package sub

import (
	"encoding/base64"
	"fmt"
	stdhtml "html"
	"html/template"
	"net/http"
	"net/url"
	"os"
	"path/filepath"
	"regexp"
	"strings"
	"sync"
	"time"
	"unicode"

	"github.com/gin-gonic/gin"
	"github.com/nicksnyder/go-i18n/v2/i18n"
	"golang.org/x/text/language"

	"github.com/mhsanaei/3x-ui/v3/internal/logger"
	"github.com/mhsanaei/3x-ui/v3/internal/web/service"
)

// writeSubError translates a service-layer result into an HTTP response.
// A nil error with no rows means the subId doesn't match anything (deleted
// client, never-existed id) and becomes 404. A real error becomes 500. No
// body — VPN clients only look at the status.
func writeSubError(c *gin.Context, err error) {
	if err == nil {
		c.Status(http.StatusNotFound)
		return
	}
	c.Status(http.StatusInternalServerError)
}

// cachedSubTemplate holds a parsed custom subscription template together with
// the modification time of the file it was parsed from, so the cache can be
// invalidated when an admin edits the template on disk.
type cachedSubTemplate struct {
	tmpl    *template.Template
	modTime time.Time
}

// SUBController handles HTTP requests for subscription links and JSON configurations.
type SUBController struct {
	subTitle         string
	subSupportUrl    string
	subProfileUrl    string
	subAnnounce      string
	subEnableRouting bool
	subRoutingRules  string
	subHideSettings  bool

	subIncyEnableRouting bool
	subIncyRoutingRules  string

	subPath            string
	subJsonPath        string
	subClashPath       string
	subClashAutoDetect bool
	clashUserAgent     *regexp.Regexp
	jsonAutoDetect     bool
	jsonUserAgent      *regexp.Regexp
	jsonAlwaysArray    bool
	jsonEnabled        bool
	clashEnabled       bool
	subEncrypt         bool
	updateInterval     string

	subService      *SubService
	subJsonService  *SubJsonService
	subClashService *SubClashService
	clientService   service.ClientService
	settingService  service.SettingService

	subTemplateMu    sync.RWMutex
	subTemplateCache map[string]*cachedSubTemplate
}

type subControllerConfig struct {
	subPath      string
	subJsonPath  string
	subClashPath string

	subClashAutoDetect     bool
	subClashUserAgentRegex string
	subJsonAutoDetect      bool
	subJsonUserAgentRegex  string
	subJsonAlwaysArray     bool
	subJsonEnabled         bool
	subClashEnabled        bool

	subEncrypt     bool
	remarkTemplate string
	updateInterval string

	subJsonMux            string
	subJsonRules          string
	subJsonFinalMask      string
	subClashEnableRouting bool
	subClashRules         string

	subTitle         string
	subSupportURL    string
	subProfileURL    string
	subAnnounce      string
	subEnableRouting bool
	subRoutingRules  string
	subHideSettings  bool

	subIncyEnableRouting bool
	subIncyRoutingRules  string
}

type SUBControllerOption func(*subControllerConfig)

func WithSUBPath(value string) SUBControllerOption {
	return func(config *subControllerConfig) { config.subPath = value }
}

func WithSUBJsonPath(value string) SUBControllerOption {
	return func(config *subControllerConfig) { config.subJsonPath = value }
}

func WithSUBClashPath(value string) SUBControllerOption {
	return func(config *subControllerConfig) { config.subClashPath = value }
}

func WithSUBClashAutoDetect(value bool) SUBControllerOption {
	return func(config *subControllerConfig) { config.subClashAutoDetect = value }
}

func WithSUBClashUserAgentRegex(value string) SUBControllerOption {
	return func(config *subControllerConfig) { config.subClashUserAgentRegex = value }
}

func WithSUBJsonAutoDetect(value bool) SUBControllerOption {
	return func(config *subControllerConfig) { config.subJsonAutoDetect = value }
}

func WithSUBJsonUserAgentRegex(value string) SUBControllerOption {
	return func(config *subControllerConfig) { config.subJsonUserAgentRegex = value }
}

func WithSUBJsonAlwaysArray(value bool) SUBControllerOption {
	return func(config *subControllerConfig) { config.subJsonAlwaysArray = value }
}

func WithSUBJsonEnabled(value bool) SUBControllerOption {
	return func(config *subControllerConfig) { config.subJsonEnabled = value }
}

func WithSUBClashEnabled(value bool) SUBControllerOption {
	return func(config *subControllerConfig) { config.subClashEnabled = value }
}

func WithSUBEncryption(value bool) SUBControllerOption {
	return func(config *subControllerConfig) { config.subEncrypt = value }
}

func WithSUBRemarkTemplate(value string) SUBControllerOption {
	return func(config *subControllerConfig) { config.remarkTemplate = value }
}

func WithSUBUpdateInterval(value string) SUBControllerOption {
	return func(config *subControllerConfig) { config.updateInterval = value }
}

func WithSUBJsonMux(value string) SUBControllerOption {
	return func(config *subControllerConfig) { config.subJsonMux = value }
}

func WithSUBJsonRules(value string) SUBControllerOption {
	return func(config *subControllerConfig) { config.subJsonRules = value }
}

func WithSUBJsonFinalMask(value string) SUBControllerOption {
	return func(config *subControllerConfig) { config.subJsonFinalMask = value }
}

func WithSUBClashEnableRouting(value bool) SUBControllerOption {
	return func(config *subControllerConfig) { config.subClashEnableRouting = value }
}

func WithSUBClashRules(value string) SUBControllerOption {
	return func(config *subControllerConfig) { config.subClashRules = value }
}

func WithSUBTitle(value string) SUBControllerOption {
	return func(config *subControllerConfig) { config.subTitle = value }
}

func WithSUBSupportURL(value string) SUBControllerOption {
	return func(config *subControllerConfig) { config.subSupportURL = value }
}

func WithSUBProfileURL(value string) SUBControllerOption {
	return func(config *subControllerConfig) { config.subProfileURL = value }
}

func WithSUBAnnounce(value string) SUBControllerOption {
	return func(config *subControllerConfig) { config.subAnnounce = value }
}

func WithSUBEnableRouting(value bool) SUBControllerOption {
	return func(config *subControllerConfig) { config.subEnableRouting = value }
}

func WithSUBRoutingRules(value string) SUBControllerOption {
	return func(config *subControllerConfig) { config.subRoutingRules = value }
}

func WithSUBHideSettings(value bool) SUBControllerOption {
	return func(config *subControllerConfig) { config.subHideSettings = value }
}

func WithSUBIncyEnableRouting(value bool) SUBControllerOption {
	return func(config *subControllerConfig) { config.subIncyEnableRouting = value }
}

func WithSUBIncyRoutingRules(value string) SUBControllerOption {
	return func(config *subControllerConfig) { config.subIncyRoutingRules = value }
}

func defaultSUBControllerConfig() subControllerConfig {
	return subControllerConfig{
		subPath:        "/sub/",
		subJsonPath:    "/json/",
		subClashPath:   "/clash/",
		subEncrypt:     true,
		remarkTemplate: service.DefaultRemarkTemplate,
		updateInterval: "12",
	}
}

// NewSUBController creates a new subscription controller with the given configuration.
func NewSUBController(g *gin.RouterGroup, options ...SUBControllerOption) *SUBController {
	config := defaultSUBControllerConfig()
	for _, option := range options {
		option(&config)
	}

	sub := NewSubService(config.remarkTemplate)
	a := &SUBController{
		subTitle:         config.subTitle,
		subSupportUrl:    config.subSupportURL,
		subProfileUrl:    config.subProfileURL,
		subAnnounce:      config.subAnnounce,
		subEnableRouting: config.subEnableRouting,
		subRoutingRules:  config.subRoutingRules,
		subHideSettings:  config.subHideSettings,

		subIncyEnableRouting: config.subIncyEnableRouting,
		subIncyRoutingRules:  config.subIncyRoutingRules,

		subPath:            config.subPath,
		subJsonPath:        config.subJsonPath,
		subClashPath:       config.subClashPath,
		subClashAutoDetect: config.subClashAutoDetect,
		clashUserAgent:     compileUserAgentRegex("Clash/Mihomo", config.subClashUserAgentRegex, service.DefaultSubClashUserAgentRegex),
		jsonAutoDetect:     config.subJsonAutoDetect,
		jsonUserAgent:      compileUserAgentRegex("Xray JSON", config.subJsonUserAgentRegex, service.DefaultSubJsonUserAgentRegex),
		jsonAlwaysArray:    config.subJsonAlwaysArray,
		jsonEnabled:        config.subJsonEnabled,
		clashEnabled:       config.subClashEnabled,
		subEncrypt:         config.subEncrypt,
		updateInterval:     config.updateInterval,

		subService:      sub,
		subJsonService:  NewSubJsonService(config.subJsonMux, config.subJsonRules, config.subJsonFinalMask, sub),
		subClashService: NewSubClashService(config.subClashEnableRouting, config.subClashRules, sub),

		subTemplateCache: map[string]*cachedSubTemplate{},
	}
	a.initRouter(g)
	return a
}

// initRouter registers HTTP routes for subscription links and JSON endpoints
// on the provided router group.
func (a *SUBController) initRouter(g *gin.RouterGroup) {
	gLink := g.Group(a.subPath)
	gLink.GET(":subid", a.subs)
	gLink.HEAD(":subid", a.subs)
	if a.jsonEnabled {
		gJson := g.Group(a.subJsonPath)
		gJson.GET(":subid", a.subJsons)
		gJson.HEAD(":subid", a.subJsons)
	}
	if a.clashEnabled {
		gClash := g.Group(a.subClashPath)
		gClash.GET(":subid", a.subClashs)
		gClash.HEAD(":subid", a.subClashs)
	}
}

// maybeServeSubPage validates the subscription and renders a copy-only page.
// The full page embeds share links and must never handle browser navigation.
func (a *SUBController) maybeServeSubPage(c *gin.Context) bool {
	explicit := explicitSubPageRequest(c)
	if !explicit && !a.isBrowserSubscriptionRequest(c) {
		return false
	}
	_, ok := a.buildSubPageData(c)
	if !ok {
		return true
	}
	a.serveSubscriptionCopyPage(c)
	return true
}

func (a *SUBController) maybeServeSubInfo(c *gin.Context) bool {
	if !strings.EqualFold(c.Query("format"), "info") {
		return false
	}
	page, ok := a.buildSubPageData(c)
	if !ok {
		return true
	}
	info := a.subPageContext(page)
	delete(info, "links")
	info["emails"] = dedupeEmails(page.Emails)
	setNoCacheHeaders(c)
	c.JSON(http.StatusOK, info)
	return true
}

func (a *SUBController) buildSubPageData(c *gin.Context) (PageData, bool) {
	subId := c.Param("subid")
	_, host, _, hostHeader := a.subService.ResolveRequest(c)
	subReq := a.subService.ForRequest(host)
	subReq.subscriptionBody = false
	subs, emails, lastOnline, traffic, err := subReq.getSubs(subId)
	if err != nil || len(subs) == 0 {
		writeSubError(c, err)
		return PageData{}, false
	}
	subURL, subJsonURL, subClashURL := subReq.BuildURLs(a.subPath, a.subJsonPath, a.subClashPath, subId)
	if !a.jsonEnabled {
		subJsonURL = ""
	}
	if !a.clashEnabled {
		subClashURL = ""
	}
	basePath, exists := c.Get("base_path")
	if !exists {
		basePath = "/"
	}
	basePathStr := basePath.(string)
	metadata := a.metadataForSubRequest(func() *SubService { return subReq }, subId, "")
	page := subReq.BuildPageData(subId, hostHeader, traffic, lastOnline, subs, emails, subURL, subJsonURL, subClashURL, basePathStr, metadata.Title, metadata.SupportURL)
	page.SubAnnounce = metadata.Announce
	return page, true
}

func dedupeEmails(emails []string) []string {
	out := make([]string, 0, len(emails))
	seen := make(map[string]struct{}, len(emails))
	for _, email := range emails {
		if email == "" {
			continue
		}
		if _, dup := seen[email]; dup {
			continue
		}
		seen[email] = struct{}{}
		out = append(out, email)
	}
	return out
}

// subs handles HTTP requests for subscription links, returning either HTML page or base64-encoded subscription data.
func (a *SUBController) subs(c *gin.Context) {
	userAgent := c.GetHeader("User-Agent")
	if a.maybeServeSubInfo(c) {
		logSubscriptionRoute(userAgent, "info")
		return
	}
	if a.maybeServeSubPage(c) {
		logSubscriptionRoute(userAgent, "html")
		return
	}
	if !a.enforceHwid(c) {
		return
	}
	if shouldAutoServeClash(a.subClashAutoDetect, a.clashEnabled, false, userAgent, a.clashUserAgent) && a.serveClashBody(c, false) {
		a.recordSubscriptionFetch(c)
		logSubscriptionRoute(userAgent, "clash")
		return
	}
	if shouldAutoServeJson(a.jsonAutoDetect, a.jsonEnabled, false, userAgent, a.jsonUserAgent) && a.serveJsonBody(c, true, "application/json; charset=utf-8", false) {
		a.recordSubscriptionFetch(c)
		logSubscriptionRoute(userAgent, "json")
		return
	}
	logSubscriptionRoute(userAgent, "raw")
	subId := c.Param("subid")
	scheme, host, hostWithPort, _ := a.subService.ResolveRequest(c)
	subReq := a.subService.ForRequest(host)
	subReq.subscriptionBody = true
	subs, _, _, traffic, err := subReq.getSubs(subId)
	if err != nil || len(subs) == 0 {
		writeSubError(c, err)
	} else {
		var result strings.Builder
		for _, sub := range subs {
			result.WriteString(sub)
			result.WriteString("\n")
		}

		// Add headers
		header := fmt.Sprintf("upload=%d; download=%d; total=%d; expire=%d", traffic.Up, traffic.Down, traffic.Total, traffic.ExpiryTime/1000)
		profileURL := fmt.Sprintf("%s://%s%s", scheme, hostWithPort, c.Request.RequestURI)
		metadata := a.metadataForSubRequest(func() *SubService { return subReq }, subId, profileURL)
		a.ApplyCommonHeaders(c, header, a.updateInterval, metadata.Title, metadata.SupportURL, metadata.ProfileURL, metadata.Announce, a.subEnableRouting, a.subRoutingRules, a.subHideSettings)

		if a.subIncyEnableRouting && a.subIncyRoutingRules != "" {
			result.WriteString(a.subIncyRoutingRules)
			result.WriteString("\n")
		}

		if a.subEncrypt {
			c.String(200, base64.StdEncoding.EncodeToString([]byte(result.String())))
		} else {
			c.String(200, result.String())
		}
		a.recordSubscriptionFetch(c)
	}
}

func (a *SUBController) recordSubscriptionFetch(c *gin.Context) {
	if c.Request == nil || c.Request.Method != http.MethodGet || c.Writer.Status() != http.StatusOK {
		return
	}
	if err := a.subService.RecordSubscriptionFetch(c.Param("subid")); err != nil {
		logger.Warning("Failed to record subscription fetch:", err)
	}
}

func shouldAutoServeClash(autoDetect, clashEnabled, wantsHTML bool, userAgent string, userAgentRegex *regexp.Regexp) bool {
	return shouldAutoServeFormat(autoDetect, clashEnabled, wantsHTML, userAgent, userAgentRegex)
}

func shouldAutoServeJson(autoDetect, jsonEnabled, wantsHTML bool, userAgent string, userAgentRegex *regexp.Regexp) bool {
	return shouldAutoServeFormat(autoDetect, jsonEnabled, wantsHTML, userAgent, userAgentRegex)
}

func shouldAutoServeFormat(autoDetect, formatEnabled, wantsHTML bool, userAgent string, userAgentRegex *regexp.Regexp) bool {
	if !autoDetect || !formatEnabled || wantsHTML || userAgentRegex == nil {
		return false
	}
	return userAgentRegex.MatchString(userAgent)
}

func logSubscriptionRoute(userAgent, branch string) {
	logger.Debugf("Subscription request routed: branch=%s user_agent=%q", branch, sanitizeUserAgentForLog(userAgent))
}

func sanitizeUserAgentForLog(userAgent string) string {
	clean := strings.Map(func(r rune) rune {
		if unicode.IsControl(r) {
			return ' '
		}
		return r
	}, userAgent)
	runes := []rune(clean)
	if len(runes) > 512 {
		return string(runes[:512])
	}
	return clean
}

func compileUserAgentRegex(name, pattern, defaultPattern string) *regexp.Regexp {
	pattern = strings.TrimSpace(pattern)
	if pattern == "" {
		pattern = strings.TrimSpace(defaultPattern)
	}
	if pattern == "" {
		return nil
	}
	compiled, err := regexp.Compile(pattern)
	if err == nil {
		return compiled
	}
	logger.Warningf("Invalid %s User-Agent regex %q; falling back to default %q: %v", name, pattern, defaultPattern, err)
	if strings.TrimSpace(defaultPattern) == "" {
		return nil
	}
	return regexp.MustCompile(defaultPattern)
}

// explicitSubPageRequest reports whether the caller explicitly asked for HTML.
func explicitSubPageRequest(c *gin.Context) bool {
	return c.Query("html") == "1" || strings.EqualFold(c.Query("view"), "html")
}

func (a *SUBController) isBrowserSubscriptionRequest(c *gin.Context) bool {
	accept := strings.ToLower(c.GetHeader("Accept"))
	if strings.Contains(accept, "text/html") {
		return true
	}

	fetchDest := strings.ToLower(c.GetHeader("Sec-Fetch-Dest"))
	fetchMode := strings.ToLower(c.GetHeader("Sec-Fetch-Mode"))
	if fetchDest == "document" || fetchMode == "navigate" {
		return true
	}

	rawUA := c.GetHeader("User-Agent")
	ua := strings.ToLower(rawUA)
	if rawUA == "" {
		return false
	}
	if shouldAutoServeClash(a.subClashAutoDetect, a.clashEnabled, false, rawUA, a.clashUserAgent) ||
		shouldAutoServeJson(a.jsonAutoDetect, a.jsonEnabled, false, rawUA, a.jsonUserAgent) {
		return false
	}
	if strings.Contains(ua, "mozilla/") {
		vpnClients := []string{
			"clash", "mihomo", "sing-box", "v2ray", "xray", "hiddify",
			"nekobox", "shadowrocket", "streisand", "v2box", "incy", "happ",
		}
		for _, client := range vpnClients {
			if strings.Contains(ua, client) {
				return false
			}
		}
		return true
	}
	return false
}

func (a *SUBController) serveSubscriptionCopyPage(c *gin.Context) {
	setNoCacheHeaders(c)
	title := localizeRequest(c, "subCopyPageTitle")
	heading := localizeRequest(c, "subCopyPageHeading")
	instructions := localizeRequest(c, "subCopyPageInstructions")
	lang := requestLanguage(c)
	page := `<!doctype html>
<html lang="{{LANG}}">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <meta name="robots" content="noindex,nofollow">
  <title>{{TITLE}}</title>
  <style>
    html, body { margin: 0; min-height: 100%; background: #050505; color: #f2f2f2; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif; }
    body { min-height: 100vh; display: flex; align-items: center; justify-content: center; text-align: center; }
    main { max-width: 520px; padding: 32px; }
    h1 { margin: 0 0 14px; font-size: 24px; font-weight: 650; letter-spacing: -0.02em; }
    p { margin: 0; color: #b8b8b8; font-size: 16px; line-height: 1.55; }
  </style>
</head>
<body>
  <main>
    <h1>{{HEADING}}</h1>
    <p>{{INSTRUCTIONS}}</p>
  </main>
</body>
</html>`
	page = strings.NewReplacer(
		"{{LANG}}", stdhtml.EscapeString(lang),
		"{{TITLE}}", stdhtml.EscapeString(title),
		"{{HEADING}}", stdhtml.EscapeString(heading),
		"{{INSTRUCTIONS}}", stdhtml.EscapeString(instructions),
	).Replace(page)
	c.Data(http.StatusOK, "text/html; charset=utf-8", []byte(page))
}

func localizeRequest(c *gin.Context, key string) string {
	if value, ok := c.Get("localizer"); ok {
		if localizer, ok := value.(*i18n.Localizer); ok {
			if msg, err := localizer.Localize(&i18n.LocalizeConfig{MessageID: key}); err == nil {
				return msg
			}
		}
	}
	fallbacks := map[string]string{
		"subCopyPageTitle":        "Subscription link",
		"subCopyPageHeading":      "This is a subscription link",
		"subCopyPageInstructions": "You do not need to open it in a browser. Copy this page address and paste it into the app.",
	}
	return fallbacks[key]
}

func requestLanguage(c *gin.Context) string {
	tag, _, _ := language.ParseAcceptLanguage(c.GetHeader("Accept-Language"))
	if len(tag) == 0 {
		return "en-US"
	}
	return tag[0].String()
}

// subPageContext builds the shared view-model map: the template context for
// custom sub themes, the window.__SUB_PAGE_DATA__ payload the SPA reads, and
// (without links) the ?format=info JSON body. The panel's "Calendar Type"
// setting decides whether dates render Gregorian or Jalali — surfaced here so
// consumers match the rest of the panel without a round-trip.
func (a *SUBController) subPageContext(page PageData) map[string]any {
	datepicker, _ := a.settingService.GetDatepicker()
	if datepicker == "" {
		datepicker = "gregorian"
	}

	return map[string]any{
		"sId":           page.SId,
		"enabled":       page.Enabled,
		"isOnline":      page.IsOnline,
		"download":      page.Download,
		"upload":        page.Upload,
		"total":         page.Total,
		"used":          page.Used,
		"remained":      page.Remained,
		"expire":        page.Expire,
		"lastOnline":    page.LastOnline,
		"downloadByte":  page.DownloadByte,
		"uploadByte":    page.UploadByte,
		"totalByte":     page.TotalByte,
		"subUrl":        page.SubUrl,
		"subJsonUrl":    page.SubJsonUrl,
		"subClashUrl":   page.SubClashUrl,
		"subTitle":      page.SubTitle,
		"subSupportUrl": page.SubSupportUrl,
		"links":         page.Result,
		"emails":        page.Emails,
		"datepicker":    datepicker,
		"announce":      page.SubAnnounce,
	}
}

func (a *SUBController) enforceHwid(c *gin.Context) bool {
	result, err := a.clientService.EnforceHwidForSubID(c.Param("subid"), service.HwidRequest{
		Hwid:        c.GetHeader("X-HWID"),
		UserAgent:   c.GetHeader("User-Agent"),
		DeviceOS:    c.GetHeader("X-Device-OS"),
		OsVersion:   c.GetHeader("X-Ver-OS"),
		DeviceModel: c.GetHeader("X-Device-Model"),
	})
	if err != nil {
		writeSubError(c, err)
		return false
	}
	applyHwidHeaders(c, result)
	if !result.Allowed {
		c.Status(http.StatusNotFound)
		return false
	}
	return true
}

func applyHwidHeaders(c *gin.Context, result service.HwidGateResult) {
	if result.Active {
		c.Header("X-Hwid-Active", "true")
	}
	if result.NotSupported {
		c.Header("X-Hwid-Not-Supported", "true")
	}
	if result.LimitReached {
		c.Header("X-Hwid-Limit", "true")
	}
	if result.MaxDevicesReached {
		c.Header("X-Hwid-Max-Devices-Reached", "true")
	}
}

// setNoCacheHeaders marks a subscription page response as non-cacheable so VPN
// clients and browsers always fetch fresh traffic/expiry data.
func setNoCacheHeaders(c *gin.Context) {
	c.Header("Cache-Control", "no-cache, no-store, must-revalidate")
	c.Header("Pragma", "no-cache")
	c.Header("Expires", "0")
}

// loadSubTemplate returns the parsed custom subscription template located in
// themeDir, preferring sub.html over index.html. Parsed templates are cached and
// only re-parsed when the underlying file's modification time changes, so admin
// edits are picked up without paying a disk read + HTML parse on every request.
//
// It returns (nil, nil) when themeDir is not a usable directory or contains no
// template file — the caller should fall back to the default page. A non-nil
// error means a template file exists but failed to parse.
func (a *SUBController) loadSubTemplate(themeDir string) (*template.Template, error) {
	info, err := os.Stat(themeDir)
	if err != nil || !info.IsDir() {
		return nil, nil
	}

	templatePath := filepath.Join(themeDir, "index.html")
	if _, err := os.Stat(filepath.Join(themeDir, "sub.html")); err == nil {
		templatePath = filepath.Join(themeDir, "sub.html")
	}

	fi, err := os.Stat(templatePath)
	if err != nil {
		return nil, nil
	}
	modTime := fi.ModTime()

	a.subTemplateMu.RLock()
	cached := a.subTemplateCache[templatePath]
	a.subTemplateMu.RUnlock()
	if cached != nil && cached.modTime.Equal(modTime) {
		return cached.tmpl, nil
	}

	tmpl, err := template.ParseFiles(templatePath)
	if err != nil {
		return nil, err
	}

	a.subTemplateMu.Lock()
	a.subTemplateCache[templatePath] = &cachedSubTemplate{tmpl: tmpl, modTime: modTime}
	a.subTemplateMu.Unlock()
	return tmpl, nil
}

// subJsons handles HTTP requests for JSON subscription configurations.
func (a *SUBController) subJsons(c *gin.Context) {
	if strings.EqualFold(c.Query("view"), "raw") {
		if !a.serveJsonBody(c, a.jsonAlwaysArray, "application/json; charset=utf-8", true) {
			writeSubError(c, nil)
		}
		a.recordSubscriptionFetch(c)
		return
	}
	if a.maybeServeSubPage(c) {
		return
	}
	if !a.enforceHwid(c) {
		return
	}
	a.serveJson(c, a.jsonAlwaysArray, "text/plain; charset=utf-8")
}

func (a *SUBController) serveJson(c *gin.Context, alwaysReturnArray bool, contentType string) {
	if !a.serveJsonBody(c, alwaysReturnArray, contentType, false) {
		writeSubError(c, nil)
	}
	a.recordSubscriptionFetch(c)
}

func (a *SUBController) serveJsonBody(c *gin.Context, alwaysReturnArray bool, contentType string, rawDownload bool) bool {
	subId := c.Param("subid")
	scheme, host, hostWithPort, _ := a.subService.ResolveRequest(c)
	jsonSub, header, err := a.subJsonService.GetJson(subId, host, alwaysReturnArray)
	if err != nil {
		writeSubError(c, err)
		return true
	}
	if len(jsonSub) == 0 {
		return false
	}
	profileURL := fmt.Sprintf("%s://%s%s", scheme, hostWithPort, c.Request.RequestURI)
	var subReq *SubService
	metadata := a.metadataForSubRequest(func() *SubService {
		if subReq == nil {
			subReq = a.subService.ForRequest(host)
		}
		return subReq
	}, subId, profileURL)
	a.ApplyCommonHeaders(c, header, a.updateInterval, metadata.Title, metadata.SupportURL, metadata.ProfileURL, metadata.Announce, a.subEnableRouting, a.subRoutingRules, a.subHideSettings)
	if rawDownload {
		c.Writer.Header().Set("Content-Disposition", `attachment; filename="subscription.json"`)
	}

	c.Data(200, contentType, []byte(jsonSub))
	return true
}

func (a *SUBController) subClashs(c *gin.Context) {
	if strings.EqualFold(c.Query("view"), "raw") {
		if !a.serveClashBody(c, true) {
			writeSubError(c, nil)
		}
		a.recordSubscriptionFetch(c)
		return
	}
	if a.maybeServeSubPage(c) {
		return
	}
	if !a.enforceHwid(c) {
		return
	}
	if !a.serveClashBody(c, false) {
		writeSubError(c, nil)
	}
	a.recordSubscriptionFetch(c)
}

func (a *SUBController) serveClashBody(c *gin.Context, rawDownload bool) bool {
	subId := c.Param("subid")
	scheme, host, hostWithPort, _ := a.subService.ResolveRequest(c)
	clashSub, header, err := a.subClashService.GetClash(subId, host)
	if err != nil {
		writeSubError(c, err)
		return true
	}
	if len(clashSub) == 0 {
		return false
	}
	profileURL := fmt.Sprintf("%s://%s%s", scheme, hostWithPort, c.Request.RequestURI)
	var subReq *SubService
	metadata := a.metadataForSubRequest(func() *SubService {
		if subReq == nil {
			subReq = a.subService.ForRequest(host)
		}
		return subReq
	}, subId, profileURL)
	a.ApplyCommonHeaders(c, header, a.updateInterval, metadata.Title, metadata.SupportURL, metadata.ProfileURL, metadata.Announce, a.subEnableRouting, a.subRoutingRules, a.subHideSettings)
	if rawDownload {
		c.Writer.Header().Set("Content-Disposition", `attachment; filename="subscription.yaml"`)
	} else if metadata.Title != "" {
		// Clash clients commonly use Content-Disposition to choose the imported profile name.
		c.Writer.Header().Set("Content-Disposition", fmt.Sprintf(`attachment; filename*=UTF-8''%s`, url.PathEscape(metadata.Title)))
	}
	c.Data(200, "application/yaml; charset=utf-8", []byte(clashSub))
	return true
}

// ApplyCommonHeaders sets common HTTP headers for subscription responses including user info, update interval, and profile title.
func (a *SUBController) ApplyCommonHeaders(
	c *gin.Context,
	header,
	updateInterval,
	profileTitle string,
	profileSupportUrl string,
	profileUrl string,
	profileAnnounce string,
	profileEnableRouting bool,
	profileRoutingRules string,
	profileHideSettings bool,
) {
	c.Writer.Header().Set("Subscription-Userinfo", header)
	c.Writer.Header().Set("Profile-Update-Interval", updateInterval)

	// Basics
	if profileTitle != "" {
		c.Writer.Header().Set("Profile-Title", "base64:"+base64.StdEncoding.EncodeToString([]byte(profileTitle)))
	}
	if profileSupportUrl != "" {
		c.Writer.Header().Set("Support-Url", profileSupportUrl)
	}
	if profileUrl != "" {
		c.Writer.Header().Set("Profile-Web-Page-Url", profileUrl)
	}
	if profileAnnounce != "" {
		c.Writer.Header().Set("Announce", "base64:"+base64.StdEncoding.EncodeToString([]byte(profileAnnounce)))
	}

	// Advanced (Happ)
	if profileEnableRouting {
		c.Writer.Header().Set("Routing-Enable", "true")
	}
	if profileRoutingRules != "" {
		c.Writer.Header().Set("Routing", profileRoutingRules)
	}
	if profileHideSettings {
		c.Writer.Header().Set("Hide-Settings", "1")
	}
}