// 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 baggage

const (
	defaultMaxValueLength = 2048
)

// Restriction determines whether a baggage key is allowed and contains any restrictions on the baggage value.
type Restriction struct {
	keyAllowed     bool
	maxValueLength int
}

// NewRestriction returns a new Restriction.
func NewRestriction(keyAllowed bool, maxValueLength int) *Restriction {
	return &Restriction{
		keyAllowed:     keyAllowed,
		maxValueLength: maxValueLength,
	}
}

// KeyAllowed returns whether the baggage key for this restriction is allowed.
func (r *Restriction) KeyAllowed() bool {
	return r.keyAllowed
}

// MaxValueLength returns the max length for the baggage value.
func (r *Restriction) MaxValueLength() int {
	return r.maxValueLength
}

// RestrictionManager keeps track of valid baggage keys and their restrictions.
type RestrictionManager interface {
	GetRestriction(key string) *Restriction
}

// DefaultRestrictionManager allows any baggage key.
type DefaultRestrictionManager struct {
	defaultRestriction *Restriction
}

// NewDefaultRestrictionManager returns a DefaultRestrictionManager.
func NewDefaultRestrictionManager(maxValueLength int) *DefaultRestrictionManager {
	if maxValueLength == 0 {
		maxValueLength = defaultMaxValueLength
	}
	return &DefaultRestrictionManager{
		defaultRestriction: &Restriction{keyAllowed: true, maxValueLength: maxValueLength},
	}
}

// GetRestriction implements RestrictionManager#GetRestriction.
func (m *DefaultRestrictionManager) GetRestriction(key string) *Restriction {
	return m.defaultRestriction
}