// app/frontend/types/globals.d.ts
import type { FlashData, SharedProps } from '@/types'

declare module '@inertiajs/core' {
  export interface InertiaConfig {
    sharedPageProps: SharedProps   // EXACT name — auto-typed for usePage().props
    flashDataType: FlashData      // EXACT name — auto-typed for usePage().flash
    errorValueType: string[]      // EXACT name — errors are arrays of strings
  }
}

// app/frontend/types/index.ts
export interface FlashData {
  notice?: string
  alert?: string
}

export interface SharedProps {
  auth: { user?: { id: number; name: string; email: string } }
}

// BAD — passing shared props as generics:
// usePage<{ users: User[], auth: AuthData, flash: FlashData }>()

// BAD — extending a SharedProps interface into page props:
// interface Props extends SharedData { users: User[] }

// BAD — declaring PageProps interface:
// interface PageProps { auth: AuthData; flash: FlashData }

// BAD — using current_user or user as top-level shared key:
// interface SharedProps { current_user: User }

// BAD — destructuring auth directly from usePage() (TS2339: 'auth' does not exist on Page):
// const { auth } = usePage()
// usePage() returns a Page object with { props, flash, component, url, ... }
// auth lives inside props, not on the Page itself

// BAD — duplicating InertiaConfig in index.ts (it belongs in globals.d.ts):
// declare module '@inertiajs/core' { ... }  ← in index.ts

// GOOD — props from usePage().props, flash from usePage().flash:
const { props, flash } = usePage()
// props.auth is typed (from SharedProps via InertiaConfig)
// flash.notice is typed (from FlashData via InertiaConfig)

// BEFORE — app/frontend/types/index.ts
export interface SharedProps {
  auth: { user?: { id: number; name: string; email: string } }
}

// AFTER — add the new key here, NOT in globals.d.ts
export interface SharedProps {
  auth: { user?: { id: number; name: string; email: string } }
  notifications: { unread_count: number }
}

// React
type Props = {
  users: User[]         // page-specific only
  // auth is NOT here — it comes from InertiaConfig globally
}

export default function Index({ users }: Props) {
  // Access shared props separately:
  const { props, flash } = usePage()
  // props.auth is typed via InertiaConfig
  // flash.notice is typed via InertiaConfig
  return <UserList users={users} />
}

<!-- Vue 3 — usePage() returns reactive object; use computed() for derived values -->
<script setup lang="ts">
import { usePage } from '@inertiajs/vue3'
import { computed } from 'vue'

const page = usePage()
const userName = computed(() => page.props.auth.user?.name) // typed via InertiaConfig
</script>

<!-- Svelte — page store from @inertiajs/svelte -->
<script lang="ts">
  import { page } from '@inertiajs/svelte'
  // $page.props.auth is typed via InertiaConfig
  // $page.flash.notice is typed via InertiaConfig
</script>