import { Value } from "./eval/value";
import { Implementation, Program } from "./program";
import { ThrownRuntimeError } from "./eval/error";
import { FunctionName } from "./expr";
import { valueToString } from "./debug/value_show";

// TODO: Primitive functions like +, -, *, div, <, <=, ==, mod

export function installPrimitives(program: Program) {
  function R(name: FunctionName, implementation: Implementation) {
    Program.registerPrimitive(program, name, implementation);
  }

  // addition
  R("+", (args: Value[]): Value => {
    let sum = 0;
    for (const arg of args) {
      if (arg.tag !== "number") {
        throw ThrownRuntimeError.error({ tag: "TypeMismatch", expected: "number", received: arg });
      }
      sum += arg.value;
    }
    return Value.number(sum);
  });

  // multiplication
  R("*", (args: Value[]): Value => {
    let product = 1;
    for (const arg of args) {
      if (arg.tag !== "number") {
        throw ThrownRuntimeError.error({ tag: "TypeMismatch", expected: "number", received: arg });
      }
      product = product*arg.value;
    }
    return Value.number(product);
  });

  // string concat
  R("++", (args: Value[]): Value => {
    let sum = "";
    for (const arg of args) {
      if (arg.tag !== "string") {
        throw ThrownRuntimeError.error({ tag: "TypeMismatch", expected: "number", received: arg });
      }
      sum += arg.value;
    }
    return Value.string(sum);
  });

  R("log", (args: Value[]): Value => {
    for (const arg of args) {
      console.log(valueToString(arg));
    }
    return Value.tuple([]);
  });

}