const BASE_URL = "http://localhost:8080/api";

// Helper function for handling fetch requests
const fetchData = async (url, options) => {
  try {
    const response = await fetch(url, options);

    // Check if response is OK (status 200-299)
    if (!response.ok) {
      let errorDetails = {};
      try {
        errorDetails = await response.json(); // Attempt to parse error response
      } catch (err) {
        console.warn("Failed to parse error details:", err);
      }
      throw new Error(
        `Error: ${response.statusText} (${response.status}) - ${
          errorDetails.message || "No details available"
        }`
      );
    }

    // Return JSON response if successful
    return await response.json();
  } catch (error) {
    console.error(`Request failed for ${url}:`, error.message);
    throw error; // Re-throw for the caller to handle
  }
};

// Fetch courses with optional filters
export const fetchCourses = async (filterData = {}) => {
  try {
    const queryString = new URLSearchParams(filterData).toString();
    const url = `${BASE_URL}/courses?${queryString}`;
    return fetchData(url, {
      method: "GET",
      headers: {
        "Content-Type": "application/json",
      },
    });
  } catch (error) {
    console.error("Error fetching courses:", error.message);
    throw error;
  }
};

// Fetch list of faculties
export const fetchFaculties = async () => {
  try {
    const url = `${BASE_URL}/faculty`;
    return fetchData(url, {
      method: "GET",
      headers: {
        "Content-Type": "application/json",
      },
    });
  } catch (error) {
    console.error("Error fetching faculties:", error.message);
    throw error;
  }
};

// Fetch available options for form dropdowns
export const fetchOptions = async () => {
  try {
    const url = `${BASE_URL}/options`;
    return fetchData(url, {
      method: "GET",
      headers: {
        "Content-Type": "application/json",
      },
    });
  } catch (error) {
    console.error("Error fetching options:", error.message);
    throw error;
  }
};

// Save multiple appointments to MongoDB
export const saveAppointment = async (appointmentsData) => {
  console.log("Saving appointments with payload:", appointmentsData);

  // Validate input format
  if (!Array.isArray(appointmentsData) || appointmentsData.length === 0) {
    const errorMessage =
      "Invalid or missing appointment data: expected a non-empty array";
    console.error(errorMessage);
    throw new Error(errorMessage);
  }

  // Validate each appointment's structure
  const invalidEntries = appointmentsData.filter(
    (appointment) =>
      !appointment.facultyId || !appointment.courseId || !Array.isArray(appointment.tasks)
  );

  if (invalidEntries.length > 0) {
    const errorMessage = `Invalid appointments detected: ${JSON.stringify(
      invalidEntries
    )}`;
    console.error(errorMessage);
    throw new Error(errorMessage);
  }

  try {
    const url = `${BASE_URL}/appointments`;
    const response = await fetchData(url, {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
      },
      body: JSON.stringify({ appointments: appointmentsData }), // Send appointments as an array
    });

    console.log("Appointments saved successfully:", response);
    return response;
  } catch (error) {
    console.error("Error saving appointments:", error.message);
    throw error;
  }
};

// Update course status
export const updateCourseStatus = async (courseId) => {
  if (!courseId) {
    throw new Error("Course ID is required to update the status");
  }

  const url = `${BASE_URL}/courses/${courseId}`;
  return fetchData(url, {
    method: "PATCH",
    headers: {
      "Content-Type": "application/json",
    },
    body: JSON.stringify({ status: "submitted" }), // Update status to "Submitted"
  });
};