import { writable } from "svelte/store"
import { createCoreApi } from "./core"
import { getStateOrValue } from "./state/getState"
import { setState, setStateFromBinding } from "./state/setState"
import { trimSlash } from "./common/trimSlash"
import { isBound } from "./state/isState"
import { _initialiseChildren } from "./render/initialiseChildren"
import { createTreeNode } from "./render/renderComponent"

export const createApp = (
  document,
  componentLibraries,
  appDefinition,
  user,
  uiFunctions
) => {
  const coreApi = createCoreApi(appDefinition, user)
  appDefinition.hierarchy = coreApi.templateApi.constructHierarchy(
    appDefinition.hierarchy
  )
  const store = writable({
    _bbuser: user,
  })

  let globalState = null
  store.subscribe(s => {
    globalState = s
  })

  const relativeUrl = url =>
    appDefinition.appRootPath
      ? appDefinition.appRootPath + "/" + trimSlash(url)
      : url

  const apiCall = method => (url, body) =>
    fetch(relativeUrl(url), {
      method: method,
      headers: {
        "Content-Type": "application/json",
      },
      body: body && JSON.stringify(body),
    })

  const api = {
    post: apiCall("POST"),
    get: apiCall("GET"),
    patch: apiCall("PATCH"),
    delete: apiCall("DELETE"),
  }

  const safeCallEvent = (event, context) => {
    const isFunction = obj =>
      !!(obj && obj.constructor && obj.call && obj.apply)

    if (isFunction(event)) event(context)
  }

  const initialiseChildrenParams = (hydrate, treeNode) => ({
    bb,
    coreApi,
    store,
    document,
    componentLibraries,
    appDefinition,
    hydrate,
    uiFunctions,
    treeNode,
  })

  const bb = (treeNode, componentProps) => ({
    hydrateChildren: _initialiseChildren(
      initialiseChildrenParams(true, treeNode)
    ),
    appendChildren: _initialiseChildren(
      initialiseChildrenParams(false, treeNode)
    ),
    insertChildren: (props, htmlElement, anchor) =>
      _initialiseChildren(initialiseChildrenParams(false, treeNode))(
        props,
        htmlElement,
        anchor
      ),
    context: treeNode.context,
    props: componentProps,
    call: safeCallEvent,
    setStateFromBinding: (binding, value) =>
      setStateFromBinding(store, binding, value),
    setState: (path, value) => setState(store, path, value),
    getStateOrValue: (prop, currentContext) =>
      getStateOrValue(globalState, prop, currentContext),
    store,
    relativeUrl,
    api,
    isBound,
    parent,
  })

  return bb(createTreeNode())
}