/*
 * Copyright (c) 2020, Psiphon Inc.
 * All rights reserved.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

package parameters

import (
	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/errors"
	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/packetman"
	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/protocol"
)

// PacketManipulationSpecs is a list of packet manipulation specs.
type PacketManipulationSpecs []*packetman.Spec

// Validate checks that each spec name is unique and that each spec compiles.
func (specs PacketManipulationSpecs) Validate() error {
	specNames := make(map[string]bool)
	for _, spec := range specs {
		if spec.Name == "" {
			return errors.TraceNew("missing spec name")
		}
		if ok, _ := specNames[spec.Name]; ok {
			return errors.TraceNew("duplicate spec name")
		}
		specNames[spec.Name] = true
		err := spec.Validate()
		if err != nil {
			return errors.Trace(err)
		}
	}
	return nil
}

// ProtocolPacketManipulations is a map from tunnel protocol names (or "All")
// to a list of packet manipulation spec names.
type ProtocolPacketManipulations map[string][]string

// Validate checks that tunnel protocol and spec names are valid. Duplicate
// spec names are allowed in each entry, enabling weighted selection.
func (manipulations ProtocolPacketManipulations) Validate(specs PacketManipulationSpecs) error {
	validSpecNames := make(map[string]bool)
	for _, spec := range specs {
		validSpecNames[spec.Name] = true
	}
	for tunnelProtocol, specNames := range manipulations {
		if tunnelProtocol != protocol.TUNNEL_PROTOCOLS_ALL {
			if !protocol.TunnelProtocolMayUseServerPacketManipulation(tunnelProtocol) {
				return errors.TraceNew("invalid tunnel protocol for packet manipulation")
			}
		}

		for _, specName := range specNames {
			if ok, _ := validSpecNames[specName]; !ok {
				return errors.TraceNew("invalid spec name")
			}
		}
	}
	return nil
}