opsxsql/backend/internal/handler/instance_detail.go

package handler

import (
	"fmt"
	"net/http"
	"reflect"

	"sql-platform/internal/model"

	"github.com/gin-gonic/gin"
	"time"
	"context"
	"github.com/redis/go-redis/v9"
	"sql-platform/internal/middleware"
	"strings"
	"strconv"
	"encoding/json"
	"bytes"
)

// GET /api/v1/instances/:id/detail/databases
func DetailListDatabases(c *gin.Context) {
	id := c.Param("id")
	var instance model.Instance
	if err := model.DB.First(&instance, id).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"detail": "Instance not found"})
		return
	}

	if instance.DBType == "redis" {
		c.JSON(http.StatusOK, []string{})
		return
	}

	db, err := getDBConnection(&instance, "")
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"detail": fmt.Sprintf("Connection failed: %v", err)})
		return
	}
	defer db.Close()

	rows, err := db.Query("SHOW DATABASES")
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"detail": err.Error()})
		return
	}
	defer rows.Close()

	var databases []string
	for rows.Next() {
		var name string
		rows.Scan(&name)
		// Filter out system databases
		if name != "information_schema" && name != "performance_schema" && name != "mysql" && name != "sys" {
			databases = append(databases, name)
		}
	}
	if databases == nil {
		databases = []string{}
	}
	c.JSON(http.StatusOK, databases)
}

// GET /api/v1/instances/:id/detail/tables
func DetailListTables(c *gin.Context) {
	id := c.Param("id")
	dbName := c.Query("database")
	var instance model.Instance
	if err := model.DB.First(&instance, id).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"detail": "Instance not found"})
		return
	}

	if instance.DBType == "redis" {
		c.JSON(http.StatusOK, []interface{}{})
		return
	}

	if dbName == "" {
		if instance.Database != nil {
			dbName = *instance.Database
		}
	}
	if dbName == "" {
		c.JSON(http.StatusBadRequest, gin.H{"detail": "database parameter required"})
		return
	}

	db, err := getDBConnection(&instance, dbName)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"detail": fmt.Sprintf("Connection failed: %v", err)})
		return
	}
	defer db.Close()

	rows, err := db.Query("SHOW TABLE STATUS")
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"detail": err.Error()})
		return
	}
	defer rows.Close()

	cols, _ := rows.Columns()
	var tables []map[string]interface{}
	for rows.Next() {
		values := make([]interface{}, len(cols))
		ptrValues := make([]interface{}, len(cols))
		for i := range values {
			ptrValues[i] = &values[i]
		}
		rows.Scan(ptrValues...)
		// Normalize to lowercase keys for frontend compatibility
		rowMap := make(map[string]interface{})
		for i, col := range cols {
			val := values[i]
			b, ok := val.([]byte)
			if ok {
				rowMap[strings.ToLower(col)] = string(b)
			} else {
				rowMap[strings.ToLower(col)] = val
			}
		}
		tables = append(tables, rowMap)
	}
	if tables == nil {
		tables = []map[string]interface{}{}
	}
	c.JSON(http.StatusOK, tables)
}

// GET /api/v1/instances/:id/detail/db-schema
func DetailDbSchema(c *gin.Context) {
	id := c.Param("id")
	dbName := c.Query("database")
	var instance model.Instance
	if err := model.DB.First(&instance, id).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"detail": "Instance not found"})
		return
	}

	if instance.DBType == "redis" {
		c.JSON(http.StatusOK, map[string]interface{}{})
		return
	}

	if dbName == "" {
		if instance.Database != nil {
			dbName = *instance.Database
		}
	}
	if dbName == "" {
		c.JSON(http.StatusBadRequest, gin.H{"detail": "database parameter required"})
		return
	}

	db, err := getDBConnection(&instance, dbName)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"detail": fmt.Sprintf("Connection failed: %v", err)})
		return
	}
	defer db.Close()

	// Get all tables and their columns
	tableRows, err := db.Query("SHOW TABLES")
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"detail": err.Error()})
		return
	}
	defer tableRows.Close()

	schema := make(map[string][]string)
	for tableRows.Next() {
		var tableName string
		tableRows.Scan(&tableName)
		// Get columns for this table
		colRows, err := db.Query("SHOW COLUMNS FROM " + "`" + tableName + "`")
		if err != nil {
			schema[tableName] = []string{}
			continue
		}
		var cols []string
		for colRows.Next() {
			var field, typ, null, key string
			var extra interface{}
			var def interface{}
			colRows.Scan(&field, &typ, &null, &key, &def, &extra)
			cols = append(cols, field+" ("+typ+")")
		}
		colRows.Close()
		if cols == nil {
			cols = []string{}
		}
		schema[tableName] = cols
	}
	c.JSON(http.StatusOK, schema)
}

// GET /api/v1/instances/:id/detail/table-detail
func DetailTableDetail(c *gin.Context) {
	id := c.Param("id")
	dbName := c.Query("database")
	tableName := c.Query("table")
	var instance model.Instance
	if err := model.DB.First(&instance, id).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"detail": "Instance not found"})
		return
	}

	if dbName == "" {
		if instance.Database != nil {
			dbName = *instance.Database
		}
	}
	if dbName == "" || tableName == "" {
		c.JSON(http.StatusBadRequest, gin.H{"detail": "database and table parameters required"})
		return
	}

	db, err := getDBConnection(&instance, dbName)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"detail": fmt.Sprintf("Connection failed: %v", err)})
		return
	}
	defer db.Close()

	// Get DDL
	var ddl string
	db.QueryRow("SHOW CREATE TABLE `"+tableName+"`").Scan(&tableName, &ddl)

	// Get columns
	colRows, err := db.Query("SHOW FULL COLUMNS FROM `" + tableName + "`")
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"detail": err.Error()})
		return
	}
	defer colRows.Close()

	colCols, _ := colRows.Columns()
	var columns []map[string]interface{}
	for colRows.Next() {
		values := make([]interface{}, len(colCols))
		ptrValues := make([]interface{}, len(colCols))
		for i := range values {
			ptrValues[i] = &values[i]
		}
		colRows.Scan(ptrValues...)
		rowMap := make(map[string]interface{})
		for i, col := range colCols {
			val := values[i]
			b, ok := val.([]byte)
			if ok {
				rowMap[col] = string(b)
			} else {
				rowMap[col] = val
			}
		}
		columns = append(columns, rowMap)
	}

	// Get indexes
	idxRows, err := db.Query("SHOW INDEX FROM `" + tableName + "`")
	if err == nil {
		defer idxRows.Close()
		idxCols, _ := idxRows.Columns()
		var indexes []map[string]interface{}
		for idxRows.Next() {
			values := make([]interface{}, len(idxCols))
			ptrValues := make([]interface{}, len(idxCols))
			for i := range values {
				ptrValues[i] = &values[i]
			}
			idxRows.Scan(ptrValues...)
			rowMap := make(map[string]interface{})
			for i, col := range idxCols {
				val := values[i]
				b, ok := val.([]byte)
				if ok {
					rowMap[col] = string(b)
				} else {
					rowMap[col] = val
				}
			}
			indexes = append(indexes, rowMap)
		}
		c.JSON(http.StatusOK, gin.H{
			"ddl":     ddl,
			"columns": columns,
			"indexes": indexes,
		})
	} else {
		c.JSON(http.StatusOK, gin.H{
			"ddl":     ddl,
			"columns": columns,
			"indexes": []interface{}{},
		})
	}
}

// GET /api/v1/instances/:id/detail/processlist
func DetailProcesslist(c *gin.Context) {
	id := c.Param("id")
	var instance model.Instance
	if err := model.DB.First(&instance, id).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"detail": "Instance not found"})
		return
	}

	if instance.DBType == "redis" {
		c.JSON(http.StatusOK, []interface{}{})
		return
	}

	dbName := ""
	if instance.Database != nil {
		dbName = *instance.Database
	}
	db, err := getDBConnection(&instance, dbName)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"detail": fmt.Sprintf("Connection failed: %v", err)})
		return
	}
	defer db.Close()

	rows, err := db.Query("SHOW PROCESSLIST")
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"detail": err.Error()})
		return
	}
	defer rows.Close()

	cols, _ := rows.Columns()
	var processes []map[string]interface{}
	for rows.Next() {
		values := make([]interface{}, len(cols))
		ptrValues := make([]interface{}, len(cols))
		for i := range values {
			ptrValues[i] = &values[i]
		}
		rows.Scan(ptrValues...)
		rowMap := make(map[string]interface{})
		for i, col := range cols {
			val := values[i]
			b, ok := val.([]byte)
			if ok {
				rowMap[col] = string(b)
			} else {
				rowMap[col] = val
			}
		}
		processes = append(processes, rowMap)
	}
	if processes == nil {
		processes = []map[string]interface{}{}
	}
	c.JSON(http.StatusOK, processes)
}

// GET /api/v1/instances/:id/detail/status
func DetailStatus(c *gin.Context) {
	id := c.Param("id")
	var instance model.Instance
	if err := model.DB.First(&instance, id).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"detail": "Instance not found"})
		return
	}

	if instance.DBType == "redis" {
		c.JSON(http.StatusOK, gin.H{
			"key_metrics": map[string]string{},
			"all_status":  []interface{}{},
		})
		return
	}

	dbName := ""
	if instance.Database != nil {
		dbName = *instance.Database
	}
	db, err := getDBConnection(&instance, dbName)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"detail": fmt.Sprintf("Connection failed: %v", err)})
		return
	}
	defer db.Close()

	rows, err := db.Query("SHOW GLOBAL STATUS")
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"detail": err.Error()})
		return
	}
	defer rows.Close()

	keyMetrics := make(map[string]string)
	var allStatus []map[string]interface{}
	importantKeys := map[string]bool{
		"Threads_connected": true, "Threads_running": true, "Threads_cached": true,
		"Queries": true, "Questions": true, "Slow_queries": true,
		"Connections": true, "Uptime": true,
		"Bytes_received": true, "Bytes_sent": true,
		"Table_locks_waited": true, "Table_locks_immediate": true,
		"Innodb_row_lock_waits": true, "Innodb_buffer_pool_reads": true,
	}

	for rows.Next() {
		var name, val string
		rows.Scan(&name, &val)
		allStatus = append(allStatus, map[string]interface{}{"name": name, "value": val})
		if importantKeys[name] {
			keyMetrics[name] = val
		}
	}
	if allStatus == nil {
		allStatus = []map[string]interface{}{}
	}
	c.JSON(http.StatusOK, gin.H{
		"key_metrics": keyMetrics,
		"all_status":  allStatus,
	})
}

// POST /api/v1/instances/:id/detail/processlist/:pid/kill
func DetailKillProcess(c *gin.Context) {
	id := c.Param("id")
	pid := c.Param("pid")
	var instance model.Instance
	if err := model.DB.First(&instance, id).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"detail": "Instance not found"})
		return
	}

	dbName := ""
	if instance.Database != nil {
		dbName = *instance.Database
	}
	db, err := getDBConnection(&instance, dbName)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"detail": fmt.Sprintf("Connection failed: %v", err)})
		return
	}
	defer db.Close()

	_, err = db.Exec("KILL " + pid)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"detail": fmt.Sprintf("Kill failed: %v", err)})
		return
	}
	c.JSON(http.StatusOK, gin.H{"message": "Process " + pid + " killed"})
}

// GET /api/v1/instances/:id/detail/users
func DetailListUsers(c *gin.Context) {
	id := c.Param("id")
	var instance model.Instance
	if err := model.DB.First(&instance, id).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"detail": "Instance not found"})
		return
	}

	if instance.DBType == "redis" {
		c.JSON(http.StatusOK, []interface{}{})
		return
	}

	dbName := ""
	if instance.Database != nil {
		dbName = *instance.Database
	}
	db, err := getDBConnection(&instance, dbName)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"detail": fmt.Sprintf("Connection failed: %v", err)})
		return
	}
	defer db.Close()

	rows, err := db.Query("SELECT User, Host FROM mysql.user")
	if err != nil {
		// Might not have permission - return empty
		c.JSON(http.StatusOK, []interface{}{})
		return
	}
	defer rows.Close()

	var users []map[string]interface{}
	for rows.Next() {
		var user, host string
		rows.Scan(&user, &host)
		users = append(users, map[string]interface{}{
			"user": user,
			"host": host,
		})
	}
	if users == nil {
		users = []map[string]interface{}{}
	}
	c.JSON(http.StatusOK, users)
}

// getDBConnection is defined in connection_tester.go or instance_detail.go
// Using the one from connection_tester.go

// POST /api/v1/query/execute
func ExecuteQuery(c *gin.Context) {
	userID, _, _ := middleware.GetCurrentUser(c)
	var input struct {
		InstanceID int    `json:"instance_id"`
		Database   string `json:"database"`
		SQL        string `json:"sql"`
		Limit      int    `json:"limit"`
		Offset     int    `json:"offset"`
	}
	if err := c.ShouldBindJSON(&input); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"detail": err.Error()})
		return
	}
	if input.InstanceID == 0 || input.SQL == "" {
		c.JSON(http.StatusBadRequest, gin.H{"detail": "instance_id and sql are required"})
		return
	}
	// Default pagination
	if input.Limit <= 0 {
		input.Limit = 100
	}
	if input.Limit > 1000 {
		input.Limit = 1000
	}
	if input.Offset < 0 {
		input.Offset = 0
	}

	var instance model.Instance
	if err := model.DB.First(&instance, input.InstanceID).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"detail": "Instance not found"})
		return
	}

	start := time.Now()

	switch instance.DBType {
	case "mysql", "postgresql", "postgres", "pg":
		result, err := executeSQLQuery(&instance, input.Database, input.SQL, input.Limit, input.Offset)
		costMs := time.Since(start).Milliseconds()
		if err != nil {
			c.JSON(http.StatusOK, gin.H{"columns": []string{}, "rows": []interface{}{}, "total": 0, "cost_ms": costMs, "error": err.Error()})
			return
		}
		result["cost_ms"] = costMs
		rowsInterface, _ := result["rows"].([]interface{})
		saveQueryHistory(userID, input.InstanceID, input.Database, input.SQL, costMs, len(rowsInterface))
		c.JSON(http.StatusOK, result)

	case "redis":
		result, err := executeRedisQuery(&instance, input.Database, input.SQL)
		costMs := time.Since(start).Milliseconds()
		if err != nil {
			c.JSON(http.StatusOK, gin.H{"columns": []string{}, "rows": []interface{}{}, "total": 0, "cost_ms": costMs, "error": err.Error()})
			return
		}
		saveQueryHistory(userID, input.InstanceID, input.Database, input.SQL, costMs, 1)
		c.JSON(http.StatusOK, result)

	default:
		c.JSON(http.StatusBadRequest, gin.H{"detail": "Unsupported database type: " + instance.DBType})
	}
}

func executeSQLQuery(instance *model.Instance, dbName string, sqlStr string, limit int, offset int) (gin.H, error) {
	db, err := getDBConnection(instance, dbName)
	if err != nil {
		return nil, fmt.Errorf("connection failed: %v", err)
	}
	defer db.Close()

	upperSQL := strings.ToUpper(strings.TrimSpace(sqlStr))

	// Count total (only when no user LIMIT and offset=0)
	total := 0
	hasLimit := strings.Contains(upperSQL, " LIMIT ")

	if !hasLimit && offset == 0 {
		if strings.HasPrefix(upperSQL, "SELECT") {
			fromIdx := strings.Index(upperSQL, " FROM ")
			if fromIdx > 0 {
				countSQL := "SELECT COUNT(*) " + sqlStr[fromIdx:]
				upperCount := strings.ToUpper(countSQL)
				if idx := strings.Index(upperCount, " ORDER BY "); idx > 0 {
					countSQL = countSQL[:idx]
				}
				if idx := strings.Index(upperCount, " GROUP BY "); idx > 0 {
					countSQL = countSQL[:idx]
				}
				db.QueryRow(countSQL).Scan(&total)
			}
		}
	}

	// Inject LIMIT/OFFSET if not already present
	if !hasLimit {
		sqlStr = fmt.Sprintf("%s LIMIT %d OFFSET %d", sqlStr, limit, offset)
	}

	rows, err := db.Query(sqlStr)
	if err != nil {
		return nil, fmt.Errorf("query failed: %v", err)
	}
	defer rows.Close()

	cols, _ := rows.Columns()
	colNames := make([]string, len(cols))
	for i, col := range cols {
		colNames[i] = col
	}

	var resultRows []interface{}
	for rows.Next() {
		values := make([]interface{}, len(cols))
		ptrValues := make([]interface{}, len(cols))
		for i := range values {
			ptrValues[i] = &values[i]
		}
		rows.Scan(ptrValues...)
		rowMap := make(map[string]interface{})
		for i, col := range colNames {
			val := values[i]
			b, ok := val.([]byte)
			if ok {
				rowMap[col] = string(b)
			} else {
				rowMap[col] = val
			}
		}
		resultRows = append(resultRows, rowMap)
	}

	return gin.H{
		"columns": colNames,
		"rows":    resultRows,
		"total":   total,
		"count":   len(resultRows),
	}, nil
}

func executeRedisQuery(instance *model.Instance, dbSelect string, command string) (gin.H, error) {
	password := instance.Password
	if strings.HasPrefix(password, "enc:") {
		decrypted, err := decryptPassword(strings.TrimPrefix(password, "enc:"))
		if err == nil {
			password = decrypted
		}
	}

	// Parse Redis DB number from dbSelect (e.g. "0", "1")
	redisDB := 0
	if dbSelect != "" {
		if n, err := strconv.Atoi(dbSelect); err == nil && n >= 0 {
			redisDB = n
		}
	}

	client := redis.NewClient(&redis.Options{
		Addr:     fmt.Sprintf("%s:%d", instance.Host, instance.Port),
		Password: password,
		DB:       redisDB,
	})
	defer client.Close()

	ctx := context.Background()
	if err := client.Ping(ctx).Err(); err != nil {
		return nil, fmt.Errorf("Redis connection failed: %v", err)
	}

	parts := strings.Fields(command)
	if len(parts) == 0 {
		return nil, fmt.Errorf("empty command")
	}

	cmd := strings.ToUpper(parts[0])
	readOnly := map[string]bool{
		"GET": true, "MGET": true, "HGET": true, "HGETALL": true,
		"LRANGE": true, "SMEMBERS": true, "ZRANGE": true,
		"TYPE": true, "TTL": true, "EXISTS": true, "KEYS": true,
		"INFO": true, "DBSIZE": true, "SCAN": true, "STRLEN": true,
		"LLEN": true, "SCARD": true, "ZCARD": true, "HLEN": true,
		"HKEYS": true, "HVALS": true, "HSCAN": true, "SSCAN": true,
		"ZSCAN": true, "ZRANGEBYSCORE": true,
		"GETSET": true, "GETRANGE": true, "SUBSTR": true,
	}
	if !readOnly[cmd] {
		return nil, fmt.Errorf("only read-only commands allowed, got: %s", cmd)
	}

	// Build args: command name + all arguments
	args := make([]interface{}, 0, len(parts))
	args = append(args, cmd)
	for _, p := range parts[1:] {
		args = append(args, p)
	}

	result, err := client.Do(ctx, args...).Result()
	if err != nil {
		return nil, fmt.Errorf("command failed: %v", err)
	}

	// Format result into rows/columns for frontend table display
	columns := []string{"key", "value"}
	var rows []interface{}

	switch v := result.(type) {
	case []interface{}:
		// Array result (MGET, LRANGE, etc.)
		if cmd == "MGET" {
			for i, val := range v {
				rows = append(rows, map[string]interface{}{
					"index": i,
					"value": fmt.Sprintf("%v", val),
				})
			}
			columns = []string{"index", "value"}
		} else {
			for i, val := range v {
				rows = append(rows, map[string]interface{}{
					"index": i,
					"value": fmt.Sprintf("%v", val),
				})
			}
		}
	case map[string]string:
		// HGETALL returns map[string]string via some redis clients
		for k, val := range v {
			rows = append(rows, map[string]interface{}{
				"field": k,
				"value": val,
			})
		}
		columns = []string{"field", "value"}
	default:
		// Use reflect to handle any map type (map[interface{}]interface{}, etc.)
		rv := reflect.ValueOf(result)
		if rv.Kind() == reflect.Map {
			iter := rv.MapRange()
			for iter.Next() {
				rows = append(rows, map[string]interface{}{
					"field": fmt.Sprintf("%v", iter.Key().Interface()),
					"value": fmt.Sprintf("%v", iter.Value().Interface()),
				})
			}
			columns = []string{"field", "value"}
		} else {
			// Single value result (GET, HGET, TYPE, TTL, etc.)
			keyName := ""
			if len(parts) > 1 {
				keyName = parts[1]
			}
			rawValue := fmt.Sprintf("%v", v)
			// Try to pretty-format JSON with Chinese characters preserved
			var prettyJSON string
			var parsed interface{}
			if json.Unmarshal([]byte(rawValue), &parsed) == nil {
				switch parsed.(type) {
				case map[string]interface{}, []interface{}:
					var buf bytes.Buffer
					enc := json.NewEncoder(&buf)
					enc.SetEscapeHTML(false)
					enc.SetIndent("", "  ")
					enc.Encode(parsed)
					prettyJSON = strings.TrimRight(buf.String(), "\n")
				}
			}
			return gin.H{
				"columns":   []string{},
				"rows":      []interface{}{},
				"total":     0,
				"raw_value": prettyJSON != "",
				"raw_key":   keyName,
				"raw_text":  rawValue,
			}, nil
		}
	}

	return gin.H{
		"columns": columns,
		"rows":    rows,
		"total":   len(rows),
	}, nil
}

// POST /api/v1/query/export — Streaming CSV export for large datasets
func ExportQueryCSV(c *gin.Context) {
	var input struct {
		InstanceID int    `json:"instance_id"`
		Database   string `json:"database"`
		SQL        string `json:"sql"`
		Limit      int    `json:"limit"`
	}
	if err := c.ShouldBindJSON(&input); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"detail": err.Error()})
		return
	}
	if input.InstanceID == 0 || input.SQL == "" {
		c.JSON(http.StatusBadRequest, gin.H{"detail": "instance_id and sql are required"})
		return
	}
	if input.Limit <= 0 {
		input.Limit = 10000 // Export max 10k rows
	}
	if input.Limit > 50000 {
		input.Limit = 50000
	}

	var instance model.Instance
	if err := model.DB.First(&instance, input.InstanceID).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"detail": "Instance not found"})
		return
	}

	if instance.DBType != "mysql" && instance.DBType != "postgresql" && instance.DBType != "postgres" && instance.DBType != "pg" {
		c.JSON(http.StatusBadRequest, gin.H{"detail": "CSV export only supports MySQL/PostgreSQL"})
		return
	}

	db, err := getDBConnection(&instance, input.Database)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"detail": "Connection failed: " + err.Error()})
		return
	}
	defer db.Close()

	// Inject LIMIT if not present
	upperSQL := strings.ToUpper(strings.TrimSpace(input.SQL))
	if !strings.Contains(upperSQL, " LIMIT ") {
		input.SQL = fmt.Sprintf("%s LIMIT %d", input.SQL, input.Limit)
	}

	rows, err := db.Query(input.SQL)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"detail": "Query failed: " + err.Error()})
		return
	}
	defer rows.Close()

	cols, _ := rows.Columns()
	colNames := make([]string, len(cols))
	for i, col := range cols {
		colNames[i] = col
	}

	// Stream CSV response
	filename := fmt.Sprintf("query_export_%s.csv", time.Now().Format("20060102_150405"))
	c.Header("Content-Type", "text/csv; charset=utf-8")
	c.Header("Content-Disposition", fmt.Sprintf("attachment; filename=%s", filename))
	// BOM for Excel UTF-8
	c.Writer.Write([]byte("\xEF\xBB\xBF"))

	// Header row
	c.Writer.Write([]byte(strings.Join(colNames, ",") + "\n"))

	// Data rows — write in chunks to avoid OOM
	batchSize := 500
	batch := make([]string, 0, batchSize)
	rowCount := 0

	for rows.Next() {
		values := make([]interface{}, len(cols))
		ptrValues := make([]interface{}, len(cols))
		for i := range values {
			ptrValues[i] = &values[i]
		}
		rows.Scan(ptrValues...)

		cells := make([]string, len(cols))
		for i, val := range values {
			s := ""
			if b, ok := val.([]byte); ok {
				s = string(b)
			} else if val != nil {
				s = fmt.Sprintf("%v", val)
			}
			// CSV escape: wrap in quotes if contains comma, quote, or newline
			if strings.ContainsAny(s, ",\"\n\r") {
				s = `"` + strings.ReplaceAll(s, `"`, `""`) + `"`
			}
			cells[i] = s
		}
		batch = append(batch, strings.Join(cells, ","))
		rowCount++

		if len(batch) >= batchSize {
			c.Writer.Write([]byte(strings.Join(batch, "\n") + "\n"))
			c.Writer.(http.Flusher).Flush()
			batch = batch[:0]
		}
	}
	// Flush remaining
	if len(batch) > 0 {
		c.Writer.Write([]byte(strings.Join(batch, "\n") + "\n"))
	}
	c.Writer.(http.Flusher).Flush()

	saveQueryHistory(0, input.InstanceID, input.Database, input.SQL, 0, rowCount)
}

func saveQueryHistory(userID int, instanceID int, database string, sqlStr string, costMs int64, rowCount int) {
	var user model.User
	var inst model.Instance
	username := ""
	instName := ""
	dbType := ""
	if model.DB.First(&user, userID).Error == nil {
		username = user.Username
	}
	if model.DB.First(&inst, instanceID).Error == nil {
		instName = inst.Name
		dbType = inst.DBType
	}

	queryType := "SELECT"
	upper := strings.ToUpper(strings.TrimSpace(sqlStr))
	if strings.HasPrefix(upper, "SHOW") || strings.HasPrefix(upper, "DESCRIBE") || strings.HasPrefix(upper, "EXPLAIN") {
		queryType = strings.SplitN(upper, " ", 2)[0]
	}

	history := model.QueryHistory{
		UserID:          userID,
		Username:        username,
		InstanceID:      instanceID,
		InstanceName:    instName,
		DBType:          dbType,
		DatabaseName:    database,
		QueryContent:    sqlStr,
		QueryType:       queryType,
		ExecutionTimeMs: int(costMs),
		ResultRows:      rowCount,
		IsSuccess:       true,
	}
	model.DB.Create(&history)
}