"use client";

import { useCallback, useMemo, useState } from "react";

import { api } from "@/lib/api/client";
import { useToast } from "@/components/Toast";

// 编辑器内「润色 / 再沟通」核心（复用同步 /refine，只读、不写库——不变量 #3）。
// 润色：对选中段回炉一次。再沟通：以上一版产出为输入 + 作者新意见再回炉，形成版本栈，
// 作者可回看每一版、择一 accept 回填正文（accept/回填由组件负责，此处只管生成与版本历史）。

export interface RefineVersion {
  // 本次回炉的输入段：首轮 = 选中原文；再沟通 = 上一版产出。
  segment: string;
  // 本次改写指令（再沟通时为作者的新意见）；无则空串。
  instruction: string;
  refined: string;
}

export type RefineStatus = "idle" | "refining" | "ready" | "error";

export interface UseRefine {
  status: RefineStatus;
  versions: RefineVersion[];
  // 版本栈顶（最新产出）。
  latest: RefineVersion | null;
  // 最初选中的原文（accept 回填的对比基线）。
  original: string | null;
  // 回炉并返回本版产出（供调用方在结束后留痕）；失败返回 null。
  refine: (
    projectId: string,
    chapterNo: number,
    segment: string,
    instruction?: string,
  ) => Promise<RefineVersion | null>;
  // 以上一版产出为输入 + 作者新意见再回炉一次。无历史版本时为空操作（返回 null）。
  recommunicate: (
    projectId: string,
    chapterNo: number,
    instruction: string,
  ) => Promise<RefineVersion | null>;
  reset: () => void;
}

export function useRefine(): UseRefine {
  const [status, setStatus] = useState<RefineStatus>("idle");
  const [versions, setVersions] = useState<RefineVersion[]>([]);
  const toast = useToast();

  const runRefine = useCallback(
    async (
      projectId: string,
      chapterNo: number,
      segment: string,
      instruction: string,
    ): Promise<RefineVersion | null> => {
      setStatus("refining");
      try {
        const trimmed = instruction.trim();
        const { data, error } = await api.POST(
          "/projects/{project_id}/chapters/{chapter_no}/refine",
          {
            params: { path: { project_id: projectId, chapter_no: chapterNo } },
            body: trimmed ? { segment, instruction: trimmed } : { segment },
          },
        );
        if (error || !data) {
          setStatus("error");
          toast("回炉失败，请重试。", "error");
          return null;
        }
        const version: RefineVersion = {
          segment,
          instruction: trimmed,
          refined: data.refined,
        };
        setVersions((prev) => [...prev, version]);
        setStatus("ready");
        return version;
      } catch {
        setStatus("error");
        toast("回炉请求异常，请检查网络。", "error");
        return null;
      }
    },
    [toast],
  );

  const refine = useCallback<UseRefine["refine"]>(
    (projectId, chapterNo, segment, instruction) =>
      runRefine(projectId, chapterNo, segment, instruction ?? ""),
    [runRefine],
  );

  const recommunicate = useCallback<UseRefine["recommunicate"]>(
    (projectId, chapterNo, instruction) => {
      const last = versions[versions.length - 1];
      // 无历史版本 → 无从「再沟通」；空操作，不打后端。
      if (!last) return Promise.resolve(null);
      return runRefine(projectId, chapterNo, last.refined, instruction);
    },
    [runRefine, versions],
  );

  const reset = useCallback((): void => {
    setStatus("idle");
    setVersions([]);
  }, []);

  const latest = versions.at(-1) ?? null;
  const original = versions[0]?.segment ?? null;

  return useMemo(
    () => ({ status, versions, latest, original, refine, recommunicate, reset }),
    [status, versions, latest, original, refine, recommunicate, reset],
  );
}