package logger

import (
	"context"
	"fmt"
	"log/slog"
	"regexp"
	"sort"
	"strings"
	"sync"
)

var secretRegistry = struct {
	sync.RWMutex
	values map[string]struct{}
}{values: map[string]struct{}{}}
var bearerPattern = regexp.MustCompile(`(?i)Bearer\s+[^\s"'<>]+`)
var credentialPattern = regexp.MustCompile(`(?i)((?:api[_-]?key|token|authorization|cookie|password|secret)["']?\s*[:=]\s*["']?)[^"'\s,;}]+`)

func RegisterSecrets(values ...string) {
	secretRegistry.Lock()
	defer secretRegistry.Unlock()
	for _, v := range values {
		if v != "" {
			secretRegistry.values[v] = struct{}{}
		}
	}
}
func redact(s string) string {
	secretRegistry.RLock()
	values := make([]string, 0, len(secretRegistry.values))
	for value := range secretRegistry.values {
		values = append(values, value)
	}
	secretRegistry.RUnlock()
	sort.Slice(values, func(i, j int) bool { return len(values[i]) > len(values[j]) })
	for _, value := range values {
		s = strings.ReplaceAll(s, value, "[redacted]")
	}
	s = bearerPattern.ReplaceAllString(s, "Bearer [redacted]")
	return credentialPattern.ReplaceAllString(s, "${1}[redacted]")
}

type redactingHandler struct{ next slog.Handler }

func (h redactingHandler) Enabled(ctx context.Context, level slog.Level) bool {
	return h.next.Enabled(ctx, level)
}
func redactAttr(a slog.Attr) slog.Attr {
	key := strings.ToLower(a.Key)
	for _, part := range []string{"apikey", "api_key", "token", "password", "secret", "authorization", "cookie", "payload", "headers", "body", "config"} {
		if strings.Contains(key, part) {
			return slog.String(a.Key, "[redacted]")
		}
	}
	v := a.Value.Resolve()
	switch v.Kind() {
	case slog.KindString:
		a.Value = slog.StringValue(redact(v.String()))
	case slog.KindAny:
		a.Value = slog.StringValue(redact(fmt.Sprint(v.Any())))
	case slog.KindGroup:
		attrs := v.Group()
		for i := range attrs {
			attrs[i] = redactAttr(attrs[i])
		}
		a.Value = slog.GroupValue(attrs...)
	}
	return a
}
func (h redactingHandler) Handle(ctx context.Context, r slog.Record) error {
	next := slog.NewRecord(r.Time, r.Level, redact(r.Message), r.PC)
	r.Attrs(func(a slog.Attr) bool { next.AddAttrs(redactAttr(a)); return true })
	return h.next.Handle(ctx, next)
}
func (h redactingHandler) WithAttrs(attrs []slog.Attr) slog.Handler {
	copy := append([]slog.Attr(nil), attrs...)
	for i := range copy {
		copy[i] = redactAttr(copy[i])
	}
	return redactingHandler{h.next.WithAttrs(copy)}
}
func (h redactingHandler) WithGroup(name string) slog.Handler {
	return redactingHandler{h.next.WithGroup(name)}
}