// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package internal

import (
	"context"
)

const (
	ExperimentFrontendFetch               = "frontend-fetch"
	ExperimentFrontendPackageAtMaster     = "frontend-package-at-master"
	ExperimentInsertDirectories           = "insert-directories"
	ExperimentInsertPlaygroundLinks       = "insert-playground-links"
	ExperimentInsertSerializable          = "insert-serializable-txn"
	ExperimentTeeProxyMakePkgGoDevRequest = "teeproxy-make-pkg-go-dev-request"
	ExperimentUseDirectories              = "use-directories"
	ExperimentUsePathInfoToCheckExistence = "use-path-info-to-check-existence"
	ExperimentTranslateHTML               = "translate-html"
)

// Experiment holds data associated with an experimental feature for frontend
// or worker.
type Experiment struct {
	// Name is the name of the feature.
	Name string

	// Rollout is the percentage of requests enrolled in the experiment.
	Rollout uint

	// Description provides a description of the experiment.
	Description string
}

// ExperimentSource is the interface used by the middleware to interact with
// experiments data.
type ExperimentSource interface {
	// GetExperiments fetches active experiments from the
	// ExperimentSource.
	GetExperiments(ctx context.Context) ([]*Experiment, error)
}

// LocalExperimentSource is used when developing locally using the direct proxy
// mode.
type LocalExperimentSource struct {
	experiments []*Experiment
}

// NewLocalExperimentSource returns a LocalExperimentSource with the provided experiments.
func NewLocalExperimentSource(experiments []*Experiment) *LocalExperimentSource {
	return &LocalExperimentSource{experiments: experiments}
}

// GetExperiments returns the experiments for the given LocalExperimentSource.
func (e *LocalExperimentSource) GetExperiments(ctx context.Context) ([]*Experiment, error) {
	return e.experiments, nil
}