import ts from "typescript";

import { ExpressionFactory } from "./ExpressionFactory";
import { IdentifierFactory } from "./IdentifierFactory";

export namespace LiteralFactory {
  export const generate = (input: any): ts.Expression => {
    if (input === null) return ts.factory.createNull();
    else if (ts.isIdentifier(input)) return input;
    else if (input instanceof Array) return generate_array(input);
    else if (typeof input === "object") return generate_object(input);
    else if (typeof input === "string") return generate_string(input);
    else if (typeof input === "boolean") return generate_value(input);
    else if (typeof input === "number") return generate_value(input);
    else if (typeof input === "bigint") return generate_bigint(input);
    // unreachable code
    else if (typeof input === "function")
      return ts.factory.createIdentifier("undefined");
    else
      throw new TypeError("Error on LiteralFactory.generate(): unknown type.");
  };

  const generate_object = (obj: object): ts.ObjectLiteralExpression =>
    ts.factory.createObjectLiteralExpression(
      Object.entries(obj)
        .filter((tuple) => tuple[1] !== undefined)
        .map(([key, value]) =>
          ts.factory.createPropertyAssignment(
            IdentifierFactory.identifier(key),
            generate(value),
          ),
        ),
      true,
    );

  const generate_array = (array: any[]): ts.ArrayLiteralExpression =>
    ts.factory.createArrayLiteralExpression(array.map(generate), true);

  const generate_value = (value: number | boolean | bigint): ts.Expression =>
    ts.factory.createIdentifier(value.toString());

  const generate_bigint = (value: bigint): ts.Expression =>
    ExpressionFactory.bigint(value);

  const generate_string = (value: string): ts.StringLiteral =>
    ts.factory.createStringLiteral(value);
}