add unit suggestion based on ingredient

backend/routes/recipes.js

@@ -65,6 +65,52 @@ router.get('/ingredients/suggestions', async (req, res) => {
   }
 });
 
+// Get unit suggestions for a specific ingredient
+router.get('/ingredients/units', async (req, res) => {
+  try {
+    const { ingredient } = req.query;
+    
+    if (!ingredient) {
+      return res.json([]);
+    }
+    
+    // Find units used with this specific ingredient
+    const unitSuggestions = await Recipe.aggregate([
+      { $unwind: '$ingredients' },
+      { 
+        $match: { 
+          'ingredients.name': { 
+            $regex: ingredient, 
+            $options: 'i' 
+          } 
+        } 
+      },
+      { 
+        $group: { 
+          _id: { $toLower: '$ingredients.unit' },
+          unit: { $first: '$ingredients.unit' },
+          count: { $sum: 1 },
+          avgAmount: { $avg: '$ingredients.amount' }
+        } 
+      },
+      { $sort: { count: -1, unit: 1 } },
+      { $limit: 8 },
+      { 
+        $project: { 
+          _id: 0, 
+          unit: 1, 
+          count: 1,
+          avgAmount: { $round: ['$avgAmount', 2] }
+        } 
+      }
+    ]);
+    
+    res.json(unitSuggestions);
+  } catch (error) {
+    res.status(500).json({ error: error.message });
+  }
+});
+
 // Get all recipes
 router.get('/', async (req, res) => {
   try {

frontend/src/components/UnitAutocomplete.css

@@ -0,0 +1,230 @@
+.unit-autocomplete {
+  position: relative;
+  width: 100%;
+}
+
+.autocomplete-input-container {
+  position: relative;
+  width: 100%;
+}
+
+.autocomplete-input {
+  width: 100%;
+  padding: 0.75rem;
+  padding-right: 2.5rem;
+  border: 2px solid #e9ecef;
+  border-radius: 8px;
+  font-size: 1rem;
+  transition: border-color 0.3s ease, box-shadow 0.3s ease;
+  background: white;
+}
+
+.autocomplete-input:focus {
+  outline: none;
+  border-color: #FF6B35;
+  box-shadow: 0 0 0 3px rgba(255, 107, 53, 0.1);
+}
+
+.autocomplete-loading {
+  position: absolute;
+  right: 0.75rem;
+  top: 50%;
+  transform: translateY(-50%);
+  display: flex;
+  align-items: center;
+  justify-content: center;
+}
+
+.loading-spinner-small {
+  width: 16px;
+  height: 16px;
+  border: 2px solid #e9ecef;
+  border-top: 2px solid #FF6B35;
+  border-radius: 50%;
+  animation: spin 1s linear infinite;
+}
+
+@keyframes spin {
+  0% { transform: rotate(0deg); }
+  100% { transform: rotate(360deg); }
+}
+
+.autocomplete-suggestions {
+  position: absolute;
+  top: 100%;
+  left: 0;
+  right: 0;
+  background: white;
+  border: 1px solid #e9ecef;
+  border-radius: 8px;
+  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
+  z-index: 1000;
+  max-height: 200px;
+  overflow-y: auto;
+  margin-top: 4px;
+}
+
+.suggestions-header {
+  padding: 0.75rem;
+  background: #f8f9fa;
+  border-bottom: 1px solid #e9ecef;
+  font-size: 0.85rem;
+  font-weight: 600;
+  color: #495057;
+  border-radius: 8px 8px 0 0;
+}
+
+.suggestion-item {
+  padding: 0.75rem;
+  cursor: pointer;
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+  transition: background-color 0.2s ease;
+  border-bottom: 1px solid #f8f9fa;
+}
+
+.suggestion-item:last-child {
+  border-bottom: none;
+  border-radius: 0 0 8px 8px;
+}
+
+.suggestion-item:hover,
+.suggestion-item.selected {
+  background-color: #f8f9fa;
+}
+
+.suggestion-item.selected {
+  background-color: #e3f2fd;
+}
+
+.suggestion-main {
+  display: flex;
+  flex-direction: column;
+  align-items: flex-start;
+  gap: 0.25rem;
+  flex: 1;
+}
+
+.suggestion-unit {
+  font-weight: 600;
+  color: #2c3e50;
+  font-size: 1rem;
+}
+
+.suggestion-meta {
+  font-size: 0.8rem;
+  color: #6c757d;
+  display: flex;
+  align-items: center;
+  gap: 0.5rem;
+}
+
+.avg-amount {
+  color: #28a745;
+  font-weight: 500;
+}
+
+/* Custom scrollbar for suggestions */
+.autocomplete-suggestions::-webkit-scrollbar {
+  width: 6px;
+}
+
+.autocomplete-suggestions::-webkit-scrollbar-track {
+  background: #f1f1f1;
+  border-radius: 3px;
+}
+
+.autocomplete-suggestions::-webkit-scrollbar-thumb {
+  background: #c1c1c1;
+  border-radius: 3px;
+}
+
+.autocomplete-suggestions::-webkit-scrollbar-thumb:hover {
+  background: #a8a8a8;
+}
+
+/* Responsive adjustments */
+@media (max-width: 768px) {
+  .autocomplete-suggestions {
+    max-height: 150px;
+  }
+  
+  .suggestion-item {
+    padding: 0.6rem;
+  }
+  
+  .suggestion-unit {
+    font-size: 0.9rem;
+  }
+  
+  .suggestion-meta {
+    font-size: 0.75rem;
+  }
+  
+  .suggestions-header {
+    padding: 0.6rem;
+    font-size: 0.8rem;
+  }
+}
+
+/* Animation for suggestions appearing */
+.autocomplete-suggestions {
+  animation: slideDown 0.2s ease-out;
+}
+
+@keyframes slideDown {
+  from {
+    opacity: 0;
+    transform: translateY(-10px);
+  }
+  to {
+    opacity: 1;
+    transform: translateY(0);
+  }
+}
+
+/* Focus states for accessibility */
+.suggestion-item:focus {
+  outline: 2px solid #FF6B35;
+  outline-offset: -2px;
+}
+
+/* High contrast mode support */
+@media (prefers-contrast: high) {
+  .autocomplete-input {
+    border-color: #000;
+  }
+  
+  .autocomplete-input:focus {
+    border-color: #FF6B35;
+    box-shadow: 0 0 0 3px rgba(255, 107, 53, 0.3);
+  }
+  
+  .suggestion-item.selected {
+    background-color: #FF6B35;
+    color: white;
+  }
+  
+  .suggestion-item.selected .suggestion-meta {
+    color: rgba(255, 255, 255, 0.8);
+  }
+  
+  .suggestion-item.selected .avg-amount {
+    color: rgba(255, 255, 255, 0.9);
+  }
+}
+
+/* Reduced motion support */
+@media (prefers-reduced-motion: reduce) {
+  .autocomplete-input,
+  .suggestion-item,
+  .loading-spinner-small {
+    transition: none;
+    animation: none;
+  }
+  
+  .autocomplete-suggestions {
+    animation: none;
+  }
+}

frontend/src/components/UnitAutocomplete.tsx

@@ -0,0 +1,189 @@
+import React, { useState, useEffect, useRef } from 'react';
+import api from '../services/api';
+import './UnitAutocomplete.css';
+
+interface UnitSuggestion {
+  unit: string;
+  count: number;
+  avgAmount: number;
+}
+
+interface UnitAutocompleteProps {
+  value: string;
+  onChange: (value: string) => void;
+  ingredient: string;
+  placeholder?: string;
+  className?: string;
+}
+
+const UnitAutocomplete: React.FC<UnitAutocompleteProps> = ({
+  value,
+  onChange,
+  ingredient,
+  placeholder = "Unit (cups, tsp, etc.)",
+  className = ""
+}) => {
+  const [suggestions, setSuggestions] = useState<UnitSuggestion[]>([]);
+  const [showSuggestions, setShowSuggestions] = useState(false);
+  const [loading, setLoading] = useState(false);
+  const [selectedIndex, setSelectedIndex] = useState(-1);
+  const inputRef = useRef<HTMLInputElement>(null);
+  const suggestionsRef = useRef<HTMLDivElement>(null);
+
+  // Debounce function to avoid too many API calls
+  const debounce = (func: Function, wait: number) => {
+    let timeout: NodeJS.Timeout;
+    return (...args: any[]) => {
+      clearTimeout(timeout);
+      timeout = setTimeout(() => func.apply(null, args), wait);
+    };
+  };
+
+  // Fetch unit suggestions based on ingredient
+  const fetchUnitSuggestions = async (ingredientName: string) => {
+    if (!ingredientName || ingredientName.length < 2) {
+      setSuggestions([]);
+      setShowSuggestions(false);
+      return;
+    }
+
+    setLoading(true);
+    try {
+      const response = await api.get(`/recipes/ingredients/units?ingredient=${encodeURIComponent(ingredientName)}`);
+      const unitData = response.data as UnitSuggestion[];
+      setSuggestions(unitData);
+      setShowSuggestions(unitData.length > 0);
+      setSelectedIndex(-1);
+    } catch (error) {
+      console.error('Error fetching unit suggestions:', error);
+      setSuggestions([]);
+      setShowSuggestions(false);
+    } finally {
+      setLoading(false);
+    }
+  };
+
+  // Debounced version of fetchUnitSuggestions
+  const debouncedFetchUnitSuggestions = debounce(fetchUnitSuggestions, 500);
+
+  useEffect(() => {
+    if (ingredient) {
+      debouncedFetchUnitSuggestions(ingredient);
+    } else {
+      setSuggestions([]);
+      setShowSuggestions(false);
+    }
+  }, [ingredient]);
+
+  const handleInputChange = (e: React.ChangeEvent<HTMLInputElement>) => {
+    const newValue = e.target.value;
+    onChange(newValue);
+  };
+
+  const handleSuggestionClick = (suggestion: UnitSuggestion) => {
+    onChange(suggestion.unit);
+    setShowSuggestions(false);
+    setSelectedIndex(-1);
+    inputRef.current?.focus();
+  };
+
+  const handleKeyDown = (e: React.KeyboardEvent) => {
+    if (!showSuggestions || suggestions.length === 0) return;
+
+    switch (e.key) {
+      case 'ArrowDown':
+        e.preventDefault();
+        setSelectedIndex(prev => 
+          prev < suggestions.length - 1 ? prev + 1 : prev
+        );
+        break;
+      case 'ArrowUp':
+        e.preventDefault();
+        setSelectedIndex(prev => prev > 0 ? prev - 1 : -1);
+        break;
+      case 'Enter':
+        e.preventDefault();
+        if (selectedIndex >= 0) {
+          handleSuggestionClick(suggestions[selectedIndex]);
+        }
+        break;
+      case 'Escape':
+        setShowSuggestions(false);
+        setSelectedIndex(-1);
+        break;
+    }
+  };
+
+  const handleBlur = (e: React.FocusEvent) => {
+    // Delay hiding suggestions to allow for clicks
+    setTimeout(() => {
+      if (!suggestionsRef.current?.contains(e.relatedTarget as Node)) {
+        setShowSuggestions(false);
+        setSelectedIndex(-1);
+      }
+    }, 150);
+  };
+
+  const handleFocus = () => {
+    if (ingredient && suggestions.length > 0) {
+      setShowSuggestions(true);
+    }
+  };
+
+  return (
+    <div className={`unit-autocomplete ${className}`}>
+      <div className="autocomplete-input-container">
+        <input
+          ref={inputRef}
+          type="text"
+          value={value}
+          onChange={handleInputChange}
+          onKeyDown={handleKeyDown}
+          onBlur={handleBlur}
+          onFocus={handleFocus}
+          placeholder={placeholder}
+          className="autocomplete-input"
+          autoComplete="off"
+        />
+        {loading && (
+          <div className="autocomplete-loading">
+            <div className="loading-spinner-small"></div>
+          </div>
+        )}
+      </div>
+
+      {showSuggestions && suggestions.length > 0 && (
+        <div 
+          ref={suggestionsRef}
+          className="autocomplete-suggestions"
+        >
+          <div className="suggestions-header">
+            Common units for "{ingredient}":
+          </div>
+          {suggestions.map((suggestion, index) => (
+            <div
+              key={suggestion.unit}
+              className={`suggestion-item ${index === selectedIndex ? 'selected' : ''}`}
+              onClick={() => handleSuggestionClick(suggestion)}
+              onMouseEnter={() => setSelectedIndex(index)}
+            >
+              <div className="suggestion-main">
+                <span className="suggestion-unit">{suggestion.unit}</span>
+                <span className="suggestion-meta">
+                  {suggestion.count} recipe{suggestion.count !== 1 ? 's' : ''}
+                  {suggestion.avgAmount && (
+                    <span className="avg-amount">
+                      • avg: {suggestion.avgAmount}
+                    </span>
+                  )}
+                </span>
+              </div>
+            </div>
+          ))}
+        </div>
+      )}
+    </div>
+  );
+};
+
+export default UnitAutocomplete;

frontend/src/pages/CreateRecipe.tsx

@@ -3,6 +3,7 @@ import { useNavigate } from 'react-router-dom';
 import { useAuth } from '../context/AuthContext';
 import api from '../services/api';
 import IngredientAutocomplete from '../components/IngredientAutocomplete';
+import UnitAutocomplete from '../components/UnitAutocomplete';
 import './CreateRecipe.css';
 
 interface Ingredient {
@@ -300,11 +301,11 @@ const CreateRecipe: React.FC = () => {
                 />
               </div>
               <div className="form-group">
-                <input
+                <UnitAutocomplete
-                  type="text"
-                  placeholder="Unit (cups, tsp, etc.)"
                   value={ingredient.unit}
-                  onChange={(e) => updateIngredient(index, 'unit', e.target.value)}
+                  onChange={(value) => updateIngredient(index, 'unit', value)}
+                  ingredient={ingredient.name}
+                  placeholder="Unit (cups, tsp, etc.)"
                 />
               </div>
               <button