import { randomUUID } from 'node:crypto'

import type { H3Event } from 'h3'

import { deleteCookie, getCookie, getRequestURL, setCookie } from 'h3'

import { randomToken } from './base64url'
import { getRedisClient } from './redis'

const DEFAULT_SESSION_TTL_SECONDS = 60 * 60 * 24 * 7
const SHORT_SESSION_TTL_SECONDS = 60 * 60 * 24

interface StoredSession {
  id: string
  userId: string
  remember: boolean
  createdAt: string
}

function getSessionCookieName() {
  const config = useRuntimeConfig()
  return config.sessionCookieName || 'dinner_ticket_session'
}

function getSessionStorageKey(token: string) {
  return `auth:session:${token}`
}

function shouldUseSecureCookies(event: H3Event) {
  const url = getRequestURL(event)
  return url.protocol === 'https:'
}

function getSessionTtl(remember: boolean) {
  return remember ? DEFAULT_SESSION_TTL_SECONDS : SHORT_SESSION_TTL_SECONDS
}

export async function createUserSession(event: H3Event, input: {
  userId: string
  remember: boolean
}) {
  const token = randomToken(32)
  const session: StoredSession = {
    id: randomUUID(),
    userId: input.userId,
    remember: input.remember,
    createdAt: new Date().toISOString()
  }
  const redis = await getRedisClient()
  const ttl = getSessionTtl(input.remember)

  await redis.set(getSessionStorageKey(token), JSON.stringify(session), {
    expiration: {
      type: 'EX',
      value: ttl
    }
  })

  setCookie(event, getSessionCookieName(), token, {
    httpOnly: true,
    sameSite: 'lax',
    secure: shouldUseSecureCookies(event),
    path: '/',
    maxAge: ttl
  })

  return session
}

export async function getUserSession(event: H3Event): Promise<StoredSession | null> {
  const token = getCookie(event, getSessionCookieName())

  if (!token) {
    return null
  }

  const redis = await getRedisClient()
  const raw = await redis.get(getSessionStorageKey(token))

  if (!raw) {
    deleteCookie(event, getSessionCookieName(), { path: '/' })
    return null
  }

  try {
    return JSON.parse(raw) as StoredSession
  } catch {
    await redis.del(getSessionStorageKey(token))
    deleteCookie(event, getSessionCookieName(), { path: '/' })
    return null
  }
}

export async function destroyUserSession(event: H3Event) {
  const token = getCookie(event, getSessionCookieName())

  if (token) {
    const redis = await getRedisClient()
    await redis.del(getSessionStorageKey(token))
  }

  deleteCookie(event, getSessionCookieName(), { path: '/' })
}