package broker

import (
	"context"
	"log/slog"

	"github.com/mochi-mqtt/server/v2/packets"
)

type redactHandler struct {
	inner slog.Handler
}

func newRedactHandler(inner slog.Handler) slog.Handler {
	if inner == nil {
		inner = slog.Default().Handler()
	}
	return &redactHandler{inner: inner}
}

func (h *redactHandler) Enabled(ctx context.Context, level slog.Level) bool {
	return h.inner.Enabled(ctx, level)
}

func (h *redactHandler) Handle(ctx context.Context, r slog.Record) error {
	rec := slog.NewRecord(r.Time, r.Level, r.Message, r.PC)
	r.Attrs(func(a slog.Attr) bool {
		rec.AddAttrs(redactSlogAttr(a))
		return true
	})
	return h.inner.Handle(ctx, rec)
}

func (h *redactHandler) WithAttrs(attrs []slog.Attr) slog.Handler {
	out := make([]slog.Attr, len(attrs))
	for i, a := range attrs {
		out[i] = redactSlogAttr(a)
	}
	return &redactHandler{inner: h.inner.WithAttrs(out)}
}

func (h *redactHandler) WithGroup(name string) slog.Handler {
	return &redactHandler{inner: h.inner.WithGroup(name)}
}

func redactSlogAttr(a slog.Attr) slog.Attr {
	a.Value = a.Value.Resolve()
	switch v := a.Value.Any().(type) {
	case packets.Packet:
		return slog.Any(a.Key, summarizePacket(v))
	case *packets.Packet:
		if v == nil {
			return a
		}
		return slog.Any(a.Key, summarizePacket(*v))
	}
	if a.Value.Kind() == slog.KindGroup {
		group := a.Value.Group()
		out := make([]slog.Attr, len(group))
		for i, g := range group {
			out[i] = redactSlogAttr(g)
		}
		return slog.Attr{Key: a.Key, Value: slog.GroupValue(out...)}
	}
	return a
}

type mqttPacketLog struct {
	Type       string `json:"type"`
	QoS        byte   `json:"qos"`
	PacketID   uint16 `json:"packet_id"`
	Topic      string `json:"topic,omitempty"`
	PayloadLen int    `json:"payload_len"`
}

func summarizePacket(pk packets.Packet) mqttPacketLog {
	name := packets.PacketNames[pk.FixedHeader.Type]
	if name == "" {
		name = "unknown"
	}
	return mqttPacketLog{
		Type:       name,
		QoS:        pk.FixedHeader.Qos,
		PacketID:   pk.PacketID,
		Topic:      pk.TopicName,
		PayloadLen: len(pk.Payload),
	}
}