/* eslint-disable prefer-spread */

/**
 * Returns f such that f() calls func(...boundArgs), i.e. optimizes `() => func(...boundArgs)`.
 * It is faster on node6 by 57-92%.
 */
export function bindB<R>(func: (...args: any[]) => R, b: any[]): () => R {
  switch (b.length) {
    case 0: return () => func();
    case 1: return () => func(b[0]);
    case 2: return () => func(b[0], b[1]);
    case 3: return () => func(b[0], b[1], b[2]);
    case 4: return () => func(b[0], b[1], b[2], b[3]);
    case 5: return () => func(b[0], b[1], b[2], b[3], b[4]);
    case 6: return () => func(b[0], b[1], b[2], b[3], b[4], b[5]);
    case 7: return () => func(b[0], b[1], b[2], b[3], b[4], b[5], b[6]);
    case 8: return () => func(b[0], b[1], b[2], b[3], b[4], b[5], b[6], b[7]);
    default: return () => func.apply(undefined, b);
  }
}

/**
 * Returns f such that f(unboundArg) calls func(unboundArg, ...boundArgs).
 * I.e. optimizes `(arg) => func(arg, ...boundArgs)`.
 * It is faster on node6 by 0-92%.
 */
export function bindUB<U, R>(func: (arg: U, ...args: any[]) => R, b: any[]): (arg: U) => R {
  switch (b.length) {
    case 0: return (arg) => func(arg);
    case 1: return (arg) => func(arg, b[0]);
    case 2: return (arg) => func(arg, b[0], b[1]);
    case 3: return (arg) => func(arg, b[0], b[1], b[2]);
    case 4: return (arg) => func(arg, b[0], b[1], b[2], b[3]);
    case 5: return (arg) => func(arg, b[0], b[1], b[2], b[3], b[4]);
    case 6: return (arg) => func(arg, b[0], b[1], b[2], b[3], b[4], b[5]);
    case 7: return (arg) => func(arg, b[0], b[1], b[2], b[3], b[4], b[5], b[6]);
    case 8: return (arg) => func(arg, b[0], b[1], b[2], b[3], b[4], b[5], b[6], b[7]);
    default: return (arg) => func(arg, ...b);
  }
}

/**
 * Returns f such that f(unboundArg) calls func(...boundArgs, unboundArg).
 * I.e. optimizes `(arg) => func(...boundArgs, arg)`.
 * It is faster on node6 by 0-92%.
 */
export function bindBU<R>(func: (...args: any[]) => R, b: any[]): (arg: any) => R {
  switch (b.length) {
    case 0: return (arg) => func(arg);
    case 1: return (arg) => func(b[0], arg);
    case 2: return (arg) => func(b[0], b[1], arg);
    case 3: return (arg) => func(b[0], b[1], b[2], arg);
    case 4: return (arg) => func(b[0], b[1], b[2], b[3], arg);
    case 5: return (arg) => func(b[0], b[1], b[2], b[3], b[4], arg);
    case 6: return (arg) => func(b[0], b[1], b[2], b[3], b[4], b[5], arg);
    case 7: return (arg) => func(b[0], b[1], b[2], b[3], b[4], b[5], b[6], arg);
    case 8: return (arg) => func(b[0], b[1], b[2], b[3], b[4], b[5], b[6], b[7], arg);
    default: return (arg) => func(...b, arg);
  }
}