import type { CoreAssistantMessage, CoreToolMessage, UIMessage } from 'ai'
import { clsx, type ClassValue } from 'clsx'
import { twMerge } from 'tailwind-merge'
import { IDocument } from '@penx/model-type'

export function cn(...inputs: ClassValue[]) {
  return twMerge(clsx(inputs))
}

interface ApplicationError extends Error {
  info: string
  status: number
}

export const fetcher = async (url: string) => {
  const res = await fetch(url)

  if (!res.ok) {
    const error = new Error(
      'An error occurred while fetching the data.',
    ) as ApplicationError

    error.info = await res.json()
    error.status = res.status

    throw error
  }

  return res.json()
}

export function getLocalStorage(key: string) {
  if (typeof window !== 'undefined') {
    return JSON.parse(localStorage.getItem(key) || '[]')
  }
  return []
}

export function generateUUID(): string {
  return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, (c) => {
    const r = (Math.random() * 16) | 0
    const v = c === 'x' ? r : (r & 0x3) | 0x8
    return v.toString(16)
  })
}

type ResponseMessageWithoutId = CoreToolMessage | CoreAssistantMessage
type ResponseMessage = ResponseMessageWithoutId & { id: string }

export function getMostRecentUserMessage(messages: Array<UIMessage>) {
  const userMessages = messages.filter((message) => message.role === 'user')
  return userMessages.at(-1)
}

export function getDocumentTimestampByIndex(
  documents: Array<IDocument>,
  index: number,
) {
  if (!documents) return new Date()
  if (index > documents.length) return new Date()

  return documents[index].createdAt
}

export function getTrailingMessageId({
  messages,
}: {
  messages: Array<ResponseMessage>
}): string | null {
  const trailingMessage = messages.at(-1)

  if (!trailingMessage) return null

  return trailingMessage.id
}