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async function getAge() {
  return 18;
}

getAge().then(age => console.log(`age: ${age}`))
// age: 18

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function delayResolve(x, timeout = 2000) {
  return new Promise((resolve) => {
    setTimeout(() => {
      resolve(x);
    }, timeout);
  });
}

async function main() {
  const x = await delayResolve(2, 2000);
  console.log(x);

  const y = await delayResolve(1, 1000);
  console.log(y);
}

main();
// 2
// 1

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try {
   const response = await axios.get('https://example.com/user');

   // 处理响应数据
   console.log('User data fetched:', response.data);
 } catch (error) {
   console.error('Error response:', error.response);
   // 做其他错误处理
 }

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function fetchUserInfo(userId) {
  return axios.get(`/api/users/${userId}`);
}

function fetchUserOrders(userId) {
  return axios.get(`/api/orders/${userId}`);
}

function generateReport(userInfo, orders) {
  // 根据用户信息和订单生成报告
  return {
    userName: userInfo.name,
    totalOrders: orders.length,
    // ...其他报告数据
  };
}

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const userId = '12345'; // 假设已知的用户ID

fetchUserInfo(userId)
  .then(response => {
    const userInfo = response.data;
    return fetchUserOrders(userInfo.id); // 使用用户ID获取订单
  })
  .then(response => {
    const orders = response.data;
    return generateReport(userInfo, orders); // 生成报告
  })
  .then(report => {
    console.log('用户报告:', report);
  })
  .catch(error => {
    console.error('在处理请求时发生错误:', error);
  });

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async function getUserReport(userId) {
  try {
    const userInfoResponse = await fetchUserInfo(userId);
    const userInfo = userInfoResponse.data;

    const userOrdersResponse = await fetchUserOrders(userInfo.id);
    const orders = userOrdersResponse.data;

    const report = generateReport(userInfo, orders);
    console.log('用户报告:', report);
  } catch (error) {
    console.error('在处理请求时发生错误:', error);
  }
}

const userId = '12345'; // 假设已知的用户ID
getUserReport(userId);

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const processFunctions = [processStep1, processStep2, processStep3, ...];

processFunctions.reduce((previousPromise, currentFunction) => {
  return previousPromise.then(result => currentFunction(result));
}, Promise.resolve(initialValue))
.then(finalResult => {
  console.log('最终结果:', finalResult);
})
.catch(error => {
  console.error('处理过程中发生错误:', error);
});

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async function handleSequentialTasks(tasks, initialResult) {
  let result = initialResult;

  try {
    for (const task of tasks) {
      result = await task(result);
    }
    console.log('最终结果:', result);
  } catch (error) {
    console.error('处理过程中发生错误:', error);
  }
}

const tasks = [task1, task2, task3, ...];
handleSequentialTasks(tasks, initialValue);

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const promise1 = fetch('https://example.com/api/data1');
const promise2 = fetch('https://example.com/api/data2');

Promise.all([promise1, promise2])
  .then(([data1, data2]) => {
    console.log('所有数据已加载:', data1, data2);
  })
  .catch(error => {
    console.error('加载数据时发生错误:', error);
  });

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Promise.allSettled([
  Promise.resolve(33),
  new Promise((resolve) => setTimeout(() => resolve(66), 0)),
  99,
  Promise.reject(new Error("an error")),
]).then((values) => console.log(values));

// [
//   { status: 'fulfilled', value: 33 },
//   { status: 'fulfilled', value: 66 },
//   { status: 'fulfilled', value: 99 },
//   { status: 'rejected', reason: Error: an error }
// ]

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function sleep(time, value, state) {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      if (state === "fulfill") {
        return resolve(value);
      } else {
        return reject(new Error(value));
      }
    }, time);
  });
}

const p1 = sleep(500, "one", "fulfill");
const p2 = sleep(100, "two", "fulfill");

Promise.race([p1, p2]).then((value) => {
  console.log(value); // "two"
  // Both fulfill, but p2 is faster
});

const p3 = sleep(100, "three", "fulfill");
const p4 = sleep(500, "four", "reject");

Promise.race([p3, p4]).then(
  (value) => {
    console.log(value); // "three"
    // p3 is faster, so it fulfills
  },
  (error) => {
    // Not called
  },
);

const p5 = sleep(500, "five", "fulfill");
const p6 = sleep(100, "six", "reject");

Promise.race([p5, p6]).then(
  (value) => {
    // Not called
  },
  (error) => {
    console.error(error.message); // "six"
    // p6 is faster, so it rejects
  },
);

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const promise1 = new Promise((resolve, reject) => {
  setTimeout(resolve, 500, "one");
});

const promise2 = new Promise((resolve, reject) => {
  setTimeout(reject, 100, "two");
});

Promise.race([promise1, promise2])
  .then((value) => {
    console.log("succeeded with value:", value);
  })
  .catch((reason) => {
    // Only promise1 is fulfilled, but promise2 is faster
    console.error("failed with reason:", reason);
  });
// failed with reason: two

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// 假设这些是返回 Promise 的函数
const tasks = [task1, task2, task3, ...];

// 分割任务数组为批次
function splitIntoBatches(tasks, batchSize) {
  let batches = [];
  for (let i = 0; i < tasks.length; i += batchSize) {
    batches.push(tasks.slice(i, i + batchSize));
  }
  return batches;
}

// 处理单个批次的函数
function processBatch(batch) {
  return Promise.all(batch.map(task => task()));
}

// 控制并发的主函数
async function processTasksInBatches(tasks, batchSize) {
  const batches = splitIntoBatches(tasks, batchSize);

  for (const batch of batches) {
    await processBatch(batch);
    // 可以在这里加入日志记录或其他处理
    console.log('一个批次处理完毕');
  }

  console.log('所有批次处理完毕');
}

// 调用主函数，假设每批次处理 10 个任务
processTasksInBatches(tasks, 10);

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function parallelLimit(tasks, {concurrency = 10}) {
  const results = [];
  const executing = new Set();

  let currentlyRunning = 0;
  let currentIndex = 0;

  return new Promise((resolve) => {
    const next = () => {
      if (currentIndex < tasks.length) {
        // 取出记录数，准备执行
        const index = currentIndex;
        const task = tasks[index];

        currentIndex += 1
        currentlyRunning += 1;

        const resultPromise = task().then((result) => {
          // 任务执行完毕，更新运行数、保存结果
          currentlyRunning -= 1;
          results[index] = result;
          executing.delete(resultPromise);

          // 开启下一个任务
          next();
        });

        executing.add(resultPromise);

        // 当前运行的任务数小于限制并且还有任务未开始时，继续添加任务
        if (currentlyRunning < concurrency && currentIndex < tasks.length) {
          next();
        }
      } else if (currentlyRunning === 0) {
        // 所有任务都已完成
        resolve(results);
      }
    };

    // 初始化
    for (let i = 0; i < Math.min(concurrency, tasks.length); i += 1) {
      next();
    }
  });
}

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function asyncTask(id) {
  return new Promise((resolve) => {
    setTimeout(() => {
      console.log(`任务 ${id} 完成`);
      resolve(`结果 ${id}`);
    }, Math.random() * 2000);
  });
}
const taskArray = Array.from({ length: 10 }, (_, i) => () => asyncTask(i + 1));

parallelLimit(taskArray, {concurrency: 3}).then((results) => {
  console.log('所有任务完成:', results);
});

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import pMap from 'p-map';

const list = Array.from({ length: 10 }, (_, i) => i)

pMap(list, asyncTask, { concurrency: 3 })
  .then((results) => {
    console.log('所有任务完成:', results);
  });