package logging

import (
	"fmt"
	"sort"
	"strconv"
	"strings"
	"time"

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

var textBufferPool = buffer.NewPool()

// textEncoder 把结构化字段输出为便于直接阅读和 grep 的单行文本。
type textEncoder struct {
	*zapcore.MapObjectEncoder
	location *time.Location
}

func newTextEncoder(location *time.Location) zapcore.Encoder {
	return &textEncoder{
		MapObjectEncoder: zapcore.NewMapObjectEncoder(),
		location:         location,
	}
}

func (e *textEncoder) Clone() zapcore.Encoder {
	cloned := &textEncoder{
		MapObjectEncoder: zapcore.NewMapObjectEncoder(),
		location:         e.location,
	}
	for key, value := range e.Fields {
		cloned.Fields[key] = value
	}
	return cloned
}

func (e *textEncoder) EncodeEntry(entry zapcore.Entry, fields []zapcore.Field) (*buffer.Buffer, error) {
	ctx := e.Clone().(*textEncoder)
	for i := range fields {
		fields[i].AddTo(ctx)
	}

	buf := textBufferPool.Get()
	buf.AppendString(entry.Time.In(e.location).Format("2006-01-02 15:04:05.000"))
	buf.AppendString(" | ")
	buf.AppendString(fmt.Sprintf("%-5s", strings.ToUpper(entry.Level.String())))
	buf.AppendString(" | ")
	buf.AppendString(cleanText(entry.Message))

	if entry.Level >= zapcore.WarnLevel && entry.Caller.Defined {
		buf.AppendString(" | caller=")
		buf.AppendString(entry.Caller.TrimmedPath())
	}

	keys := orderedKeys(ctx.Fields)
	for _, key := range keys {
		value := ctx.Fields[key]
		if isEmptyValue(value) {
			continue
		}
		buf.AppendString(" | ")
		buf.AppendString(key)
		buf.AppendByte('=')
		buf.AppendString(formatValue(value))
	}
	if entry.Stack != "" {
		buf.AppendString(" | stack=")
		buf.AppendString(strconv.Quote(entry.Stack))
	}
	buf.AppendByte('\n')
	return buf, nil
}

func orderedKeys(fields map[string]any) []string {
	priority := []string{
		"module", "request_id", "method", "route", "path", "status", "code",
		"duration_ms", "rows", "user_id", "admin_id", "client_ip", "error",
	}
	keys := make([]string, 0, len(fields))
	seen := make(map[string]bool, len(fields))
	for _, key := range priority {
		if _, ok := fields[key]; ok {
			keys = append(keys, key)
			seen[key] = true
		}
	}
	rest := make([]string, 0, len(fields)-len(keys))
	for key := range fields {
		if !seen[key] {
			rest = append(rest, key)
		}
	}
	sort.Strings(rest)
	return append(keys, rest...)
}

func formatValue(value any) string {
	switch typed := value.(type) {
	case string:
		if typed != "" && !strings.ContainsAny(typed, " \t\r\n|=\"") {
			return typed
		}
		return strconv.Quote(typed)
	case []byte:
		return strconv.Quote(string(typed))
	case time.Time:
		return typed.Format(time.RFC3339)
	case time.Duration:
		return typed.String()
	default:
		return cleanText(fmt.Sprint(typed))
	}
}

func cleanText(value string) string {
	return strings.NewReplacer("\r", `\r`, "\n", `\n`, "\t", `\t`).Replace(value)
}

func isEmptyValue(value any) bool {
	if value == nil {
		return true
	}
	text, ok := value.(string)
	return ok && strings.TrimSpace(text) == ""
}