import { isComparable } from '../drop/comparable'
import { Context } from '../context'
import { toValue } from '../util'
import { isFalsy, isTruthy } from '../render/boolean'
import { isArray, isString } from '../util/underscore'

export type UnaryOperatorHandler = (operand: any, ctx: Context) => boolean;
export type BinaryOperatorHandler = (lhs: any, rhs: any, ctx: Context) => boolean;
export type OperatorHandler = UnaryOperatorHandler | BinaryOperatorHandler;
export type Operators = Record<string, OperatorHandler>

export const defaultOperators: Operators = {
  '==': equal,
  '!=': (l: any, r: any) => !equal(l, r),
  '>': (l: any, r: any) => {
    if (isComparable(l)) return l.gt(r)
    if (isComparable(r)) return r.lt(l)
    return toValue(l) > toValue(r)
  },
  '<': (l: any, r: any) => {
    if (isComparable(l)) return l.lt(r)
    if (isComparable(r)) return r.gt(l)
    return toValue(l) < toValue(r)
  },
  '>=': (l: any, r: any) => {
    if (isComparable(l)) return l.geq(r)
    if (isComparable(r)) return r.leq(l)
    return toValue(l) >= toValue(r)
  },
  '<=': (l: any, r: any) => {
    if (isComparable(l)) return l.leq(r)
    if (isComparable(r)) return r.geq(l)
    return toValue(l) <= toValue(r)
  },
  'contains': (l: any, r: any) => {
    l = toValue(l)
    if (isArray(l)) return l.some((i) => equal(i, r))
    if (isString(l)) return l.indexOf(toValue(r)) > -1
    return false
  },
  'not': (v: any, ctx: Context) => isFalsy(toValue(v), ctx),
  'and': (l: any, r: any, ctx: Context) => isTruthy(toValue(l), ctx) && isTruthy(toValue(r), ctx),
  'or': (l: any, r: any, ctx: Context) => isTruthy(toValue(l), ctx) || isTruthy(toValue(r), ctx)
}

function equal (lhs: any, rhs: any): boolean {
  if (isComparable(lhs)) return lhs.equals(rhs)
  if (isComparable(rhs)) return rhs.equals(lhs)
  lhs = toValue(lhs)
  rhs = toValue(rhs)
  if (isArray(lhs)) {
    return isArray(rhs) && arrayEqual(lhs, rhs)
  }
  return lhs === rhs
}

function arrayEqual (lhs: any[], rhs: any[]): boolean {
  if (lhs.length !== rhs.length) return false
  return !lhs.some((value, i) => !equal(value, rhs[i]))
}