import { Extension } from "@codemirror/state"
import { hoverTooltip } from "@codemirror/tooltip"
import {
  Decoration,
  EditorView,
  MatchDecorator,
  PluginField,
  ViewPlugin,
  ViewUpdate,
  WidgetType,
} from "@codemirror/view"
import { useReadonlyStream } from "~/helpers/utils/composables"
import { aggregateEnvs$ } from "~/newstore/environments"

const cursorTooltipField = hoverTooltip((view, pos, side) => {
  const { from, to, text } = view.state.doc.lineAt(pos)
  let start = pos
  let end = pos

  while (start > from && /\w/.test(text[start - from - 1])) start--
  while (end < to && /\w/.test(text[end - from])) end++

  if (
    (start === pos && side < 0) ||
    (end === pos && side > 0) ||
    !/(<<\w+>>)/g.test(text.slice(start - from - 2, end - from + 2))
  )
    return null

  const aggregateEnvs = useReadonlyStream(aggregateEnvs$, null)
  const envName = getEnvName(
    aggregateEnvs.value?.find(
      (env: { key: string }) => env.key === text.slice(start - from, end - from)
    )?.sourceEnv
  )
  const envValue = getEnvValue(
    aggregateEnvs.value?.find(
      (env: { key: string }) => env.key === text.slice(start - from, end - from)
    )?.value
  )
  const textContent = `${envName} <kbd>${envValue}</kbd>`

  return {
    pos: start,
    end,
    above: true,
    create() {
      const dom = document.createElement("span")
      dom.innerHTML = textContent
      dom.className = "tooltip-theme"
      return { dom }
    },
  }
})

function getEnvName(name: any) {
  if (name) return name
  return "choose an environment"
}

function getEnvValue(value: string) {
  if (value) return value.replace(/"/g, "&quot;")
  // it does not filter special characters before adding them to HTML.
  return "not found"
}

const environmentDecorator = new MatchDecorator({
  // eslint-disable-next-line prefer-regex-literals
  regexp: new RegExp(/(<<\w+>>)/g),
  decoration: () =>
    Decoration.replace({
      widget: new (class extends WidgetType {
        toDOM(_view: EditorView) {
          const element = document.createElement("span")
          element.textContent = "view"
          return element
        }
      })(),
      inclusive: false,
    }),
})

export const environmentHighlightStyle = ViewPlugin.define(
  (view: EditorView) => ({
    decorations: environmentDecorator.createDeco(view),
    update(_update: ViewUpdate) {
      this.decorations = environmentDecorator.updateDeco(
        _update,
        this.decorations
      )
    },
  }),
  {
    decorations: (v) => v.decorations,
    provide: PluginField.atomicRanges.from((v) => v.decorations),
  }
)

export const environmentTooltip: Extension = [
  cursorTooltipField,
  environmentHighlightStyle,
]