feat: add asset import services

src/lib/services/clone-icon.ts

@@ -0,0 +1,64 @@
+import { cropRgba, decodePng } from '@/lib/services/imager/png-decode'
+import { encodePng, parseNitroBundle } from '@/lib/services/swf/nitro-builder'
+
+interface FurniAsset {
+  x?: number
+  y?: number
+  source?: string
+}
+interface FurniFrame {
+  frame: { x: number; y: number; w: number; h: number }
+  rotated?: boolean
+}
+interface FurniNitroJson {
+  name?: string
+  assets?: Record<string, FurniAsset>
+  spritesheet?: { frames?: Record<string, FurniFrame> }
+}
+
+/**
+ * Extract the furni catalog icon — the `{name}_icon_a` sprite — from a Nitro
+ * bundle and return it as a standalone PNG, or null if the bundle has no icon
+ * asset / usable frame. Used for sources that embed furni icons inside the
+ * `.nitro` instead of serving a separate `{classname}_icon.png`.
+ */
+export function extractFurniIconPng(nitro: Buffer): Buffer | null {
+  let json: FurniNitroJson
+  let png: Buffer
+  try {
+    const parsed = parseNitroBundle(nitro)
+    json = parsed.json as FurniNitroJson
+    png = parsed.png
+  } catch {
+    return null
+  }
+  const name = json.name
+  if (!name || !json.assets) return null
+
+  // The icon asset is conventionally `${name}_icon_a`; fall back to any
+  // `${name}_icon*` the bundle exposes.
+  const iconKey = json.assets[`${name}_icon_a`]
+    ? `${name}_icon_a`
+    : Object.keys(json.assets).find((k) => k.startsWith(`${name}_icon`))
+  if (!iconKey) return null
+
+  const asset = json.assets[iconKey]
+  // An asset may alias another's pixels via `source`; the frame key is the
+  // bundle name prefixed onto the asset name. Different converters pack the
+  // key with or without a trailing `.png`, so try both.
+  const pixelAsset = asset.source ?? iconKey
+  const frames = json.spritesheet?.frames ?? {}
+  const frame = frames[`${name}_${pixelAsset}`] ?? frames[`${name}_${pixelAsset}.png`]
+  if (!frame || frame.rotated) return null
+  const { x, y, w, h } = frame.frame
+  if (w <= 0 || h <= 0) return null
+
+  try {
+    const sheet = decodePng(png)
+    const px = cropRgba(sheet.rgba, sheet.width, x, y, w, h)
+    return encodePng(w, h, px)
+  } catch {
+    return null
+  }
+}
+