import type { Eq } from "@principia/prelude/Eq";
import { fromEquals } from "@principia/prelude/Eq";

import { eqFiberId } from "../../Fiber/FiberId";
import type { Cause } from "./model";

/*
 * -------------------------------------------
 * Eq Cause
 * -------------------------------------------
 */

export const equalsCause = <E>(x: Cause<E>, y: Cause<E>): boolean => {
   switch (x._tag) {
      case "Fail": {
         return y._tag === "Fail" && x.value === y.value;
      }
      case "Empty": {
         return y._tag === "Empty";
      }
      case "Die": {
         return (
            y._tag === "Die" &&
            ((x.value instanceof Error &&
               y.value instanceof Error &&
               x.value.name === y.value.name &&
               x.value.message === y.value.message) ||
               x.value === y.value)
         );
      }
      case "Interrupt": {
         return y._tag === "Interrupt" && eqFiberId.equals(x.fiberId)(y.fiberId);
      }
      case "Both": {
         return y._tag === "Both" && equalsCause(x.left, y.left) && equalsCause(x.right, y.right);
      }
      case "Then": {
         return y._tag === "Then" && equalsCause(x.left, y.left) && equalsCause(x.right, y.right);
      }
   }
};

export const eqCause: Eq<Cause<any>> = fromEquals(equalsCause);