function parseJsonReply(reply) {
  const text = String(reply ?? '').trim();
  if (!text) return null;
  const fenced = text.match(/```(?:json)?\s*([\s\S]*?)```/i);
  const candidate = fenced?.[1] ?? text;
  try {
    return JSON.parse(candidate);
  } catch {
    return null;
  }
}

const IMAGE_ONLY_MODEL_HINTS = /(?:image|ocr|vision|vl-ocr|文生图|图生文)/iu;

export function isLlmProviderUnavailable(result) {
  if (result?.ok) return false;
  if (Number(result?.status) === 402 || Number(result?.status) === 429) return true;
  const message = String(result?.message ?? '').toLowerCase();
  return /insufficient balance|余额不足|quota|rate limit|too many requests/u.test(message);
}

function isLikelyChatProviderKey(key) {
  if (!key || key.status === 'disabled') return false;
  const label = `${key.name ?? ''} ${key.defaultModel ?? ''} ${(key.models ?? []).join(' ')}`;
  return !IMAGE_ONLY_MODEL_HINTS.test(label);
}

function buildManageLlmMessages(text, taskList) {
  return [
    {
      role: 'system',
      content: [
        '你是微信服务号定时自动任务管理助手，只做任务选择，不做页面生成。',
        '输入包含用户原话和当前 active 定时任务列表（JSON）。',
        '请严格输出 JSON，不要输出解释。',
        '允许 action:',
        '- cancel：用户明确要取消某个任务，且能从列表中唯一确定 taskId',
        '- clarify：用户想取消但无法唯一确定是哪一个，message 用中文简短追问',
        '- none：不是取消任务，或信息不足且不应猜测',
        'cancel 时必须返回列表里存在的 taskId；禁止编造 taskId。',
        '如果只有一条任务且用户明确要取消/停止定时任务，可以返回该 taskId。',
        '如果用户在要求生成/修改 HTML 页面，而不是管理已有定时任务，返回 none。',
      ].join('\n'),
    },
    {
      role: 'user',
      content: JSON.stringify({
        userMessage: String(text ?? '').trim(),
        activeTasks: taskList,
      }),
    },
  ];
}

async function createManageLlmChatCompletion({
  llmProviderService,
  modelProviderKeyId = null,
  model = null,
  messages,
  logger = console,
} = {}) {
  const candidates = [];
  const seen = new Set();

  const pushCandidate = (providerKeyId, candidateModel) => {
    const key = providerKeyId ?? '__default__';
    if (seen.has(key)) return;
    seen.add(key);
    candidates.push({
      providerKeyId,
      model: candidateModel ?? model ?? null,
    });
  };

  pushCandidate(modelProviderKeyId, model);
  pushCandidate(null, model);

  if (typeof llmProviderService.listKeys === 'function') {
    try {
      const keys = await llmProviderService.listKeys();
      for (const key of keys ?? []) {
        if (!isLikelyChatProviderKey(key)) continue;
        pushCandidate(key.id, model ?? key.defaultModel ?? null);
      }
    } catch (err) {
      logger?.warn?.(
        '[wechat-scheduled-task-manage-llm] provider list failed:',
        err instanceof Error ? err.message : err,
      );
    }
  }

  let lastResult = null;
  let sawUnavailable = false;

  for (const candidate of candidates) {
    const result = await llmProviderService.createChatCompletion({
      ...(candidate.providerKeyId ? { providerKeyId: candidate.providerKeyId } : {}),
      ...(candidate.model ? { model: candidate.model } : {}),
      temperature: 0,
      messages,
    });
    lastResult = result;
    if (result?.ok) return result;
    if (isLlmProviderUnavailable(result)) {
      sawUnavailable = true;
      logger?.warn?.(
        '[wechat-scheduled-task-manage-llm] provider unavailable:',
        candidate.providerKeyId ?? 'default',
        result?.message ?? 'unknown',
      );
      continue;
    }
    logger?.warn?.(
      '[wechat-scheduled-task-manage-llm] provider failed:',
      candidate.providerKeyId ?? 'default',
      result?.message ?? 'unknown',
    );
  }

  return {
    ...(lastResult ?? { ok: false, message: '聊天模型不可用' }),
    llmUnavailable: sawUnavailable,
  };
}

export function buildScheduledTaskListPayload(tasks = []) {
  return tasks.map((task) => ({
    taskId: task.id,
    title: task.title,
    recurrence: task.recurrence,
    hour: task.hour,
    minute: task.minute ?? 0,
    taskSpec: String(task.taskSpec ?? '').slice(0, 240),
  }));
}

export function normalizeScheduledTaskManageLlmDecision(payload, tasks = []) {
  const action = String(payload?.action ?? 'none').trim();
  const taskIds = new Set(tasks.map((task) => String(task.id ?? '').trim()).filter(Boolean));

  if (action === 'clarify') {
    const message = String(payload?.message ?? '').trim()
      || '我找到多个定时任务，请告诉我要取消哪一个。';
    return { action: 'clarify', message };
  }

  if (action === 'cancel') {
    const taskId = String(payload?.taskId ?? '').trim();
    if (taskId && taskIds.has(taskId)) {
      return { action: 'cancel', taskId };
    }
    return { action: 'none' };
  }

  return { action: 'none' };
}

export async function resolveScheduledTaskCancelWithLlm({
  text,
  tasks = [],
  llmProviderService,
  modelProviderKeyId = null,
  model = null,
  logger = console,
} = {}) {
  if (!llmProviderService || typeof llmProviderService.createChatCompletion !== 'function') {
    return { action: 'none' };
  }
  if (!Array.isArray(tasks) || tasks.length === 0) {
    return { action: 'none' };
  }

  const taskList = buildScheduledTaskListPayload(tasks);
  const messages = buildManageLlmMessages(text, taskList);

  try {
    const result = await createManageLlmChatCompletion({
      llmProviderService,
      modelProviderKeyId,
      model,
      messages,
      logger,
    });

    if (!result?.ok) {
      logger?.warn?.(
        '[wechat-scheduled-task-manage-llm] parse skipped:',
        result?.message ?? 'unknown',
      );
      return {
        action: 'none',
        ...(result?.llmUnavailable ? { llmUnavailable: true } : {}),
      };
    }

    return normalizeScheduledTaskManageLlmDecision(parseJsonReply(result.reply), tasks);
  } catch (err) {
    logger?.warn?.(
      '[wechat-scheduled-task-manage-llm] parse skipped:',
      err instanceof Error ? err.message : err,
    );
    return { action: 'none' };
  }
}