import { NextRequest, NextResponse } from "next/server";
import {
  getDomesticOrderBook,
  KisDomesticOrderBookOutput,
} from "@/lib/kis/domestic";
import { DashboardStockOrderBookResponse } from "@/features/trade/types/trade.types";
import { hasKisApiSession } from "@/app/api/kis/_session";
import {
  KisCredentialInput,
  hasKisConfig,
  normalizeTradingEnv,
} from "@/lib/kis/config";
import {
  DOMESTIC_KIS_SESSION_OVERRIDE_HEADER,
  parseDomesticKisSession,
} from "@/lib/kis/domestic-market-session";

/**
 * @file app/api/kis/domestic/orderbook/route.ts
 * @description 국내주식 호가 조회 API
 */

export async function GET(request: NextRequest) {
  const hasSession = await hasKisApiSession();
  if (!hasSession) {
    return NextResponse.json({ error: "로그인이 필요합니다." }, { status: 401 });
  }

  const { searchParams } = new URL(request.url);
  const symbol = (searchParams.get("symbol") ?? "").trim();

  if (!/^\d{6}$/.test(symbol)) {
    return NextResponse.json(
      { error: "symbol은 6자리 숫자여야 합니다." },
      { status: 400 },
    );
  }

  const credentials = readKisCredentialsFromHeaders(request.headers);

  if (!hasKisConfig(credentials)) {
    return NextResponse.json(
      {
        error: "KIS API 키 설정이 필요합니다.",
      },
      { status: 400 },
    );
  }

  try {
    const sessionOverride = readSessionOverrideFromHeaders(request.headers);
    const raw = await getDomesticOrderBook(symbol, credentials, {
      sessionOverride,
    });

    const levels = Array.from({ length: 10 }, (_, i) => {
      const idx = i + 1;
      return {
        askPrice: readOrderBookNumber(raw, `askp${idx}`, `ovtm_untp_askp${idx}`),
        bidPrice: readOrderBookNumber(raw, `bidp${idx}`, `ovtm_untp_bidp${idx}`),
        askSize: readOrderBookNumber(
          raw,
          `askp_rsqn${idx}`,
          `ovtm_untp_askp_rsqn${idx}`,
        ),
        bidSize: readOrderBookNumber(raw, ...resolveBidSizeKeys(idx)),
      };
    });

    const response: DashboardStockOrderBookResponse = {
      symbol,
      source: "kis",
      levels,
      totalAskSize: readOrderBookNumber(
        raw,
        "total_askp_rsqn",
        "ovtm_untp_total_askp_rsqn",
        "ovtm_total_askp_rsqn",
      ),
      totalBidSize: readOrderBookNumber(
        raw,
        "total_bidp_rsqn",
        "ovtm_untp_total_bidp_rsqn",
        "ovtm_total_bidp_rsqn",
      ),
      businessHour: readOrderBookString(raw, "bsop_hour", "ovtm_untp_last_hour"),
      hourClassCode: readOrderBookString(raw, "hour_cls_code"),
      tradingEnv: normalizeTradingEnv(credentials.tradingEnv),
      fetchedAt: new Date().toISOString(),
    };

    return NextResponse.json(response, {
      headers: {
        "cache-control": "no-store",
      },
    });
  } catch (error) {
    const message =
      error instanceof Error
        ? error.message
        : "호가 조회 중 오류가 발생했습니다.";
    return NextResponse.json({ error: message }, { status: 500 });
  }
}

function readKisCredentialsFromHeaders(headers: Headers): KisCredentialInput {
  const appKey = headers.get("x-kis-app-key")?.trim();
  const appSecret = headers.get("x-kis-app-secret")?.trim();
  const tradingEnv = normalizeTradingEnv(
    headers.get("x-kis-trading-env") ?? undefined,
  );

  return {
    appKey,
    appSecret,
    tradingEnv,
  };
}

function readSessionOverrideFromHeaders(headers: Headers) {
  if (process.env.NODE_ENV === "production") return null;
  const raw = headers.get(DOMESTIC_KIS_SESSION_OVERRIDE_HEADER);
  return parseDomesticKisSession(raw);
}

/**
 * @description 호가 응답 필드를 대소문자 모두 허용해 숫자로 읽습니다.
 * @see app/api/kis/domestic/orderbook/route.ts GET에서 output/output1 키 차이 방어 로직으로 사용합니다.
 */
function readOrderBookNumber(raw: KisDomesticOrderBookOutput, ...keys: string[]) {
  const record = raw as Record<string, unknown>;
  const value = resolveOrderBookValue(record, keys) ?? "0";
  const normalized =
    typeof value === "string"
      ? value.replaceAll(",", "").trim()
      : String(value ?? "0");
  const parsed = Number(normalized);
  return Number.isFinite(parsed) ? parsed : 0;
}

/**
 * @description 호가 응답 필드를 문자열로 읽습니다.
 * @see app/api/kis/domestic/orderbook/route.ts GET 응답 생성 시 businessHour/hourClassCode 추출
 */
function readOrderBookString(raw: KisDomesticOrderBookOutput, ...keys: string[]) {
  const record = raw as Record<string, unknown>;
  const value = resolveOrderBookValue(record, keys);
  if (value === undefined || value === null) return undefined;
  const text = String(value).trim();
  return text.length > 0 ? text : undefined;
}

function resolveOrderBookValue(record: Record<string, unknown>, keys: string[]) {
  for (const key of keys) {
    const direct = record[key];
    if (direct !== undefined && direct !== null) return direct;

    const upper = record[key.toUpperCase()];
    if (upper !== undefined && upper !== null) return upper;
  }

  return undefined;
}

function resolveBidSizeKeys(index: number) {
  if (index === 2) {
    return [`bidp_rsqn${index}`, `ovtm_untp_bidp_rsqn${index}`, "ovtm_untp_bidp_rsqn"];
  }

  return [`bidp_rsqn${index}`, `ovtm_untp_bidp_rsqn${index}`];
}