feat: sync drill-down state across mini-charts and months

- Add currentDrillPath to track category hierarchy during drill-down
- Mini-charts now update to show the same category breakdown when
  drilling into a category on the main chart
- Switching months while drilled down preserves the category path,
  navigating to the same category in the new month
- Empty state shown for months that don't have the drilled category
- Browser back/forward navigation syncs mini-charts correctly

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app.js

@@ -8,16 +8,20 @@ let showDefaultView = null; // Reference to reset details panel to default view
 // Drill-down history for back/forward navigation
 let drillDownHistory = [];
 let historyIndex = -1;
+let currentDrillPath = [];  // Tracks drill-down hierarchy: ["Еда", "Рестораны", ...]
 
 // Save current chart state to history
-function saveToHistory(data, total, contextName, isInitial = false) {
+function saveToHistory(data, total, contextName, isInitial = false, path = []) {
     // Remove any forward history when drilling down from middle of history
     if (historyIndex < drillDownHistory.length - 1) {
         drillDownHistory = drillDownHistory.slice(0, historyIndex + 1);
     }
-    drillDownHistory.push({ data, total, contextName });
+    drillDownHistory.push({ data, total, contextName, path: [...path] });
     historyIndex = drillDownHistory.length - 1;
 
+    // Update current drill path
+    currentDrillPath = [...path];
+
     // Push to browser history (use replaceState for initial state)
     const state = { drillDown: historyIndex };
     if (isInitial) {
@@ -31,6 +35,7 @@ function saveToHistory(data, total, contextName, isInitial = false) {
 function resetHistory() {
     drillDownHistory = [];
     historyIndex = -1;
+    currentDrillPath = [];
 }
 
 // Navigate to a specific history state
@@ -46,6 +51,10 @@ function navigateToHistoryState(state) {
 
     myChart.setOption(option, { replaceMerge: ['series'] });
     setupHoverEvents({ total: state.total, data: state.data }, state.contextName);
+
+    // Restore drill path and update mini-charts
+    currentDrillPath = state.path ? [...state.path] : [];
+    updateAllMonthPreviews();
 }
 
 // Go back in drill-down history
@@ -421,7 +430,7 @@ function renderChart(data) {
 
     // Reset and initialize history with the root state
     resetHistory();
-    saveToHistory(sunburstData.data, sunburstData.total, null, true);
+    saveToHistory(sunburstData.data, sunburstData.total, null, true, []);
     
     // Get the currently selected month
     const selectedMonth = document.getElementById('month-select').value;
@@ -876,8 +885,9 @@ function renderChart(data) {
                 });
             }
             
-            // Save new state to history
-            saveToHistory(newData, params.value, params.name);
+            // Build the new path by appending the clicked category
+            const newPath = [...currentDrillPath, params.name];
+            saveToHistory(newData, params.value, params.name, false, newPath);
 
             // Update the chart with the new data structure
             option.series.data = newData;
@@ -890,6 +900,9 @@ function renderChart(data) {
 
             // Update hover events with the new data structure, passing the drilled-down name
             setupHoverEvents({ total: params.value, data: newData }, params.name);
+
+            // Update mini-chart previews to reflect drill-down
+            updateAllMonthPreviews();
         }
     });
     
@@ -1042,6 +1055,141 @@ function generateMonthPreviewGradient(data) {
     return `conic-gradient(${gradientStops.join(', ')})`;
 }
 
+// Find category data at a given path in month's transaction data
+function findCategoryDataAtPath(monthData, path) {
+    if (!path || path.length === 0) {
+        return null;  // No drill-down, use full data
+    }
+
+    // Group transactions by the hierarchy at this path level
+    const categoryName = path[0];
+
+    // Filter transactions belonging to this category
+    const filteredTransactions = monthData.filter(item => item.category === categoryName);
+
+    if (filteredTransactions.length === 0) {
+        return { empty: true };  // Category doesn't exist in this month
+    }
+
+    if (path.length === 1) {
+        // Return subcategory breakdown
+        return { transactions: filteredTransactions, level: 'subcategory' };
+    }
+
+    // Path length >= 2, filter by subcategory
+    const subcategoryName = path[1];
+    const subFiltered = filteredTransactions.filter(item => item.subcategory === subcategoryName);
+
+    if (subFiltered.length === 0) {
+        return { empty: true };
+    }
+
+    if (path.length === 2) {
+        // Return microcategory breakdown
+        return { transactions: subFiltered, level: 'microcategory' };
+    }
+
+    // Path length >= 3, filter by microcategory
+    const microcategoryName = path[2];
+    const microFiltered = subFiltered.filter(item => item.microcategory === microcategoryName);
+
+    if (microFiltered.length === 0) {
+        return { empty: true };
+    }
+
+    // Return transaction-level breakdown
+    return { transactions: microFiltered, level: 'transaction' };
+}
+
+// Get the base color for a drill-down path
+function getPathBaseColor(path) {
+    if (!path || path.length === 0) {
+        return categoryColors[0];
+    }
+
+    const categoryName = path[0];
+    const categoryIndex = categoryOrder.indexOf(categoryName);
+
+    if (categoryIndex !== -1) {
+        return categoryColors[categoryIndex];
+    }
+
+    return categoryColors[0];
+}
+
+// Generate gradient for a month at the current drill-down path
+function generateDrilledDownGradient(monthData, path) {
+    const result = findCategoryDataAtPath(monthData, path);
+
+    // No drill-down - use original function
+    if (!result) {
+        return generateMonthPreviewGradient(monthData);
+    }
+
+    // Empty state - category doesn't exist
+    if (result.empty) {
+        return 'conic-gradient(#e0e0e0 0deg 360deg)';
+    }
+
+    const { transactions, level } = result;
+
+    // Group by the appropriate field based on level
+    const groupField = level === 'subcategory' ? 'subcategory'
+                     : level === 'microcategory' ? 'microcategory'
+                     : 'simple_name';
+
+    const totals = {};
+    let total = 0;
+
+    transactions.forEach(item => {
+        const key = item[groupField] || '(без категории)';
+        const amount = Math.abs(parseFloat(item.amount_rub));
+        if (!isNaN(amount)) {
+            totals[key] = (totals[key] || 0) + amount;
+            total += amount;
+        }
+    });
+
+    if (total === 0) {
+        return 'conic-gradient(#e0e0e0 0deg 360deg)';
+    }
+
+    // Sort by value descending
+    const sortedKeys = Object.keys(totals).sort((a, b) => totals[b] - totals[a]);
+
+    // Generate gradient with color variations
+    const baseColor = getPathBaseColor(path);
+    const colors = generateColorGradient(baseColor, sortedKeys.length);
+
+    const gradientStops = [];
+    let currentAngle = 0;
+
+    sortedKeys.forEach((key, index) => {
+        const percentage = totals[key] / total;
+        const angle = percentage * 360;
+        const color = colors[index] || categoryColors[index % categoryColors.length];
+
+        gradientStops.push(`${color} ${currentAngle}deg ${currentAngle + angle}deg`);
+        currentAngle += angle;
+    });
+
+    return `conic-gradient(${gradientStops.join(', ')})`;
+}
+
+// Update all month preview gradients based on current drill path
+function updateAllMonthPreviews() {
+    const buttons = document.querySelectorAll('.month-btn');
+
+    buttons.forEach(btn => {
+        const month = btn.dataset.month;
+        const preview = btn.querySelector('.month-preview');
+
+        if (preview && monthDataCache[month]) {
+            preview.style.background = generateDrilledDownGradient(monthDataCache[month], currentDrillPath);
+        }
+    });
+}
+
 // Format month for display: "2025-01" -> "Январь'25"
 function formatMonthLabel(dateStr) {
     const [year, month] = dateStr.split('-');
@@ -1130,6 +1278,203 @@ async function loadAvailableMonths() {
     });
 }
 
+// Transform children data for drill-down (extracted from click handler)
+function transformDrillDownData(parentNode) {
+    const colorPalette = [
+        '#5470c6', '#91cc75', '#fac858', '#ee6666', '#73c0de',
+        '#3ba272', '#fc8452', '#9a60b4', '#ea7ccc', '#4cae72'
+    ];
+
+    const newData = [];
+    const sortedChildren = [...parentNode.children].sort((a, b) => b.value - a.value);
+
+    sortedChildren.forEach((child, i) => {
+        const color = colorPalette[i % colorPalette.length];
+        const newCategory = {
+            name: child.name,
+            value: child.value,
+            transactions: child.transactions,
+            itemStyle: { color: color },
+            children: []
+        };
+
+        if (child.children && child.children.length > 0) {
+            const sortedMicros = [...child.children].sort((a, b) => b.value - a.value);
+            const microColors = generateColorGradient(color, sortedMicros.length);
+
+            sortedMicros.forEach((micro, j) => {
+                const microCategory = {
+                    name: micro.name,
+                    value: micro.value,
+                    transactions: micro.transactions,
+                    itemStyle: { color: microColors[j] },
+                    children: []
+                };
+
+                if (micro.transactions && micro.transactions.length > 0) {
+                    const sortedTransactions = [...micro.transactions].sort((a, b) => b.value - a.value);
+                    const transactionColors = generateColorGradient(microColors[j], sortedTransactions.length);
+
+                    sortedTransactions.forEach((transaction, k) => {
+                        microCategory.children.push({
+                            name: transaction.name,
+                            value: transaction.value,
+                            itemStyle: { color: transactionColors[k] },
+                            originalRow: transaction.originalRow
+                        });
+                    });
+                }
+
+                newCategory.children.push(microCategory);
+            });
+        }
+
+        if (child.transactions) {
+            const transactionsWithoutMicro = child.transactions.filter(t => t.displayMicrocategory === '');
+            if (transactionsWithoutMicro.length > 0) {
+                const transactionGroups = {};
+                transactionsWithoutMicro.forEach(t => {
+                    if (!transactionGroups[t.name]) {
+                        transactionGroups[t.name] = { name: t.name, value: 0, transactions: [] };
+                    }
+                    transactionGroups[t.name].value += t.value;
+                    transactionGroups[t.name].transactions.push(t);
+                });
+
+                const groups = Object.values(transactionGroups).sort((a, b) => b.value - a.value);
+                const transactionColors = generateColorGradient(color, groups.length);
+
+                groups.forEach((group, j) => {
+                    const transactionCategory = {
+                        name: group.name,
+                        value: group.value,
+                        transactions: group.transactions,
+                        itemStyle: { color: transactionColors[j] },
+                        children: []
+                    };
+
+                    if (group.transactions.length > 0) {
+                        const sortedTransactions = [...group.transactions].sort((a, b) => b.value - a.value);
+                        const individualColors = generateColorGradient(transactionColors[j], sortedTransactions.length);
+
+                        sortedTransactions.forEach((transaction, k) => {
+                            transactionCategory.children.push({
+                                name: transaction.name,
+                                value: transaction.value,
+                                itemStyle: { color: individualColors[k] },
+                                originalRow: transaction.originalRow
+                            });
+                        });
+                    }
+
+                    newCategory.children.push(transactionCategory);
+                });
+            }
+        }
+
+        newData.push(newCategory);
+    });
+
+    return newData;
+}
+
+// Transform transaction-only data for drill-down
+function transformTransactionData(node) {
+    const colorPalette = [
+        '#5470c6', '#91cc75', '#fac858', '#ee6666', '#73c0de',
+        '#3ba272', '#fc8452', '#9a60b4', '#ea7ccc', '#4cae72'
+    ];
+
+    const transactionGroups = {};
+    node.transactions.forEach(t => {
+        if (!transactionGroups[t.name]) {
+            transactionGroups[t.name] = { name: t.name, value: 0, transactions: [] };
+        }
+        transactionGroups[t.name].value += t.value;
+        transactionGroups[t.name].transactions.push(t);
+    });
+
+    const newData = [];
+    const groups = Object.values(transactionGroups).sort((a, b) => b.value - a.value);
+
+    groups.forEach((group, i) => {
+        const color = colorPalette[i % colorPalette.length];
+        const transactionCategory = {
+            name: group.name,
+            value: group.value,
+            transactions: group.transactions,
+            itemStyle: { color: color },
+            children: []
+        };
+
+        if (group.transactions.length > 0) {
+            const sortedTransactions = [...group.transactions].sort((a, b) => b.value - a.value);
+            const transactionColors = generateColorGradient(color, sortedTransactions.length);
+
+            sortedTransactions.forEach((transaction, j) => {
+                transactionCategory.children.push({
+                    name: transaction.name,
+                    value: transaction.value,
+                    itemStyle: { color: transactionColors[j] },
+                    originalRow: transaction.originalRow
+                });
+            });
+        }
+
+        newData.push(transactionCategory);
+    });
+
+    return newData;
+}
+
+// Navigate to a path in the given sunburst data, returns drilled data or null if path not found
+function navigateToPath(sunburstData, path) {
+    if (!path || path.length === 0) {
+        return null;  // Stay at root
+    }
+
+    // Try to find each level of the path
+    let currentData = sunburstData.data;
+    let currentTotal = sunburstData.total;
+    let currentName = null;
+    let validPath = [];
+
+    for (let i = 0; i < path.length; i++) {
+        const targetName = path[i];
+        const found = currentData.find(item => item.name === targetName);
+
+        if (!found) {
+            // Path level not found, return what we have so far
+            break;
+        }
+
+        validPath.push(targetName);
+        currentName = targetName;
+        currentTotal = found.value;
+
+        // Transform this level's children to become top-level (same as click handler logic)
+        if (found.children && found.children.length > 0) {
+            currentData = transformDrillDownData(found);
+        } else if (found.transactions && found.transactions.length > 0) {
+            currentData = transformTransactionData(found);
+        } else {
+            // No more levels to drill into
+            break;
+        }
+    }
+
+    if (validPath.length === 0) {
+        return null;  // Couldn't match any part of path
+    }
+
+    return {
+        data: currentData,
+        total: currentTotal,
+        contextName: currentName,
+        path: validPath
+    };
+}
+
 // Select and load a specific month
 async function selectMonth(index) {
     currentMonthIndex = index;
@@ -1143,7 +1488,7 @@ async function selectMonth(index) {
     updateMonthNavigator();
 
     // Load and render data
-    const data = await parseCSV(`altcats-${month}.csv`);
+    const data = monthDataCache[month] || await parseCSV(`altcats-${month}.csv`);
 
     // Check if chart already has data (for animation)
     if (option && option.series && option.series.data) {
@@ -1152,32 +1497,49 @@ async function selectMonth(index) {
         // Update the module-level original data for center-click reset
         originalSunburstData = JSON.parse(JSON.stringify(sunburstData));
 
-        // Reset and initialize history for the new month
+        // Save the current drill path before modifying state
+        const savedPath = [...currentDrillPath];
+
+        // Reset history for the new month
         resetHistory();
-        saveToHistory(sunburstData.data, sunburstData.total, null, true);
 
-        // Update only the series data and preserve layout
-        const oldData = option.series.data;
-        const newData = sunburstData.data;
+        // Try to navigate to the same path in the new month
+        const navigatedState = navigateToPath(sunburstData, savedPath);
 
-        // Map old values to new data to preserve positions
-        newData.forEach((newItem, idx) => {
-            if (oldData[idx]) {
-                newItem.layoutId = oldData[idx].name;
+        let targetData, targetTotal, targetName, targetPath;
+
+        if (navigatedState) {
+            // Successfully navigated to (part of) the path
+            targetData = navigatedState.data;
+            targetTotal = navigatedState.total;
+            targetName = navigatedState.contextName;
+            targetPath = navigatedState.path;
+        } else {
+            // Stay at root level
+            targetData = sunburstData.data;
+            targetTotal = sunburstData.total;
+            targetName = null;
+            targetPath = [];
         }
-        });
+
+        // Save initial state with the path
+        saveToHistory(targetData, targetTotal, targetName, true, targetPath);
 
         // Update the data
-        option.series.data = newData;
+        option.series.data = targetData;
 
         // Update the total amount in the center text
         const russianMonth = getRussianMonthName(month);
-        option.graphic.elements[0].style.text = russianMonth + '\n' + sunburstData.total.toFixed(0).toLocaleString() + ' ₽';
+        if (targetName) {
+            option.graphic.elements[0].style.text = `${russianMonth}\n${targetName}\n${targetTotal.toFixed(0).toLocaleString()} ₽`;
+        } else {
+            option.graphic.elements[0].style.text = russianMonth + '\n' + targetTotal.toFixed(0).toLocaleString() + ' ₽';
+        }
 
         myChart.setOption({
             series: [{
                 type: 'sunburst',
-                data: newData,
+                data: targetData,
                 layoutAnimation: true,
                 animationDuration: 500,
                 animationEasing: 'cubicInOut'
@@ -1189,7 +1551,10 @@ async function selectMonth(index) {
         });
 
         // Update hover events
-        setupHoverEvents(sunburstData);
+        setupHoverEvents({ total: targetTotal, data: targetData }, targetName);
+
+        // Update mini-chart previews
+        updateAllMonthPreviews();
     } else {
         // Initial render
         renderChart(data);
@@ -1563,6 +1928,15 @@ function setupHoverEvents(sunburstData, contextName = null) {
                 nameSpan.appendChild(document.createTextNode(item.name));
                 itemDiv.appendChild(nameSpan);
 
+                // Add percentage after name if we have a parent value
+                if (parentValue) {
+                    const percentSpan = document.createElement('span');
+                    percentSpan.className = 'top-item-percent';
+                    const percentage = ((item.value / parentValue) * 100).toFixed(1);
+                    percentSpan.textContent = percentage + '%';
+                    itemDiv.appendChild(percentSpan);
+                }
+
                 // Add eye button for viewing transaction details
                 const eyeBtn = document.createElement('button');
                 eyeBtn.className = 'eye-btn';
@@ -1577,13 +1951,6 @@ function setupHoverEvents(sunburstData, contextName = null) {
                 const amountSpan = document.createElement('span');
                 amountSpan.className = 'top-item-amount';
                 amountSpan.textContent = item.value.toLocaleString() + ' ₽';
-
-                // Add percentage if we have a parent value
-                if (parentValue) {
-                    const percentage = ((item.value / parentValue) * 100).toFixed(1);
-                    amountSpan.textContent += ` (${percentage}%)`;
-                }
-
                 itemDiv.appendChild(amountSpan);
                 topItemsElement.appendChild(itemDiv);
             });
@@ -1663,8 +2030,8 @@ function setupHoverEvents(sunburstData, contextName = null) {
             });
         }
 
-        // Show top categories as default items
-        displayDetailsItems(sunburstData.data, sunburstData.total);
+        // Show top categories as default items (sorted by value descending)
+        displayDetailsItems([...sunburstData.data].sort((a, b) => b.value - a.value), sunburstData.total);
     }
     
     // Show default view initially