// Copyright 2026 Alibaba Group
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package logging

import (
	"context"
	"log/slog"
)

// MultiHandler fans out slog records to multiple handlers.
// Each handler applies its own level filter independently.
type MultiHandler struct {
	handlers []slog.Handler
}

// NewMultiHandler creates a handler that writes to all provided handlers.
func NewMultiHandler(handlers ...slog.Handler) *MultiHandler {
	return &MultiHandler{handlers: handlers}
}

func (h *MultiHandler) Enabled(ctx context.Context, level slog.Level) bool {
	for _, handler := range h.handlers {
		if handler.Enabled(ctx, level) {
			return true
		}
	}
	return false
}

func (h *MultiHandler) Handle(ctx context.Context, record slog.Record) error {
	for _, handler := range h.handlers {
		if handler.Enabled(ctx, record.Level) {
			if err := handler.Handle(ctx, record); err != nil {
				return err
			}
		}
	}
	return nil
}

func (h *MultiHandler) WithAttrs(attrs []slog.Attr) slog.Handler {
	handlers := make([]slog.Handler, len(h.handlers))
	for i, handler := range h.handlers {
		handlers[i] = handler.WithAttrs(attrs)
	}
	return &MultiHandler{handlers: handlers}
}

func (h *MultiHandler) WithGroup(name string) slog.Handler {
	handlers := make([]slog.Handler, len(h.handlers))
	for i, handler := range h.handlers {
		handlers[i] = handler.WithGroup(name)
	}
	return &MultiHandler{handlers: handlers}
}