// Copyright 2023 The frp Authors
//
// Licensed 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 v1

import (
	"reflect"

	"github.com/fatedier/frp/pkg/util/jsonx"
	"github.com/fatedier/frp/pkg/util/util"
)

type VisitorTransport struct {
	UseEncryption  bool `json:"useEncryption,omitempty"`
	UseCompression bool `json:"useCompression,omitempty"`
}

type VisitorBaseConfig struct {
	Name string `json:"name"`
	Type string `json:"type"`
	// Enabled controls whether this visitor is enabled. nil or true means enabled, false means disabled.
	// This allows individual control over each visitor, complementing the global "start" field.
	Enabled   *bool            `json:"enabled,omitempty"`
	Transport VisitorTransport `json:"transport,omitempty"`
	SecretKey string           `json:"secretKey,omitempty"`
	// if the server user is not set, it defaults to the current user
	ServerUser string `json:"serverUser,omitempty"`
	ServerName string `json:"serverName,omitempty"`
	BindAddr   string `json:"bindAddr,omitempty"`
	// BindPort is the port that visitor listens on.
	// It can be less than 0, it means don't bind to the port and only receive connections redirected from
	// other visitors. (This is not supported for SUDP now)
	BindPort int `json:"bindPort,omitempty"`

	// Plugin specifies what plugin should be used.
	Plugin TypedVisitorPluginOptions `json:"plugin,omitempty"`
}

func (c VisitorBaseConfig) Clone() VisitorBaseConfig {
	out := c
	out.Enabled = util.ClonePtr(c.Enabled)
	out.Plugin = c.Plugin.Clone()
	return out
}

func (c *VisitorBaseConfig) GetBaseConfig() *VisitorBaseConfig {
	return c
}

func (c *VisitorBaseConfig) Complete() {
	if c.BindAddr == "" {
		c.BindAddr = "127.0.0.1"
	}
}

type VisitorConfigurer interface {
	Complete()
	GetBaseConfig() *VisitorBaseConfig
	Clone() VisitorConfigurer
}

type VisitorType string

const (
	VisitorTypeSTCP VisitorType = "stcp"
	VisitorTypeXTCP VisitorType = "xtcp"
	VisitorTypeSUDP VisitorType = "sudp"
)

var visitorConfigTypeMap = map[VisitorType]reflect.Type{
	VisitorTypeSTCP: reflect.TypeFor[STCPVisitorConfig](),
	VisitorTypeXTCP: reflect.TypeFor[XTCPVisitorConfig](),
	VisitorTypeSUDP: reflect.TypeFor[SUDPVisitorConfig](),
}

type TypedVisitorConfig struct {
	Type string `json:"type"`
	VisitorConfigurer
}

func (c *TypedVisitorConfig) UnmarshalJSON(b []byte) error {
	configurer, err := DecodeVisitorConfigurerJSON(b, DecodeOptions{})
	if err != nil {
		return err
	}

	c.Type = configurer.GetBaseConfig().Type
	c.VisitorConfigurer = configurer
	return nil
}

func (c *TypedVisitorConfig) MarshalJSON() ([]byte, error) {
	return jsonx.Marshal(c.VisitorConfigurer)
}

func NewVisitorConfigurerByType(t VisitorType) VisitorConfigurer {
	v, ok := visitorConfigTypeMap[t]
	if !ok {
		return nil
	}
	vc := reflect.New(v).Interface().(VisitorConfigurer)
	vc.GetBaseConfig().Type = string(t)
	return vc
}

var _ VisitorConfigurer = &STCPVisitorConfig{}

type STCPVisitorConfig struct {
	VisitorBaseConfig
}

func (c *STCPVisitorConfig) Clone() VisitorConfigurer {
	out := *c
	out.VisitorBaseConfig = c.VisitorBaseConfig.Clone()
	return &out
}

var _ VisitorConfigurer = &SUDPVisitorConfig{}

type SUDPVisitorConfig struct {
	VisitorBaseConfig
}

func (c *SUDPVisitorConfig) Clone() VisitorConfigurer {
	out := *c
	out.VisitorBaseConfig = c.VisitorBaseConfig.Clone()
	return &out
}

var _ VisitorConfigurer = &XTCPVisitorConfig{}

type XTCPVisitorConfig struct {
	VisitorBaseConfig

	Protocol          string `json:"protocol,omitempty"`
	KeepTunnelOpen    bool   `json:"keepTunnelOpen,omitempty"`
	MaxRetriesAnHour  int    `json:"maxRetriesAnHour,omitempty"`
	MinRetryInterval  int    `json:"minRetryInterval,omitempty"`
	FallbackTo        string `json:"fallbackTo,omitempty"`
	FallbackTimeoutMs int    `json:"fallbackTimeoutMs,omitempty"`

	// NatTraversal configuration for NAT traversal
	NatTraversal *NatTraversalConfig `json:"natTraversal,omitempty"`
}

func (c *XTCPVisitorConfig) Complete() {
	c.VisitorBaseConfig.Complete()

	c.Protocol = util.EmptyOr(c.Protocol, "quic")
	c.MaxRetriesAnHour = util.EmptyOr(c.MaxRetriesAnHour, 8)
	c.MinRetryInterval = util.EmptyOr(c.MinRetryInterval, 90)
	c.FallbackTimeoutMs = util.EmptyOr(c.FallbackTimeoutMs, 1000)
}

func (c *XTCPVisitorConfig) Clone() VisitorConfigurer {
	out := *c
	out.VisitorBaseConfig = c.VisitorBaseConfig.Clone()
	out.NatTraversal = c.NatTraversal.Clone()
	return &out
}