/**
 * Central currency symbol placement for Yatra admin + public UIs.
 *
 * Settings → Currency uses: left, right, left_space, right_space.
 * Legacy stored values: before, after (mapped for backward compatibility).
 */

import { __ } from "./i18n";
import { getCurrency, getCurrencySymbol } from "../data/currencies";

export type CurrencyPlacement = "left" | "right" | "left_space" | "right_space";

/**
 * Normalize option / legacy values to one of the four placement modes.
 */
export function normalizeCurrencyPosition(
  raw: string | undefined | null,
): CurrencyPlacement {
  const p = (raw ?? "before").toString().toLowerCase().trim();
  if (p === "before") {
    return "left_space";
  }
  if (p === "after") {
    return "right_space";
  }
  if (
    p === "right" ||
    p === "right_space" ||
    p === "left" ||
    p === "left_space"
  ) {
    return p as CurrencyPlacement;
  }
  return "left_space";
}

/**
 * Join a pre-formatted numeric string with the currency symbol per placement.
 */
export function applyCurrencyPosition(
  formattedAmount: string,
  currencySymbol: string,
  rawPosition?: string | null,
): string {
  const mode = normalizeCurrencyPosition(rawPosition);
  switch (mode) {
    case "right":
      return `${formattedAmount}${currencySymbol}`;
    case "right_space":
      return `${formattedAmount} ${currencySymbol}`;
    case "left":
      return `${currencySymbol}${formattedAmount}`;
    case "left_space":
    default:
      return `${currencySymbol} ${formattedAmount}`;
  }
}

type AdminWindow = Window & {
  yatraAdmin?: Record<string, unknown>;
  yatraBookingData?: Record<string, unknown>;
  yatraTripData?: Record<string, unknown>;
  yatraAccountPage?: Record<string, unknown>;
};

/**
 * Read raw currency position from localized globals (camelCase or snake_case).
 */
export function readYatraCurrencyPositionFromWindow(): string {
  if (typeof window === "undefined") {
    return "before";
  }
  const w = window as AdminWindow;
  const pick = (o: Record<string, unknown> | undefined): string | undefined => {
    if (!o) {
      return undefined;
    }
    const a = o.currencyPosition;
    const b = o.currency_position;
    if (typeof a === "string" && a !== "") {
      return a;
    }
    if (typeof b === "string" && b !== "") {
      return b;
    }
    return undefined;
  };

  return (
    pick(w.yatraAdmin as Record<string, unknown> | undefined) ??
    pick(w.yatraBookingData as Record<string, unknown> | undefined) ??
    pick(w.yatraTripData as Record<string, unknown> | undefined) ??
    pick(w.yatraAccountPage as Record<string, unknown> | undefined) ??
    "before"
  );
}

function readYatraNumberFormatConfig(): {
  decimalPlaces: number;
  thousandSeparator: string;
  decimalSeparator: string;
} {
  const fallback = {
    decimalPlaces: 2,
    thousandSeparator: ",",
    decimalSeparator: ".",
  };
  if (typeof window === "undefined") {
    return fallback;
  }
  // Read from the SAME set of globals as the currency position, not just
  // yatraAdmin. On public pages (customer account, checkout, single trip)
  // window.yatraAdmin is absent, so reading separators only from it made the
  // decimal/thousand separators silently fall back to defaults ("." / ",")
  // while the position — read from these public globals — was correct. That is
  // the "decimal separator ignored in payment amounts" bug on the storefront.
  const w = window as AdminWindow;
  const sources: Array<Record<string, unknown> | undefined> = [
    w.yatraAdmin as Record<string, unknown> | undefined,
    w.yatraBookingData as Record<string, unknown> | undefined,
    w.yatraTripData as Record<string, unknown> | undefined,
    w.yatraAccountPage as Record<string, unknown> | undefined,
  ];
  const pickString = (field: string): string | undefined => {
    for (const o of sources) {
      const v = o?.[field];
      if (typeof v === "string" && v !== "") {
        return v;
      }
    }
    return undefined;
  };
  const pickNumber = (...fields: string[]): number | undefined => {
    for (const o of sources) {
      if (!o) {
        continue;
      }
      for (const field of fields) {
        const v = o[field];
        if (v !== undefined && v !== null && v !== "" && !Number.isNaN(Number(v))) {
          return Number(v);
        }
      }
    }
    return undefined;
  };
  const decimals = pickNumber("decimalPlaces", "currency_decimals") ?? 2;
  return {
    decimalPlaces: Math.max(0, Math.min(4, decimals)),
    thousandSeparator: pickString("thousandSeparator") ?? ",",
    decimalSeparator: pickString("decimalSeparator") ?? ".",
  };
}

/**
 * Format a numeric amount using Yatra currency + separator settings and symbol placement.
 *
 * @param zeroAsUnknown When true, zero/empty shows “Contact for pricing” (trip/marketing UIs).
 */
export function formatYatraMoney(
  amount: number,
  currencyCode: string,
  options?: { zeroAsUnknown?: boolean },
): string {
  const zeroAsUnknown = options?.zeroAsUnknown === true;
  const num = Number(amount) || 0;
  if (zeroAsUnknown && num === 0) {
    return __("Contact for pricing", "yatra");
  }

  const { decimalPlaces, thousandSeparator, decimalSeparator } =
    readYatraNumberFormatConfig();
  const currencyData = getCurrency(currencyCode);
  const decimals =
    currencyData?.decimalDigits !== undefined
      ? Math.max(0, Math.min(4, currencyData.decimalDigits))
      : decimalPlaces;

  // Format with a FIXED "en-US" base (grouping ",", decimal ".") so the
  // replace-with-configured-separators step below is deterministic. Using the
  // viewer's locale here (undefined) would already yield locale separators and
  // the naive comma/dot replacement would swap them for e.g. German browsers.
  const formattedCore = new Intl.NumberFormat("en-US", {
    minimumFractionDigits: decimals,
    maximumFractionDigits: decimals,
  })
    .format(num)
    .replace(/,/g, "TEMP_THOUSAND")
    .replace(/\./g, "TEMP_DECIMAL")
    .replace(/TEMP_THOUSAND/g, thousandSeparator)
    .replace(/TEMP_DECIMAL/g, decimalSeparator);

  const symbol = getCurrencySymbol(currencyCode);
  const position = readYatraCurrencyPositionFromWindow();

  return applyCurrencyPosition(formattedCore, symbol, position);
}