/**
 * This module contains utility functions to get environment variables with default values and validation.
 */

const normalizeValue = (value?: string | null): string | undefined => {
  if (value === undefined || value === null) {
    return undefined;
  }

  const trimmed = value.trim();
  if (!trimmed) {
    return undefined;
  }

  const lowered = trimmed.toLowerCase();
  if (lowered === "undefined" || lowered === "null") {
    return undefined;
  }

  return trimmed;
};

const warnInvalid = (key: string, rawValue: string | undefined, reason: string) => {
  const received = rawValue !== undefined ? `; received "${rawValue}"` : "";
  console.warn(`[config] ${key} ${reason}${received}`); // eslint-disable-line no-console
};

export const getEnvString = (key: string, defaultValue = ""): string => {
  const normalized = normalizeValue(process.env[key]);
  return normalized ?? defaultValue;
};

export const getEnvNumber = (
  key: string,
  defaultValue: number
): number => {
  const normalized = normalizeValue(process.env[key]);
  if (normalized === undefined) {
    return defaultValue;
  }

  const parsed = Number.parseInt(normalized, 10);
  if (Number.isNaN(parsed)) {
    warnInvalid(key, normalized, `is not a valid number for key ${key}; falling back to default ${defaultValue}`);
    return defaultValue;
  }

  return parsed;
};

/**
 * Like {@link getEnvNumber} but preserves fractional values (parseFloat, not parseInt).
 * Use for ratio/fraction settings such as RECONCILE_MAX_DELETE_FRACTION.
 */
export const getEnvFloat = (
  key: string,
  defaultValue: number
): number => {
  const normalized = normalizeValue(process.env[key]);
  if (normalized === undefined) {
    return defaultValue;
  }

  const parsed = Number.parseFloat(normalized);
  if (Number.isNaN(parsed)) {
    warnInvalid(key, normalized, `is not a valid number for key ${key}; falling back to default ${defaultValue}`);
    return defaultValue;
  }

  return parsed;
};

export const getEnvBoolean = (key: string, defaultValue = false): boolean => {
  const normalized = normalizeValue(process.env[key]);
  if (normalized === undefined) {
    return defaultValue;
  }

  const truthyValues = new Set(["true", "1", "yes", "y", "on"]);
  const falsyValues = new Set(["false", "0", "no", "n", "off"]);
  const lowered = normalized.toLowerCase();

  if (truthyValues.has(lowered)) {
    return true;
  }
  if (falsyValues.has(lowered)) {
    return false;
  }

  warnInvalid(key, normalized, "is not a recognized boolean; falling back to default");
  return defaultValue;
};

export const getOptionalEnv = (key: string): string | undefined => {
  return normalizeValue(process.env[key]);
};