import { BadRequestException, Body, Controller, Get, Param, Patch } from "@nestjs/common";
import { ApiBearerAuth, ApiOperation, ApiTags } from "@nestjs/swagger";
import { CURRENCY_CODES, CurrencyCode, CurrentUser } from "@edr/api-common";
import type { TCurrentUser } from "@tria-plc/api-common/modules/auth/types/current-user.type";

import { BookingStaff } from "../../common/booking-guards";
import { FREIGHT_PERMS } from "../../seed/freight-permissions.registry";
import { UpdateExchangeSettingDto } from "./dto/update-exchange-setting.dto";
import { ExchangeSettingsService } from "./exchange-settings.service";

/**
 * Sane manual-rate ceiling per currency — bounded well outside any plausible
 * published rate but far short of a fat-fingered magnitude error. USD trades
 * in the hundreds (ETB per USD); DJF trades under 2 (ETB per DJF, since DJF
 * itself is worth roughly 1/177th of a USD).
 */
const RATE_BOUNDS: Record<CurrencyCode, number> = {
  ETB: 1,
  USD: 10_000,
  DJF: 100,
};

const FOREIGN_CURRENCIES = CURRENCY_CODES.filter((c) => c !== "ETB");

function assertSupportedCurrency(currency: string): (typeof FOREIGN_CURRENCIES)[number] {
  const code = currency?.toUpperCase();
  const match = FOREIGN_CURRENCIES.find((c) => c === code);
  if (!match) {
    throw new BadRequestException(
      `Unsupported currency "${currency}" — must be one of ${FOREIGN_CURRENCIES.join(", ")}`,
    );
  }
  return match;
}

@ApiTags("exchange-settings")
@ApiBearerAuth()
@Controller("exchange-settings")
export class ExchangeSettingsController {
  constructor(private readonly service: ExchangeSettingsService) {}

  @Get()
  @BookingStaff([FREIGHT_PERMS.settings.exchangeRate.view, FREIGHT_PERMS.admin])
  @ApiOperation({
    summary: "Current X→ETB fallback rates and CBE feed health, one entry per currency",
  })
  async list() {
    const settings = await this.service.list();
    const byCurrency = new Map(settings.map((s) => [s.currency, s]));

    return FOREIGN_CURRENCIES.map((code) => {
      const setting = byCurrency.get(code);
      return {
        currency: code,
        fallbackRate: setting?.fallbackRate ?? null,
        fallbackSource: setting?.fallbackSource ?? null,
        lastSyncedAt: setting?.lastSyncedAt ?? null,
        updatedById: setting?.updatedById ?? null,
        feed: this.service.getFeedStatus(code),
      };
    });
  }

  @Patch(":currency")
  @BookingStaff([FREIGHT_PERMS.settings.exchangeRate.manage, FREIGHT_PERMS.admin])
  @ApiOperation({
    summary:
      "Set a currency's X→ETB fallback by hand (used only while CBE is unreachable)",
  })
  async update(
    @Param("currency") currency: string,
    @Body() dto: UpdateExchangeSettingDto,
    @CurrentUser() user: TCurrentUser,
  ) {
    const code = assertSupportedCurrency(currency);
    if (dto.fallbackRate > RATE_BOUNDS[code]) {
      throw new BadRequestException(
        `Fallback rate ${dto.fallbackRate} is outside the accepted range for ${code} (max ${RATE_BOUNDS[code]})`,
      );
    }

    const updated = await this.service.setManualRate(
      code,
      dto.fallbackRate,
      user?.id ?? null,
    );

    return {
      currency: updated.currency,
      fallbackRate: updated.fallbackRate,
      fallbackSource: updated.fallbackSource,
      lastSyncedAt: updated.lastSyncedAt,
      updatedById: updated.updatedById,
    };
  }
}