import type { Component, CSSProperties, Prop, VNodeChild } from 'vue'
import type { Axis, Block, DataRefer, DynamicTheme, DynamicValue, ToStatic, ViewChildren } from './types'
import type { EngineContext } from './context'
import { defineComponent, h } from 'vue'
import { provideBlockId, useBlockId, useContext } from './context'
import {
  align,
  background,
  bordering,
  clip,
  dynamic,
  gap,
  insets,
  isRefer,
  radii,
  shadowing,
  size,
  stack,
  unit,
} from './utils'
import DddView from './views/View.vue'

// /**
//  * 相关框架组件渲染函数
//  */
// export type WidgetRenderFunction = (widget: Widget, view: View, axis?: Axis) => VNodeChild

// /**
//  * 注册的外部组件渲染函数
//  */
// const widgets: Record<string, WidgetRenderFunction> = {}

const views: Record<string, Component> = {}

export function registerView(v: Record<string, Component>): void {
  for (const [key, comp] of Object.entries(v)) {
    views[key] = comp
  }
}

// export function registerWidget(some: Record<string, WidgetRenderFunction>): void {
//   for (const [key, func] of Object.entries(some)) {
//     widgets[key] = func
//   }
// }
//
// function renderWidget(widget: Widget, view: View, axis?: Axis): VNodeChild {
//   const func = widgets[widget.name]
//   if (typeof func !== 'function') {
//     throw new TypeError(`unknown widget: ${widget.name}`)
//   }
//   return func(widget, view, axis)
// }
//
// const isWidget = (s: any): s is Widget => s != null && 'name' in s

export function renderRefer(refer: DataRefer, axis?: Axis): VNodeChild {
  const { key, type, ...attrs } = refer
  const component = views[type]
  if (component) {
    return h(component, {
      source: key,
      axis,
      ...attrs,
    })
  }
  return h('b', {
    style: {
      color: 'red',
      fontSize: '36px',
    },
  }, 'unimplemented')
}

export function isFlexible(theme: DynamicTheme,  value: ToStatic) {
  return value(theme.axis) != null
    || value(theme.mainAlign) != null
    || value(theme.crossAlign) != null
    || value(theme.wrap) != null
    || value(theme.gap) != null
}

export function render(
  ctx: EngineContext,
  blockId: string,
  view?: ViewChildren,
  axis?: Axis,
): VNodeChild {
  if (view == null) {
    return null
  }
  if (typeof view === 'string' || typeof view === 'number') {
    return view
  }
  if (Array.isArray(view)) {
    return view.map(child => render(ctx, blockId, child, axis))
  }
  if (isRefer(view)) {
    return renderRefer(view)
  }
  // if (isWidget(view.theme)) {
  //   return renderWidget(view.theme, view, axis)
  // }
  const theme = view.theme

  const value = <T>(v: DynamicValue<T>): T => dynamic<T>(ctx, blockId, v)

  const css: CSSProperties = {
    // boxed & spatial
    ...insets('padding', value(theme?.padding)),
    ...insets('margin', value(theme?.margin)),
    ...size(axis, theme, value), // todo
    // decoration
    ...background(value(theme?.color), value(theme?.image), value(theme?.gradient)),
    ...bordering(value(theme?.border)),
    ...radii(value(theme?.radius)),
    ...shadowing(value(theme?.shadow)),
    // textual
    color: value(theme?.textColor),
    fontSize: unit(value(theme?.fontSize)),
    textAlign: value(theme?.textAlign),
    lineHeight: value(theme?.lineHeight),
    // clip
    ...clip(value(theme?.clip)),
    // stack
    ...stack(theme, value),
  }
  // note: 在前面初始化 css 时使用了参数 axis，
  // 所以在这里复用它用于子视图构建
  axis = value(theme?.axis)
  const flexible = value(theme?.flexible)
  if (flexible || (theme && flexible == null && isFlexible(theme, value))) {
    Object.assign(css, {
      display: 'flex',
      flexDirection: axis === 'y' ? 'column' : undefined,
      justifyContent: align(value(theme?.mainAlign)),
      alignItems: align(value(theme?.crossAlign)),
      flexWrap: value(theme?.wrap) ? 'wrap' : undefined,
      ...gap(value(theme?.gap)),
    })
  }
  return h(DddView, {
    vid: view.vid,
    class: 'ddd-view',
    style: css,
  }, () => render(ctx, blockId, view.children, axis))
}

export const RenderView = defineComponent({
  name: 'RenderView',

  props: {
    view: {
      // type: [Object | Array],
      required: true,
    } as Prop<ViewChildren>,
  },

  setup(props) {
    const ctx = useContext()
    const blockId = useBlockId()
    return () => render(ctx, blockId, props.view)
  }
})

export const RenderBlock = defineComponent({
  name: 'RenderBlock',

  props: {
    block: {
      type: Object,
      required: true,
    } as Prop<Block>,
  },

  setup(props) {
    // const ctx = useContext()
    provideBlockId(props.block!.vid)
    return () => {
      if (props.block == null) {
        return null
      }
      // return render(ctx, props.block.vid, props.block)
      return h(RenderView, {
        view: props.block,
      })
    }
  },
})