import {OptionConfig} from './option-config.js'

import {insertText} from './text.js'

import {shouldSkipFormatting} from './paste-keyboard-shortcut-helper.js'

const pasteLinkAsPlainTextOverSelectedTextMap = new WeakMap<HTMLElement, boolean>()

export function install(el: HTMLElement, optionConfig?: OptionConfig): void {

pasteLinkAsPlainTextOverSelectedTextMap.set(el, optionConfig?.defaultPlainTextPaste?.urlLinks === true)

el.addEventListener('paste', onPaste)

}

export function uninstall(el: HTMLElement): void {

el.removeEventListener('paste', onPaste)

}

function onPaste(event: ClipboardEvent) {

const {currentTarget: el} = event

const element = el as HTMLElement

const shouldPasteAsPlainText = pasteLinkAsPlainTextOverSelectedTextMap.get(element) ?? false

const shouldSkipDefaultBehavior = shouldSkipFormatting(element)

if (

(!shouldPasteAsPlainText && shouldSkipDefaultBehavior) ||

(shouldPasteAsPlainText && !shouldSkipDefaultBehavior)

) {

return

}

const transfer = event.clipboardData

if (!transfer || !hasPlainText(transfer)) return

const field = event.currentTarget

if (!(field instanceof HTMLTextAreaElement)) return

const text = transfer.getData('text/plain')

if (!text) return

if (!isURL(text)) return

if (isWithinLink(field)) return

const selectedText = field.value.substring(field.selectionStart, field.selectionEnd)

if (!selectedText.length) return

// Prevent linkification when replacing an URL

// Trim whitespace in case whitespace is selected by mistake or by intention

if (isURL(selectedText.trim())) return

event.stopPropagation()

event.preventDefault()

insertText(field, linkify(selectedText, text.trim()))

}

function hasPlainText(transfer: DataTransfer): boolean {

return Array.from(transfer.types).includes('text/plain')

}

function isWithinLink(textarea: HTMLTextAreaElement): boolean {

const selectionStart = textarea.selectionStart || 0

if (selectionStart > 1) {

const previousChars = textarea.value.substring(selectionStart - 2, selectionStart)

return previousChars === ']('

} else {

return false

}

}

function linkify(selectedText: string, text: string): string {

return `[${selectedText}](${text})`

}

function isURL(url: string): boolean {

try {

//eslint-disable-next-line no-restricted-syntax

const parsedURL = new URL(url)

return removeTrailingSlash(parsedURL.href).trim() === removeTrailingSlash(url).trim()

} catch {

return false

}

}

function removeTrailingSlash(url: string) {

return url.endsWith('/') ? url.slice(0, url.length - 1) : url

}