package log

import (
	"bufio"
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"sync"
	"sync/atomic"
	"time"

	"github.com/rs/zerolog"
)

const maxCaptureLine = 10 << 20 // 10MB，支持 GetReqMap 等大 body 单行日志

var (
	origStderr     io.Writer
	origStderrOnce sync.Once
)

func saveOrigStderr() {
	origStderrOnce.Do(func() {
		origStderr = os.Stderr
	})
}

func seqWriteStderr(format string, args ...interface{}) {
	if origStderr != nil {
		fmt.Fprintf(origStderr, format, args...)
	} else {
		fmt.Fprintf(os.Stderr, format, args...)
	}
}

// ErrorRecord 错误历史记录条目
type ErrorRecord struct {
	Err    error
	Msg    string
	Time   time.Time
	Caller string
}

// Logger 日志核心结构体，封装 zerolog
type Logger struct {
	zl        zerolog.Logger
	mw        *multiWriter // 动态多输出，支持运行时追加 SeqWriter 等
	logLevel  int
	errors    []ErrorRecord
	errIdx    int // 环形缓冲写入位置
	errCount  int // 实际写入总数（用于判断缓冲是否满）
	errorsMu  sync.RWMutex
	maxErrors int
}

// NewLogger 创建日志实例
// logLevel: 0=仅 error，>=1=全部
// logFile: 文件路径模板（如 "logs/20060102.txt"），空则不写文件
// maxErrors: 错误历史最大条数，0 则不记录
func NewLogger(logLevel int, logFile string, maxErrors int) *Logger {
	saveOrigStderr()
	zerolog.CallerMarshalFunc = callerMarshalFunc
	zerolog.TimeFieldFormat = "2006-01-02 15:04:05"

	var level zerolog.Level
	if logLevel == 0 {
		level = zerolog.ErrorLevel
	} else {
		level = zerolog.DebugLevel
	}

	consoleWriter := zerolog.ConsoleWriter{
		Out:         os.Stderr,
		TimeFormat:  "2006-01-02 15:04:05",
		NoColor:     false,
		FormatLevel: formatLevelColor,
		FormatCaller: func(i interface{}) string {
			if i == nil {
				return ""
			}
			return fmt.Sprintf("[%s]", i)
		},
	}

	var writers []io.Writer
	writers = append(writers, consoleWriter)

	if logFile != "" {
		fw := &TemplateFileWriter{pathTemplate: logFile}
		writers = append(writers, fw)
	}

	mw := &multiWriter{writers: writers}
	zl := zerolog.New(mw).
		Level(level).
		With().
		Timestamp().
		Caller().
		Logger()

	l := &Logger{
		zl:        zl,
		mw:        mw,
		logLevel:  logLevel,
		maxErrors: maxErrors,
	}
	if maxErrors > 0 {
		l.errors = make([]ErrorRecord, maxErrors)
	}

	return l
}

// NewLoggerNoCaller 创建不带自动 Caller 字段的日志实例（用于访问日志等 caller 无意义的场景）
func NewLoggerNoCaller(logLevel int, logFile string, maxErrors int) *Logger {
	saveOrigStderr()
	zerolog.CallerMarshalFunc = callerMarshalFunc
	zerolog.TimeFieldFormat = "2006-01-02 15:04:05"

	var level zerolog.Level
	if logLevel == 0 {
		level = zerolog.ErrorLevel
	} else {
		level = zerolog.DebugLevel
	}

	consoleWriter := zerolog.ConsoleWriter{
		Out:         os.Stderr,
		TimeFormat:  "2006-01-02 15:04:05",
		NoColor:     false,
		FormatLevel: formatLevelColor,
	}

	var writers []io.Writer
	writers = append(writers, consoleWriter)

	if logFile != "" {
		fw := &TemplateFileWriter{pathTemplate: logFile}
		writers = append(writers, fw)
	}

	mw := &multiWriter{writers: writers}
	zl := zerolog.New(mw).
		Level(level).
		With().
		Timestamp().
		Logger()

	l := &Logger{
		zl:        zl,
		mw:        mw,
		logLevel:  logLevel,
		maxErrors: maxErrors,
	}
	if maxErrors > 0 {
		l.errors = make([]ErrorRecord, maxErrors)
	}

	return l
}

// NewTestLogger 创建用于测试的静默 Logger（输出到 io.Discard）
func NewTestLogger() *Logger {
	zl := zerolog.New(io.Discard).Level(zerolog.Disabled)
	return &Logger{zl: zl, logLevel: 0}
}

// SetOutput 设置日志输出（用于测试等场景）
func (l *Logger) SetOutput(w io.Writer) {
	if w == io.Discard {
		l.zl = zerolog.New(w).Level(zerolog.Disabled)
		l.mw = nil
		return
	}
	consoleWriter := zerolog.ConsoleWriter{
		Out:         w,
		TimeFormat:  "2006-01-02 15:04:05",
		NoColor:     true,
		FormatLevel: formatLevelPlain,
		FormatCaller: func(i interface{}) string {
			if i == nil {
				return ""
			}
			return fmt.Sprintf("[%s]", i)
		},
	}
	mw := &multiWriter{writers: []io.Writer{consoleWriter}}
	l.mw = mw
	l.zl = zerolog.New(mw).
		With().
		Timestamp().
		Caller().
		Logger()
}

// GetLevel 获取当前日志等级
func (l *Logger) GetLevel() int {
	return l.logLevel
}

// EmitCaptured 将捕获的 stdout/stderr 等输出直写 multiWriter，绕过主 Logger 的 level 过滤。
// 保证 logLevel=0 时 fmt.Println / log.Println 仍能进 Seq。
func (l *Logger) EmitCaptured(level zerolog.Level, source, msg string) {
	if l == nil || l.mw == nil || msg == "" {
		return
	}
	zl := zerolog.New(l.mw)
	zl.WithLevel(level).Timestamp().Str("source", source).Msg(msg)
}

// EmitRecoveredPanic 记录 recover 到的 panic：错误原因 + 调用栈，source=panic。
func (l *Logger) EmitRecoveredPanic(err interface{}) {
	if l == nil || l.mw == nil || err == nil {
		return
	}
	zl := zerolog.New(l.mw)
	zl.WithLevel(zerolog.ErrorLevel).Timestamp().
		Str("source", "panic").
		Str("stack", string(debugStack())).
		Msg(fmt.Sprint(err))
}

func debugStack() []byte {
	buf := make([]byte, 64*1024)
	n := runtime.Stack(buf, false)
	return buf[:n]
}

// CaptureStream 从 reader 持续读取行并写入 Logger（用于 stdout/stderr 管道）。
// 单行超过 maxCaptureLine 时截断并标注，读取出错后重启读取，避免永久失效。
func CaptureStream(l *Logger, level zerolog.Level, source string, r io.Reader) {
	rd := bufio.NewReader(r)
	for {
		line, err := rd.ReadString('\n')
		if len(line) > 0 {
			msg := strings.TrimRight(line, "\r\n")
			if msg != "" {
				if len(msg) > maxCaptureLine {
					msg = msg[:maxCaptureLine] + "...(truncated)"
				}
				l.EmitCaptured(level, source, msg)
			}
		}
		if err != nil {
			if err == io.EOF {
				if len(line) == 0 {
					return
				}
				continue
			}
			l.EmitCaptured(zerolog.ErrorLevel, source+"-capture", err.Error())
			return
		}
	}
}

// --- 链式调用 API ---
// 以下方法兼容两种调用风格：
//   无参数：返回 *zerolog.Event 用于链式调用，如 l.Error().Str("k","v").Msg("...")
//   有参数：直接拼接并打印日志（logrus 兼容），返回 no-op Event

func (l *Logger) Debug(args ...interface{}) *zerolog.Event {
	if len(args) > 0 {
		l.zl.Debug().Msg(fmt.Sprint(args...))
		nop := zerolog.Nop()
		return nop.Debug()
	}
	return l.zl.Debug()
}

func (l *Logger) Info(args ...interface{}) *zerolog.Event {
	if len(args) > 0 {
		l.zl.Info().Msg(fmt.Sprint(args...))
		nop := zerolog.Nop()
		return nop.Info()
	}
	return l.zl.Info()
}

func (l *Logger) Warn(args ...interface{}) *zerolog.Event {
	if len(args) > 0 {
		l.zl.Warn().Msg(fmt.Sprint(args...))
		nop := zerolog.Nop()
		return nop.Warn()
	}
	return l.zl.Warn()
}

func (l *Logger) Error(args ...interface{}) *zerolog.Event {
	if len(args) > 0 {
		msg := fmt.Sprint(args...)
		if l.maxErrors > 0 {
			l.recordError(msg, nil)
		}
		l.zl.Error().Msg(msg)
		nop := zerolog.Nop()
		return nop.Error()
	}
	if l.maxErrors > 0 {
		l.recordError("", nil)
	}
	return l.zl.Error()
}

// RecordError 手动记录一条错误到历史（用于需要指定详情的场景）
func (l *Logger) RecordError(err error, msg string, caller string) {
	if l.maxErrors <= 0 {
		return
	}
	l.errorsMu.Lock()
	defer l.errorsMu.Unlock()
	l.errors[l.errIdx] = ErrorRecord{
		Err:    err,
		Msg:    msg,
		Time:   time.Now(),
		Caller: caller,
	}
	l.errIdx = (l.errIdx + 1) % l.maxErrors
	l.errCount++
}

func (l *Logger) recordError(msg string, err error) {
	_, file, line, ok := runtime.Caller(2)
	caller := ""
	if ok {
		caller = formatCaller(file, line)
	}
	l.RecordError(err, msg, caller)
}

// GetRecentErrors 获取最近 N 条错误（不传则返回全部已存储的）
func (l *Logger) GetRecentErrors(n ...int) []ErrorRecord {
	if l.maxErrors <= 0 {
		return nil
	}
	l.errorsMu.RLock()
	defer l.errorsMu.RUnlock()

	total := l.errCount
	if total > l.maxErrors {
		total = l.maxErrors
	}
	if total == 0 {
		return nil
	}

	want := total
	if len(n) > 0 && n[0] > 0 && n[0] < want {
		want = n[0]
	}

	result := make([]ErrorRecord, 0, want)
	// 从最新的往前读
	for i := 0; i < want; i++ {
		idx := (l.errIdx - 1 - i + l.maxErrors) % l.maxErrors
		if l.errors[idx].Time.IsZero() {
			break
		}
		result = append(result, l.errors[idx])
	}
	return result
}

// --- 格式化快捷方法 ---

func (l *Logger) Debugf(format string, v ...interface{}) {
	l.zl.Debug().Msgf(format, v...)
}
func (l *Logger) Infof(format string, v ...interface{}) {
	l.zl.Info().Msgf(format, v...)
}
func (l *Logger) Warnf(format string, v ...interface{}) {
	l.zl.Warn().Msgf(format, v...)
}
func (l *Logger) Errorf(format string, v ...interface{}) {
	if l.maxErrors > 0 {
		l.recordError(fmt.Sprintf(format, v...), nil)
	}
	l.zl.Error().Msgf(format, v...)
}

// --- 日志级别颜色 ---

func formatLevelColor(i interface{}) string {
	level := strings.ToUpper(fmt.Sprintf("%s", i))
	switch level {
	case "DEBUG":
		return fmt.Sprintf("\x1b[36m|%s|\x1b[0m", level) // cyan
	case "INFO":
		return fmt.Sprintf("\x1b[32m|%s|\x1b[0m", level) // green
	case "WARN":
		return fmt.Sprintf("\x1b[33m|%s|\x1b[0m", level) // yellow
	case "ERROR":
		return fmt.Sprintf("\x1b[31m|%s|\x1b[0m", level) // red
	case "FATAL":
		return fmt.Sprintf("\x1b[35m|%s|\x1b[0m", level) // magenta
	default:
		return fmt.Sprintf("|%s|", level)
	}
}

func formatLevelPlain(i interface{}) string {
	return fmt.Sprintf("|%s|", strings.ToUpper(fmt.Sprintf("%s", i)))
}

// --- TemplateFileWriter ---

// TemplateFileWriter 按时间模板切换文件路径的 Writer
type TemplateFileWriter struct {
	pathTemplate string
	mu           sync.Mutex
	currentPath  string
	file         *os.File
	writer       *bufio.Writer
}

func (w *TemplateFileWriter) Write(p []byte) (n int, err error) {
	w.mu.Lock()
	defer w.mu.Unlock()

	path := time.Now().Format(w.pathTemplate)
	if path != w.currentPath {
		if w.writer != nil {
			_ = w.writer.Flush()
		}
		if w.file != nil {
			_ = w.file.Close()
		}
		_ = os.MkdirAll(filepath.Dir(path), 0755)
		w.file, err = os.OpenFile(path, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
		if err != nil {
			return 0, err
		}
		w.writer = bufio.NewWriterSize(w.file, 4096)
		w.currentPath = path
	}
	n, err = w.writer.Write(p)
	_ = w.writer.Flush()
	return
}

// --- 调用者智能过滤 ---

func callerMarshalFunc(_ uintptr, file string, line int) string {
	return findCaller(file, line)
}

func findCaller(origFile string, origLine int) string {
	var lastInfraFile string
	var lastInfraLine int
	var primaryCaller string
	var appLayerCaller string

	for i := 1; i < 20; i++ {
		_, file, line, ok := runtime.Caller(i)
		if !ok {
			break
		}
		shortFile := shortenPath(file)

		if isInfrastructureFile(shortFile) {
			lastInfraFile = shortFile
			lastInfraLine = line
			continue
		}

		if primaryCaller == "" {
			primaryCaller = fmt.Sprintf("%s:%d", shortFile, line)
		}
		if appLayerCaller == "" && !strings.Contains(strings.ToLower(file), "hotime") {
			appLayerCaller = fmt.Sprintf("%s:%d", shortFile, line)
		}
	}

	result := ""
	if primaryCaller != "" {
		result = primaryCaller
	} else if lastInfraFile != "" {
		result = fmt.Sprintf("%s:%d", lastInfraFile, lastInfraLine)
	} else {
		result = fmt.Sprintf("%s:%d", shortenPath(origFile), origLine)
	}

	if appLayerCaller != "" && result != appLayerCaller {
		result += " <- " + appLayerCaller
	}

	return result
}

func formatCaller(file string, line int) string {
	return fmt.Sprintf("%s:%d", shortenPath(file), line)
}

func shortenPath(file string) string {
	n := 0
	for i := len(file) - 1; i > 0; i-- {
		if file[i] == '/' || file[i] == '\\' {
			n++
			if n >= 2 {
				return file[i+1:]
			}
		}
	}
	return file
}

// --- multiWriter: 支持运行时追加输出目标 ---

// multiWriter 实现 zerolog.LevelWriter，允许在 Logger 创建后动态追加新的输出（如 SeqWriter）
type multiWriter struct {
	mu      sync.RWMutex
	writers []io.Writer
}

func (mw *multiWriter) Write(p []byte) (int, error) {
	mw.mu.RLock()
	defer mw.mu.RUnlock()
	for _, w := range mw.writers {
		_, _ = w.Write(p)
	}
	return len(p), nil
}

// WriteLevel 实现 zerolog.LevelWriter，使 zerolog 的级别过滤正确传递给各子 Writer
func (mw *multiWriter) WriteLevel(l zerolog.Level, p []byte) (int, error) {
	mw.mu.RLock()
	defer mw.mu.RUnlock()
	for _, w := range mw.writers {
		if lw, ok := w.(zerolog.LevelWriter); ok {
			_, _ = lw.WriteLevel(l, p)
		} else {
			_, _ = w.Write(p)
		}
	}
	return len(p), nil
}

func (mw *multiWriter) add(w io.Writer) {
	mw.mu.Lock()
	mw.writers = append(mw.writers, w)
	mw.mu.Unlock()
}

// --- SeqWriter: 异步推送到 Seq（CLEF 格式）---

// SeqWriter 将 zerolog JSON 日志通过 channel 队列异步发送到 Seq。
// Write() 仅做 channel <- bytes，O(1) 非阻塞，绝不阻塞 web 请求处理 goroutine。
// channel 容量 10000，满时丢弃新条目（dropped 计数），不会影响主服务。
type SeqWriter struct {
	seqUrl   string
	apiKey   string
	instance string
	queue    chan []byte
	dropped  int64
	client   *http.Client
}

func newSeqWriter(seqUrl, apiKey, instance string) *SeqWriter {
	w := &SeqWriter{
		seqUrl:   strings.TrimRight(seqUrl, "/"),
		apiKey:   apiKey,
		instance: instance,
		queue:    make(chan []byte, 10000),
		client:   &http.Client{Timeout: 5 * time.Second},
	}
	go w.run()
	return w
}

// Write 将字节塞入 channel 即返回，由后台 goroutine 消费发送
func (w *SeqWriter) Write(p []byte) (int, error) {
	clef := w.toClef(p)
	select {
	case w.queue <- clef:
	default:
		n := atomic.AddInt64(&w.dropped, 1)
		if n == 1 || n%100 == 0 {
			seqWriteStderr("[seq] queue full, dropped=%d\n", n)
		}
	}
	return len(p), nil
}

// toClef 将 zerolog JSON 字段映射到 Seq CLEF 格式
// zerolog: time/level/message(msg) → CLEF: @t/@l/@mt
func (w *SeqWriter) toClef(p []byte) []byte {
	trimmed := bytes.TrimSpace(p)
	var m map[string]interface{}
	if err := json.Unmarshal(trimmed, &m); err != nil {
		// 非 JSON（如 fmt.Println 直接输出），包装为纯文本日志
		return []byte(fmt.Sprintf(`{"@t":%q,"@l":"Information","@mt":%q,"source":"stdout","instance":%q}`,
			time.Now().Format(time.RFC3339), strings.TrimSpace(string(p)), w.instance))
	}

	clef := make(map[string]interface{}, len(m)+3)
	for k, v := range m {
		clef[k] = v
	}

	// time → @t（zerolog 格式 "2006-01-02 15:04:05" → ISO 8601）
	if t, ok := m["time"].(string); ok {
		delete(clef, "time")
		if pt, err := time.ParseInLocation("2006-01-02 15:04:05", t, time.Local); err == nil {
			clef["@t"] = pt.Format(time.RFC3339)
		} else {
			clef["@t"] = t
		}
	} else {
		clef["@t"] = time.Now().Format(time.RFC3339)
	}

	// level → @l
	if lv, ok := m["level"].(string); ok {
		delete(clef, "level")
		switch lv {
		case "debug":
			clef["@l"] = "Debug"
		case "info":
			clef["@l"] = "Information"
		case "warn":
			clef["@l"] = "Warning"
		case "error":
			clef["@l"] = "Error"
		case "fatal":
			clef["@l"] = "Fatal"
		default:
			clef["@l"] = lv
		}
	}

	// message/msg → @mt
	if msg, ok := m["message"].(string); ok {
		delete(clef, "message")
		clef["@mt"] = msg
	} else if msg, ok := m["msg"].(string); ok {
		delete(clef, "msg")
		clef["@mt"] = msg
	}

	if w.instance != "" {
		clef["instance"] = w.instance
	}

	b, _ := json.Marshal(clef)
	return b
}

// run 后台 goroutine：每 100 条或 500ms 批量 POST 到 Seq
func (w *SeqWriter) run() {
	batch := make([][]byte, 0, 100)
	ticker := time.NewTicker(500 * time.Millisecond)
	defer ticker.Stop()
	for {
		select {
		case entry := <-w.queue:
			batch = append(batch, entry)
			if len(batch) >= 100 {
				w.flush(batch)
				batch = batch[:0]
			}
		case <-ticker.C:
			if len(batch) > 0 {
				w.flush(batch)
				batch = batch[:0]
			}
		}
	}
}

func (w *SeqWriter) flush(batch [][]byte) {
	var buf bytes.Buffer
	for _, entry := range batch {
		buf.Write(entry)
		buf.WriteByte('\n')
	}
	req, err := http.NewRequest("POST", w.seqUrl+"/api/events/raw?clef", &buf)
	if err != nil {
		seqWriteStderr("[seq] build request error: %v\n", err)
		return
	}
	req.Header.Set("Content-Type", "application/vnd.serilog.clef")
	if w.apiKey != "" {
		req.Header.Set("X-Seq-ApiKey", w.apiKey)
	}
	resp, err := w.client.Do(req)
	if err != nil {
		seqWriteStderr("[seq] send error: %v (dropped=%d)\n", err, atomic.LoadInt64(&w.dropped))
		return
	}
	defer resp.Body.Close()
	if resp.StatusCode >= 400 {
		body, _ := io.ReadAll(resp.Body)
		seqWriteStderr("[seq] server returned %d: %s\n", resp.StatusCode, string(body))
	}
}

// SetSeqWriter 将 Seq HTTP 推送器附加到当前 Logger（不影响已有的控制台/文件输出）
// seqUrl: Seq 服务地址，如 "http://127.0.0.1:5341"
// apiKey: Seq API Key，免费单用户版留空
// instance: 实例标识，建议用 config 的 port 字段区分同机多进程，如 "8085"
func (l *Logger) SetSeqWriter(seqUrl, apiKey, instance string) {
	if seqUrl == "" || l.mw == nil {
		return
	}
	sw := newSeqWriter(seqUrl, apiKey, instance)
	l.mw.add(sw)
}

// isInfrastructureFile 判断文件是否为基础设施（日志/DB/缓存/通用工具）管线，
// 这些文件在调用栈中会被跳过，以显示真正的业务调用者。
// context.go 是 Display/View 的纯中间层，也作为基础设施跳过。
// application.go、code/makecode.go 等保留，会作为有意义的调用者返回。
func isInfrastructureFile(file string) bool {
	if strings.HasPrefix(file, "zerolog/") || strings.HasPrefix(file, "zerolog@") {
		return true
	}
	if strings.HasPrefix(file, "logrus/") || strings.HasPrefix(file, "logrus@") {
		return true
	}
	if strings.HasPrefix(file, "runtime/") {
		return true
	}
	if strings.HasPrefix(file, "log/") {
		return true
	}

	infraPrefixes := []string{"db/", "cache/", "common/", "dri/"}
	for _, prefix := range infraPrefixes {
		if strings.HasPrefix(file, prefix) {
			return true
		}
	}

	lowerFile := strings.ToLower(file)
	if strings.Contains(lowerFile, "hotime") {
		infraDirs := []string{"db/", "cache/", "common/", "log/", "dri/"}
		for _, dir := range infraDirs {
			if strings.Contains(file, dir) {
				return true
			}
		}
		if strings.HasSuffix(file, "/context.go") || strings.HasSuffix(file, "\\context.go") {
			return true
		}
	}

	return false
}