// --- API Interaction Functions ---

/**
 * Makes a fetch request and handles common scenarios like JSON parsing and HTTP errors.
 * @param {string} url - The URL to fetch.
 * @param {object} options - Fetch options (method, headers, body, etc.).
 * @returns {Promise<object>} - A promise that resolves with the parsed JSON data.
 * @throws {Error} - Throws an error if the fetch fails or the response is not ok.
 */
async function fetchApi(url, options = {}) {
    try {
        const response = await fetch(url, options);

        // Try to parse JSON regardless of status code for potential error details
        let data = {};
        try {
            // Handle potential non-JSON responses (e.g., empty body on 204)
            const text = await response.text();
            if (text) {
                data = JSON.parse(text);
            } else {
                data = { success: response.ok, message: response.statusText }; // Basic success/failure if body empty
            }
        } catch (e) {
            console.warn(`Could not parse JSON response from ${url}. Status: ${response.status}`);
            // If JSON parsing fails, still check the HTTP status
            if (!response.ok) {
                throw new Error(options.errorMessage || `Request failed with status ${response.status}. No details available.`);
            }
             // If response was OK but JSON failed, might be acceptable depending on endpoint
             // Or return a default success object if appropriate
             data = { success: true, message: "Operation successful, but response was not valid JSON." };
        }

        if (!response.ok) {
            // Use the message from parsed JSON if available, otherwise default error
            throw new Error(data.message || options.errorMessage || `Request failed with status ${response.status}`);
        }

        // Ensure the returned data always has a `success` property if not present
        if (typeof data.success === 'undefined') {
            data.success = true; // Assume success if HTTP status was OK and no success flag found
        }

        return data;
    } catch (error) {
        console.error(`API Error (${options.method || 'GET'} ${url}):`, error);
        // Re-throw the error so the calling function can handle it (e.g., display to user)
        throw error; // Keep original error type/message if possible
    }
}

// --- Specific API Call Functions ---

/**
 * Fetches the list of PDF files for a given project.
 * @param {string} projectName - The name of the project.
 * @returns {Promise<object>} - The API response (e.g., { success: true, files: [...] }).
 */
async function apiListPdfs(projectName) {
    return fetchApi(`/list_pdfs/${encodeURIComponent(projectName)}`, {
        errorMessage: 'Failed to list PDF files'
    });
}

/**
 * Deletes a specific PDF file from a project.
 * @param {string} projectName - The name of the project.
 * @param {string} filename - The name of the PDF file to delete.
 * @returns {Promise<object>} - The API response (e.g., { success: true, message: "..." }).
 */
async function apiDeletePdf(projectName, filename) {
    return fetchApi(`/delete_pdf/${encodeURIComponent(projectName)}`, {
        method: 'POST',
        headers: {
            'Content-Type': 'application/json',
        },
        body: JSON.stringify({ filename: filename }),
        errorMessage: 'Failed to delete PDF file'
    });
}

/**
 * Uploads one or more PDF files to a project.
 * @param {string} projectName - The name of the project.
 * @param {FormData} formData - The FormData object containing the files.
 * @returns {Promise<object>} - The API response (e.g., { success: true, message: "..." }).
 */
async function apiUploadPdfs(projectName, formData) {
    return fetchApi(`/upload_pdfs/${encodeURIComponent(projectName)}`, {
        method: 'POST',
        body: formData, // FormData sets Content-Type automatically
        errorMessage: 'File upload failed'
    });
}

/**
 * Triggers a background analysis for a specific project.
 * @param {string} projectName - The name of the project.
 * @returns {Promise<object>} - The API response (e.g., { success: true, message: "..." }).
 */
async function apiTriggerAnalysis(projectName) {
    return fetchApi(`/trigger_analysis/${encodeURIComponent(projectName)}`, {
        method: 'POST',
        errorMessage: 'Failed to trigger analysis'
    });
}

/**
 * Adds a new project.
 * @param {FormData} formData - The FormData object containing project details and files.
 * @returns {Promise<object>} - The API response (e.g., { success: true, message: "..." }).
 */
async function apiAddProject(formData) {
    return fetchApi('/add_project', {
        method: 'POST',
        body: formData,
        errorMessage: 'Failed to add project'
    });
}

/**
 * Deletes an entire project.
 * @param {string} projectName - The name of the project to delete.
 * @returns {Promise<object>} - The API response (e.g., { success: true, message: "..." }).
 */
async function apiDeleteProject(projectName) {
    return fetchApi(`/delete_project/${encodeURIComponent(projectName)}`, {
        method: 'POST', // Backend expects POST
        errorMessage: 'Failed to delete project'
    });
}

/**
 * Uploads and overwrites the manifest file for a project.
 * @param {string} projectName - The name of the project.
 * @param {FormData} formData - The FormData object containing the manifest file.
 * @returns {Promise<object>} - The API response (e.g., { success: true, message: "..." }).
 */
async function apiUploadManifest(projectName, formData) {
    return fetchApi(`/upload_manifest/${encodeURIComponent(projectName)}`, {
        method: 'POST',
        body: formData,
        errorMessage: 'Failed to upload manifest'
    });
}

// --- Export (if using modules in the future) ---
// export { apiListPdfs, apiDeletePdf, apiUploadPdfs, apiTriggerAnalysis, apiAddProject, apiDeleteProject, apiUploadManifest };