UPDATED, ({ featureName, project }) => {
            featureFlagUpdateTotal.increment({
                toggle: featureName,
                project,
                environment: 'n/a',
                environmentType: 'n/a',
            });
        });
        eventStore.on(FEATURE_UPDATED, ({ featureName, project }) => {
            featureFlagUpdateTotal.increment({
                toggle: featureName,
                project,
                environment: 'default',
                environmentType: 'production',
            });
        });
        eventStore.on(
            FEATURE_STRATEGY_ADD,
            async ({ featureName, project, environment }) => {
                const environmentType = await this.resolveEnvironmentType(
                    environment,
                    cachedEnvironments,
                );
                featureFlagUpdateTotal.increment({
                    toggle: featureName,
                    project,
                    environment,
                    environmentType,
                });
            },
        );
        eventStore.on(
            FEATURE_STRATEGY_REMOVE,
            async ({ featureName, project, environment }) => {
                const environmentType = await this.resolveEnvironmentType(
                    environment,
                    cachedEnvironments,
                );
                featureFlagUpdateTotal.increment({
                    toggle: featureName,
                    project,
                    environment,
                    environmentType,
                });
            },
        );
        eventStore.on(
            FEATURE_STRATEGY_UPDATE,
            async ({ featureName, project, environment }) => {
                const environmentType = await this.resolveEnvironmentType(
                    environment,
                    cachedEnvironments,
                );
                featureFlagUpdateTotal.increment({
                    toggle: featureName,
                    project,
                    environment,
                    environmentType,
                });
            },
        );
        eventStore.on(
            FEATURE_ENVIRONMENT_DISABLED,
            async ({ featureName, project, environment }) => {
                const environmentType = await this.resolveEnvironmentType(
                    environment,
                    cachedEnvironments,
                );
                featureFlagUpdateTotal.increment({
                    toggle: featureName,
                    project,
                    environment,
                    environmentType,
                });
            },
        );
        eventStore.on(
            FEATURE_ENVIRONMENT_ENABLED,
            async ({ featureName, project, environment }) => {
                const environmentType = await this.resolveEnvironmentType(
                    environment,
                    cachedEnvironments,
                );
                featureFlagUpdateTotal.increment({
                    toggle: featureName,
                    project,
                    environment,
                    environmentType,
                });
            },
        );
        eventStore.on(FEATURE_ARCHIVED, ({ featureName, project }) => {
            featureFlagUpdateTotal.increment({
                toggle: featureName,
                project,
                environment: 'n/a',
                environmentType: 'n/a',
            });
        });
        eventStore.on(FEATURE_REVIVED, ({ featureName, project }) => {
            featureFlagUpdateTotal.increment({
                toggle: featureName,
                project,
                environment: 'n/a',
                environmentType: 'n/a',
            });
        });

        const logger = config.getLogger('metrics.ts');
        eventBus.on(CLIENT_METRICS, (metrics: IClientMetricsEnv[]) => {
            try {
                for (const metric of metrics) {
                    featureFlagUsageTotal.increment(
                        {
                            toggle: metric.featureName,
                            active: 'true',
                            appName: metric.appName,
                        },
                        metric.yes,
                    );
                    featureFlagUsageTotal.increment(
                        {
                            toggle: metric.featureName,
                            active: 'false',
                            appName: metric.appName,
                        },
                        metric.no,
                    );
                }
            } catch (e) {
                logger.warn('Metrics registration failed', e);
            }
        });

        eventStore.on(CLIENT_REGISTER, (heartbeatEvent: ISdkHeartbeat) => {
            if (!heartbeatEvent.sdkName || !heartbeatEvent.sdkVersion) {
                return;
            }

            if (flagResolver.isEnabled('extendedMetrics')) {
                clientSdkVersionUsage.increment({
                    sdk_name: heartbeatEvent.sdkName,
                    sdk_version: heartbeatEvent.sdkVersion,
                    platform_name:
                        heartbeatEvent.metadata?.platformName ?? 'not-set',
                    platform_version:
                        heartbeatEvent.metadata?.platformVersion ?? 'not-set',
                    yggdrasil_version:
                        heartbeatEvent.metadata?.yggdrasilVersion ?? 'not-set',
                    spec_version:
                        heartbeatEvent.metadata?.specVersion ?? 'not-set',
                });
            } else {
                clientSdkVersionUsage.increment({
                    sdk_name: heartbeatEvent.sdkName,
                    sdk_version: heartbeatEvent.sdkVersion,
                    platform_name: 'not-set',
                    platform_version: 'not-set',
                    yggdrasil_version: 'not-set',
                    spec_version: 'not-set',
                });
            }
        });

        eventStore.on(PROJECT_ENVIRONMENT_REMOVED, ({ project }) => {
            projectEnvironmentsDisabled.increment({ project_id: project });
        });

        await this.configureDbMetrics(
            db,
            eventBus,
            schedulerService,
            stores.settingStore,
        );

        return Promise.resolve();
    }

    async configureDbMetrics(
        db: Knex,
        eventBus: EventEmitter,
        schedulerService: SchedulerService,
        settingStore: ISettingStore,
    ): Promise<void> {
        if (db?.client) {
            const dbPoolMin = createGauge({
                name: 'db_pool_min',
                help: 'Minimum DB pool size',
            });
            dbPoolMin.set(db.client.pool.min);
            const dbPoolMax = createGauge({
                name: 'db_pool_max',
                help: 'Maximum DB pool size',
            });
            dbPoolMax.set(db.client.pool.max);
            const dbPoolFree = createGauge({
                name: 'db_pool_free',
                help: 'Current free connections in DB pool',
            });
            const dbPoolUsed = createGauge({
                name: 'db_pool_used',
                help: 'Current connections in use in DB pool',
            });
            const dbPoolPendingCreates = createGauge({
                name: 'db_pool_pending_creates',
                help: 'how many asynchronous create calls are running in DB pool',
            });
            const dbPoolPendingAcquires = createGauge({
                name: 'db_pool_pending_acquires',
                help: 'how many acquires are waiting for a resource to be released in DB pool',
            });

            eventBus.on(DB_POOL_UPDATE, (data) => {
                dbPoolFree.set(data.free);
                dbPoolUsed.set(data.used);
                dbPoolPendingCreates.set(data.pendingCreates);
                dbPoolPendingAcquires.set(data.pendingAcquires);
            });

            await schedulerService.schedule(
                async () =>
                    this.registerPoolMetrics.bind(
                        this,
                        db.client.pool,
                        eventBus,
                    ),
                minutesToMilliseconds(1),
                'registerPoolMetrics',
                0, // no jitter
            );
            const postgresVersion = await settingStore.postgresVersion();
            const database_version = createGauge({
                name: 'postgres_version',
                help: 'Which version of postgres is running (SHOW server_version)',
                labelNames: ['version'],
            });
            database_version.labels({ version: postgresVersion }).set(1);
        }
    }

    // eslint-disable-next-line @typescript-eslint/explicit-module-boundary-types
    registerPoolMetrics(pool: any, eventBus: EventEmitter) {
        try {
            eventBus.emit(DB_POOL_UPDATE, {
                used: pool.numUsed(),
                free: pool.numFree(),
                pendingCreates: pool.numPendingCreates(),
                pendingAcquires: pool.numPendingAcquires(),
            });
            // eslint-disable-next-line no-empty
        } catch (e) {}
    }

    async resolveEnvironmentType(
        environment: string,
        cachedEnvironments: () => Promise<IEnvironment[]>,
    ): Promise<string> {
        const environments = await cachedEnvironments();
        const env = environments.find((e) => e.name === environment);

        if (env) {
            return env.type;
        } else {
            return 'unknown';
        }
    }
}

export function createMetricsMonitor(): MetricsMonitor {
    return new MetricsMonitor();
}

module.exports = {
    createMetricsMonitor,
};