package accesslogs

import (
	"encoding/json"
	"fmt"
	"log"
	"os"
	"path/filepath"
	"strings"
	"sync"

	"github.com/TeaOSLab/EdgeCommon/pkg/rpc/pb"
	"github.com/TeaOSLab/EdgeCommon/pkg/serverconfigs"
	"gopkg.in/natefinch/lumberjack.v2"
)

const (
	defaultHTTPDNSLogDir = "/var/log/edge/edge-httpdns"
	envHTTPDNSLogDir     = "EDGE_HTTPDNS_LOG_DIR"
)

var (
	sharedHTTPDNSFileWriter     *HTTPDNSFileWriter
	sharedHTTPDNSFileWriterOnce sync.Once
)

// SharedHTTPDNSFileWriter 返回 HTTPDNS 本地日志写入器（单例）.
func SharedHTTPDNSFileWriter() *HTTPDNSFileWriter {
	sharedHTTPDNSFileWriterOnce.Do(func() {
		sharedHTTPDNSFileWriter = NewHTTPDNSFileWriter()
	})
	return sharedHTTPDNSFileWriter
}

// HTTPDNSFileWriter 将 HTTPDNS 访问日志以 JSON Lines 写入本地文件，供 Fluent Bit 采集。
type HTTPDNSFileWriter struct {
	dir          string
	mu           sync.Mutex
	file         *lumberjack.Logger
	rotateConfig *serverconfigs.AccessLogRotateConfig
	inited       bool
}

// NewHTTPDNSFileWriter 创建 HTTPDNS 本地日志写入器.
func NewHTTPDNSFileWriter() *HTTPDNSFileWriter {
	logDir := resolveDefaultHTTPDNSLogDir()
	return &HTTPDNSFileWriter{
		dir:          logDir,
		rotateConfig: serverconfigs.NewDefaultAccessLogRotateConfig(),
	}
}

func resolveDefaultHTTPDNSLogDir() string {
	logDir := strings.TrimSpace(os.Getenv(envHTTPDNSLogDir))
	if logDir == "" {
		return defaultHTTPDNSLogDir
	}
	return logDir
}

// SetDir 更新日志目录并重置文件句柄。
func (w *HTTPDNSFileWriter) SetDir(dir string) {
	if strings.TrimSpace(dir) == "" {
		dir = resolveDefaultHTTPDNSLogDir()
	}

	w.mu.Lock()
	defer w.mu.Unlock()

	if dir == w.dir {
		return
	}

	if w.file != nil {
		_ = w.file.Close()
		w.file = nil
	}
	w.inited = false
	w.dir = dir
}

// Dir 返回当前日志目录.
func (w *HTTPDNSFileWriter) Dir() string {
	return w.dir
}

// EnsureInit 在启动时预创建目录与 access.log.
func (w *HTTPDNSFileWriter) EnsureInit() error {
	if w.dir == "" {
		return nil
	}
	return w.init()
}

func (w *HTTPDNSFileWriter) init() error {
	w.mu.Lock()
	defer w.mu.Unlock()

	if w.inited && w.file != nil {
		return nil
	}

	if w.dir == "" {
		return nil
	}

	if err := os.MkdirAll(w.dir, 0755); err != nil {
		log.Println("[HTTPDNS_ACCESS_LOG]mkdir log dir failed:", err.Error())
		return err
	}

	rotateConfig := w.rotateConfig.Normalize()
	w.file = &lumberjack.Logger{
		Filename:   filepath.Join(w.dir, "access.log"),
		MaxSize:    rotateConfig.MaxSizeMB,
		MaxBackups: rotateConfig.MaxBackups,
		MaxAge:     rotateConfig.MaxAgeDays,
		Compress:   *rotateConfig.Compress,
		LocalTime:  *rotateConfig.LocalTime,
	}

	w.inited = true
	return nil
}

// WriteBatch 批量写入 HTTPDNS 访问日志.
func (w *HTTPDNSFileWriter) WriteBatch(logs []*pb.HTTPDNSAccessLog) {
	if len(logs) == 0 || w.dir == "" {
		return
	}
	if err := w.init(); err != nil {
		return
	}

	w.mu.Lock()
	file := w.file
	w.mu.Unlock()
	if file == nil {
		return
	}

	for _, logItem := range logs {
		ingestLog := FromPBAccessLog(logItem)
		if ingestLog == nil {
			continue
		}
		line, err := json.Marshal(ingestLog)
		if err != nil {
			continue
		}
		_, _ = file.Write(append(line, '\n'))
	}
}

// Close 关闭日志文件.
func (w *HTTPDNSFileWriter) Close() error {
	w.mu.Lock()
	defer w.mu.Unlock()

	if w.file == nil {
		return nil
	}

	err := w.file.Close()
	w.file = nil
	w.inited = false
	if err != nil {
		log.Println(fmt.Sprintf("[HTTPDNS_ACCESS_LOG]close access.log failed: %v", err))
		return err
	}
	return nil
}