import { join } from 'path'
import { existsSync } from 'fs'
import { execFile } from 'child_process'
import { promisify } from 'util'

const execFileAsync = promisify(execFile)

/**
 * Compress a GLTF/GLB model using Blender's Draco compression.
 * Returns a structured result so callers can decide whether to fall back or stop.
 */
export async function compressWithBlender(
  inputPath: string,
  outputPath: string,
): Promise<{ success: boolean; error?: string }> {
  const blenderPath = process.env.BLENDER_PATH || 'blender'
  const timeout = Number(process.env.BLENDER_TIMEOUT_MS || 600_000)
  const scriptPath = join(process.cwd(), 'scripts', 'compress.py')

  if (!existsSync(scriptPath)) {
    return { success: false, error: 'scripts/compress.py introuvable' }
  }

  try {
    await execFileAsync(
      blenderPath,
      [
        '--background',
        '--python', scriptPath,
        '--',
        '-i', inputPath,
        '-o', outputPath,
        '--draco-level', '7',
        '--texture-size', '512',
        '-q',
      ],
      { timeout },
    )

    if (!existsSync(outputPath)) {
      return { success: false, error: "Blender n'a pas produit de fichier compresse" }
    }

    return { success: true }
  } catch (err) {
    const message = err instanceof Error ? err.message : String(err)
    return { success: false, error: `Compression Blender echouee: ${message}` }
  }
}