import { commands, Range, window } from 'vscode'
import { GoToRange } from './gotoRange'
import { CurrentFile, KeyDetector, KeyInDocument } from '~/core'
import { Commands } from '~/extension'
import { ExtensionModule } from '~/modules'
import { EditorPanel } from '~/webview/panel'

export function getCurrentUsagePos() {
  const editor = window.activeTextEditor
  const document = editor?.document
  if (!editor || !document)
    return

  const usages = KeyDetector.getUsages(document, CurrentFile.loader)
  if (!usages?.keys.length)
    return

  const current = document.offsetAt(editor.selection.start)

  function getDiff(i: KeyInDocument) {
    const diff = current - i.start
    if (diff < 0)
      return Infinity
    return diff
  }

  const last = Array.from(usages.keys).sort((a, b) => getDiff(a) - getDiff(b))[0]

  if (!last)
    return

  const index = usages.keys.indexOf(last)

  return { index, usages, document }
}

export function GoToNextUsage() {
  const result = getCurrentUsagePos()
  if (result == null)
    return

  const { index, usages, document } = result

  const next = (index + 1) % usages.keys.length
  const nextKey = usages.keys[next]

  if (!nextKey)
    return

  if (EditorPanel.currentPanel) {
    EditorPanel.currentPanel.navigateKey({
      keyIndex: next,
      filepath: document.uri.fsPath,
      ...nextKey,
    })
  }
  else {
    const range = new Range(document.positionAt(nextKey.start), document.positionAt(nextKey.end))
    GoToRange(document, range)
  }
}

export function GoToPrevUsage() {
  const result = getCurrentUsagePos()
  if (result == null)
    return

  const { index, usages, document } = result

  const next = (index - 1 + usages.keys.length) % usages.keys.length
  const prevKey = usages.keys[next]

  if (!prevKey)
    return

  if (EditorPanel.currentPanel) {
    EditorPanel.currentPanel.navigateKey({
      keyIndex: next,
      filepath: document.uri.fsPath,
      ...prevKey,
    })
  }
  else {
    const range = new Range(document.positionAt(prevKey.start), document.positionAt(prevKey.end))
    GoToRange(document, range)
  }
}

export default <ExtensionModule> function() {
  return [
    commands.registerCommand(Commands.go_to_next_usage, GoToNextUsage),
    commands.registerCommand(Commands.go_to_prev_usage, GoToPrevUsage),
  ]
}