package db

import (
	"database/sql"
	"fmt"
	"log"
	"os"
	"strings"
	"time"

	_ "github.com/taosdata/driver-go/v3/taosRestful"
)

var TD *sql.DB

func InitTDengine() {
	dsn := os.Getenv("TD_DSN")
	if dsn == "" {
		log.Println("TD_DSN not set, skipping TDengine initialization")
		return
	}

	// Connect to TDengine using RESTful driver (CGO_ENABLED=0 friendly)
	var err error
	TD, err = sql.Open("taosRestful", dsn)
	if err != nil {
		log.Printf("Failed to open TDengine connection: %v\n", err)
		return
	}

	if err := TD.Ping(); err != nil {
		log.Printf("Failed to ping TDengine: %v\n", err)
		return
	}

	log.Println("Connected to TDengine")

	// Initialize Schema
	initSchema()
}

func initSchema() {
	// Create Database
	_, err := TD.Exec("CREATE DATABASE IF NOT EXISTS power_db KEEP 365 DURATION 10 BUFFER 16")
	if err != nil {
		log.Printf("Failed to create database: %v\n", err)
		return
	}

	// Switch to database
	_, err = TD.Exec("USE power_db")
	if err != nil {
		log.Printf("Failed to use database: %v\n", err)
		return
	}

	// Create Super Table for standard metrics
	// Using a "Single Value" model for flexibility:
	// ts: timestamp
	// val: double value
	// Tags: device_id, metric (e.g., 'power', 'voltage'), location_id
	
	stSql := `CREATE STABLE IF NOT EXISTS readings (
		ts TIMESTAMP,
		val DOUBLE
	) TAGS (
		device_id BINARY(64),
		metric BINARY(256),
		location_id BINARY(64)
	)`

	_, err = TD.Exec(stSql)
	if err != nil {
		log.Printf("Failed to create stable readings: %v\n", err)
	} else {
		log.Println("TDengine schema initialized")
	}

	// Create Super Table for switch logs
	stSwitchSql := `CREATE STABLE IF NOT EXISTS switch_logs (
		ts TIMESTAMP,
		val BOOL
	) TAGS (
		device_id BINARY(64),
		metric BINARY(256),
		location_id BINARY(64)
	)`

	_, err = TD.Exec(stSwitchSql)
	if err != nil {
		log.Printf("Failed to create stable switch_logs: %v\n", err)
	}

	// Upgrade schema for existing tables (ignore error if redundant)
	_, _ = TD.Exec("ALTER STABLE readings MODIFY TAG metric BINARY(256)")
}

// InsertReading inserts a single reading
func InsertReading(deviceID string, metric string, val float64, locationID string, ts time.Time) error {
	if TD == nil {
		return fmt.Errorf("TDengine not initialized")
	}

	// Sanitize table name: d_{device_id}_{metric}
	// We need to ensure device_id and metric are safe for table names.
	// UUIDs are safe (with hyphens replaced by underscores).
	// Metrics should be alphanumeric.
	
	// Actually, using automatic table creation via INSERT ... USING is best.
	// Table name: t_{device_id}_{metric} (hash or sanitized)
	// But simple string concatenation is risky if not sanitized.
	// Let's rely on prepared statements or careful construction.
	
	// Construct table name
	// deviceID: usually UUID
	// metric: e.g. "power", "voltage"
	// locationID: UUID or empty
	
	// Safe table name construction
	// Replace '-' with '_' and '.' with '_' to ensure valid table name
	safeMetric := metric
	safeMetric = strings.ReplaceAll(safeMetric, ".", "_")
	safeMetric = strings.ReplaceAll(safeMetric, "-", "_")
	
	safeDID := fmt.Sprintf("d_%s_%s", strings.ReplaceAll(deviceID, "-", "_"), safeMetric)
	// Remove special chars if any (simplified)
	
	// SQL: INSERT INTO {table_name} USING readings TAGS (...) VALUES (?, ?)
	// Note: taosSql driver might not support prepared statement for Table Name or Tags in USING clause well in all versions.
	// Standard approach: fmt.Sprintf for the SQL structure.
	
	query := fmt.Sprintf("INSERT INTO `%s` USING readings TAGS ('%s', '%s', '%s') VALUES (?, ?)",
		safeDID, deviceID, metric, locationID)
	
	_, err := TD.Exec(query, ts, val)
	return err
}

// InsertSwitchLog inserts a switch status log
func InsertSwitchLog(deviceID string, metric string, val bool, locationID string, ts time.Time) error {
	if TD == nil {
		return fmt.Errorf("TDengine not initialized")
	}

	safeMetric := metric
	safeMetric = strings.ReplaceAll(safeMetric, ".", "_")
	safeMetric = strings.ReplaceAll(safeMetric, "-", "_")
	
	// Use 's_' prefix for switch tables
	safeDID := fmt.Sprintf("s_%s_%s", strings.ReplaceAll(deviceID, "-", "_"), safeMetric)
	
	query := fmt.Sprintf("INSERT INTO `%s` USING switch_logs TAGS ('%s', '%s', '%s') VALUES (?, ?)",
		safeDID, deviceID, metric, locationID)
	
	_, err := TD.Exec(query, ts, val)
	return err
}

// ReadingHistory represents aggregated historical data
type ReadingHistory struct {
	Ts       string  `json:"ts"`
	Open     float64 `json:"open"`
	High     float64 `json:"high"`
	Low      float64 `json:"low"`
	Close    float64 `json:"close"`
	Avg      float64 `json:"avg"`
	DeviceID string  `json:"device_id"`
}

// GetReadings fetches aggregated historical data
func GetReadings(deviceIDs []string, metric string, start, end time.Time, interval string) ([]ReadingHistory, error) {
	if TD == nil {
		return nil, fmt.Errorf("TDengine not initialized")
	}

	if len(deviceIDs) == 0 {
		return []ReadingHistory{}, nil
	}

	// Construct device_id IN clause
	// device_id is BINARY in TDengine, so we quote them
	inClause := ""
	for i, id := range deviceIDs {
		if i > 0 {
			inClause += ", "
		}
		inClause += fmt.Sprintf("'%s'", id)
	}

	// Metric Filter
	metricFilter := ""
	if metric != "" {
		metricFilter = fmt.Sprintf("AND metric = '%s'", metric)
	}

	var query string
	
	// 如果 interval 为 "raw"，查询原始数据（不聚合）
	// 这有助于在数据量少时直接查看，或者调试
	if interval == "raw" {
		// 限制 2000 条以防止数据量过大
		// 选择 val 重复 5 次是为了复用 Scan 逻辑 (Open, High, Low, Close, Avg)
		query = fmt.Sprintf(`SELECT 
			ts, val, val, val, val, val, device_id
			FROM readings 
			WHERE device_id IN (%s) %s AND ts >= '%s' AND ts <= '%s' 
			ORDER BY ts ASC LIMIT 2000`,
			inClause, metricFilter, start.Format("2006-01-02 15:04:05"), end.Format("2006-01-02 15:04:05"))
	} else {
		// 聚合查询
		if interval == "" {
			interval = "1h"
		}
		if interval == "1y" {
			interval = "365d"
		}

		// TDengine Query: Simplified to avoid GROUP BY + INTERVAL conflict
		query = fmt.Sprintf(`SELECT 
			_wstart, FIRST(val), MAX(val), MIN(val), LAST(val), AVG(val)
			FROM readings 
			WHERE device_id IN (%s) %s AND ts >= '%s' AND ts <= '%s' 
			INTERVAL(%s)
			ORDER BY _wstart ASC`,
			inClause, metricFilter, start.Format("2006-01-02 15:04:05"), end.Format("2006-01-02 15:04:05"), interval)
	}

	rows, err := TD.Query(query)
	if err != nil {
		log.Printf("TDengine Query Error: %v\nQuery: %s", err, query)
		return nil, err
	}
	defer rows.Close()

	var results []ReadingHistory
	for rows.Next() {
		var r ReadingHistory
		var ts time.Time
		// var did sql.NullString 

		// Result columns: ts, open, high, low, close, avg
		if err := rows.Scan(&ts, &r.Open, &r.High, &r.Low, &r.Close, &r.Avg); err != nil {
			log.Printf("Scan error: %v", err)
			continue
		}
		r.Ts = ts.Format("2006-01-02 15:04:05")
		
		// If we only queried one device, we can fill it here
		if len(deviceIDs) == 1 {
			r.DeviceID = deviceIDs[0]
		}
		
		results = append(results, r)
	}
	return results, nil
}