import type { H3Event } from 'h3'

interface DiarySession {
  unlocked?: boolean
}

const SESSION_MAX_AGE_S = 60 * 60 * 24 * 30

export function diarySession(event: H3Event) {
  const { sessionSecret } = useRuntimeConfig(event)
  if (!sessionSecret || sessionSecret.length < 32) {
    throw createError({ statusCode: 500, statusMessage: 'NUXT_SESSION_SECRET must be set (at least 32 characters)' })
  }
  return useSession<DiarySession>(event, {
    name: 'diary',
    password: sessionSecret,
    maxAge: SESSION_MAX_AGE_S,
    cookie: { httpOnly: true, sameSite: 'lax', secure: !import.meta.dev }
  })
}

async function sha256(text: string): Promise<Uint8Array> {
  return new Uint8Array(await crypto.subtle.digest('SHA-256', new TextEncoder().encode(text)))
}

export async function passwordMatches(event: H3Event, guess: string): Promise<boolean> {
  const { diaryPassword } = useRuntimeConfig(event)
  if (!diaryPassword) {
    throw createError({ statusCode: 500, statusMessage: 'NUXT_DIARY_PASSWORD is not set' })
  }

  const [a, b] = await Promise.all([sha256(guess), sha256(diaryPassword)])
  let difference = 0
  for (let i = 0; i < a.length; i++) difference |= a[i]! ^ b[i]!
  return difference === 0
}