import shallowEqual from 'shallowequal'
import omit from 'omit.js'
import { getOptionProps } from '../props-util'
import PropTypes from '../vue-types'
import proxyComponent from '../proxyComponent'

function getDisplayName (WrappedComponent) {
  return WrappedComponent.name || 'Component'
}

const defaultMapStateToProps = () => ({})
export default function connect (mapStateToProps) {
  const shouldSubscribe = !!mapStateToProps
  const finnalMapStateToProps = mapStateToProps || defaultMapStateToProps
  return function wrapWithConnect (WrappedComponent) {
    const tempProps = omit(WrappedComponent.props || {}, ['store'])
    const props = {
      __propsSymbol__: PropTypes.any,
    }
    Object.keys(tempProps).forEach(k => { props[k] = ({ ...k, required: false }) })
    const Connect = {
      name: `Connect_${getDisplayName(WrappedComponent)}`,
      props,
      inject: {
        storeContext: { default: {}},
      },
      data () {
        this.store = this.storeContext.store
        this.preProps = { ...omit(getOptionProps(this), ['__propsSymbol__']) }
        return {
          subscribed: finnalMapStateToProps(this.store.getState(), this.$props),
        }
      },
      watch: {
        __propsSymbol__ () {
          if (mapStateToProps && mapStateToProps.length === 2) {
            this.subscribed = finnalMapStateToProps(this.store.getState(), this.$props)
          }
        },
      },
      mounted () {
        this.trySubscribe()
      },

      beforeDestroy () {
        this.tryUnsubscribe()
      },
      methods: {
        handleChange () {
          if (!this.unsubscribe) {
            return
          }
          const props = getOptionProps(this)
          const nextSubscribed = finnalMapStateToProps(this.store.getState(), props)
          if (!shallowEqual(this.preProps, props) || !shallowEqual(this.subscribed, nextSubscribed)) {
            this.subscribed = nextSubscribed
          }
        },

        trySubscribe () {
          if (shouldSubscribe) {
            this.unsubscribe = this.store.subscribe(this.handleChange)
            this.handleChange()
          }
        },

        tryUnsubscribe () {
          if (this.unsubscribe) {
            this.unsubscribe()
            this.unsubscribe = null
          }
        },
        getWrappedInstance () {
          return this.$refs.wrappedInstance
        },
      },
      render () {
        this.preProps = { ...this.$props }
        const { $listeners, $slots = {}, $attrs, $scopedSlots, subscribed, store } = this
        const props = getOptionProps(this)
        this.preProps = { ...omit(props, ['__propsSymbol__']) }
        const wrapProps = {
          props: {
            ...props,
            ...subscribed,
            store,
          },
          on: $listeners,
          attrs: $attrs,
          scopedSlots: $scopedSlots,
        }
        return (
          <WrappedComponent {...wrapProps} ref='wrappedInstance'>
            {Object.keys($slots).map(name => {
              return <template slot={name}>{$slots[name]}</template>
            })}
          </WrappedComponent>
        )
      },
    }
    return proxyComponent(Connect)
  }
}