package notice

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"sort"
	"sync"

	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
)

type zapNoticeCore struct {
	senders []Sender                   `json:"-" dc:"日志通知使用的消息发送实例列表"`
	levels  map[zapcore.Level]struct{} `json:"-" dc:"触发消息通知的精确日志等级集合"`
	fields  []zapcore.Field            `json:"-" dc:"通过 Logger.With 附加的上下文字段"`
	pending *sync.WaitGroup            `json:"-" dc:"等待尚未完成的异步消息发送"`
	onError func(error)                `json:"-" dc:"异步消息发送失败处理函数"`
}

func (f *Factory) WrapZap(base *zap.Logger, config ZapConfig) (*zap.Logger, error) {
	if base == nil {
		return nil, fmt.Errorf("%w: base logger is nil", ErrInvalidZapConfig)
	}
	channels, levels, err := normalizeZapConfig(config)
	if err != nil {
		return nil, err
	}
	senders := make([]Sender, 0, len(channels))
	for _, channel := range channels {
		sender, getErr := f.Get(channel)
		if getErr != nil {
			return nil, getErr
		}
		senders = append(senders, sender)
	}
	core := &zapNoticeCore{
		senders: senders,
		levels:  levels,
		fields:  []zapcore.Field{},
		pending: &sync.WaitGroup{},
		onError: config.OnError,
	}
	return base.WithOptions(zap.WrapCore(func(original zapcore.Core) zapcore.Core {
		return zapcore.NewTee(original, core)
	})), nil
}

func normalizeZapConfig(config ZapConfig) ([]Channel, map[zapcore.Level]struct{}, error) {
	if len(config.Channels) == 0 {
		return nil, nil, fmt.Errorf("%w: channels are empty", ErrInvalidZapConfig)
	}
	seen := make(map[Channel]struct{}, len(config.Channels))
	channels := make([]Channel, 0, len(config.Channels))
	for _, channel := range config.Channels {
		if !validChannel(channel) {
			return nil, nil, fmt.Errorf("%w: unsupported channel %q", ErrInvalidZapConfig, channel)
		}
		if _, exists := seen[channel]; exists {
			continue
		}
		seen[channel] = struct{}{}
		channels = append(channels, channel)
	}
	configuredLevels := config.Levels
	if len(configuredLevels) == 0 {
		configuredLevels = []zapcore.Level{zapcore.WarnLevel, zapcore.ErrorLevel}
	}
	levels := make(map[zapcore.Level]struct{}, len(configuredLevels))
	for _, level := range configuredLevels {
		if level < zapcore.DebugLevel || level > zapcore.FatalLevel {
			return nil, nil, fmt.Errorf("%w: invalid level %d", ErrInvalidZapConfig, level)
		}
		levels[level] = struct{}{}
	}
	return channels, levels, nil
}

func (c *zapNoticeCore) Enabled(level zapcore.Level) bool {
	_, exists := c.levels[level]
	return exists
}

func (c *zapNoticeCore) With(fields []zapcore.Field) zapcore.Core {
	cloned := *c
	cloned.fields = make([]zapcore.Field, 0, len(c.fields)+len(fields))
	cloned.fields = append(cloned.fields, c.fields...)
	cloned.fields = append(cloned.fields, fields...)
	return &cloned
}

func (c *zapNoticeCore) Check(entry zapcore.Entry, checked *zapcore.CheckedEntry) *zapcore.CheckedEntry {
	if c.Enabled(entry.Level) {
		return checked.AddCore(entry, c)
	}
	return checked
}

func (c *zapNoticeCore) Write(entry zapcore.Entry, fields []zapcore.Field) error {
	message := zapEntryMessage(entry, append(append([]zapcore.Field{}, c.fields...), fields...))
	c.pending.Add(1)
	go func() {
		defer c.pending.Done()
		var sendErrors []error
		for index, sender := range c.senders {
			if err := sender.Send(context.Background(), message); err != nil {
				sendErrors = append(sendErrors, fmt.Errorf("notice sender %d: %w", index, err))
			}
		}
		if len(sendErrors) > 0 && c.onError != nil {
			c.onError(errors.Join(sendErrors...))
		}
	}()
	return nil
}

func (c *zapNoticeCore) Sync() error {
	c.pending.Wait()
	return nil
}

func zapEntryMessage(entry zapcore.Entry, fields []zapcore.Field) Message {
	titleSuffix := entry.LoggerName
	if titleSuffix == "" {
		titleSuffix = "日志告警"
	}
	cardFields := encodeZapFields(fields)
	cardFields = append(cardFields, CardField{Name: "timestamp", Value: entry.Time.Format("2006-01-02T15:04:05.000Z07:00")})
	if entry.Caller.Defined {
		cardFields = append(cardFields, CardField{Name: "caller", Value: entry.Caller.TrimmedPath()})
	}
	return Card(CardContent{
		Title:    fmt.Sprintf("[%s] %s", entry.Level.CapitalString(), titleSuffix),
		Theme:    zapLevelTheme(entry.Level),
		Markdown: entry.Message,
		Fields:   cardFields,
	})
}

func encodeZapFields(fields []zapcore.Field) []CardField {
	encoder := zapcore.NewMapObjectEncoder()
	for _, field := range fields {
		field.AddTo(encoder)
	}
	keys := make([]string, 0, len(encoder.Fields))
	for key := range encoder.Fields {
		keys = append(keys, key)
	}
	sort.Strings(keys)
	result := make([]CardField, 0, len(keys))
	for _, key := range keys {
		data, err := json.Marshal(encoder.Fields[key])
		if err != nil {
			data = []byte(fmt.Sprint(encoder.Fields[key]))
		}
		result = append(result, CardField{Name: key, Value: string(data)})
	}
	return result
}

func zapLevelTheme(level zapcore.Level) CardTheme {
	switch {
	case level >= zapcore.ErrorLevel:
		return CardThemeRed
	case level == zapcore.WarnLevel:
		return CardThemeOrange
	default:
		return CardThemeBlue
	}
}