// ---------------------------------------------------------------------------
// Client-side folder validation
// ---------------------------------------------------------------------------

import { REQUIRED_TEXTURES, TEXTURE_EXTENSIONS } from '@/lib/constants'
import type { TextureFile } from '@/lib/client-types'

const TEXTURE_EXT_ARRAY = [...TEXTURE_EXTENSIONS]

function getTextureType(filename: string): string | null {
  const name = filename.toLowerCase().replace(/\.[^.]+$/, '')
  if ((REQUIRED_TEXTURES as readonly string[]).includes(name)) return name
  return null
}

/** Discriminated union: either valid (with model) or invalid (with errors). */
export type ValidationResult =
  | { ok: true; model: File; textures: TextureFile[]; warnings: string[] }
  | { ok: false; errors: string[] }

export function validateFolder(files: File[]): ValidationResult {
  const textures: TextureFile[] = []
  const warnings: string[] = []
  const errors: string[] = []

  const modelFiles = files.filter((f) => {
    const name = f.name.toLowerCase()
    return name === 'model.glb' || name === 'model.gltf'
  })

  if (modelFiles.length === 0) {
    return { ok: false, errors: ['model.glb ou model.gltf manquant (obligatoire)'] }
  }

  const textureFiles = files.filter((f) => {
    const ext = f.name.slice(f.name.lastIndexOf('.')).toLowerCase()
    return TEXTURE_EXT_ARRAY.includes(ext) && getTextureType(f.name) !== null
  })

  for (const tf of textureFiles) {
    textures.push({ name: tf.name, file: tf })
  }

  const foundTextures = new Set(
    textures.map((t) => t.name.toLowerCase().replace(/\.[^.]+$/, '')),
  )
  for (const req of REQUIRED_TEXTURES) {
    if (!foundTextures.has(req)) {
      warnings.push(`${req}.webp/png/jpg manquant`)
    }
  }

  if (errors.length > 0) {
    return { ok: false, errors }
  }

  return { ok: true, model: modelFiles[0], textures, warnings }
}