// 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.

package jaeger

import (
	opentracing "github.com/opentracing/opentracing-go"
)

// ContribObserver can be registered with the Tracer to receive notifications
// about new Spans. Modelled after github.com/opentracing-contrib/go-observer.
type ContribObserver interface {
	// Create and return a span observer. Called when a span starts.
	// If the Observer is not interested in the given span, it must return (nil, false).
	// E.g :
	//     func StartSpan(opName string, opts ...opentracing.StartSpanOption) {
	//         var sp opentracing.Span
	//         sso := opentracing.StartSpanOptions{}
	//         if spanObserver, ok := Observer.OnStartSpan(span, opName, sso); ok {
	//             // we have a valid SpanObserver
	//         }
	//         ...
	//     }
	OnStartSpan(sp opentracing.Span, operationName string, options opentracing.StartSpanOptions) (ContribSpanObserver, bool)
}

// ContribSpanObserver is created by the Observer and receives notifications
// about other Span events. This interface is meant to match
// github.com/opentracing-contrib/go-observer, via duck typing, without
// directly importing the go-observer package.
type ContribSpanObserver interface {
	OnSetOperationName(operationName string)
	OnSetTag(key string, value interface{})
	OnFinish(options opentracing.FinishOptions)
}

// wrapper observer for the old observers (see observer.go)
type oldObserver struct {
	obs Observer
}

func (o *oldObserver) OnStartSpan(sp opentracing.Span, operationName string, options opentracing.StartSpanOptions) (ContribSpanObserver, bool) {
	spanObserver := o.obs.OnStartSpan(operationName, options)
	return spanObserver, spanObserver != nil
}