export async function fetchGenerationOptions(): Promise<unknown> {
  const response = await fetch("/api/comfy/models");
  if (!response.ok) throw new Error("Unable to load ComfyUI models");
  return response.json() as Promise<unknown>;
}

export type GenerationResult = { source: string; mimeType: string; seed: number };

export async function requestSemanticSelection(body: { inputImage: string; x: number; y: number; model?: string }, signal?: AbortSignal): Promise<{ source: string; mimeType: string }> {
  const response = await fetch("/api/comfy/segment", { method: "POST", headers: { "content-type": "application/json" }, body: JSON.stringify(body), signal });
  if (!response.ok) throw new Error(await response.text());
  return response.json() as Promise<{ source: string; mimeType: string }>;
}

export async function requestGeneration(body: unknown, signal?: AbortSignal, onProgress?: (progress: number, detail: string) => void): Promise<{ results: GenerationResult[] }> {
  const response = await fetch("/api/comfy/generate", { method: "POST", headers: { "content-type": "application/json", accept: "application/x-ndjson" }, body: JSON.stringify(body), signal });
  if (!response.ok) throw new Error(await response.text());
  const contentType = response.headers.get("content-type") ?? "";
  if (contentType.includes("application/x-ndjson") && response.body) {
    const reader = response.body.getReader();
    const decoder = new TextDecoder();
    let pending = "";
    while (true) {
      const { value, done } = await reader.read();
      pending += decoder.decode(value, { stream: !done });
      const lines = pending.split("\n");
      pending = lines.pop() ?? "";
      for (const line of lines) {
        if (!line.trim()) continue;
        const event = JSON.parse(line) as { type: "progress"; progress: number; detail: string } | { type: "result"; results: GenerationResult[] } | { type: "error"; message: string };
        if (event.type === "progress") onProgress?.(event.progress, event.detail);
        if (event.type === "error") throw new Error(event.message);
        if (event.type === "result") return { results: event.results };
      }
      if (done) break;
    }
    throw new Error("Generation stream ended without results");
  }
  const payload = await response.json() as { results?: GenerationResult[]; source?: string; mimeType?: string };
  if (payload.results?.length) return { results: payload.results };
  if (payload.source) return { results: [{ source: payload.source, mimeType: payload.mimeType ?? "image/png", seed: 0 }] };
  throw new Error("Generation returned no results");
}