import { compareSymbols, compareInts } from "../../compare/primitives.js";
import { compareFunctions } from "../../compare/structures.js";
import { makeTypeParser } from "../../parser/type_parser.js";
import { newDynamic } from "../../primitives/dynamic.js";
import { makeEnumCompareFn } from "../../structures/enum.js";
import { makeStructCompareFn } from "../../structures/struct.js";
import { Slot, Transformation, Value, Write } from "./value_slot.js";


// comparison functions are mutually recursive...

export const compareSlot = compareElems => makeEnumCompareFn([
  { l: "new", r: () => compareSymbols },
  { l: "write", r: () => compareWrite(compareElems) },
]);

export const compareWrite = compareElems => makeStructCompareFn([
  { l: "slot", r: () => compareSlot(compareElems) },
  { l: "value", r: () => compareValue(compareElems) },
  { l: "depth", r: () => compareInts },
]);

export const compareTransformation = compareInputs => compareOutputs => makeStructCompareFn([
  { l: "input", r: () => compareValue(compareInputs) },
  { l: "fn", r: () => compareValue(compareFunctions(compareInputs)(compareOutputs)) },
  { l: "output", r: () => compareOutputs },
]);

export const compareValue = compareElems => makeEnumCompareFn([
  { l: "literal", r: () => compareElems },
  { l: "read", r: () => compareWrite(compareElems) },
  { l: "transform", r: () =>
    compareTransformation
      (_a => _b => 0) // <- we cheat here, because we don't statically know the input type of the transformation.
      (compareElems) },
]);

const mkType = makeTypeParser({
  extraBracketOperators: [
    [':=', ['=:', Slot]],
    ['*=', ['=*', Value]],
    ['*:=', ['=:*', Write]],
  ],
  extraInfixOperators: [
    ['===>', Transformation],
  ],
});

export const ModuleVersioningCompare = [
  // comparison
  ["compareSlot" , newDynamic(compareSlot )(mkType("(a -> a -> Ordering) ->  :=a=:  ->  :=a=:  -> Ordering"))],
  ["compareValue", newDynamic(compareValue)(mkType("(a -> a -> Ordering) ->  *=a=*  ->  *=a=*  -> Ordering"))],
  ["compareWrite", newDynamic(compareWrite)(mkType("(a -> a -> Ordering) -> *:=a=:* -> *:=a=:* -> Ordering"))],
  ["compareTransformation", newDynamic(compareTransformation)(mkType("(a -> a -> Ordering) -> (b -> b -> Ordering) -> (a ===> b) -> (a ===> b) -> Ordering"))],
];