package service

import (
	"encoding/json"
	"errors"
	"path/filepath"
	"runtime"
	"strings"
	"sync"

	"github.com/mhsanaei/3x-ui/v3/internal/config"
	"github.com/mhsanaei/3x-ui/v3/internal/database/model"
	"github.com/mhsanaei/3x-ui/v3/internal/logger"
	"github.com/mhsanaei/3x-ui/v3/internal/util/json_util"
	"github.com/mhsanaei/3x-ui/v3/internal/xray"

	"go.uber.org/atomic"
)

var (
	p                 *xray.Process
	lock              sync.Mutex
	isNeedXrayRestart atomic.Bool // Indicates that restart was requested for Xray
	isManuallyStopped atomic.Bool // Indicates that Xray was stopped manually from the panel
	result            string
)

// XrayService provides business logic for Xray process management.
// It handles starting, stopping, restarting Xray, and managing its configuration.
type XrayService struct {
	inboundService InboundService
	settingService SettingService
	xrayAPI        xray.XrayAPI
}

// IsXrayRunning checks if the Xray process is currently running.
func (s *XrayService) IsXrayRunning() bool {
	return p != nil && p.IsRunning()
}

// XrayProcess returns the current Xray process instance (may be nil when Xray
// is not running). It exposes the package-level process to callers outside this
// package (e.g. the tgbot subpackage) without changing access semantics.
func XrayProcess() *xray.Process {
	return p
}

// GetXrayErr returns the error from the Xray process, if any.
func (s *XrayService) GetXrayErr() error {
	if p == nil {
		return nil
	}

	err := p.GetErr()
	if err == nil {
		return nil
	}

	if runtime.GOOS == "windows" && err.Error() == "exit status 1" {
		// exit status 1 on Windows means that Xray process was killed
		// as we kill process to stop in on Windows, this is not an error
		return nil
	}

	return err
}

// GetXrayResult returns the result string from the Xray process.
func (s *XrayService) GetXrayResult() string {
	if result != "" {
		return result
	}
	if s.IsXrayRunning() {
		return ""
	}
	if p == nil {
		return ""
	}

	result = p.GetResult()

	if runtime.GOOS == "windows" && result == "exit status 1" {
		// exit status 1 on Windows means that Xray process was killed
		// as we kill process to stop in on Windows, this is not an error
		return ""
	}

	return result
}

// GetXrayVersion returns the version of the running Xray process.
func (s *XrayService) GetXrayVersion() string {
	if p == nil {
		return "Unknown"
	}
	return p.GetVersion()
}

// RemoveIndex removes an element at the specified index from a slice.
// Returns a new slice with the element removed.
func RemoveIndex(s []any, index int) []any {
	return append(s[:index], s[index+1:]...)
}

// GetXrayConfig retrieves and builds the Xray configuration from settings and inbounds.
func (s *XrayService) GetXrayConfig() (*xray.Config, error) {
	templateConfig, err := s.settingService.GetXrayConfigTemplate()
	if err != nil {
		return nil, err
	}

	xrayConfig := &xray.Config{}
	err = json.Unmarshal([]byte(templateConfig), xrayConfig)
	if err != nil {
		return nil, err
	}
	xrayConfig.LogConfig = resolveXrayLogPaths(xrayConfig.LogConfig)
	xrayConfig.API = ensureAPIServices(xrayConfig.API)

	_, _, _ = s.inboundService.AddTraffic(nil, nil)

	inbounds, err := s.inboundService.GetAllInbounds()
	if err != nil {
		return nil, err
	}
	for _, inbound := range inbounds {
		if !inbound.Enable {
			continue
		}
		if inbound.NodeID != nil {
			continue
		}
		if inbound.Protocol == model.MTProto {
			continue
		}
		settings := map[string]any{}
		json.Unmarshal([]byte(inbound.Settings), &settings)

		dbClients, listErr := s.inboundService.clientService.ListForInbound(nil, inbound.Id)
		if listErr != nil {
			return nil, listErr
		}

		clientStats := inbound.ClientStats
		enableMap := make(map[string]bool, len(clientStats))
		for _, clientTraffic := range clientStats {
			enableMap[clientTraffic.Email] = clientTraffic.Enable
		}

		var finalClients []any
		for i := range dbClients {
			c := dbClients[i]
			if enable, exists := enableMap[c.Email]; exists && !enable {
				logger.Infof("Remove Inbound User %s due to expiration or traffic limit", c.Email)
				continue
			}
			if !c.Enable {
				continue
			}
			flow := c.Flow
			if flow == "xtls-rprx-vision-udp443" {
				flow = "xtls-rprx-vision"
			}
			entry := map[string]any{"email": c.Email}
			switch inbound.Protocol {
			case model.VLESS:
				if c.ID != "" {
					entry["id"] = c.ID
				}
				if flow != "" {
					entry["flow"] = flow
				}
				if c.Reverse != nil {
					entry["reverse"] = c.Reverse
				}
			case model.VMESS:
				if c.ID != "" {
					entry["id"] = c.ID
				}
				if c.Security != "" {
					entry["security"] = c.Security
				}
			case model.Trojan:
				if c.Password != "" {
					entry["password"] = c.Password
				}
				if flow != "" {
					entry["flow"] = flow
				}
			case model.Shadowsocks:
				if c.Password != "" {
					entry["password"] = c.Password
				}
			case model.Hysteria:
				if c.Auth != "" {
					entry["auth"] = c.Auth
				}
			}
			finalClients = append(finalClients, entry)
		}

		_, hadClients := settings["clients"]
		mutated := hadClients || len(finalClients) > 0
		if mutated {
			settings["clients"] = finalClients
		}

		if inboundCanHostFallbacks(inbound) {
			fallbacks, fbErr := s.inboundService.fallbackService.BuildFallbacksJSON(nil, inbound.Id)
			if fbErr != nil {
				return nil, fbErr
			}
			if len(fallbacks) > 0 {
				generic := make([]any, 0, len(fallbacks))
				for _, f := range fallbacks {
					generic = append(generic, f)
				}
				settings["fallbacks"] = generic
				mutated = true
			}
		}

		if mutated {
			modifiedSettings, err := json.MarshalIndent(settings, "", "  ")
			if err != nil {
				return nil, err
			}
			inbound.Settings = string(modifiedSettings)
		}

		if len(inbound.StreamSettings) > 0 {
			// Unmarshal stream JSON
			var stream map[string]any
			json.Unmarshal([]byte(inbound.StreamSettings), &stream)

			// Remove the "settings" field under "tlsSettings" and "realitySettings"
			tlsSettings, ok1 := stream["tlsSettings"].(map[string]any)
			realitySettings, ok2 := stream["realitySettings"].(map[string]any)
			if ok1 || ok2 {
				if ok1 {
					delete(tlsSettings, "settings")
				} else if ok2 {
					delete(realitySettings, "settings")
				}
			}

			delete(stream, "externalProxy")

			newStream, err := json.MarshalIndent(stream, "", "  ")
			if err != nil {
				return nil, err
			}
			inbound.StreamSettings = string(newStream)
		}

		if inbound.Protocol == model.Shadowsocks {
			if healed, ok := model.HealShadowsocksClientMethods(inbound.Settings); ok {
				inbound.Settings = healed
			}
		}

		inboundConfig := inbound.GenXrayInboundConfig()
		xrayConfig.InboundConfigs = append(xrayConfig.InboundConfigs, *inboundConfig)
	}

	// Merge subscription-derived outbounds (if any) into the final outbounds array.
	// These are additive: each subscription is placed before or after the template
	// outbounds based on its Prepend flag, ordered by Priority. Tags assigned by the
	// subscription service are kept stable across refreshes so that balancers and
	// routing rules continue to work.
	subSvc := &OutboundSubscriptionService{}
	if prepend, appendList, err := subSvc.activeOutboundsSplit(); err == nil && (len(prepend) > 0 || len(appendList) > 0) {
		mergeSubscriptionOutbounds(xrayConfig, prepend, appendList)
	}

	// Wire the panel's own HTTP traffic through the configured outbound, after
	// the subscription merge so subscription outbound tags are valid targets.
	if egressTag, err := s.settingService.GetPanelOutbound(); err != nil {
		logger.Warning("read panelOutbound setting failed:", err)
	} else if egressTag != "" {
		injectPanelEgress(xrayConfig, egressTag)
	}

	return xrayConfig, nil
}

// PanelEgressInboundTag is the tag of the loopback SOCKS inbound injected into
// the generated config when a panel outbound is configured. The panel's own
// HTTP clients dial through it to egress via the chosen outbound.
const PanelEgressInboundTag = "panel-egress"

// panelEgressBasePort is the first port tried for the egress bridge; ports
// already taken by other inbounds in the generated config are skipped.
const panelEgressBasePort = 62790

// injectPanelEgress appends a loopback SOCKS inbound to the generated config
// and prepends a routing rule sending it to outboundTag. Both live only in the
// generated config — the stored template is never modified — and both are
// hot-appliable, so changing the panel outbound never restarts the core.
func injectPanelEgress(cfg *xray.Config, outboundTag string) {
	for i := range cfg.InboundConfigs {
		if cfg.InboundConfigs[i].Tag == PanelEgressInboundTag {
			logger.Warning("panel egress: inbound tag [", PanelEgressInboundTag, "] already exists, skipping injection")
			return
		}
	}

	// The rule must exist before the inbound takes traffic, otherwise the
	// bridge would silently egress through the default outbound instead.
	routing := map[string]any{}
	if len(cfg.RouterConfig) > 0 {
		if err := json.Unmarshal(cfg.RouterConfig, &routing); err != nil {
			logger.Warning("panel egress: routing section is unparsable, skipping injection:", err)
			return
		}
	}
	rules, _ := routing["rules"].([]any)
	rule := map[string]any{
		"type":        "field",
		"inboundTag":  []any{PanelEgressInboundTag},
		"outboundTag": outboundTag,
	}
	routing["rules"] = append([]any{rule}, rules...)
	newRouting, err := json.Marshal(routing)
	if err != nil {
		logger.Warning("panel egress: failed to rebuild routing section, skipping injection:", err)
		return
	}
	cfg.RouterConfig = json_util.RawMessage(newRouting)

	used := make(map[int]struct{}, len(cfg.InboundConfigs))
	for i := range cfg.InboundConfigs {
		used[cfg.InboundConfigs[i].Port] = struct{}{}
	}
	port := panelEgressBasePort
	for {
		if _, taken := used[port]; !taken {
			break
		}
		port++
	}

	cfg.InboundConfigs = append(cfg.InboundConfigs, xray.InboundConfig{
		Listen:   json_util.RawMessage(`"127.0.0.1"`),
		Port:     port,
		Protocol: "socks",
		Settings: json_util.RawMessage(`{"auth":"noauth","udp":false}`),
		Tag:      PanelEgressInboundTag,
	})
}

// mergeSubscriptionOutbounds appends the subscription outbounds to the
// OutboundConfigs array of the xray config. It works on the already-unmarshaled
// template so that manually configured outbounds are never overwritten.
//
// Safety: if we cannot parse the template's outbounds array, we leave
// OutboundConfigs exactly as it came from the template (we do not inject
// subscription outbounds). This prevents us from accidentally dropping the
// user's manually configured outbounds when the template is in a weird state.
func mergeSubscriptionOutbounds(cfg *xray.Config, prepend, appendList []any) {
	if len(prepend) == 0 && len(appendList) == 0 {
		return
	}
	var templateOutbounds []any
	if len(cfg.OutboundConfigs) > 0 {
		if err := json.Unmarshal(cfg.OutboundConfigs, &templateOutbounds); err != nil {
			// Corrupt template outbounds — do not touch the field at all.
			// The user will see problems on Xray start / next save.
			return
		}
	}
	merged := make([]any, 0, len(prepend)+len(templateOutbounds)+len(appendList))
	merged = append(merged, prepend...)
	merged = append(merged, templateOutbounds...)
	merged = append(merged, appendList...)
	combined, err := json.MarshalIndent(merged, "", "  ")
	if err != nil {
		return
	}
	cfg.OutboundConfigs = json_util.RawMessage(combined)
}

// ensureAPIServices guarantees the gRPC services the panel depends on are
// listed in the generated config's api block: HandlerService and StatsService
// have always been required for inbound/user management and traffic polling,
// and RoutingService enables hot routing reload on templates saved before it
// was added to the default template. The stored template itself is not
// modified — only the generated runtime config.
func ensureAPIServices(api json_util.RawMessage) json_util.RawMessage {
	if len(api) == 0 {
		// No api block means the panel's API integration is deliberately
		// disabled; don't resurrect it behind the user's back.
		return api
	}
	var parsed map[string]any
	if err := json.Unmarshal(api, &parsed); err != nil {
		return api
	}
	services, _ := parsed["services"].([]any)
	have := make(map[string]bool, len(services))
	for _, svc := range services {
		if name, ok := svc.(string); ok {
			have[name] = true
		}
	}
	added := false
	for _, name := range []string{"HandlerService", "StatsService", "RoutingService"} {
		if !have[name] {
			services = append(services, name)
			added = true
		}
	}
	if !added {
		return api
	}
	parsed["services"] = services
	out, err := json.Marshal(parsed)
	if err != nil {
		return api
	}
	return out
}

// resolveXrayLogPaths rewrites relative `log.access` / `log.error` values to
// absolute paths under config.GetLogFolder(), so Xray writes those files
// alongside the panel's other logs regardless of the working directory the
// panel was launched from. Values that are empty, "none", or already absolute
// are left untouched, as are unparseable log blocks.
func resolveXrayLogPaths(logCfg json_util.RawMessage) json_util.RawMessage {
	if len(logCfg) == 0 {
		return logCfg
	}
	var parsed map[string]any
	if err := json.Unmarshal(logCfg, &parsed); err != nil {
		return logCfg
	}
	changed := false
	for _, key := range []string{"access", "error"} {
		v, ok := parsed[key].(string)
		if !ok {
			continue
		}
		trimmed := strings.TrimSpace(v)
		if trimmed == "" || strings.EqualFold(trimmed, "none") {
			continue
		}
		if filepath.IsAbs(trimmed) {
			continue
		}
		cleaned := filepath.ToSlash(filepath.Clean(trimmed))
		base := filepath.Base(cleaned)
		if base == "" || base == "." || base == string(filepath.Separator) {
			continue
		}
		// Only rewrite bare names ("./access.log", "access.log").
		// A nested relative path like "./logs/foo.log" is treated as
		// a deliberate user choice and left alone.
		if cleaned != base {
			continue
		}
		parsed[key] = filepath.Join(config.GetLogFolder(), base)
		changed = true
	}
	if !changed {
		return logCfg
	}
	out, err := json.Marshal(parsed)
	if err != nil {
		return logCfg
	}
	return out
}

// GetXrayTraffic fetches the current traffic statistics from the running Xray process.
func (s *XrayService) GetXrayTraffic() ([]*xray.Traffic, []*xray.ClientTraffic, error) {
	if !s.IsXrayRunning() {
		err := errors.New("xray is not running")
		logger.Debug("Attempted to fetch Xray traffic, but Xray is not running:", err)
		return nil, nil, err
	}
	apiPort := p.GetAPIPort()
	if err := s.xrayAPI.Init(apiPort); err != nil {
		logger.Debug("Failed to initialize Xray API:", err)
		return nil, nil, err
	}
	defer s.xrayAPI.Close()

	traffic, clientTraffic, err := s.xrayAPI.GetTraffic()
	if err != nil {
		logger.Debug("Failed to fetch Xray traffic:", err)
		return nil, nil, err
	}
	return traffic, clientTraffic, nil
}

// BalancerStatus is the live view of one balancer for the panel UI. Running
// is false when the balancer isn't present in the running core (e.g. xray is
// stopped or the balancer hasn't been saved/applied yet).
type BalancerStatus struct {
	Tag      string   `json:"tag"`
	Running  bool     `json:"running"`
	Override string   `json:"override"`
	Selected []string `json:"selected"`
}

// GetBalancersStatus queries the running core for the live state of the
// given balancer tags. Per-tag failures are reported as Running=false rather
// than failing the whole call, so the UI can render saved-but-not-applied
// balancers alongside live ones.
func (s *XrayService) GetBalancersStatus(tags []string) ([]BalancerStatus, error) {
	statuses := make([]BalancerStatus, 0, len(tags))
	if !s.IsXrayRunning() {
		for _, tag := range tags {
			statuses = append(statuses, BalancerStatus{Tag: tag})
		}
		return statuses, nil
	}
	if err := s.xrayAPI.Init(p.GetAPIPort()); err != nil {
		return nil, err
	}
	defer s.xrayAPI.Close()

	for _, tag := range tags {
		info, err := s.xrayAPI.GetBalancerInfo(tag)
		if err != nil {
			logger.Debug("get balancer info [", tag, "] failed:", err)
			statuses = append(statuses, BalancerStatus{Tag: tag})
			continue
		}
		statuses = append(statuses, BalancerStatus{
			Tag:      tag,
			Running:  true,
			Override: info.Override,
			Selected: info.Selected,
		})
	}
	return statuses, nil
}

// OverrideBalancer forces a balancer in the running core to use the given
// outbound tag; an empty target clears the override.
func (s *XrayService) OverrideBalancer(tag, target string) error {
	if !s.IsXrayRunning() {
		return errors.New("xray is not running")
	}
	if err := s.xrayAPI.Init(p.GetAPIPort()); err != nil {
		return err
	}
	defer s.xrayAPI.Close()
	return s.xrayAPI.SetBalancerTarget(tag, target)
}

// TestRoute asks the running core which outbound its router picks for the
// described connection.
func (s *XrayService) TestRoute(req xray.RouteTestRequest) (*xray.RouteTestResult, error) {
	if !s.IsXrayRunning() {
		return nil, errors.New("xray is not running")
	}
	if err := s.xrayAPI.Init(p.GetAPIPort()); err != nil {
		return nil, err
	}
	defer s.xrayAPI.Close()
	return s.xrayAPI.TestRoute(req)
}

// RestartXray reconciles the running Xray process with the current desired
// config. When isForce is false it first tries to apply the changes through
// the Xray gRPC API without restarting the process (inbounds, outbounds and
// routing rules/balancers are hot-reloadable); only changes the core cannot
// take at runtime — or a force request — stop and restart the process.
func (s *XrayService) RestartXray(isForce bool) error {
	lock.Lock()
	defer lock.Unlock()
	logger.Debug("restart Xray, force:", isForce)
	isManuallyStopped.Store(false)

	xrayConfig, err := s.GetXrayConfig()
	if err != nil {
		return err
	}

	if s.IsXrayRunning() {
		configUnchanged := p.GetConfig().Equals(xrayConfig)
		if !isForce && configUnchanged && !isNeedXrayRestart.Load() {
			logger.Debug("It does not need to restart Xray")
			return nil
		}
		if !isForce && !configUnchanged && s.tryHotApply(xrayConfig) {
			logger.Info("Xray config changes applied through the core API, no restart needed")
			return nil
		}
		p.Stop()
	}

	p = xray.NewProcess(xrayConfig)
	result = ""
	s.xrayAPI.StatsLastValues = nil
	err = p.Start()
	if err != nil {
		return err
	}

	return nil
}

// tryHotApply attempts to reconcile the running Xray instance with newCfg
// through the core gRPC API (HandlerService for inbounds/outbounds,
// RoutingService for rules/balancers). It returns true when the running
// instance now matches newCfg; on any failure it returns false and the
// caller falls back to a full process restart, which cleans up whatever was
// partially applied. Callers must hold the package-level lock.
func (s *XrayService) tryHotApply(newCfg *xray.Config) bool {
	oldCfg := p.GetConfig()
	diff, ok := xray.ComputeHotDiff(oldCfg, newCfg)
	if !ok {
		logger.Debug("hot apply: config change is not API-applicable, falling back to restart")
		return false
	}
	if diff.Empty() {
		p.SetConfig(newCfg)
		return true
	}

	apiPort := p.GetAPIPort()
	if apiPort <= 0 {
		return false
	}
	// A dedicated client: s.xrayAPI may be in use by traffic polling on other
	// service instances and is reset around restarts.
	hotAPI := xray.XrayAPI{}
	if err := hotAPI.Init(apiPort); err != nil {
		logger.Debug("hot apply: failed to init xray api:", err)
		return false
	}
	defer hotAPI.Close()

	// Removals first so changed handlers and port swaps never collide with
	// the additions that follow.
	for _, tag := range diff.RemovedInboundTags {
		if err := hotAPI.DelInbound(tag); err != nil && !xray.IsMissingHandlerErr(err) {
			logger.Info("hot apply: remove inbound [", tag, "] failed:", err)
			return false
		}
	}
	for _, tag := range diff.RemovedOutboundTags {
		if err := hotAPI.DelOutbound(tag); err != nil && !xray.IsMissingHandlerErr(err) {
			logger.Info("hot apply: remove outbound [", tag, "] failed:", err)
			return false
		}
	}
	for _, ob := range diff.AddedOutbounds {
		if err := addOutboundReconciling(&hotAPI, ob); err != nil {
			logger.Info("hot apply: add outbound failed:", err)
			return false
		}
	}
	for _, ib := range diff.AddedInbounds {
		if err := addInboundReconciling(&hotAPI, ib); err != nil {
			logger.Info("hot apply: add inbound failed:", err)
			return false
		}
	}
	if diff.RoutingConfig != nil {
		if err := hotAPI.ApplyRoutingConfig(diff.RoutingConfig); err != nil {
			logger.Info("hot apply: apply routing config failed:", err)
			return false
		}
	}

	p.SetConfig(newCfg)
	return true
}

// addInboundReconciling adds an inbound, and on a tag conflict (the handler
// was already created through the runtime API while the stored snapshot was
// stale) replaces the existing handler instead.
func addInboundReconciling(api *xray.XrayAPI, inbound []byte) error {
	err := api.AddInbound(inbound)
	if err == nil || !xray.IsExistingTagErr(err) {
		return err
	}
	var meta struct {
		Tag string `json:"tag"`
	}
	if jsonErr := json.Unmarshal(inbound, &meta); jsonErr != nil || meta.Tag == "" {
		return err
	}
	if delErr := api.DelInbound(meta.Tag); delErr != nil && !xray.IsMissingHandlerErr(delErr) {
		return delErr
	}
	return api.AddInbound(inbound)
}

// addOutboundReconciling mirrors addInboundReconciling for outbounds.
func addOutboundReconciling(api *xray.XrayAPI, outbound []byte) error {
	err := api.AddOutbound(outbound)
	if err == nil || !xray.IsExistingTagErr(err) {
		return err
	}
	var meta struct {
		Tag string `json:"tag"`
	}
	if jsonErr := json.Unmarshal(outbound, &meta); jsonErr != nil || meta.Tag == "" {
		return err
	}
	if delErr := api.DelOutbound(meta.Tag); delErr != nil && !xray.IsMissingHandlerErr(delErr) {
		return delErr
	}
	return api.AddOutbound(outbound)
}

// StopXray stops the running Xray process.
func (s *XrayService) StopXray() error {
	lock.Lock()
	defer lock.Unlock()
	isManuallyStopped.Store(true)
	logger.Debug("Attempting to stop Xray...")
	if s.IsXrayRunning() {
		return p.Stop()
	}
	return errors.New("xray is not running")
}

// SetToNeedRestart marks that Xray needs to be restarted.
func (s *XrayService) SetToNeedRestart() {
	isNeedXrayRestart.Store(true)
}

// GetXrayAPIPort returns the port the local xray process is listening on
// for its gRPC HandlerService, or 0 when xray isn't currently running.
// Exposed for the runtime package's LocalRuntime adapter — runtime can't
// reach into the package-level `p` directly without a service-package
// import cycle.
func (s *XrayService) GetXrayAPIPort() int {
	if p == nil || !p.IsRunning() {
		return 0
	}
	return p.GetAPIPort()
}

// IsNeedRestartAndSetFalse checks if restart is needed and resets the flag to false.
func (s *XrayService) IsNeedRestartAndSetFalse() bool {
	return isNeedXrayRestart.CompareAndSwap(true, false)
}

// DidXrayCrash checks if Xray crashed by verifying it's not running and wasn't manually stopped.
func (s *XrayService) DidXrayCrash() bool {
	return !s.IsXrayRunning() && !isManuallyStopped.Load()
}