import type { QuoteContractRates } from "@/workers/rpa/quote-capture/quote-contract-guard";

/** 归一化后的报价 rates（契约校验唯一输入） */
export type CanonicalQuote = {
  rates: QuoteContractRates;
  /** 解析来源路径（debug） */
  sourcePath: string;
};

function isRatesObject(value: unknown): value is QuoteContractRates {
  return value != null && typeof value === "object" && !Array.isArray(value);
}

function hasRatesBranchShape(rates: QuoteContractRates): boolean {
  return (
    "standard" in rates ||
    "guaranteed" in rates ||
    "fastest" in rates
  );
}

function readPath(obj: unknown, ...keys: string[]): unknown {
  let cur = obj;
  for (const key of keys) {
    if (cur == null || typeof cur !== "object" || Array.isArray(cur)) {
      return undefined;
    }
    cur = (cur as Record<string, unknown>)[key];
  }
  return cur;
}

type RatesCandidate = { rates: QuoteContractRates; sourcePath: string };

function tryRatesAt(
  rates: unknown,
  sourcePath: string,
): RatesCandidate | null {
  if (!isRatesObject(rates) || !hasRatesBranchShape(rates)) {
    return null;
  }
  return { rates, sourcePath };
}

/**
 * 从 API body 解析 rates（支持常见嵌套变体）。
 * body.rates | body.data.rates | body.result.rates | array[0].rates
 */
export function resolveRatesFromBody(body: unknown): RatesCandidate | null {
  if (body == null) {
    return null;
  }

  if (Array.isArray(body)) {
  if (body.length > 0) {
      const fromFirst = tryRatesAt(
        readPath(body[0], "rates"),
        "[0].rates",
      );
      if (fromFirst) {
        return fromFirst;
      }
    }
    return null;
  }

  if (typeof body !== "object") {
    return null;
  }

  const candidates: RatesCandidate[] = [];
  const direct = tryRatesAt(readPath(body, "rates"), "rates");
  if (direct) {
    candidates.push(direct);
  }
  const fromData = tryRatesAt(readPath(body, "data", "rates"), "data.rates");
  if (fromData) {
    candidates.push(fromData);
  }
  const fromResult = tryRatesAt(
    readPath(body, "result", "rates"),
    "result.rates",
  );
  if (fromResult) {
    candidates.push(fromResult);
  }

  return candidates[0] ?? null;
}

/** body → CanonicalQuote；无法解析 rates 时返回 null */
export function normalizeQuote(body: unknown): CanonicalQuote | null {
  const resolved = resolveRatesFromBody(body);
  if (!resolved) {
    return null;
  }
  return {
    rates: resolved.rates,
    sourcePath: resolved.sourcePath,
  };
}