feat(dashboard): Implemented basic message types, handlers and API endpoints

Author: kushagra0902

src/dashboard-service/api/dashboard-router.ts

@@ -0,0 +1,12 @@
+import { Router } from 'express'
+
+import { createGetKPISnapshotRequestHandler } from '../handlers/request-handlers/get-kpi-snapshot-request-handler'
+import { SnapshotService } from '../services/snapshot-service'
+
+export const createDashboardRouter = (snapshotService: SnapshotService): Router => {
+  const router = Router()
+
+  router.get('/snapshot', createGetKPISnapshotRequestHandler(snapshotService))
+
+  return router
+}

src/dashboard-service/controllers/get-health-controller.ts

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+import { Request, Response } from 'express'
+
+import { IController } from '../../@types/controllers'
+
+export class GetHealthController implements IController {
+  public async handleRequest(_request: Request, response: Response): Promise<void> {
+    response
+      .status(200)
+      .setHeader('content-type', 'application/json; charset=utf-8')
+      .send({ status: 'ok' })
+  }
+}

src/dashboard-service/controllers/get-kpi-snapshot-controller.ts

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+import { Request, Response } from 'express'
+
+import { DashboardSnapshotResponse } from '../types'
+import { IController } from '../../@types/controllers'
+import { SnapshotService } from '../services/snapshot-service'
+
+export class GetKPISnapshotController implements IController {
+  public constructor(private readonly snapshotService: SnapshotService) { }
+
+  public async handleRequest(_request: Request, response: Response): Promise<void> {
+    const payload: DashboardSnapshotResponse = {
+      data: this.snapshotService.getSnapshot(),
+    }
+
+    response
+      .status(200)
+      .setHeader('content-type', 'application/json; charset=utf-8')
+      .send(payload)
+  }
+}

src/dashboard-service/handlers/request-handlers/get-health-request-handler.ts

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+import { withController } from '../../../handlers/request-handlers/with-controller-request-handler'
+
+import { GetHealthController } from '../../controllers/get-health-controller'
+
+export const getHealthRequestHandler = withController(() => new GetHealthController())

src/dashboard-service/handlers/request-handlers/get-kpi-snapshot-request-handler.ts

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+import { withController } from '../../../handlers/request-handlers/with-controller-request-handler'
+
+import { GetKPISnapshotController } from '../../controllers/get-kpi-snapshot-controller'
+import { SnapshotService } from '../../services/snapshot-service'
+
+export const createGetKPISnapshotRequestHandler = (snapshotService: SnapshotService) => {
+  return withController(() => new GetKPISnapshotController(snapshotService))
+}

src/dashboard-service/types.ts

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+export interface TopTalker {
+  pubkey: string
+  count: number
+}
+
+export interface KPISnapshot {
+  sequence: number
+  generatedAt: string
+  status: 'placeholder'
+  metrics: {
+    eventsByKind: Array<{ kind: string, count: number }>
+    admittedUsers: number | null
+    satsPaid: number | null
+    topTalkers: TopTalker[]
+  }
+}
+
+export interface DashboardSnapshotResponse {
+  data: KPISnapshot
+}
+
+export interface DashboardWebSocketEnvelope<TType extends string, TPayload> {
+  type: TType
+  payload: TPayload
+}
+
+export type DashboardServerMessage =
+  | DashboardWebSocketEnvelope<'dashboard.connected', { at: string }>
+  | DashboardWebSocketEnvelope<'kpi.snapshot', KPISnapshot>
+  | DashboardWebSocketEnvelope<'kpi.tick', { at: string, sequence: number }>