export const MAX_CANVAS_TEMPLATE_REPLACE_SOURCES = 5;

export type CanvasTemplateReplaceSource = {
  id: string;
  imageUrl: string;
  title: string;
  origin: "canvas" | "upload";
  sourceNodeId?: string;
};

function normalizeSource(
  source: CanvasTemplateReplaceSource | null | undefined
): CanvasTemplateReplaceSource | null {
  if (!source) return null;

  const imageUrl = String(source.imageUrl || "").trim();
  if (!/^https?:\/\//i.test(imageUrl)) return null;

  return {
    id: String(source.id || imageUrl).trim() || imageUrl,
    imageUrl,
    title: String(source.title || "替换素材").trim() || "替换素材",
    origin: source.origin === "upload" ? "upload" : "canvas",
    sourceNodeId: String(source.sourceNodeId || "").trim() || undefined,
  };
}

export function normalizeCanvasTemplateReplaceSources(
  sources: Array<CanvasTemplateReplaceSource | null | undefined>
): CanvasTemplateReplaceSource[] {
  const seenUrls = new Set<string>();
  const normalized: CanvasTemplateReplaceSource[] = [];

  for (const source of sources) {
    const nextSource = normalizeSource(source);
    if (!nextSource || seenUrls.has(nextSource.imageUrl)) continue;
    seenUrls.add(nextSource.imageUrl);
    normalized.push(nextSource);
    if (normalized.length >= MAX_CANVAS_TEMPLATE_REPLACE_SOURCES) break;
  }

  return normalized;
}

export function createCanvasTemplateReplaceSlots(
  sources: Array<CanvasTemplateReplaceSource | null | undefined>
): Array<CanvasTemplateReplaceSource | null> {
  const slots = normalizeCanvasTemplateReplaceSources(sources);
  return Array.from(
    { length: MAX_CANVAS_TEMPLATE_REPLACE_SOURCES },
    (_, index) => slots[index] || null
  );
}

export function replaceCanvasTemplateSourceSlot(
  slots: Array<CanvasTemplateReplaceSource | null>,
  slotIndex: number,
  source: CanvasTemplateReplaceSource | null
): Array<CanvasTemplateReplaceSource | null> {
  const nextSlots = createCanvasTemplateReplaceSlots([]);
  slots.slice(0, MAX_CANVAS_TEMPLATE_REPLACE_SOURCES).forEach((item, index) => {
    nextSlots[index] = normalizeSource(item);
  });

  if (slotIndex < 0 || slotIndex >= MAX_CANVAS_TEMPLATE_REPLACE_SOURCES) {
    return nextSlots;
  }

  const normalizedSource = normalizeSource(source);
  if (normalizedSource) {
    nextSlots.forEach((item, index) => {
      if (index !== slotIndex && item?.imageUrl === normalizedSource.imageUrl) {
        nextSlots[index] = null;
      }
    });
  }
  nextSlots[slotIndex] = normalizedSource;
  return nextSlots;
}