// ---- previewSlice ----
//
// 拥有 previewKey / previewCode / previewCodeSize / previewLoading / previewError。
// Action: loadPreview (用 AbortController 取消旧请求 + request-id 序列号忽略过期响应)。

import type { StateCreator } from "zustand";

import {
  bumpPreviewRequest,
  getPreviewController,
  getPreviewRequest,
  setPreviewController,
} from "./helpers";

import type {
  PreviewSliceActions,
  PreviewSliceState,
} from "./types";
import type { ScriptWorkspaceStore } from "./useScriptWorkspaceStore";

export const createPreviewSlice: StateCreator<
  ScriptWorkspaceStore,
  [],
  [],
  PreviewSliceState & PreviewSliceActions
> = (set) => {
  const initial: PreviewSliceState = {
    previewKey: null,
    previewCode: null,
    previewCodeSize: null,
    previewLoading: false,
    previewError: null,
  };

  return {
    ...initial,

    loadPreview: async (workspaceId, filePath) => {
      const existing = getPreviewController();
      if (existing) {
        existing.abort();
      }
      const requestId = bumpPreviewRequest();
      const previewKey = `${workspaceId}::${filePath}`;

      set({ previewKey, previewLoading: true, previewError: null });

      const controller = new AbortController();
      setPreviewController(controller);

      try {
        const url =
          `/jupyter/${workspaceId}/api/contents/${filePath}` +
          `?type=file&content=1&hash=1&format=text`;
        const response = await fetch(url, {
          signal: controller.signal,
          credentials: "include",
          cache: "no-store",
        });
        if (!response.ok) {
          throw new Error(`Failed to load file: ${response.status}`);
        }
        const data = await response.json();
        if (getPreviewRequest() !== requestId) return;
        set({
          previewKey,
          previewCode: data.content ?? "",
          previewCodeSize: data.size ?? 0,
          previewLoading: false,
          previewError: null,
        });
      } catch (error) {
        if (getPreviewRequest() !== requestId) return;
        if (error instanceof Error && error.name === "AbortError") return;
        set({
          previewKey,
          previewCode: null,
          previewCodeSize: null,
          previewLoading: false,
          previewError:
            error instanceof Error ? error.message : "加载预览失败",
        });
      } finally {
        if (getPreviewRequest() === requestId) {
          setPreviewController(null);
        }
      }
    },
  };
};