implement exchange settings management and fallback rate handling

apps/edr-freight-api/src/modules/exchange-settings/exchange-settings.controller.ts

@@ -0,0 +1,68 @@
+import { Body, Controller, Get, Patch } from "@nestjs/common";
+import { ApiBearerAuth, ApiOperation, ApiTags } from "@nestjs/swagger";
+import { CurrentUser, ExchangeService } from "@edr/api-common";
+import type { TCurrentUser } from "@tria-plc/api-common/modules/auth/types/current-user.type";
+
+import { FreightAdmin } from "../../common/booking-guards";
+import { UpdateExchangeSettingDto } from "./dto/update-exchange-setting.dto";
+import { ExchangeSettingsService } from "./exchange-settings.service";
+
+@ApiTags("exchange-settings")
+@ApiBearerAuth()
+@Controller("exchange-settings")
+export class ExchangeSettingsController {
+  constructor(
+    private readonly service: ExchangeSettingsService,
+    private readonly exchangeService: ExchangeService,
+  ) {}
+
+  @Get()
+  @FreightAdmin()
+  @ApiOperation({
+    summary: "Current USD→ETB fallback rate and CBE feed health",
+  })
+  async get() {
+    const [setting, status] = [
+      await this.service.get(),
+      this.exchangeService.getProviderStatus(),
+    ];
+
+    return {
+      fallbackRate: setting.fallbackRate,
+      fallbackSource: setting.fallbackSource,
+      lastSyncedAt: setting.lastSyncedAt,
+      updatedById: setting.updatedById,
+      feed: {
+        rate: status.rate,
+        source: status.source,
+        lastSuccessAt: status.lastSuccessAt
+          ? new Date(status.lastSuccessAt).toISOString()
+          : null,
+        lastError: status.lastError,
+      },
+    };
+  }
+
+  @Patch()
+  @FreightAdmin()
+  @ApiOperation({
+    summary:
+      "Set the USD→ETB fallback by hand (used only while CBE is unreachable)",
+  })
+  async update(
+    @Body() dto: UpdateExchangeSettingDto,
+    @CurrentUser() user: TCurrentUser,
+  ) {
+    const updated = await this.service.setManualRate(
+      dto.fallbackRate,
+      user?.id ?? null,
+    );
+
+    return {
+      fallbackRate: updated.fallbackRate,
+      fallbackSource: updated.fallbackSource,
+      lastSyncedAt: updated.lastSyncedAt,
+      updatedById: updated.updatedById,
+    };
+  }
+}