// --- Server-Sent Events (SSE) Management ---

// Note: Relies on several functions and variables being globally accessible:
// - Global state: currentProjectData, selectedProjectName, eventSource
// - State helpers: isProcessing, setSelectedProject
// - UI functions: uiUpdateStatusBar, uiShowProcessingState, uiClearProcessingState, uiUpdateProjectSelector, uiClearProjectDisplay
// - Core update functions: handleProjectChange, updateUIScadaCore, updateUIDrawingCore, updateUIConflictsCore
// - Utility: debounce

/**
 * Processes the full data update received from the SSE stream.
 * Updates the internal state and triggers UI updates based on the data.
 * @param {object} fullData - The complete data object from the server.
 */
function sseProcessUpdate(fullData) {
    console.log("[SSE] Received Full Data:", fullData);

    // Store the latest full data globally
    currentProjectData = {}; // Reset first
    const incomingProjects = fullData.projects || [];
    incomingProjects.forEach(projName => {
         currentProjectData[projName] = {
             status: fullData.status ? fullData.status[projName] : 'Unknown',
             last_commit: fullData.last_commit ? fullData.last_commit[projName] : 'N/A',
             // Ensure progress exists and has expected structure
             progress: (fullData.progress && fullData.progress[projName]) 
                       ? fullData.progress[projName] 
                       : { overall: {}, panels: {} } 
         };
    });

    // --- Update Project Selector Dropdown ---
    const selectionChanged = uiUpdateProjectSelector(incomingProjects);
    if (selectionChanged) {
        // If the selection was forced (e.g., previous deleted, list empty)
        // handleProjectChange will update the UI for the new/empty selection
        console.log("[SSE] Project selection changed by dropdown update. Calling handleProjectChange.");
        handleProjectChange(); // Needs global access
        return; // Stop further processing here
    }

    // --- Process data for the currently selected project --- 
    const currentSelection = document.getElementById('projectSelector')?.value; // Check selector exists
    // Update global state if needed (should normally match after selector update)
    if (selectedProjectName !== currentSelection) {
         setSelectedProject(currentSelection); // Needs global access
    }

    if (!selectedProjectName || !currentProjectData[selectedProjectName]) {
        console.log("[SSE] No project selected or no data available for selected project.");
        // Update UI to reflect lack of selection/data
        const projectSelector = document.getElementById('projectSelector');
        if (projectSelector && projectSelector.options.length > 0 && projectSelector.value) {
             uiUpdateStatusBar(selectedProjectName, 'Waiting for data...', 'N/A'); 
             uiShowProcessingState('Waiting for data...'); 
        } else {
             uiUpdateStatusBar('...', 'No projects available', 'N/A');
             uiClearProjectDisplay();
        }
        return;
    }

    const projectData = currentProjectData[selectedProjectName];

    // Update status bar immediately
    uiUpdateStatusBar(selectedProjectName, projectData.status, projectData.last_commit);

    // Update main UI based on processing state
    const projectIsCurrentlyProcessing = isProcessing(projectData.status);
    console.log(`[SSE] Status Check: Project '${selectedProjectName}', Status: '${projectData.status}', isProcessing: ${projectIsCurrentlyProcessing}`);

    if (projectIsCurrentlyProcessing) {
        // If *any* project is processing, the global flag should remain true
        isAnalysisGloballyActive = true; 
        console.log(`[State] isAnalysisGloballyActive set/kept true due to processing status: "${projectData.status}"`);
        uiShowProcessingState(projectData.status);
    } else {
        // --- Update Global Flag: Check if ANY project is still processing --- 
        let anyProjectStillProcessing = false;
        const projectNames = Object.keys(currentProjectData);
        for (const projName of projectNames) {
            if (currentProjectData[projName] && isProcessing(currentProjectData[projName].status)) {
                anyProjectStillProcessing = true;
                console.log(`[State] Project ${projName} is still processing. Keeping isAnalysisGloballyActive true.`);
                break; // Found one, no need to check others
            }
        }
        if (!anyProjectStillProcessing) {
            isAnalysisGloballyActive = false;
            console.log("[State] No projects are processing. isAnalysisGloballyActive set to false.");
        }
        // --- End Global Flag Update ---

        // Added Debugging: Log before clearing and redrawing
        console.log(`[SSE] Clearing processing state and triggering redraw for ${selectedProjectName}`);

        uiClearProcessingState();
        // Call core redraws immediately
        if(projectData && !isProcessing(projectData.status)) { 
            console.log(`[SSE] Confirmed non-processing state for ${selectedProjectName}. Calling core redraw functions.`);
            updateUIScadaCore(projectData); // Needs global access
            updateUIDrawingCore(projectData); // Needs global access
            updateUIConflictsCore(projectData); // Needs global access
         } else {
             // This case handles if the status somehow flipped back to processing
             // between the initial check and this point (very unlikely but safe).
             const latestStatus = projectData?.status || "Processing...";
             console.warn(`[SSE] State unexpectedly indicates processing just before redraw for ${selectedProjectName}. Status: '${latestStatus}'. Showing processing state again.`);
             uiShowProcessingState(latestStatus);
         }
    }
}

// Create a debounced version of the process update function
const debouncedProcessUpdate = debounce(sseProcessUpdate, 250);

/**
 * Initializes the Server-Sent Events connection and sets up message handlers.
 */
function sseInitialize() {
    console.log("[SSE] Initializing connection...");
    // Use global eventSource variable from state.js
    if (eventSource) {
        console.log("[SSE] Closing existing connection.");
        eventSource.close();
    }
    
    try {
        eventSource = new EventSource("/stream");

        eventSource.onmessage = function(event) {
            try {
                const data = JSON.parse(event.data);
                // Call the debounced processor
                debouncedProcessUpdate(data);
            } catch (error) {
                console.error("[SSE] Error parsing data:", error, "Data:", event.data);
                // Update UI to show error
                uiUpdateStatusBar(selectedProjectName, 'Error processing server update.', 'N/A');
            }
        };

        eventSource.onerror = function(err) {
            console.error("[SSE] Connection error:", err);
            // Update UI to show error
            uiUpdateStatusBar(selectedProjectName, 'Connection lost. Retrying...', 'N/A');
            // Simple retry mechanism: close and re-initialize after a delay
            if (eventSource) {
                eventSource.close();
                eventSource = null; // Nullify to allow re-creation
            }
            setTimeout(sseInitialize, 5000); // Attempt to reconnect after 5 seconds
        };

        eventSource.onopen = function() {
            console.log("[SSE] Connection opened.");
            // Optionally update UI to show connected status
             uiUpdateStatusBar(selectedProjectName, "Connected. Waiting for updates...", currentProjectData[selectedProjectName]?.last_commit);
        };

        console.log("[SSE] Event handlers set up.");

    } catch (error) {
        console.error("[SSE] Failed to create EventSource:", error);
        uiUpdateStatusBar(selectedProjectName, 'Failed to connect to server.', 'N/A');
    }
}

// --- Export (if using modules) ---
// export { sseInitialize };