package main

import (
	"database/sql"
	"encoding/json"
	"fmt"
	"log"
	"strconv"
	"sync"
	"time"
)

// LiquidationHandler handles allLiquidation stream messages, saving events to hot DB and bucketing 5s features.
type LiquidationHandler struct {
	cfg           Config
	storage       *StreamStorage
	mu            sync.Mutex
	currentBucket int64
	events        []Liquidation
	hotDB         *sql.DB
	featDB        *sql.DB
}

func NewLiquidationHandler(cfg Config, sm *StorageManager) (*LiquidationHandler, error) {
	ss := sm.GetStreamStorage("liquidations")
	if ss == nil {
		return nil, fmt.Errorf("liquidations stream storage not found")
	}

	hotDB, err := OpenDBWithAutoVacuum(ss.DBPath("hot_liquidations.db"))
	if err != nil {
		return nil, fmt.Errorf("open hot_liquidations db: %w", err)
	}

	featDB, err := OpenDBWithAutoVacuum(ss.DBPath("features.db"))
	if err != nil {
		hotDB.Close()
		return nil, fmt.Errorf("open liquidation features db: %w", err)
	}

	return &LiquidationHandler{
		cfg:     cfg,
		storage: ss,
		hotDB:   hotDB,
		featDB:  featDB,
	}, nil
}

func (lh *LiquidationHandler) Topics() []string {
	return []string{fmt.Sprintf("allLiquidation.%s", lh.cfg.Symbol)}
}

func (lh *LiquidationHandler) HandleMessage(data []byte) {
	var msg BybitLiquidationMessage
	if err := json.Unmarshal(data, &msg); err != nil {
		return
	}

	raw := msg.Data
	if raw.S != "" && raw.S != lh.cfg.Symbol {
		return // Filter by target symbol
	}

	price, err := strconv.ParseFloat(raw.P, 64)
	if err != nil {
		return
	}
	qty, err := strconv.ParseFloat(raw.V, 64)
	if err != nil {
		return
	}

	ts := raw.T
	if ts == 0 {
		ts = msg.TS
	}
	if ts == 0 {
		ts = time.Now().UnixMilli()
	}

	liq := Liquidation{
		Timestamp: ts,
		Side:      raw.SD,
		Price:     price,
		Quantity:  qty,
		Value:     price * qty,
	}

	// 1. Write event directly to hot DB
	_, err = lh.hotDB.Exec(`
		INSERT INTO liquidations (timestamp, side, price, quantity, value)
		VALUES (?, ?, ?, ?, ?)
	`, liq.Timestamp, liq.Side, liq.Price, liq.Quantity, liq.Value)
	if err != nil {
		log.Printf("[liquidation_handler] hot db insert error: %v", err)
	}

	// 2. Aggregate into 5-second feature buckets
	lh.mu.Lock()
	defer lh.mu.Unlock()

	bucketTS := (liq.Timestamp / 5000) * 5000

	if lh.currentBucket == 0 {
		lh.currentBucket = bucketTS
	}

	if bucketTS > lh.currentBucket {
		if len(lh.events) > 0 {
			lh.flushBucket()
		}
		lh.currentBucket = bucketTS
		lh.events = lh.events[:0]
	}

	lh.events = append(lh.events, liq)
}

func (lh *LiquidationHandler) flushBucket() {
	if len(lh.events) == 0 {
		return
	}

	feat := computeLiquidationFeatures(lh.currentBucket, lh.events)

	_, err := lh.featDB.Exec(`
		INSERT OR IGNORE INTO liquidation_features (
			timestamp, count_total, count_long, count_short,
			volume_total, volume_long, volume_short,
			value_total, value_long, value_short,
			avg_price, net_value
		) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
	`, feat.Timestamp, feat.CountTotal, feat.CountLong, feat.CountShort,
		feat.VolumeTotal, feat.VolumeLong, feat.VolumeShort,
		feat.ValueTotal, feat.ValueLong, feat.ValueShort,
		feat.AvgPrice, feat.NetValue)

	if err != nil {
		log.Printf("[liquidation_handler] feature insert error: %v", err)
	}
}

func computeLiquidationFeatures(bucketTS int64, events []Liquidation) LiquidationFeature {
	feat := LiquidationFeature{
		Timestamp:  bucketTS,
		CountTotal: len(events),
	}

	var sumPrice float64
	for _, ev := range events {
		sumPrice += ev.Price
		feat.VolumeTotal += ev.Quantity
		feat.ValueTotal += ev.Value

		if ev.Side == "Buy" { // Buy = long liquidated
			feat.CountLong++
			feat.VolumeLong += ev.Quantity
			feat.ValueLong += ev.Value
		} else { // Sell = short liquidated
			feat.CountShort++
			feat.VolumeShort += ev.Quantity
			feat.ValueShort += ev.Value
		}
	}

	if feat.CountTotal > 0 {
		feat.AvgPrice = sumPrice / float64(feat.CountTotal)
	}
	feat.NetValue = feat.ValueLong - feat.ValueShort

	return feat
}

func (lh *LiquidationHandler) Close() {
	lh.mu.Lock()
	defer lh.mu.Unlock()

	if len(lh.events) > 0 {
		lh.flushBucket()
	}

	if lh.hotDB != nil {
		lh.hotDB.Close()
	}
	if lh.featDB != nil {
		lh.featDB.Close()
	}
}