// Package logging 提供统一的日志功能
package logging

import (
	"encoding/json"
	"fmt"
	"io"
	"log"
	"os"
	"path/filepath"
	"runtime"
	"time"
)

// ==================== 日志级别 ====================

// Level 日志级别
type Level string

const (
	LevelDebug Level = "DEBUG"
	LevelInfo  Level = "INFO"
	LevelWarn  Level = "WARN"
	LevelError Level = "ERROR"
)

// ==================== 初始化 ====================

// Init 初始化日志系统
func Init(dir string) error {
	if dir == "" {
		dir = "log"
	}
	if err := os.MkdirAll(dir, 0755); err != nil {
		return err
	}
	name := fmt.Sprintf("server-%s.log", time.Now().Format("20060102"))
	p := filepath.Join(dir, name)
	f, err := os.OpenFile(p, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0644)
	if err != nil {
		return err
	}
	mw := io.MultiWriter(os.Stdout, f)
	log.SetOutput(mw)
	log.SetFlags(0)
	return nil
}

// ==================== 结构化日志 ====================

// JSON 输出JSON格式日志
func JSON(level string, fields map[string]interface{}) {
	m := map[string]interface{}{"level": level, "ts": time.Now().Format(time.RFC3339)}
	for k, v := range fields {
		m[k] = v
	}
	b, _ := json.Marshal(m)
	log.Println(string(b))
}

// ==================== 便捷方法 ====================

// Debug 输出Debug级别日志
func Debug(event string, fields map[string]interface{}) {
	if fields == nil {
		fields = make(map[string]interface{})
	}
	fields["event"] = event
	JSON(string(LevelDebug), fields)
}

// Info 输出Info级别日志
func Info(event string, fields map[string]interface{}) {
	if fields == nil {
		fields = make(map[string]interface{})
	}
	fields["event"] = event
	JSON(string(LevelInfo), fields)
}

// Warn 输出Warn级别日志
func Warn(event string, fields map[string]interface{}) {
	if fields == nil {
		fields = make(map[string]interface{})
	}
	fields["event"] = event
	JSON(string(LevelWarn), fields)
}

// Error 输出Error级别日志
func Error(event string, err error, fields map[string]interface{}) {
	if fields == nil {
		fields = make(map[string]interface{})
	}
	fields["event"] = event
	if err != nil {
		fields["error"] = err.Error()
	}
	// 添加调用位置信息
	_, file, line, ok := runtime.Caller(1)
	if ok {
		fields["caller"] = fmt.Sprintf("%s:%d", filepath.Base(file), line)
	}
	JSON(string(LevelError), fields)
}

// ==================== 专用日志 ====================

// DBError 数据库错误日志
func DBError(action string, jobID uint64, err error) {
	Error("db_error", err, map[string]interface{}{
		"action": action,
		"job_id": jobID,
	})
}

// ExportProgress 导出进度日志
func ExportProgress(jobID uint64, totalRows int64) {
	Info("progress_update", map[string]interface{}{
		"job_id":     jobID,
		"total_rows": totalRows,
	})
}

// ExportSQL 导出SQL日志
func ExportSQL(jobID uint64, datasource, mainTable, sql string, args []interface{}) {
	Info("export_sql", map[string]interface{}{
		"job_id":     jobID,
		"datasource": datasource,
		"main_table": mainTable,
		"sql":        sql,
		"args":       args,
	})
}

// FieldsRemoved 字段移除日志
func FieldsRemoved(event string, removed []string, reason string) {
	Info(event, map[string]interface{}{
		"removed": removed,
		"reason":  reason,
	})
}