poe2-data/packages/api/src/services/trend-analysis.ts

import { eq, desc } from 'drizzle-orm';
import { getDatabase, items, priceHistory } from '@poe2data/database';

export interface TrendMover {
  id: number;
  name: string;
  category: string;
  iconUrl: string | null;
  currentValue: number;
  change7d: number;
  volume: number;
  chaosValue: number;
}

export interface CategorySummary {
  category: string;
  itemCount: number;
  topItem: string;
  topValue: number;
  avgChange7d: number;
}

export interface LeagueStartPriority {
  name: string;
  category: string;
  currentValue: number;
  change7d: number;
  volume: number;
  priority: 'high' | 'medium' | 'low';
  reason: string;
}

export class TrendAnalysisService {
  private db = getDatabase();

  /**
   * Get all items with current prices
   */
  async getAllItems(category?: string): Promise<TrendMover[]> {
    // Get all items
    const allItems = await this.db.select().from(items).all();

    // Get latest price for each item - using Drizzle query builder
    // We'll get all prices and pick the latest per item in JS
    const allPrices = await this.db
      .select()
      .from(priceHistory)
      .orderBy(desc(priceHistory.recordedAt))
      .all();

    // Group by item and get the latest
    const priceMap = new Map<number, typeof allPrices[0]>();
    for (const price of allPrices) {
      if (!priceMap.has(price.itemId)) {
        priceMap.set(price.itemId, price);
      }
    }

    let result = allItems.map(item => {
      const price = priceMap.get(item.id);
      return {
        id: item.id,
        name: item.name,
        category: item.category,
        iconUrl: item.iconUrl,
        currentValue: price?.divineValue || 0,
        change7d: price?.change7d || 0,
        volume: price?.volume || 0,
        chaosValue: (price?.divineValue || 0) * (price?.chaosRate || 42),
      };
    });

    if (category) {
      result = result.filter(i => i.category === category);
    }

    return result.sort((a, b) => b.currentValue - a.currentValue);
  }

  /**
   * Get top movers (gainers and losers)
   */
  async getTopMovers(limit: number = 20): Promise<{ gainers: TrendMover[]; losers: TrendMover[] }> {
    const allItems = await this.getAllItems();

    // Filter items with valid change data
    const movers = allItems.filter(m => m.change7d !== 0 && m.currentValue > 0);

    // Sort for gainers (highest positive change)
    const gainers = [...movers]
      .filter(m => m.change7d > 0)
      .sort((a, b) => b.change7d - a.change7d)
      .slice(0, limit);

    // Sort for losers (most negative change)
    const losers = [...movers]
      .filter(m => m.change7d < 0)
      .sort((a, b) => a.change7d - b.change7d)
      .slice(0, limit);

    return { gainers, losers };
  }

  /**
   * Get category summaries
   */
  async getCategorySummaries(): Promise<CategorySummary[]> {
    const allItems = await this.getAllItems();

    const byCategory = new Map<string, TrendMover[]>();
    for (const item of allItems) {
      const list = byCategory.get(item.category) || [];
      list.push(item);
      byCategory.set(item.category, list);
    }

    const summaries: CategorySummary[] = [];
    for (const [category, categoryItems] of byCategory) {
      const sorted = categoryItems.sort((a, b) => b.currentValue - a.currentValue);
      const validChanges = categoryItems.filter(i => i.change7d !== 0);
      const avgChange = validChanges.length > 0
        ? validChanges.reduce((sum, i) => sum + i.change7d, 0) / validChanges.length
        : 0;

      summaries.push({
        category,
        itemCount: categoryItems.length,
        topItem: sorted[0]?.name || 'N/A',
        topValue: sorted[0]?.currentValue || 0,
        avgChange7d: avgChange,
      });
    }

    return summaries.sort((a, b) => b.topValue - a.topValue);
  }

  /**
   * Get league start priorities - items to farm early
   */
  async getLeagueStartPriorities(): Promise<LeagueStartPriority[]> {
    const allItems = await this.getAllItems();

    const priorities: LeagueStartPriority[] = [];

    for (const item of allItems) {
      let priority: 'high' | 'medium' | 'low' = 'low';
      let reason = '';

      // High priority: High value + rising + good volume
      if (item.currentValue > 1 && item.change7d > 20 && item.volume > 100) {
        priority = 'high';
        reason = 'High value, rising price, good demand';
      }
      // High priority: Very high value items
      else if (item.currentValue > 50) {
        priority = 'high';
        reason = 'Very high value item';
      }
      // Medium priority: Rising prices
      else if (item.change7d > 50) {
        priority = 'medium';
        reason = 'Rapidly rising price';
      }
      // Medium priority: Decent value with volume
      else if (item.currentValue > 0.5 && item.volume > 500) {
        priority = 'medium';
        reason = 'Good value with high liquidity';
      }
      // Skip low value items
      else if (item.currentValue < 0.01) {
        continue;
      }
      // Low priority: everything else valuable
      else if (item.currentValue > 0.1) {
        priority = 'low';
        reason = 'Moderate value';
      } else {
        continue;
      }

      priorities.push({
        name: item.name,
        category: item.category,
        currentValue: item.currentValue,
        change7d: item.change7d,
        volume: item.volume,
        priority,
        reason,
      });
    }

    // Sort by priority then value
    const priorityOrder = { high: 0, medium: 1, low: 2 };
    return priorities.sort((a, b) => {
      const pDiff = priorityOrder[a.priority] - priorityOrder[b.priority];
      if (pDiff !== 0) return pDiff;
      return b.currentValue - a.currentValue;
    });
  }

  /**
   * Get price history for an item
   */
  async getItemHistory(itemId: number): Promise<{ timestamp: number; value: number; volume: number }[]> {
    const history = await this.db
      .select({
        recordedAt: priceHistory.recordedAt,
        divineValue: priceHistory.divineValue,
        volume: priceHistory.volume,
      })
      .from(priceHistory)
      .where(eq(priceHistory.itemId, itemId))
      .orderBy(priceHistory.recordedAt)
      .all();

    return history.map(h => ({
      timestamp: h.recordedAt?.getTime() || 0,
      value: h.divineValue || 0,
      volume: h.volume || 0,
    }));
  }
}