package starlog

import (
	"context"
	"errors"
	"fmt"
	"io"
	"math/rand"
	"strconv"
	"strings"
	"sync"
	"sync/atomic"
	"time"

	"b612.me/starlog/colorable"
)

const (
	LvDebug = iota
	LvInfo
	LvNotice
	LvWarning
	LvError
	LvCritical
	LvPanic
	LvFatal
)

type ColorMode int

const (
	ColorModeOff ColorMode = iota
	ColorModeFullLine
	ColorModeLevelOnly
)

type PendingDropPolicy int

const (
	PendingDropOldest PendingDropPolicy = iota
	PendingDropNewest
	PendingBlock
)

type RedactFailMode int

const (
	RedactFailMaskAll RedactFailMode = iota
	RedactFailOpen
	RedactFailDrop
)

const (
	FieldTypeString = "string"
	FieldTypeNumber = "number"
	FieldTypeBool   = "bool"
	FieldTypeError  = "error"
	FieldTypeNil    = "nil"
	FieldTypeOther  = "other"
)

var (
	ErrAsyncHandlerPanic   = errors.New("async handler panic")
	ErrAsyncHandlerTimeout = errors.New("async handler timeout")
	ErrAsyncQueueFull      = errors.New("async queue full")
	ErrPendingWriteDropped = errors.New("pending write dropped")
	ErrInvalidLevel        = errors.New("invalid log level")
	ErrRedactionFailed     = errors.New("redaction failed")

	levels = map[int]string{
		LvDebug:    "DEBUG",
		LvInfo:     "INFO",
		LvNotice:   "NOTICE",
		LvWarning:  "WARNING",
		LvError:    "ERROR",
		LvCritical: "CRITICAL",
		LvPanic:    "PANIC",
		LvFatal:    "FATAL",
	}
	levelAliases = map[string]int{
		"debug":    LvDebug,
		"info":     LvInfo,
		"notice":   LvNotice,
		"warn":     LvWarning,
		"warning":  LvWarning,
		"err":      LvError,
		"error":    LvError,
		"critical": LvCritical,
		"crit":     LvCritical,
		"panic":    LvPanic,
		"fatal":    LvFatal,
	}
	stacks        *starChanStack
	stackStarted  bool = false
	stackStopChan chan struct{}
	stackDoneChan chan struct{}
	stackMu       sync.Mutex
	stackDrop     uint64
	stackAlert    func(error, LogData)
	stackAlertMu  sync.RWMutex
	stackFallback uint32 = 1
	stackTimeout  int64

	writeErrCount   uint64
	writeErrHandler func(error, LogData)
	writeErrMu      sync.RWMutex

	stdScreen io.Writer = colorable.NewColorableStdout()
	errScreen io.Writer = colorable.NewColorableStderr()
)

type starlog struct {
	mu                  *sync.Mutex
	output              io.Writer
	minLevel            int
	errOutputLevel      int
	showFuncName        bool
	showThread          bool
	showLevel           bool
	showDeatilFile      bool
	showColor           bool
	switching           bool
	showStd             bool
	onlyColorLevel      bool
	autoAppendNewline   bool
	stopWriter          bool
	id                  string
	name                string
	colorList           map[int][]Attr
	colorMe             map[int]*Color
	keywordColors       map[string][]Attr
	keywordOrder        []string
	keywordColorizers   map[string]*Color
	keywordMatcher      *keywordMatcher
	keywordMatchOptions KeywordMatchOptions
	showFieldColor      bool
	fieldKeyColor       []Attr
	fieldTypeColors     map[string][]Attr
	fieldValueColors    map[string][]Attr
	entryHandler        Handler
	redactor            Redactor
	redactRules         []RedactRule
	redactFailMode      RedactFailMode
	redactMaskToken     string
	redactErrorCount    uint64
	formatter           Formatter
	sink                Sink
	pendingCond         *sync.Cond
	pendingWrites       []string
	pendingWriteLimit   int
	pendingDropPolicy   PendingDropPolicy
	pendingDropCount    uint64
	pendingBlockCount   uint64
	pendingPeakLen      uint64
	rateLimiter         *rateLimiter
	sampler             *sampler
	deduper             *deduper
	contextFields       func(context.Context) Fields
	entryHandlerTimeout time.Duration
}

type StarLogger struct {
	thread      string
	handlerFunc func(LogData)
	logcore     *starlog
	isStd       bool
	fields      Fields
	logErr      error
	logCtx      context.Context
}

type logTransfer struct {
	handlerFunc func(LogData)
	LogData
}

type LogData struct {
	Name   string
	Log    string
	Colors []Attr
}

type PendingStats struct {
	Limit      int
	Length     int
	PeakLength int
	DropCount  uint64
	BlockCount uint64
	Policy     PendingDropPolicy
	Switching  bool
}

type KeywordMatchOptions struct {
	IgnoreCase bool
	WholeWord  bool
}

// Config is a logger core snapshot that can be read and applied atomically.
// Prefer GetConfig + UpdateConfig/ApplyConfig for multi-field configuration.
type Config struct {
	Name              string
	Level             int
	StdErrLevel       int
	ShowFuncName      bool
	ShowFlag          bool
	ShowLevel         bool
	ShowOriginFile    bool
	ShowColor         bool
	OnlyColorLevel    bool
	ShowStd           bool
	StopWriter        bool
	AutoAppendNewline bool
	Switching         bool
	LevelColors       map[int][]Attr
	KeywordColors     map[string][]Attr
	KeywordMatch      KeywordMatchOptions
	ShowFieldColor    bool
	FieldKeyColor     []Attr
	FieldTypeColors   map[string][]Attr
	FieldValueColors  map[string][]Attr

	EntryHandler        Handler
	EntryHandlerTimeout time.Duration
	Formatter           Formatter
	Sink                Sink
	Writer              io.Writer

	PendingWriteLimit int
	PendingDropPolicy PendingDropPolicy

	Redactor        Redactor
	RedactRules     []RedactRule
	RedactFailMode  RedactFailMode
	RedactMaskToken string

	RateLimit RateLimitConfig
	Sampling  SamplingConfig
	Dedup     DedupConfig

	ContextFieldExtractor func(context.Context) Fields
}

func newLogCore(out io.Writer) *starlog {
	core := &starlog{
		mu:             &sync.Mutex{},
		output:         out,
		minLevel:       LvDebug,
		errOutputLevel: LvError,
		showFuncName:   true,
		showThread:     true,
		showLevel:      true,
		showStd:        true,
		showDeatilFile: true,
		switching:      false,
		stopWriter:     false,
		showColor:      true,
		id:             generateId(),
		colorList: map[int][]Attr{
			LvDebug:    []Attr{FgWhite},
			LvInfo:     []Attr{FgGreen},
			LvNotice:   []Attr{FgCyan},
			LvWarning:  []Attr{FgYellow},
			LvError:    []Attr{FgMagenta},
			LvCritical: []Attr{FgRed, Bold},
			LvPanic:    []Attr{FgRed, Bold},
			LvFatal:    []Attr{FgRed},
		},
		colorMe: map[int]*Color{
			LvDebug:    NewColor([]Attr{FgWhite}...),
			LvInfo:     NewColor([]Attr{FgGreen}...),
			LvNotice:   NewColor([]Attr{FgCyan}...),
			LvWarning:  NewColor([]Attr{FgYellow}...),
			LvError:    NewColor([]Attr{FgMagenta}...),
			LvCritical: NewColor([]Attr{FgRed, Bold}...),
			LvPanic:    NewColor([]Attr{FgRed, Bold}...),
			LvFatal:    NewColor([]Attr{FgRed}...),
		},
		keywordColors:     make(map[string][]Attr),
		keywordOrder:      nil,
		keywordColorizers: nil,
		keywordMatcher:    nil,
		showFieldColor:    true,
		fieldKeyColor:     []Attr{FgHiBlue},
		fieldTypeColors: map[string][]Attr{
			FieldTypeString: []Attr{FgGreen},
			FieldTypeNumber: []Attr{FgYellow},
			FieldTypeBool:   []Attr{FgMagenta},
			FieldTypeError:  []Attr{FgRed},
			FieldTypeNil:    []Attr{FgHiBlack},
			FieldTypeOther:  []Attr{FgCyan},
		},
		fieldValueColors:    make(map[string][]Attr),
		redactRules:         make([]RedactRule, 0, 4),
		redactFailMode:      RedactFailMaskAll,
		redactMaskToken:     "[REDACTED]",
		pendingWrites:       make([]string, 0, 16),
		pendingWriteLimit:   1024,
		pendingDropPolicy:   PendingDropOldest,
		rateLimiter:         newRateLimiter(),
		sampler:             newSampler(),
		deduper:             newDeduper(),
		entryHandlerTimeout: 0,
	}
	core.rebuildKeywordCachesLocked()
	core.pendingCond = sync.NewCond(core.mu)
	return core
}

func ParseLevel(level string) (int, error) {
	val := strings.TrimSpace(strings.ToLower(level))
	if val == "" {
		return 0, fmt.Errorf("%w: empty", ErrInvalidLevel)
	}
	if parsed, ok := levelAliases[val]; ok {
		return parsed, nil
	}
	num, err := strconv.Atoi(val)
	if err == nil {
		return num, nil
	}
	return 0, fmt.Errorf("%w: %s", ErrInvalidLevel, level)
}

func NewStarlog(out io.Writer) *StarLogger {
	return &StarLogger{
		handlerFunc: nil,
		thread:      "MAN",
		logcore:     newLogCore(out),
		isStd:       false,
		fields:      nil,
		logErr:      nil,
		logCtx:      nil,
	}
}

func (logger *StarLogger) StdErrLevel() int {
	logger.logcore.mu.Lock()
	defer logger.logcore.mu.Unlock()
	return logger.logcore.errOutputLevel
}

func (logger *StarLogger) SetStdErrLevel(level int) {
	logger.logcore.mu.Lock()
	defer logger.logcore.mu.Unlock()
	logger.logcore.errOutputLevel = level
}

func (logger *StarLogger) NewFlag() *StarLogger {
	return &StarLogger{
		thread:      getRandomFlag(false),
		handlerFunc: logger.handlerFunc,
		logcore:     logger.logcore,
		isStd:       false,
		fields:      cloneFields(logger.fields),
		logErr:      logger.logErr,
		logCtx:      logger.logCtx,
	}
}
func (logger *StarLogger) SetNewRandomFlag() {
	logger.thread = getRandomFlag(false)
}

func (logger *StarLogger) SetName(name string) {
	logger.logcore.mu.Lock()
	defer logger.logcore.mu.Unlock()
	logger.logcore.name = name
}

func (logger *StarLogger) GetName() string {
	logger.logcore.mu.Lock()
	defer logger.logcore.mu.Unlock()
	return logger.logcore.name
}

func getRandomFlag(isMain bool) string {
	rand.Seed(time.Now().UnixNano())
	if isMain {
		return "MAN"
	}
	flag := "MAN"
	for flag == "MAN" {
		flag = string([]byte{uint8(rand.Intn(26) + 65), uint8(rand.Intn(26) + 65), uint8(rand.Intn(26) + 65)})
	}
	return flag
}

func generateId() string {
	rand.Seed(time.Now().UnixNano())
	return fmt.Sprintf("%dstar%db612%d", time.Now().UnixNano(), rand.Intn(1000000), rand.Intn(1000000))
}

func StartStacks() {
	stackMu.Lock()
	if stackStarted {
		stackMu.Unlock()
		return
	}
	stackStarted = true
	stackStopChan = make(chan struct{})
	stackDoneChan = make(chan struct{})
	stacks = newStarChanStack(1024)
	stopChan := stackStopChan
	doneChan := stackDoneChan
	stackMu.Unlock()
	go func(stop <-chan struct{}, done chan struct{}) {
		defer close(done)
		defer func() {
			stackMu.Lock()
			stackStarted = false
			stackMu.Unlock()
		}()
		for {
			select {
			case <-stop:
				return
			default:
			}
			poped, err := stacks.Pop()
			if err != nil {
				if errors.Is(err, io.EOF) {
					return
				}
				return
			}
			val, ok := poped.(logTransfer)
			if !ok {
				continue
			}
			if val.handlerFunc != nil {
				invokeAsyncHandlerSafely(val.handlerFunc, val.LogData)
			}
		}
	}(stopChan, doneChan)
}

func StopStacks() {
	stackMu.Lock()
	if !stackStarted {
		stackMu.Unlock()
		return
	}
	stopChan := stackStopChan
	doneChan := stackDoneChan
	current := stacks
	stackStopChan = nil
	stackDoneChan = nil
	stackMu.Unlock()

	if stopChan != nil {
		func() {
			defer func() {
				recover()
			}()
			close(stopChan)
		}()
	}
	if current != nil {
		_ = current.Close()
	}
	if doneChan != nil {
		<-doneChan
	}
}

func Stop() {
	StopStacks()
}

func SetAsyncErrorHandler(alert func(error, LogData)) {
	stackAlertMu.Lock()
	defer stackAlertMu.Unlock()
	stackAlert = alert
}

func SetAsyncFallbackToSync(enable bool) {
	if enable {
		atomic.StoreUint32(&stackFallback, 1)
		return
	}
	atomic.StoreUint32(&stackFallback, 0)
}

func GetAsyncFallbackToSync() bool {
	return atomic.LoadUint32(&stackFallback) == 1
}

func SetAsyncHandlerTimeout(timeout time.Duration) {
	if timeout < 0 {
		timeout = 0
	}
	atomic.StoreInt64(&stackTimeout, int64(timeout))
}

func GetAsyncHandlerTimeout() time.Duration {
	return time.Duration(atomic.LoadInt64(&stackTimeout))
}

func GetAsyncDropCount() uint64 {
	return atomic.LoadUint64(&stackDrop)
}

func reportAsyncDrop(err error, data LogData) {
	atomic.AddUint64(&stackDrop, 1)
	stackAlertMu.RLock()
	alert := stackAlert
	stackAlertMu.RUnlock()
	if alert != nil {
		func() {
			defer func() {
				recover()
			}()
			alert(err, data)
		}()
	}
}

func invokeAsyncHandlerSafely(handler func(LogData), data LogData) bool {
	if handler == nil {
		return true
	}
	timeout := GetAsyncHandlerTimeout()
	if timeout <= 0 {
		return invokeAsyncHandlerDirect(handler, data)
	}
	done := make(chan bool, 1)
	go func() {
		done <- invokeAsyncHandlerDirect(handler, data)
	}()
	select {
	case ok := <-done:
		return ok
	case <-time.After(timeout):
		reportAsyncDrop(ErrAsyncHandlerTimeout, data)
		return false
	}
}

func invokeAsyncHandlerDirect(handler func(LogData), data LogData) (ok bool) {
	defer func() {
		if panicErr := recover(); panicErr != nil {
			reportAsyncDrop(fmt.Errorf("%w: %v", ErrAsyncHandlerPanic, panicErr), data)
			ok = false
		}
	}()
	handler(data)
	return true
}

func SetWriteErrorHandler(alert func(error, LogData)) {
	writeErrMu.Lock()
	defer writeErrMu.Unlock()
	writeErrHandler = alert
}

func GetWriteErrorCount() uint64 {
	return atomic.LoadUint64(&writeErrCount)
}

func reportWriteError(err error, data LogData) {
	if err == nil {
		return
	}
	atomic.AddUint64(&writeErrCount, 1)
	writeErrMu.RLock()
	alert := writeErrHandler
	writeErrMu.RUnlock()
	if alert != nil {
		func() {
			defer func() {
				recover()
			}()
			alert(err, data)
		}()
	}
}

func resetAsyncMetricsForTest() {
	atomic.StoreUint64(&stackDrop, 0)
	SetAsyncErrorHandler(nil)
	SetAsyncFallbackToSync(true)
	SetAsyncHandlerTimeout(0)
	atomic.StoreUint64(&writeErrCount, 0)
	SetWriteErrorHandler(nil)
}