package conf

import (
	"encoding/json"
	"strings"

	core "github.com/v2fly/v2ray-core/v4"
	"github.com/v2fly/v2ray-core/v4/app/dispatcher"
	"github.com/v2fly/v2ray-core/v4/app/proxyman"
	"github.com/v2fly/v2ray-core/v4/app/stats"
	"github.com/v2fly/v2ray-core/v4/common/serial"
	"github.com/v2fly/v2ray-core/v4/infra/conf/cfgcommon"
)

var (
	inboundConfigLoader = NewJSONConfigLoader(ConfigCreatorCache{
		"dokodemo-door": func() interface{} { return new(DokodemoConfig) },
		"http":          func() interface{} { return new(HTTPServerConfig) },
		"shadowsocks":   func() interface{} { return new(ShadowsocksServerConfig) },
		"socks":         func() interface{} { return new(SocksServerConfig) },
		"vless":         func() interface{} { return new(VLessInboundConfig) },
		"vmess":         func() interface{} { return new(VMessInboundConfig) },
		"trojan":        func() interface{} { return new(TrojanServerConfig) },
	}, "protocol", "settings")

	outboundConfigLoader = NewJSONConfigLoader(ConfigCreatorCache{
		"blackhole":   func() interface{} { return new(BlackholeConfig) },
		"freedom":     func() interface{} { return new(FreedomConfig) },
		"http":        func() interface{} { return new(HTTPClientConfig) },
		"shadowsocks": func() interface{} { return new(ShadowsocksClientConfig) },
		"socks":       func() interface{} { return new(SocksClientConfig) },
		"vless":       func() interface{} { return new(VLessOutboundConfig) },
		"vmess":       func() interface{} { return new(VMessOutboundConfig) },
		"trojan":      func() interface{} { return new(TrojanClientConfig) },
		"dns":         func() interface{} { return new(DNSOutboundConfig) },
		"loopback":    func() interface{} { return new(LoopbackConfig) },
	}, "protocol", "settings")
)

func toProtocolList(s []string) ([]proxyman.KnownProtocols, error) {
	kp := make([]proxyman.KnownProtocols, 0, 8)
	for _, p := range s {
		switch strings.ToLower(p) {
		case "http":
			kp = append(kp, proxyman.KnownProtocols_HTTP)
		case "https", "tls", "ssl":
			kp = append(kp, proxyman.KnownProtocols_TLS)
		default:
			return nil, newError("Unknown protocol: ", p)
		}
	}
	return kp, nil
}

type SniffingConfig struct {
	Enabled      bool                  `json:"enabled"`
	DestOverride *cfgcommon.StringList `json:"destOverride"`
	MetadataOnly bool                  `json:"metadataOnly"`
}

// Build implements Buildable.
func (c *SniffingConfig) Build() (*proxyman.SniffingConfig, error) {
	var p []string
	if c.DestOverride != nil {
		for _, domainOverride := range *c.DestOverride {
			switch strings.ToLower(domainOverride) {
			case "http":
				p = append(p, "http")
			case "tls", "https", "ssl":
				p = append(p, "tls")
			case "fakedns":
				p = append(p, "fakedns")
			case "fakedns+others":
				p = append(p, "fakedns+others")
			default:
				return nil, newError("unknown protocol: ", domainOverride)
			}
		}
	}

	return &proxyman.SniffingConfig{
		Enabled:             c.Enabled,
		DestinationOverride: p,
		MetadataOnly:        c.MetadataOnly,
	}, nil
}

type MuxConfig struct {
	Enabled     bool  `json:"enabled"`
	Concurrency int16 `json:"concurrency"`
}

// Build creates MultiplexingConfig, Concurrency < 0 completely disables mux.
func (m *MuxConfig) Build() *proxyman.MultiplexingConfig {
	if m.Concurrency < 0 {
		return nil
	}

	var con uint32 = 8
	if m.Concurrency > 0 {
		con = uint32(m.Concurrency)
	}

	return &proxyman.MultiplexingConfig{
		Enabled:     m.Enabled,
		Concurrency: con,
	}
}

type InboundDetourAllocationConfig struct {
	Strategy    string  `json:"strategy"`
	Concurrency *uint32 `json:"concurrency"`
	RefreshMin  *uint32 `json:"refresh"`
}

// Build implements Buildable.
func (c *InboundDetourAllocationConfig) Build() (*proxyman.AllocationStrategy, error) {
	config := new(proxyman.AllocationStrategy)
	switch strings.ToLower(c.Strategy) {
	case "always":
		config.Type = proxyman.AllocationStrategy_Always
	case "random":
		config.Type = proxyman.AllocationStrategy_Random
	case "external":
		config.Type = proxyman.AllocationStrategy_External
	default:
		return nil, newError("unknown allocation strategy: ", c.Strategy)
	}
	if c.Concurrency != nil {
		config.Concurrency = &proxyman.AllocationStrategy_AllocationStrategyConcurrency{
			Value: *c.Concurrency,
		}
	}

	if c.RefreshMin != nil {
		config.Refresh = &proxyman.AllocationStrategy_AllocationStrategyRefresh{
			Value: *c.RefreshMin,
		}
	}

	return config, nil
}

type InboundDetourConfig struct {
	Protocol       string                         `json:"protocol"`
	PortRange      *cfgcommon.PortRange           `json:"port"`
	ListenOn       *cfgcommon.Address             `json:"listen"`
	Settings       *json.RawMessage               `json:"settings"`
	Tag            string                         `json:"tag"`
	Allocation     *InboundDetourAllocationConfig `json:"allocate"`
	StreamSetting  *StreamConfig                  `json:"streamSettings"`
	DomainOverride *cfgcommon.StringList          `json:"domainOverride"`
	SniffingConfig *SniffingConfig                `json:"sniffing"`
}

// Build implements Buildable.
func (c *InboundDetourConfig) Build() (*core.InboundHandlerConfig, error) {
	receiverSettings := &proxyman.ReceiverConfig{}

	if c.ListenOn == nil {
		// Listen on anyip, must set PortRange
		if c.PortRange == nil {
			return nil, newError("Listen on AnyIP but no Port(s) set in InboundDetour.")
		}
		receiverSettings.PortRange = c.PortRange.Build()
	} else {
		// Listen on specific IP or Unix Domain Socket
		receiverSettings.Listen = c.ListenOn.Build()
		listenDS := c.ListenOn.Family().IsDomain() && (c.ListenOn.Domain()[0] == '/' || c.ListenOn.Domain()[0] == '@')
		listenIP := c.ListenOn.Family().IsIP() || (c.ListenOn.Family().IsDomain() && c.ListenOn.Domain() == "localhost")
		switch {
		case listenIP:
			// Listen on specific IP, must set PortRange
			if c.PortRange == nil {
				return nil, newError("Listen on specific ip without port in InboundDetour.")
			}
			// Listen on IP:Port
			receiverSettings.PortRange = c.PortRange.Build()
		case listenDS:
			if c.PortRange != nil {
				// Listen on Unix Domain Socket, PortRange should be nil
				receiverSettings.PortRange = nil
			}
		default:
			return nil, newError("unable to listen on domain address: ", c.ListenOn.Domain())
		}
	}

	if c.Allocation != nil {
		concurrency := -1
		if c.Allocation.Concurrency != nil && c.Allocation.Strategy == "random" {
			concurrency = int(*c.Allocation.Concurrency)
		}
		portRange := int(c.PortRange.To - c.PortRange.From + 1)
		if concurrency >= 0 && concurrency >= portRange {
			return nil, newError("not enough ports. concurrency = ", concurrency, " ports: ", c.PortRange.From, " - ", c.PortRange.To)
		}

		as, err := c.Allocation.Build()
		if err != nil {
			return nil, err
		}
		receiverSettings.AllocationStrategy = as
	}
	if c.StreamSetting != nil {
		ss, err := c.StreamSetting.Build()
		if err != nil {
			return nil, err
		}
		receiverSettings.StreamSettings = ss
	}
	if c.SniffingConfig != nil {
		s, err := c.SniffingConfig.Build()
		if err != nil {
			return nil, newError("failed to build sniffing config").Base(err)
		}
		receiverSettings.SniffingSettings = s
	}
	if c.DomainOverride != nil {
		kp, err := toProtocolList(*c.DomainOverride)
		if err != nil {
			return nil, newError("failed to parse inbound detour config").Base(err)
		}
		receiverSettings.DomainOverride = kp
	}

	settings := []byte("{}")
	if c.Settings != nil {
		settings = ([]byte)(*c.Settings)
	}
	rawConfig, err := inboundConfigLoader.LoadWithID(settings, c.Protocol)
	if err != nil {
		return nil, newError("failed to load inbound detour config.").Base(err)
	}
	if dokodemoConfig, ok := rawConfig.(*DokodemoConfig); ok {
		receiverSettings.ReceiveOriginalDestination = dokodemoConfig.Redirect
	}
	ts, err := rawConfig.(Buildable).Build()
	if err != nil {
		return nil, err
	}

	return &core.InboundHandlerConfig{
		Tag:              c.Tag,
		ReceiverSettings: serial.ToTypedMessage(receiverSettings),
		ProxySettings:    serial.ToTypedMessage(ts),
	}, nil
}

type OutboundDetourConfig struct {
	Protocol      string             `json:"protocol"`
	SendThrough   *cfgcommon.Address `json:"sendThrough"`
	Tag           string             `json:"tag"`
	Settings      *json.RawMessage   `json:"settings"`
	StreamSetting *StreamConfig      `json:"streamSettings"`
	ProxySettings *ProxyConfig       `json:"proxySettings"`
	MuxSettings   *MuxConfig         `json:"mux"`
}

// Build implements Buildable.
func (c *OutboundDetourConfig) Build() (*core.OutboundHandlerConfig, error) {
	senderSettings := &proxyman.SenderConfig{}

	if c.SendThrough != nil {
		address := c.SendThrough
		if address.Family().IsDomain() {
			return nil, newError("unable to send through: " + address.String())
		}
		senderSettings.Via = address.Build()
	}

	if c.StreamSetting != nil {
		ss, err := c.StreamSetting.Build()
		if err != nil {
			return nil, err
		}
		senderSettings.StreamSettings = ss
	}

	if c.ProxySettings != nil {
		ps, err := c.ProxySettings.Build()
		if err != nil {
			return nil, newError("invalid outbound detour proxy settings.").Base(err)
		}
		senderSettings.ProxySettings = ps
	}

	if c.MuxSettings != nil {
		senderSettings.MultiplexSettings = c.MuxSettings.Build()
	}

	settings := []byte("{}")
	if c.Settings != nil {
		settings = ([]byte)(*c.Settings)
	}
	rawConfig, err := outboundConfigLoader.LoadWithID(settings, c.Protocol)
	if err != nil {
		return nil, newError("failed to parse to outbound detour config.").Base(err)
	}
	ts, err := rawConfig.(Buildable).Build()
	if err != nil {
		return nil, err
	}

	return &core.OutboundHandlerConfig{
		SenderSettings: serial.ToTypedMessage(senderSettings),
		Tag:            c.Tag,
		ProxySettings:  serial.ToTypedMessage(ts),
	}, nil
}

type StatsConfig struct{}

// Build implements Buildable.
func (c *StatsConfig) Build() (*stats.Config, error) {
	return &stats.Config{}, nil
}

type Config struct {
	// Port of this Point server.
	// Deprecated: Port exists for historical compatibility
	// and should not be used.
	Port uint16 `json:"port"`

	// Deprecated: InboundConfig exists for historical compatibility
	// and should not be used.
	InboundConfig *InboundDetourConfig `json:"inbound"`

	// Deprecated: OutboundConfig exists for historical compatibility
	// and should not be used.
	OutboundConfig *OutboundDetourConfig `json:"outbound"`

	// Deprecated: InboundDetours exists for historical compatibility
	// and should not be used.
	InboundDetours []InboundDetourConfig `json:"inboundDetour"`

	// Deprecated: OutboundDetours exists for historical compatibility
	// and should not be used.
	OutboundDetours []OutboundDetourConfig `json:"outboundDetour"`

	LogConfig        *LogConfig              `json:"log"`
	RouterConfig     *RouterConfig           `json:"routing"`
	DNSConfig        *DNSConfig              `json:"dns"`
	InboundConfigs   []InboundDetourConfig   `json:"inbounds"`
	OutboundConfigs  []OutboundDetourConfig  `json:"outbounds"`
	Transport        *TransportConfig        `json:"transport"`
	Policy           *PolicyConfig           `json:"policy"`
	API              *APIConfig              `json:"api"`
	Stats            *StatsConfig            `json:"stats"`
	Reverse          *ReverseConfig          `json:"reverse"`
	FakeDNS          *FakeDNSConfig          `json:"fakeDns"`
	BrowserForwarder *BrowserForwarderConfig `json:"browserForwarder"`
	Observatory      *ObservatoryConfig      `json:"observatory"`

	Services map[string]*json.RawMessage `json:"services"`
}

func (c *Config) findInboundTag(tag string) int {
	found := -1
	for idx, ib := range c.InboundConfigs {
		if ib.Tag == tag {
			found = idx
			break
		}
	}
	return found
}

func (c *Config) findOutboundTag(tag string) int {
	found := -1
	for idx, ob := range c.OutboundConfigs {
		if ob.Tag == tag {
			found = idx
			break
		}
	}
	return found
}

func applyTransportConfig(s *StreamConfig, t *TransportConfig) {
	if s.TCPSettings == nil {
		s.TCPSettings = t.TCPConfig
	}
	if s.KCPSettings == nil {
		s.KCPSettings = t.KCPConfig
	}
	if s.WSSettings == nil {
		s.WSSettings = t.WSConfig
	}
	if s.HTTPSettings == nil {
		s.HTTPSettings = t.HTTPConfig
	}
	if s.DSSettings == nil {
		s.DSSettings = t.DSConfig
	}
}

// Build implements Buildable.
func (c *Config) Build() (*core.Config, error) {
	if err := PostProcessConfigureFile(c); err != nil {
		return nil, err
	}

	config := &core.Config{
		App: []*serial.TypedMessage{
			serial.ToTypedMessage(&dispatcher.Config{}),
			serial.ToTypedMessage(&proxyman.InboundConfig{}),
			serial.ToTypedMessage(&proxyman.OutboundConfig{}),
		},
	}

	if c.API != nil {
		apiConf, err := c.API.Build()
		if err != nil {
			return nil, err
		}
		config.App = append(config.App, serial.ToTypedMessage(apiConf))
	}

	if c.Stats != nil {
		statsConf, err := c.Stats.Build()
		if err != nil {
			return nil, err
		}
		config.App = append(config.App, serial.ToTypedMessage(statsConf))
	}

	var logConfMsg *serial.TypedMessage
	if c.LogConfig != nil {
		logConfMsg = serial.ToTypedMessage(c.LogConfig.Build())
	} else {
		logConfMsg = serial.ToTypedMessage(DefaultLogConfig())
	}
	// let logger module be the first App to start,
	// so that other modules could print log during initiating
	config.App = append([]*serial.TypedMessage{logConfMsg}, config.App...)

	if c.RouterConfig != nil {
		routerConfig, err := c.RouterConfig.Build()
		if err != nil {
			return nil, err
		}
		config.App = append(config.App, serial.ToTypedMessage(routerConfig))
	}

	if c.DNSConfig != nil {
		dnsApp, err := c.DNSConfig.Build()
		if err != nil {
			return nil, newError("failed to parse DNS config").Base(err)
		}
		config.App = append(config.App, serial.ToTypedMessage(dnsApp))
	}

	if c.Policy != nil {
		pc, err := c.Policy.Build()
		if err != nil {
			return nil, err
		}
		config.App = append(config.App, serial.ToTypedMessage(pc))
	}

	if c.Reverse != nil {
		r, err := c.Reverse.Build()
		if err != nil {
			return nil, err
		}
		config.App = append(config.App, serial.ToTypedMessage(r))
	}

	if c.FakeDNS != nil {
		r, err := c.FakeDNS.Build()
		if err != nil {
			return nil, err
		}
		config.App = append(config.App, serial.ToTypedMessage(r))
	}

	if c.BrowserForwarder != nil {
		r, err := c.BrowserForwarder.Build()
		if err != nil {
			return nil, err
		}
		config.App = append(config.App, serial.ToTypedMessage(r))
	}

	if c.Observatory != nil {
		r, err := c.Observatory.Build()
		if err != nil {
			return nil, err
		}
		config.App = append(config.App, serial.ToTypedMessage(r))
	}

	// Load Additional Services that do not have a json translator

	if msg, err := c.BuildServices(c.Services); err != nil {
		developererr := newError("Loading a V2Ray Features as a service is intended for developers only. " +
			"This is used for developers to prototype new features or for an advanced client to use special features in V2Ray," +
			" instead of allowing end user to enable it without special tool and knowledge.")
		sb := strings.Builder{}
		return nil, newError("Cannot load service").Base(developererr).Base(err).Base(newError(sb.String()))
	} else { // nolint: golint
		// Using a else here is required to keep msg in scope
		config.App = append(config.App, msg...)
	}

	var inbounds []InboundDetourConfig

	if c.InboundConfig != nil {
		inbounds = append(inbounds, *c.InboundConfig)
	}

	if len(c.InboundDetours) > 0 {
		inbounds = append(inbounds, c.InboundDetours...)
	}

	if len(c.InboundConfigs) > 0 {
		inbounds = append(inbounds, c.InboundConfigs...)
	}

	// Backward compatibility.
	if len(inbounds) > 0 && inbounds[0].PortRange == nil && c.Port > 0 {
		inbounds[0].PortRange = &cfgcommon.PortRange{
			From: uint32(c.Port),
			To:   uint32(c.Port),
		}
	}

	for _, rawInboundConfig := range inbounds {
		if c.Transport != nil {
			if rawInboundConfig.StreamSetting == nil {
				rawInboundConfig.StreamSetting = &StreamConfig{}
			}
			applyTransportConfig(rawInboundConfig.StreamSetting, c.Transport)
		}
		ic, err := rawInboundConfig.Build()
		if err != nil {
			return nil, err
		}
		config.Inbound = append(config.Inbound, ic)
	}

	var outbounds []OutboundDetourConfig

	if c.OutboundConfig != nil {
		outbounds = append(outbounds, *c.OutboundConfig)
	}

	if len(c.OutboundDetours) > 0 {
		outbounds = append(outbounds, c.OutboundDetours...)
	}

	if len(c.OutboundConfigs) > 0 {
		outbounds = append(outbounds, c.OutboundConfigs...)
	}

	for _, rawOutboundConfig := range outbounds {
		if c.Transport != nil {
			if rawOutboundConfig.StreamSetting == nil {
				rawOutboundConfig.StreamSetting = &StreamConfig{}
			}
			applyTransportConfig(rawOutboundConfig.StreamSetting, c.Transport)
		}
		oc, err := rawOutboundConfig.Build()
		if err != nil {
			return nil, err
		}
		config.Outbound = append(config.Outbound, oc)
	}

	return config, nil
}