import { Vue } from 'vue/types/vue'
import { VNode, VNodeDirective, FunctionalComponentOptions } from 'vue/types'

export function createSimpleFunctional (
  c: string,
  el = 'div',
  name?: string
): FunctionalComponentOptions {
  return {
    name: name || c.replace(/__/g, '-'),

    functional: true,

    render (h, { data, children }): VNode {
      data.staticClass = (`${c} ${data.staticClass || ''}`).trim()

      return h(el, data, children)
    }
  }
}

function mergeTransitions (
  transitions: undefined | Function | Function[],
  array: Function[]
) {
  if (Array.isArray(transitions)) return transitions.concat(array)
  if (transitions) array.push(transitions)
  return array
}

export function createSimpleTransition (
  name: string,
  origin = 'top center 0',
  mode?: string
): FunctionalComponentOptions {
  return {
    name,

    functional: true,

    props: {
      group: {
        type: Boolean,
        default: false
      },
      hideOnLeave: {
        type: Boolean,
        default: false
      },
      leaveAbsolute: {
        type: Boolean,
        default: false
      },
      mode: {
        type: String,
        default: mode
      },
      origin: {
        type: String,
        default: origin
      }
    },

    render (h, context): VNode {
      const tag = `transition${context.props.group ? '-group' : ''}`
      context.data = context.data || {}
      context.data.props = {
        name,
        mode: context.props.mode
      }
      context.data.on = context.data.on || {}
      if (!Object.isExtensible(context.data.on)) {
        context.data.on = { ...context.data.on }
      }

      const ourBeforeEnter: Function[] = []
      const ourLeave: Function[] = []
      const absolute = (el: HTMLElement) => (el.style.position = 'absolute')

      ourBeforeEnter.push((el: HTMLElement) => {
        el.style.transformOrigin = context.props.origin
        el.style.webkitTransformOrigin = context.props.origin
      })

      if (context.props.leaveAbsolute) ourLeave.push(absolute)
      if (context.props.hideOnLeave) {
        ourLeave.push((el: HTMLElement) => (el.style.display = 'none'))
      }

      const { beforeEnter, leave } = context.data.on

      // Type says Function | Function[] but
      // will only work if provided a function
      context.data.on.beforeEnter = () => mergeTransitions(beforeEnter, ourBeforeEnter)
      context.data.on.leave = mergeTransitions(leave, ourLeave)

      return h(tag, context.data, context.children)
    }
  }
}

export function createJavaScriptTransition (
  name: string,
  functions: Record<string, () => any>,
  mode = 'in-out'
): FunctionalComponentOptions {
  return {
    name,

    functional: true,

    props: {
      mode: {
        type: String,
        default: mode
      }
    },

    render (h, context): VNode {
      const data = {
        props: {
          ...context.props,
          name
        },
        on: functions
      }

      return h('transition', data, context.children)
    }
  }
}

export type BindingConfig = Pick<VNodeDirective, 'arg' | 'modifiers' | 'value'>
export function directiveConfig (binding: BindingConfig, defaults = {}): VNodeDirective {
  return {
    ...defaults,
    ...binding.modifiers,
    value: binding.arg,
    ...(binding.value || {})
  }
}

export function addOnceEventListener (el: EventTarget, event: string, cb: () => void): void {
  var once = () => {
    cb()
    el.removeEventListener(event, once, false)
  }

  el.addEventListener(event, once, false)
}

export function getNestedValue (obj: any, path: (string | number)[], fallback?: any): any {
  const last = path.length - 1

  if (last < 0) return obj === undefined ? fallback : obj

  for (let i = 0; i < last; i++) {
    if (obj == null) {
      return fallback
    }
    obj = obj[path[i]]
  }

  if (obj == null) return fallback

  return obj[path[last]] === undefined ? fallback : obj[path[last]]
}

export function deepEqual (a: any, b: any): boolean {
  if (a === b) return true

  if (a instanceof Date && b instanceof Date) {
    // If the values are Date, they were convert to timestamp with getTime and compare it
    if (a.getTime() !== b.getTime()) return false
  }

  if (a !== Object(a) || b !== Object(b)) {
    // If the values aren't objects, they were already checked for equality
    return false
  }

  const props = Object.keys(a)

  if (props.length !== Object.keys(b).length) {
    // Different number of props, don't bother to check
    return false
  }

  return props.every(p => deepEqual(a[p], b[p]))
}

export function getObjectValueByPath (obj: object, path: string, fallback?: any): any {
  // credit: http://stackoverflow.com/questions/6491463/accessing-nested-javascript-objects-with-string-key#comment55278413_6491621
  if (!path || path.constructor !== String) return fallback
  path = path.replace(/\[(\w+)\]/g, '.$1') // convert indexes to properties
  path = path.replace(/^\./, '') // strip a leading dot
  return getNestedValue(obj, path.split('.'), fallback)
}

export function getPropertyFromItem (
  item: object,
  property: string | (string | number)[] | ((item: object, fallback?: any) => any),
  fallback?: any
): any {
  if (property == null) return item === undefined ? fallback : item

  if (item !== Object(item)) return fallback === undefined ? item : fallback

  if (typeof property === 'string') return getObjectValueByPath(item, property, fallback)

  if (Array.isArray(property)) return getNestedValue(item, property, fallback)

  if (typeof property !== 'function') return fallback

  const value = property(item, fallback)

  return typeof value === 'undefined' ? fallback : value
}

export function createRange (length: number): number[] {
  return Array.from({ length }, (v, k) => k)
}

export function getZIndex (el?: Element | null): number {
  if (!el || el.nodeType !== Node.ELEMENT_NODE) return 0

  const index = +window.getComputedStyle(el).getPropertyValue('z-index')

  if (isNaN(index)) return getZIndex(el.parentNode as Element)
  return index
}

const tagsToReplace = {
  '&': '&amp;',
  '<': '&lt;',
  '>': '&gt;'
} as any

export function escapeHTML (str: string): string {
  return str.replace(/[&<>]/g, tag => tagsToReplace[tag] || tag)
}

export function filterObjectOnKeys<T, K extends keyof T> (obj: T, keys: K[]): { [N in K]: T[N] } {
  const filtered = {} as { [N in K]: T[N] }

  for (let i = 0; i < keys.length; i++) {
    const key = keys[i]
    if (typeof obj[key] !== 'undefined') {
      filtered[key] = obj[key]
    }
  }

  return filtered
}

export function filterChildren (array: VNode[] = [], tag: string): VNode[] {
  return array.filter(child => {
    return child.componentOptions &&
      child.componentOptions.Ctor.options.name === tag
  })
}

export function convertToUnit (str: string | number | null | undefined, unit = 'px'): string | undefined {
  if (str == null || str === '') {
    return undefined
  } else if (isNaN(+str!)) {
    return String(str)
  } else {
    return `${Number(str)}${unit}`
  }
}

export function kebabCase (str: string): string {
  return (str || '').replace(/([a-z])([A-Z])/g, '$1-$2').toLowerCase()
}

export function isObject (obj: any): obj is object {
  return obj !== null && typeof obj === 'object'
}

// KeyboardEvent.keyCode aliases
export const keyCodes = Object.freeze({
  enter: 13,
  tab: 9,
  delete: 46,
  esc: 27,
  space: 32,
  up: 38,
  down: 40,
  left: 37,
  right: 39,
  end: 35,
  home: 36,
  del: 46,
  backspace: 8,
  insert: 45,
  pageup: 33,
  pagedown: 34
})

const ICONS_PREFIX = '$vuetify.icons.'

// This remaps internal names like '$vuetify.icons.cancel' to the current name
// for that icon.
export function remapInternalIcon (vm: Vue, iconName: string): string {
  if (!iconName.startsWith(ICONS_PREFIX)) {
    return iconName
  }

  // Now look up icon indirection name, e.g. '$vuetify.icons.cancel'
  return getObjectValueByPath(vm, iconName, iconName)
}

export function keys<O> (o: O) {
  return Object.keys(o) as (keyof O)[]
}

/**
 * Camelize a hyphen-delimited string.
 */
const camelizeRE = /-(\w)/g
export const camelize = (str: string): string => {
  return str.replace(camelizeRE, (_, c) => c ? c.toUpperCase() : '')
}