feat: tag items depending on region and gold state when bought

match_collector/champion_stat.ts

@@ -2,12 +2,14 @@ import { MongoClient } from 'mongodb'
 import {
   ItemTree,
   GoldAdvantageTag,
+  PlatformCounts,
   treeInit,
   treeMerge,
   treeCutBranches,
   treeSort,
   treeMergeTree,
-  areTreeSimilars
+  areTreeSimilars,
+  treeDeriveTags
 } from './item_tree'
 
 import { Match, Timeline, Participant, Frame } from './api'
@@ -101,6 +103,8 @@ type LaneData = {
   builds: Builds
   matchups?: Array<MatchupData>
   summonerSpells: Array<{ id: number; count: number; pickrate?: number }>
+  // Region distribution for this lane (used for tag derivation)
+  regionDistribution?: PlatformCounts
 }
 type ChampionData = {
   champion: Champion
@@ -332,11 +336,21 @@ function handleMatch(match: Match, champions: Map<number, ChampionData>, platfor
         winrate: 0,
         pickrate: 0,
         summonerSpells: [],
-        matchups: []
+        matchups: [],
+        regionDistribution: { euw: 0, eun: 0, na: 0, kr: 0 }
       }
       champion.lanes.push(lane)
     } else lane.count += 1
 
+    // Track region distribution for this lane
+    if (lane.regionDistribution && platform) {
+      const platformKey = platform.toLowerCase()
+      if (platformKey === 'euw1') lane.regionDistribution.euw++
+      else if (platformKey === 'eun1') lane.regionDistribution.eun++
+      else if (platformKey === 'na1') lane.regionDistribution.na++
+      else if (platformKey === 'kr') lane.regionDistribution.kr++
+    }
+
     // Initialize matchups if not present
     if (!lane.matchups) {
       lane.matchups = []
@@ -589,6 +603,9 @@ function cleanupLaneBuilds(lane: LaneData) {
     treeCutBranches(build.items, 4, 0.05)
     treeSort(build.items)
 
+    // Derive tags from purchase patterns (gold advantage, region)
+    treeDeriveTags(build.items, lane.regionDistribution)
+
     // Remove boots that are not within percentage threshold
     arrayRemovePercentage(build.boots, build.count, 0.05)
     build.boots.sort((a, b) => b.count - a.count)