import { GeminiProvider } from '@/add-log/food-detection/providers/GeminiProvider';
import { formatDateKey } from '@/common/utils/format';
import type { FoodLog, FoodRecommendation, UserProfile } from '@/types/foodlog';
import type { NutrientKey, Nutrition } from '@/types/nutrition';
import { strings } from '@/common/strings';
import { BASE_DAILY_TARGETS } from '@/common/constants/nutrition';

type NutrientGap = {
  key: NutrientKey;
  label: string;
  consumed: number;
  target: number;
  fillPercent: number;
  weight: number;
  priority: number;
};

const SCORED_NUTRIENTS: { key: NutrientKey; label: string; weight: number }[] = [
  // Level 1 - MUST
  { key: 'protein_g', label: 'Protein', weight: 12 },
  { key: 'carbs_g', label: 'Carbs', weight: 6 },
  { key: 'fat_g', label: 'Fat', weight: 6 },
  { key: 'fiber_g', label: 'Fiber', weight: 10 },
  { key: 'soluble_fiber_g', label: 'Soluble Fiber', weight: 4 },
  { key: 'insoluble_fiber_g', label: 'Insoluble Fiber', weight: 4 },
  { key: 'a_mcg', label: 'Vitamin A', weight: 6 },
  { key: 'retinol_mcg', label: 'Retinol', weight: 3 },
  { key: 'b1_mg', label: 'Thiamin (B1)', weight: 4 },
  { key: 'b2_mg', label: 'Riboflavin (B2)', weight: 4 },
  { key: 'b3_mg', label: 'Niacin (B3)', weight: 4 },
  { key: 'b5_mg', label: 'Pantothenic Acid (B5)', weight: 4 },
  { key: 'b6_mg', label: 'Vitamin B6', weight: 5 },
  { key: 'b9_mcg', label: 'Folate (B9)', weight: 6 },
  { key: 'b12_mcg', label: 'Vitamin B12', weight: 7 },
  { key: 'c_mg', label: 'Vitamin C', weight: 6 },
  { key: 'e_mg', label: 'Vitamin E', weight: 5 },
  { key: 'k_mcg', label: 'Vitamin K', weight: 5 },
  { key: 'calcium_mg', label: 'Calcium', weight: 7 },
  { key: 'iron_mg', label: 'Iron', weight: 7 },
  { key: 'magnesium_mg', label: 'Magnesium', weight: 7 },
  { key: 'zinc_mg', label: 'Zinc', weight: 6 },
  { key: 'potassium_mg', label: 'Potassium', weight: 6 },
  { key: 'phosphorus_mg', label: 'Phosphorus', weight: 4 },
  { key: 'selenium_mcg', label: 'Selenium', weight: 5 },
  { key: 'chromium_mcg', label: 'Chromium', weight: 3 },
  { key: 'molybdenum_mcg', label: 'Molybdenum', weight: 3 },
  { key: 'iodine_mcg', label: 'Iodine', weight: 5 },
  { key: 'omega_3_mg', label: 'Omega-3', weight: 10 },
  { key: 'ala_mg', label: 'ALA', weight: 4 },
  { key: 'epa_mg', label: 'EPA', weight: 6 },
  { key: 'dha_mg', label: 'DHA', weight: 6 },
  { key: 'biotin_mcg', label: 'Biotin', weight: 4 },
  { key: 'probiotics_cfu', label: 'Probiotics', weight: 5 },
  { key: 'copper_mg', label: 'Copper', weight: 4 },
  { key: 'manganese_mg', label: 'Manganese', weight: 4 },
  { key: 'choline_mg', label: 'Choline', weight: 6 },
  { key: 'usa_gov_dga_protein_g', label: 'Protein Foods', weight: 6 },
  { key: 'usa_gov_dga_healthy_fats_tsp_eq', label: 'Healthy Fats', weight: 4 },
  { key: 'usa_gov_dga_vegetables_cup_eq', label: 'Vegetables', weight: 8 },
  { key: 'usa_gov_dga_fruits_cup_eq', label: 'Fruits', weight: 6 },
  { key: 'usa_gov_dga_dairy_cup_eq', label: 'Dairy', weight: 5 },
  { key: 'usa_gov_dga_whole_grains_oz_eq', label: 'Whole Grains', weight: 5 },
  { key: 'usa_gov_dga_dark_green_veg_cup_eq', label: 'Dark Green Vegetables', weight: 5 },
  { key: 'usa_gov_dga_red_orange_veg_cup_eq', label: 'Red/Orange Vegetables', weight: 4 },
  { key: 'usa_gov_dga_beans_peas_lentils_veg_cup_eq', label: 'Legumes', weight: 5 },
  { key: 'usa_gov_dga_starchy_veg_cup_eq', label: 'Starchy Vegetables', weight: 3 },
  { key: 'usa_gov_dga_other_veg_cup_eq', label: 'Other Vegetables', weight: 3 },
  { key: 'omega_6_mg', label: 'Omega-6', weight: 3 },
  { key: 'lycopene_mcg', label: 'Lycopene', weight: 4 },
  { key: 'lutein_zeaxanthin_mcg', label: 'Lutein/Zeaxanthin', weight: 4 },
  { key: 'beta_carotene_mcg', label: 'Beta Carotene', weight: 4 },
  { key: 'tryptophan_mg', label: 'Tryptophan', weight: 3 },
  { key: 'tyrosine_mg', label: 'Tyrosine', weight: 3 },
  { key: 'alpha_carotene_mcg', label: 'Alpha Carotene', weight: 2 },
  { key: 'cryptoxanthin_mcg', label: 'Cryptoxanthin', weight: 2 },
  { key: 'anthocyanins_mg', label: 'Anthocyanins', weight: 3 },
  { key: 'monounsaturated_fat_g', label: 'Monounsaturated Fat', weight: 3 },
  { key: 'polyunsaturated_fat_g', label: 'Polyunsaturated Fat', weight: 3 },
  { key: 'phytosterols_mg', label: 'Phytosterols', weight: 2 },
  { key: 'dpa_mg', label: 'DPA', weight: 3 },
  { key: 'valine_g', label: 'Valine', weight: 3 },
  { key: 'glutamine_g', label: 'Glutamine', weight: 3 },
  { key: 'betaine_mg', label: 'Betaine', weight: 2 },
  // Level 2 - CANNOT AS FOOD (supplement-only)
  { key: 'vitamin_d_mcg', label: 'Vitamin D', weight: 8 },
  { key: 'collagen_g', label: 'Collagen', weight: 3 },
  { key: 'coq10_mg', label: 'CoQ10', weight: 3 },
  { key: 'curcumin_mg', label: 'Curcumin', weight: 3 },
  { key: 'creatine_g', label: 'Creatine', weight: 3 },
  { key: 'resveratrol_mg', label: 'Resveratrol', weight: 2 },
  { key: 'astaxanthin_mcg', label: 'Astaxanthin', weight: 2 },
  // Level 3 - BONUS
  { key: 'water_ml', label: 'Water', weight: 2 },
  { key: 'caffeine_mg', label: 'Caffeine', weight: 1 },
  { key: 'theobromine_mg', label: 'Theobromine', weight: 1 },
  { key: 'taurine_mg', label: 'Taurine', weight: 2 },
];

export const DAYS_TO_REVIEW = 3;

function getRecentDates(today: Date, days: number): string[] {
  return Array.from({ length: days }, (_, i) => {
    const d = new Date(today);
    d.setDate(d.getDate() - i);
    return formatDateKey(d);
  });
}

function extractRecentIngredients(logs: FoodLog[], dates: string[]): string[] {
  const ingredients = new Set<string>();
  for (const foodLog of logs) {
    if (!dates.includes(foodLog.date)) continue;
    if (foodLog.processingStatus !== 'completed') continue;
    for (const ing of foodLog.ingredients || []) {
      ingredients.add(ing.toLowerCase());
    }
  }
  return Array.from(ingredients);
}

function computeRecentNutrition(logs: FoodLog[], dates: string[]): Nutrition {
  const consumed: Nutrition = {};

  for (const foodLog of logs) {
    if (!dates.includes(foodLog.date) || foodLog.processingStatus !== 'completed') continue;
    if (!foodLog.nutrition) continue;
    for (const [k, v] of Object.entries(foodLog.nutrition)) {
      const key = k as NutrientKey;
      consumed[key] = (consumed[key] ?? 0) + (v ?? 0);
    }
  }

  return consumed;
}

function identifyNutritionGaps(consumed: Nutrition, days: number): NutrientGap[] {
  const gaps: NutrientGap[] = [];

  for (const { key, label, weight } of SCORED_NUTRIENTS) {
    const c = consumed[key] ?? 0;
    const t = (BASE_DAILY_TARGETS[key] ?? 0) * days;
    if (t <= 0) continue;

    const fillPercent = Math.min((c / t) * 100, 100);
    const priority = weight * (1 - fillPercent / 100);

    gaps.push({ key, label, consumed: c, target: t, fillPercent, weight, priority });
  }

  return gaps.sort((a, b) => b.priority - a.priority);
}

function buildPrompt(
  gaps: NutrientGap[],
  recentIngredients: string[],
  profile: UserProfile | null,
  days: number
): string {
  const topGaps = gaps.filter(g => g.fillPercent < 80).slice(0, 8);

  const gapLines = topGaps
    .map(
      (g, i) =>
        `${i + 1}. ${g.label}: ${Math.round(g.consumed)} / ${Math.round(g.target)} (${Math.round(g.fillPercent)}%)`
    )
    .join('\n');

  const restrictions = profile?.food_restrictions?.length
    ? profile.food_restrictions.join(', ')
    : 'none';
  const preferences = profile?.food_preferences?.length
    ? profile.food_preferences.join(', ')
    : 'none';
  const conditions = profile?.health_conditions?.length
    ? profile.health_conditions.join(', ')
    : 'none';

  const recentList =
    recentIngredients.length > 0 ? recentIngredients.slice(0, 20).join(', ') : 'none';

  return strings.ai.recommendIngredients({
    days,
    gapLines,
    recentIngredients: recentList,
    restrictions,
    preferences,
    conditions,
  });
}

type RecommendationResult = {
  ingredients: string[];
  foods: FoodRecommendation[];
};

function parseResponse(response: string): RecommendationResult {
  try {
    const cleaned = response.replace(/```json\n?|\n?```/g, '').trim();
    const parsed = JSON.parse(cleaned);

    const ingredients = Array.isArray(parsed.ingredients) ? parsed.ingredients : [];
    const foods: FoodRecommendation[] = [];

    if (Array.isArray(parsed.foods)) {
      for (const f of parsed.foods) {
        if (f.name && Array.isArray(f.ingredients)) {
          foods.push({ recommendedFoodName: f.name, ingredients: f.ingredients });
        }
      }
    }

    return { ingredients, foods };
  } catch {
    return { ingredients: [], foods: [] };
  }
}

export async function generateRecommendations(
  logs: FoodLog[],
  today: Date,
  profile: UserProfile | null,
  days: number = DAYS_TO_REVIEW
): Promise<RecommendationResult> {
  const dates = getRecentDates(today, days);
  const recentIngredients = extractRecentIngredients(logs, dates);
  const consumed = computeRecentNutrition(logs, dates);
  const gaps = identifyNutritionGaps(consumed, days);

  if (gaps.every(g => g.fillPercent >= 80)) {
    return { ingredients: [], foods: [] };
  }

  const prompt = buildPrompt(gaps, recentIngredients, profile, days);
  const provider = new GeminiProvider();

  try {
    const response = await provider.query(prompt);
    return parseResponse(response);
  } catch (error) {
    console.error('Recommendation generation failed:', error);
    return { ingredients: [], foods: [] };
  }
}

export { computeRecentNutrition, identifyNutritionGaps };