// Licensed to Elasticsearch B.V. under one or more contributor
// license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright
// ownership. Elasticsearch B.V. licenses this file to you 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 internal

import (
	"fmt"
	"sync"

	"github.com/pkg/errors"
	"go.uber.org/zap/zapcore"
)

type ecsError struct {
	error
}

func NewError(err error) zapcore.ObjectMarshaler {
	return ecsError{err}
}

func (err ecsError) MarshalLogObject(enc zapcore.ObjectEncoder) error {
	enc.AddString("message", err.Error())
	if e, ok := err.error.(stackTracer); ok {
		enc.AddString("stack_trace", fmt.Sprintf("%+v", e.StackTrace()))
	}

	// TODO(simitt): support for improved error handling
	// https://github.com/elastic/ecs-logging-go-zap/issues/8
	if e, ok := err.error.(errorGroup); ok {
		if errorCause := e.Errors(); len(errorCause) > 0 {
			return enc.AddArray("cause", errArray(errorCause))
		}
	}
	return nil
}

// interface used by github.com/pkg/errors
type stackTracer interface {
	StackTrace() errors.StackTrace
}

// *** code below this line is mostly copied from github.com/zapcore/core.go
//       and is subject to the license below***

// Copyright (c) 2017 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

type errorGroup interface {
	// Provides read-only access to the underlying list of errors, preferably
	// without causing any allocs.
	Errors() []error
}

// Note that errArry and errArrayElem are very similar to the version
// implemented in the top-level error.go file. We can't re-use this because
// that would require exporting errArray as part of the zapcore API.

// Encodes a list of errors using the standard error encoding logic.
type errArray []error

func (errs errArray) MarshalLogArray(arr zapcore.ArrayEncoder) error {
	for i := range errs {
		if errs[i] == nil {
			continue
		}

		el := newErrArrayElem(errs[i])
		arr.AppendObject(el)
		el.Free()
	}
	return nil
}

var _errArrayElemPool = sync.Pool{New: func() interface{} {
	return &errArrayElem{}
}}

// Encodes any error into a {"error": ...} re-using the same errors logic.
//
// May be passed in place of an array to build a single-element array.
type errArrayElem struct{ err error }

func newErrArrayElem(err error) *errArrayElem {
	e := _errArrayElemPool.Get().(*errArrayElem)
	e.err = err
	return e
}

func (e *errArrayElem) MarshalLogArray(arr zapcore.ArrayEncoder) error {
	return arr.AppendObject(e)
}

func (e *errArrayElem) MarshalLogObject(enc zapcore.ObjectEncoder) error {
	return ecsError{e.err}.MarshalLogObject(enc)
}

func (e *errArrayElem) Free() {
	e.err = nil
	_errArrayElemPool.Put(e)
}