import {
  Observer,
  Property,
  Event,
  isValue,
  valueEvent,
  endEvent,
  PropertySeed,
  Function0,
  Function1,
  Function2,
  Function3,
  Function4,
  Function5,
  Function6,
  isProperty,
  Desc,
} from "./abstractions"
import {
  StatelessProperty,
  PropertySeedImpl,
  StatefulProperty,
} from "./property"
import { globalScope, intersectionScope } from "./scope"
import { argumentsToObservablesAndFunction } from "./argumentstoobservables"
import { cached } from "./cached"
import { nop, rename, toString } from "./util"
import { cachedFn } from "./cachedFn"

/**
  Combines given *n* Properties and
  EventStreams using the given n-ary function `f(v1, v2 ...)`.

  To calculate the current sum of three numeric Properties, you can do

```js
function sum3(x,y,z) { return x + y + z }
    combine(sum3, p1, p2, p3)
```
*/
export type PropertyLike<V> = Property<V> | PropertySeed<V>

export function combineAsArray<V>(observables: Property<V>[]): Property<V[]>
export function combineAsArray<V>(
  observables: PropertySeed<V>[]
): PropertySeed<V[]>

export function combineAsArray<V>(
  observables: Property<V>[] | PropertySeed<V>[]
): PropertyLike<V[]> {
  return rename(
    ["combineAsArray", observables],
    combine(observables as any, (...xs: V[]) => xs)
  )
}

export function combine<R>(fn: Function0<R>): Property<R>
export function combine<V, R>(a: Property<V>, fn: Function1<V, R>): Property<R>
export function combine<V, V2, R>(
  a: Property<V>,
  b: Property<V2>,
  fn: Function2<V, V2, R>
): Property<R>
export function combine<V, V2, V3, R>(
  a: Property<V>,
  b: Property<V2>,
  c: Property<V3>,
  fn: Function3<V, V2, V3, R>
): Property<R>
export function combine<V, V2, V3, V4, R>(
  a: Property<V>,
  b: Property<V2>,
  c: Property<V3>,
  d: Property<V4>,
  fn: Function4<V, V2, V3, V4, R>
): Property<R>
export function combine<V, V2, V3, V4, V5, R>(
  a: Property<V>,
  b: Property<V2>,
  c: Property<V3>,
  d: Property<V4>,
  e: Property<V5>,
  fn: Function5<V, V2, V3, V4, V5, R>
): Property<R>
export function combine<V, V2, V3, V4, V5, V6, R>(
  a: Property<V>,
  b: Property<V2>,
  c: Property<V3>,
  d: Property<V4>,
  e: Property<V5>,
  f: Property<V6>,
  fn: Function6<V, V2, V3, V4, V5, V6, R>
): Property<R>
export function combine<V, R>(
  properties: Property<V>[],
  fn: (...values: V[]) => R
): Property<R>

export function combine<V, R>(fn: Function1<V, R>, a: Property<V>): Property<R>
export function combine<V, V2, R>(
  fn: Function2<V, V2, R>,
  a: Property<V>,
  b: Property<V2>
): Property<R>
export function combine<V, V2, V3, R>(
  fn: Function3<V, V2, V3, R>,
  a: Property<V>,
  b: Property<V2>,
  c: Property<V3>
): Property<R>
export function combine<V, V2, V3, V4, R>(
  fn: Function4<V, V2, V3, V4, R>,
  a: Property<V>,
  b: Property<V2>,
  c: Property<V3>,
  d: Property<V4>
): Property<R>
export function combine<V, V2, V3, V4, V5, R>(
  fn: Function5<V, V2, V3, V4, V5, R>,
  a: Property<V>,
  b: Property<V2>,
  c: Property<V3>,
  d: Property<V4>,
  e: Property<V5>
): Property<R>
export function combine<V, V2, V3, V4, V5, V6, R>(
  fn: Function6<V, V2, V3, V4, V5, V6, R>,
  a: Property<V>,
  b: Property<V2>,
  c: Property<V3>,
  d: Property<V4>,
  e: Property<V5>,
  f: Property<V6>
): Property<R>
export function combine<V, R>(
  fn: (...values: V[]) => R,
  Propertys: Property<any>[]
): Property<R>

export function combine<V, R>(
  a: PropertySeed<V>,
  fn: Function1<V, R>
): PropertySeed<R>
export function combine<V, V2, R>(
  a: PropertySeed<V>,
  b: PropertySeed<V2>,
  fn: Function2<V, V2, R>
): PropertySeed<R>
export function combine<V, V2, V3, R>(
  a: PropertySeed<V>,
  b: PropertySeed<V2>,
  c: PropertySeed<V3>,
  fn: Function3<V, V2, V3, R>
): PropertySeed<R>
export function combine<V, V2, V3, V4, R>(
  a: PropertySeed<V>,
  b: PropertySeed<V2>,
  c: PropertySeed<V3>,
  d: PropertySeed<V4>,
  fn: Function4<V, V2, V3, V4, R>
): PropertySeed<R>
export function combine<V, V2, V3, V4, V5, R>(
  a: PropertySeed<V>,
  b: PropertySeed<V2>,
  c: PropertySeed<V3>,
  d: PropertySeed<V4>,
  e: PropertySeed<V5>,
  fn: Function5<V, V2, V3, V4, V5, R>
): PropertySeed<R>
export function combine<V, V2, V3, V4, V5, V6, R>(
  a: PropertySeed<V>,
  b: PropertySeed<V2>,
  c: PropertySeed<V3>,
  d: PropertySeed<V4>,
  e: PropertySeed<V5>,
  f: PropertySeed<V6>,
  fn: Function6<V, V2, V3, V4, V5, V6, R>
): PropertySeed<R>
export function combine<V, R>(
  properties: PropertySeed<V>[],
  fn: (...values: V[]) => R
): PropertySeed<R>

export function combine<V, R>(
  fn: Function1<V, R>,
  a: PropertySeed<V>
): PropertySeed<R>
export function combine<V, V2, R>(
  fn: Function2<V, V2, R>,
  a: PropertySeed<V>,
  b: PropertySeed<V2>
): PropertySeed<R>
export function combine<V, V2, V3, R>(
  fn: Function3<V, V2, V3, R>,
  a: PropertySeed<V>,
  b: PropertySeed<V2>,
  c: PropertySeed<V3>
): PropertySeed<R>
export function combine<V, V2, V3, V4, R>(
  fn: Function4<V, V2, V3, V4, R>,
  a: PropertySeed<V>,
  b: PropertySeed<V2>,
  c: PropertySeed<V3>,
  d: PropertySeed<V4>
): PropertySeed<R>
export function combine<V, V2, V3, V4, V5, R>(
  fn: Function5<V, V2, V3, V4, V5, R>,
  a: PropertySeed<V>,
  b: PropertySeed<V2>,
  c: PropertySeed<V3>,
  d: PropertySeed<V4>,
  e: PropertySeed<V5>
): PropertySeed<R>
export function combine<V, V2, V3, V4, V5, V6, R>(
  fn: Function6<V, V2, V3, V4, V5, V6, R>,
  a: PropertySeed<V>,
  b: PropertySeed<V2>,
  c: PropertySeed<V3>,
  d: PropertySeed<V4>,
  e: PropertySeed<V5>,
  f: PropertySeed<V6>
): PropertySeed<R>
export function combine<V, R>(
  fn: (...values: V[]) => R,
  Propertys: PropertySeed<any>[]
): PropertySeed<R>

export function combine<Out>(...args: any[]): PropertyLike<Out> {
  let [properties, combinator] = argumentsToObservablesAndFunction<
    Out,
    Property<Out>
  >(args)
  const seeds = !(properties.length === 0 || isProperty(properties[0]))

  combinator = cachedFn(combinator)

  function getCurrentArray(): any[] {
    return properties.map((s) => s.get())
  }

  const get = () => combinator(...getCurrentArray())
  const subscribe = (seeds ? subscribeSeeds : subscribeProps)(
    properties,
    getCurrentArray,
    combinator
  )

  const desc = ["combine", [properties, combinator]] as Desc
  if (!seeds) {
    const scope = intersectionScope(properties.map((p) => p.getScope()))
    return new StatelessProperty<Out, Property<Out>>(
      desc,
      get,
      subscribe,
      scope
    )
  } else {
    return new PropertySeedImpl<Out>(desc, get, subscribe)
  }
}

const subscribeProps =
  <Out>(
    properties: Property<Out>[],
    getCurrentArray: () => any[],
    combinator: (...args: any[]) => Out
  ) =>
  (onValue: Observer<Out>, onEnd: Observer<void> = nop) => {
    let endCount = 0
    const unsubs = properties.map((src, i) => {
      return src.onChange(
        () => {
          onValue(combinator(...getCurrentArray()))
        },
        () => {
          endCount++
          if (endCount == properties.length) {
            onEnd()
          }
        }
      )
    })

    return () => {
      unsubs.forEach((f) => f())
    }
  }

const subscribeSeeds =
  <Out>(
    properties: Property<Out>[],
    getCurrentArray: () => any[],
    combinator: (...args: any[]) => Out
  ) =>
  (onValue: Observer<Out>, onEnd: Observer<void> = nop) => {
    let endCount = 0
    const unsubs = properties.map((src, i) => {
      return src.onChange(
        (value) => {
          currentArray[i] = value
          onValue(combinator(...currentArray))
        },
        () => {
          endCount++
          if (endCount == properties.length) {
            onEnd()
          }
        }
      )
    })
    let currentArray = getCurrentArray()

    return () => {
      unsubs.forEach((f) => f())
    }
  }