export type Severity = "off" | "info" | "warning" | "error";

export function toSeverity(str: string): Severity {
  if (str === "off" || str === "info" || str === "warning" || str === "error") {
    return str;
  } else {
    throw new Error(`Invalid severity: ${str}`);
  }
}

export class Options {
  readonly severity: Severity;
  private readonly custom: any;

  constructor(severity: Severity, custom: any) {
    this.severity = severity;
    this.custom = custom;
  }

  number(option: string): number;
  number(option: string, or: number): number;
  number(option: string, or: null): number | null;
  number(option: string, or?: number | null): number | null {
    const value = this.custom[option];
    if (value !== undefined && value !== null) {
      const parsed = parseFloat(value);
      if (isNaN(parsed)) {
        throw invalidValue(option, value);
      }
      return parsed;
    }
    if (or === undefined) {
      throw missingOption(option);
    }
    return or;
  }

  string(option: string): string;
  string(option: string, or: string): string;
  string(option: string, or: null): string | null;
  string(option: string, or?: string | null): string | null {
    const value = this.custom[option];
    if (value !== undefined && value !== null) {
      if (typeof value !== "string") {
        throw invalidValue(option, value);
      }
      return value;
    }
    if (or === undefined) {
      throw missingOption(option);
    }
    return or;
  }

  stringList(option: string): string[] {
    const value = this.custom[option];
    if (value !== undefined && value !== null) {
      if (typeof value === "string") {
        return [value];
      } else if (Array.isArray(value)) {
        for (const item of value) {
          if (typeof item !== "string") {
            throw invalidValue(option, item);
          }
        }
        return value;
      }
      throw invalidValue(option, value);
    }
    return [];
  }
}

function invalidValue(option, value) {
  return new Error(`Invalid value for ${option}: ${value}`);
}

function missingOption(option) {
  return new Error(`Missing option: ${option}`);
}