package webserver

import (
	"fmt"
	"io"
	"net/http"
	"strings"
	"time"

	"github.com/go-chi/chi/v5"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
)

// splitLines splits a newline-delimited string into non-empty trimmed lines.
func splitLines(s string) []interface{} {
	var out []interface{}
	for _, line := range strings.Split(s, "\n") {
		if v := strings.TrimSpace(line); v != "" {
			out = append(out, v)
		}
	}
	return out
}

func (ws *WebServer) registerRoutes(r chi.Router) {
	r.Handle("/static/*", http.StripPrefix("/static/", http.FileServer(http.FS(ws.staticFS))))

	r.Get("/", ws.handleRoot)
	r.HandleFunc("/init", ws.handleInit)
	r.HandleFunc("/unseal", ws.handleUnseal)
	r.HandleFunc("/login", ws.handleLogin)
	r.Get("/dashboard", ws.requireAuth(ws.handleDashboard))
	r.Post("/dashboard/mount-ca", ws.requireAuth(ws.handleDashboardMountCA))

	r.Route("/pki", func(r chi.Router) {
		r.Get("/", ws.requireAuth(ws.handlePKI))
		r.Post("/import-root", ws.requireAuth(ws.handleImportRoot))
		r.Post("/create-issuer", ws.requireAuth(ws.handleCreateIssuer))
		r.Post("/issue", ws.requireAuth(ws.handleIssueCert))
		r.Get("/issuer/{issuer}", ws.requireAuth(ws.handleIssuerDetail))
		r.Get("/{issuer}", ws.requireAuth(ws.handlePKIIssuer))
	})
}

// requireAuth validates the token cookie against the vault and injects TokenInfo.
func (ws *WebServer) requireAuth(next http.HandlerFunc) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		state, err := ws.vault.Status(r.Context())
		if err != nil || state != "unsealed" {
			http.Redirect(w, r, "/", http.StatusFound)
			return
		}
		token := extractCookie(r)
		if token == "" {
			http.Redirect(w, r, "/login", http.StatusFound)
			return
		}
		info, err := ws.vault.ValidateToken(r.Context(), token)
		if err != nil {
			http.Redirect(w, r, "/login", http.StatusFound)
			return
		}
		r = r.WithContext(withTokenInfo(r.Context(), info))
		next(w, r)
	}
}

func (ws *WebServer) handleRoot(w http.ResponseWriter, r *http.Request) {
	state, err := ws.vault.Status(r.Context())
	if err != nil {
		ws.renderTemplate(w, "unseal.html", map[string]interface{}{"Error": "Cannot reach vault"})
		return
	}
	switch state {
	case "uninitialized", "initializing":
		http.Redirect(w, r, "/init", http.StatusFound)
	case "sealed":
		http.Redirect(w, r, "/unseal", http.StatusFound)
	case "unsealed":
		http.Redirect(w, r, "/dashboard", http.StatusFound)
	default:
		http.Redirect(w, r, "/unseal", http.StatusFound)
	}
}

func (ws *WebServer) handleInit(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case http.MethodGet:
		state, _ := ws.vault.Status(r.Context())
		if state != "uninitialized" && state != "" {
			http.Redirect(w, r, "/", http.StatusFound)
			return
		}
		ws.renderTemplate(w, "init.html", nil)
	case http.MethodPost:
		r.Body = http.MaxBytesReader(w, r.Body, 1<<20)
		_ = r.ParseForm()
		password := r.FormValue("password")
		if password == "" {
			ws.renderTemplate(w, "init.html", map[string]interface{}{"Error": "Password is required"})
			return
		}
		if err := ws.vault.Init(r.Context(), password); err != nil {
			ws.renderTemplate(w, "init.html", map[string]interface{}{"Error": grpcMessage(err)})
			return
		}
		http.Redirect(w, r, "/dashboard", http.StatusFound)
	default:
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
	}
}

func (ws *WebServer) handleUnseal(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case http.MethodGet:
		state, _ := ws.vault.Status(r.Context())
		if state == "uninitialized" {
			http.Redirect(w, r, "/init", http.StatusFound)
			return
		}
		if state == "unsealed" {
			http.Redirect(w, r, "/dashboard", http.StatusFound)
			return
		}
		ws.renderTemplate(w, "unseal.html", nil)
	case http.MethodPost:
		r.Body = http.MaxBytesReader(w, r.Body, 1<<20)
		_ = r.ParseForm()
		password := r.FormValue("password")
		if err := ws.vault.Unseal(r.Context(), password); err != nil {
			msg := "Invalid password"
			if st, ok := status.FromError(err); ok && st.Code() == codes.ResourceExhausted {
				msg = "Too many attempts. Please wait 60 seconds."
			}
			ws.renderTemplate(w, "unseal.html", map[string]interface{}{"Error": msg})
			return
		}
		http.Redirect(w, r, "/dashboard", http.StatusFound)
	default:
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
	}
}

func (ws *WebServer) handleLogin(w http.ResponseWriter, r *http.Request) {
	state, _ := ws.vault.Status(r.Context())
	if state != "unsealed" {
		http.Redirect(w, r, "/", http.StatusFound)
		return
	}
	switch r.Method {
	case http.MethodGet:
		ws.renderTemplate(w, "login.html", nil)
	case http.MethodPost:
		r.Body = http.MaxBytesReader(w, r.Body, 1<<20)
		_ = r.ParseForm()
		token, err := ws.vault.Login(r.Context(),
			r.FormValue("username"),
			r.FormValue("password"),
			r.FormValue("totp_code"),
		)
		if err != nil {
			ws.renderTemplate(w, "login.html", map[string]interface{}{"Error": "Invalid credentials"})
			return
		}
		http.SetCookie(w, &http.Cookie{
			Name:     "metacrypt_token",
			Value:    token,
			Path:     "/",
			HttpOnly: true,
			Secure:   true,
			SameSite: http.SameSiteStrictMode,
		})
		http.Redirect(w, r, "/dashboard", http.StatusFound)
	default:
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
	}
}

func (ws *WebServer) handleDashboard(w http.ResponseWriter, r *http.Request) {
	info := tokenInfoFromContext(r.Context())
	token := extractCookie(r)
	mounts, _ := ws.vault.ListMounts(r.Context(), token)
	state, _ := ws.vault.Status(r.Context())
	ws.renderTemplate(w, "dashboard.html", map[string]interface{}{
		"Username": info.Username,
		"IsAdmin":  info.IsAdmin,
		"Roles":    info.Roles,
		"Mounts":   mounts,
		"State":    state,
	})
}

func (ws *WebServer) handleDashboardMountCA(w http.ResponseWriter, r *http.Request) {
	info := tokenInfoFromContext(r.Context())
	if !info.IsAdmin {
		http.Error(w, "forbidden", http.StatusForbidden)
		return
	}

	r.Body = http.MaxBytesReader(w, r.Body, 1<<20)
	if err := r.ParseMultipartForm(1 << 20); err != nil {
		r.Body = http.MaxBytesReader(w, r.Body, 1<<20)
		_ = r.ParseForm()
	}

	mountName := r.FormValue("name")
	if mountName == "" {
		ws.renderDashboardWithError(w, r, info, "Mount name is required")
		return
	}

	cfg := map[string]interface{}{}
	if org := r.FormValue("organization"); org != "" {
		cfg["organization"] = org
	}

	var certPEM, keyPEM string
	if f, _, err := r.FormFile("cert_file"); err == nil {
		defer func() { _ = f.Close() }()
		data, _ := io.ReadAll(io.LimitReader(f, 1<<20))
		certPEM = string(data)
	}
	if f, _, err := r.FormFile("key_file"); err == nil {
		defer func() { _ = f.Close() }()
		data, _ := io.ReadAll(io.LimitReader(f, 1<<20))
		keyPEM = string(data)
	}
	if certPEM != "" && keyPEM != "" {
		cfg["root_cert_pem"] = certPEM
		cfg["root_key_pem"] = keyPEM
	}

	token := extractCookie(r)
	if err := ws.vault.Mount(r.Context(), token, mountName, "ca", cfg); err != nil {
		ws.renderDashboardWithError(w, r, info, grpcMessage(err))
		return
	}
	http.Redirect(w, r, "/pki", http.StatusFound)
}

func (ws *WebServer) renderDashboardWithError(w http.ResponseWriter, r *http.Request, info *TokenInfo, errMsg string) {
	token := extractCookie(r)
	mounts, _ := ws.vault.ListMounts(r.Context(), token)
	state, _ := ws.vault.Status(r.Context())
	ws.renderTemplate(w, "dashboard.html", map[string]interface{}{
		"Username":   info.Username,
		"IsAdmin":    info.IsAdmin,
		"Roles":      info.Roles,
		"Mounts":     mounts,
		"State":      state,
		"MountError": errMsg,
	})
}

func (ws *WebServer) handlePKI(w http.ResponseWriter, r *http.Request) {
	info := tokenInfoFromContext(r.Context())
	token := extractCookie(r)

	mountName, err := ws.findCAMount(r, token)
	if err != nil {
		http.Redirect(w, r, "/dashboard", http.StatusFound)
		return
	}

	data := map[string]interface{}{
		"Username":  info.Username,
		"IsAdmin":   info.IsAdmin,
		"MountName": mountName,
	}

	if rootPEM, err := ws.vault.GetRootCert(r.Context(), mountName); err == nil && len(rootPEM) > 0 {
		if cert, err := parsePEMCert(rootPEM); err == nil {
			data["RootCN"] = cert.Subject.CommonName
			data["RootOrg"] = strings.Join(cert.Subject.Organization, ", ")
			data["RootNotBefore"] = cert.NotBefore.Format(time.RFC3339)
			data["RootNotAfter"] = cert.NotAfter.Format(time.RFC3339)
			data["RootExpired"] = time.Now().After(cert.NotAfter)
			data["HasRoot"] = true
		}
	}

	if resp, err := ws.vault.EngineRequest(r.Context(), token, mountName, "list-issuers", nil); err == nil {
		data["Issuers"] = resp["issuers"]
	}

	ws.renderTemplate(w, "pki.html", data)
}

func (ws *WebServer) handleImportRoot(w http.ResponseWriter, r *http.Request) {
	info := tokenInfoFromContext(r.Context())
	if !info.IsAdmin {
		http.Error(w, "forbidden", http.StatusForbidden)
		return
	}

	token := extractCookie(r)
	mountName, err := ws.findCAMount(r, token)
	if err != nil {
		http.Error(w, "no CA engine mounted", http.StatusNotFound)
		return
	}

	r.Body = http.MaxBytesReader(w, r.Body, 1<<20)
	if err := r.ParseMultipartForm(1 << 20); err != nil {
		r.Body = http.MaxBytesReader(w, r.Body, 1<<20)
		_ = r.ParseForm()
	}

	certPEM := r.FormValue("cert_pem")
	keyPEM := r.FormValue("key_pem")
	if certPEM == "" {
		if f, _, err := r.FormFile("cert_file"); err == nil {
			defer func() { _ = f.Close() }()
			data, _ := io.ReadAll(io.LimitReader(f, 1<<20))
			certPEM = string(data)
		}
	}
	if keyPEM == "" {
		if f, _, err := r.FormFile("key_file"); err == nil {
			defer func() { _ = f.Close() }()
			data, _ := io.ReadAll(io.LimitReader(f, 1<<20))
			keyPEM = string(data)
		}
	}

	if certPEM == "" || keyPEM == "" {
		ws.renderPKIWithError(w, r, mountName, info, "Certificate and private key are required")
		return
	}

	_, err = ws.vault.EngineRequest(r.Context(), token, mountName, "import-root", map[string]interface{}{
		"cert_pem": certPEM,
		"key_pem":  keyPEM,
	})
	if err != nil {
		ws.renderPKIWithError(w, r, mountName, info, grpcMessage(err))
		return
	}
	http.Redirect(w, r, "/pki", http.StatusFound)
}

func (ws *WebServer) handleCreateIssuer(w http.ResponseWriter, r *http.Request) {
	info := tokenInfoFromContext(r.Context())
	if !info.IsAdmin {
		http.Error(w, "forbidden", http.StatusForbidden)
		return
	}

	token := extractCookie(r)
	mountName, err := ws.findCAMount(r, token)
	if err != nil {
		http.Error(w, "no CA engine mounted", http.StatusNotFound)
		return
	}

	r.Body = http.MaxBytesReader(w, r.Body, 1<<20)
	_ = r.ParseForm()
	name := r.FormValue("name")
	if name == "" {
		ws.renderPKIWithError(w, r, mountName, info, "Issuer name is required")
		return
	}

	reqData := map[string]interface{}{"name": name}
	if v := r.FormValue("expiry"); v != "" {
		reqData["expiry"] = v
	}
	if v := r.FormValue("max_ttl"); v != "" {
		reqData["max_ttl"] = v
	}
	if v := r.FormValue("key_algorithm"); v != "" {
		reqData["key_algorithm"] = v
	}
	if v := r.FormValue("key_size"); v != "" {
		var size float64
		if _, err := fmt.Sscanf(v, "%f", &size); err == nil {
			reqData["key_size"] = size
		}
	}

	_, err = ws.vault.EngineRequest(r.Context(), token, mountName, "create-issuer", reqData)
	if err != nil {
		ws.renderPKIWithError(w, r, mountName, info, grpcMessage(err))
		return
	}
	http.Redirect(w, r, "/pki", http.StatusFound)
}

func (ws *WebServer) handlePKIIssuer(w http.ResponseWriter, r *http.Request) {
	token := extractCookie(r)
	mountName, err := ws.findCAMount(r, token)
	if err != nil {
		http.Error(w, "no CA engine mounted", http.StatusNotFound)
		return
	}

	issuerName := chi.URLParam(r, "issuer")
	certPEM, err := ws.vault.GetIssuerCert(r.Context(), mountName, issuerName)
	if err != nil {
		http.Error(w, "issuer not found", http.StatusNotFound)
		return
	}

	w.Header().Set("Content-Type", "application/x-pem-file")
	w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=%s.pem", issuerName))
	_, _ = w.Write(certPEM) //nolint:gosec
}

func (ws *WebServer) handleIssuerDetail(w http.ResponseWriter, r *http.Request) {
	info := tokenInfoFromContext(r.Context())
	token := extractCookie(r)

	mountName, err := ws.findCAMount(r, token)
	if err != nil {
		http.Error(w, "no CA engine mounted", http.StatusNotFound)
		return
	}

	issuerName := chi.URLParam(r, "issuer")

	resp, err := ws.vault.EngineRequest(r.Context(), token, mountName, "list-certs", nil)
	if err != nil {
		http.Error(w, "failed to list certificates", http.StatusInternalServerError)
		return
	}

	nameFilter := strings.ToLower(r.URL.Query().Get("name"))
	sortBy := r.URL.Query().Get("sort")
	if sortBy == "" {
		sortBy = "cn"
	}

	var certs []map[string]interface{}
	if raw, ok := resp["certs"]; ok {
		if list, ok := raw.([]interface{}); ok {
			for _, item := range list {
				if m, ok := item.(map[string]interface{}); ok {
					issuer, _ := m["issuer"].(string)
					if issuer != issuerName {
						continue
					}
					if nameFilter != "" {
						cn, _ := m["cn"].(string)
						if !strings.Contains(strings.ToLower(cn), nameFilter) {
							continue
						}
					}
					certs = append(certs, m)
				}
			}
		}
	}

	// Sort: by expiry date or by common name (default).
	if sortBy == "expiry" {
		for i := 1; i < len(certs); i++ {
			for j := i; j > 0; j-- {
				a, _ := certs[j-1]["expires_at"].(string)
				b, _ := certs[j]["expires_at"].(string)
				if a > b {
					certs[j-1], certs[j] = certs[j], certs[j-1]
				}
			}
		}
	} else {
		for i := 1; i < len(certs); i++ {
			for j := i; j > 0; j-- {
				a, _ := certs[j-1]["cn"].(string)
				b, _ := certs[j]["cn"].(string)
				if strings.ToLower(a) > strings.ToLower(b) {
					certs[j-1], certs[j] = certs[j], certs[j-1]
				}
			}
		}
	}

	data := map[string]interface{}{
		"Username":   info.Username,
		"IsAdmin":    info.IsAdmin,
		"MountName":  mountName,
		"IssuerName": issuerName,
		"Certs":      certs,
		"NameFilter": r.URL.Query().Get("name"),
		"SortBy":     sortBy,
	}

	ws.renderTemplate(w, "issuer_detail.html", data)
}

func (ws *WebServer) handleIssueCert(w http.ResponseWriter, r *http.Request) {
	info := tokenInfoFromContext(r.Context())
	token := extractCookie(r)

	mountName, err := ws.findCAMount(r, token)
	if err != nil {
		http.Error(w, "no CA engine mounted", http.StatusNotFound)
		return
	}

	r.Body = http.MaxBytesReader(w, r.Body, 1<<20)
	_ = r.ParseForm()

	commonName := r.FormValue("common_name")
	if commonName == "" {
		ws.renderPKIWithError(w, r, mountName, info, "Common name is required")
		return
	}
	issuer := r.FormValue("issuer")
	if issuer == "" {
		ws.renderPKIWithError(w, r, mountName, info, "Issuer is required")
		return
	}

	reqData := map[string]interface{}{
		"common_name": commonName,
		"issuer":      issuer,
	}
	if v := r.FormValue("profile"); v != "" {
		reqData["profile"] = v
	}
	if v := r.FormValue("ttl"); v != "" {
		reqData["ttl"] = v
	}
	if lines := splitLines(r.FormValue("dns_names")); len(lines) > 0 {
		reqData["dns_names"] = lines
	}
	if lines := splitLines(r.FormValue("ip_addresses")); len(lines) > 0 {
		reqData["ip_addresses"] = lines
	}

	resp, err := ws.vault.EngineRequest(r.Context(), token, mountName, "issue", reqData)
	if err != nil {
		ws.renderPKIWithError(w, r, mountName, info, grpcMessage(err))
		return
	}

	// Re-render the PKI page with the issued certificate displayed.
	data := map[string]interface{}{
		"Username":  info.Username,
		"IsAdmin":   info.IsAdmin,
		"MountName": mountName,
		"IssuedCert": resp,
	}
	if rootPEM, err := ws.vault.GetRootCert(r.Context(), mountName); err == nil && len(rootPEM) > 0 {
		if cert, err := parsePEMCert(rootPEM); err == nil {
			data["RootCN"] = cert.Subject.CommonName
			data["RootOrg"] = strings.Join(cert.Subject.Organization, ", ")
			data["RootNotBefore"] = cert.NotBefore.Format(time.RFC3339)
			data["RootNotAfter"] = cert.NotAfter.Format(time.RFC3339)
			data["RootExpired"] = time.Now().After(cert.NotAfter)
			data["HasRoot"] = true
		}
	}
	if issuerResp, err := ws.vault.EngineRequest(r.Context(), token, mountName, "list-issuers", nil); err == nil {
		data["Issuers"] = issuerResp["issuers"]
	}
	ws.renderTemplate(w, "pki.html", data)
}

func (ws *WebServer) renderPKIWithError(w http.ResponseWriter, r *http.Request, mountName string, info *TokenInfo, errMsg string) {
	token := extractCookie(r)
	data := map[string]interface{}{
		"Username":  info.Username,
		"IsAdmin":   info.IsAdmin,
		"MountName": mountName,
		"Error":     errMsg,
	}

	if rootPEM, err := ws.vault.GetRootCert(r.Context(), mountName); err == nil && len(rootPEM) > 0 {
		if cert, err := parsePEMCert(rootPEM); err == nil {
			data["RootCN"] = cert.Subject.CommonName
			data["RootOrg"] = strings.Join(cert.Subject.Organization, ", ")
			data["RootNotBefore"] = cert.NotBefore.Format(time.RFC3339)
			data["RootNotAfter"] = cert.NotAfter.Format(time.RFC3339)
			data["RootExpired"] = time.Now().After(cert.NotAfter)
			data["HasRoot"] = true
		}
	}
	if resp, err := ws.vault.EngineRequest(r.Context(), token, mountName, "list-issuers", nil); err == nil {
		data["Issuers"] = resp["issuers"]
	}

	ws.renderTemplate(w, "pki.html", data)
}

func (ws *WebServer) findCAMount(r *http.Request, token string) (string, error) {
	mounts, err := ws.vault.ListMounts(r.Context(), token)
	if err != nil {
		return "", err
	}
	for _, m := range mounts {
		if m.Type == "ca" {
			return m.Name, nil
		}
	}
	return "", fmt.Errorf("no CA engine mounted")
}

// grpcMessage extracts a human-readable message from a gRPC error.
func grpcMessage(err error) string {
	if st, ok := status.FromError(err); ok {
		return st.Message()
	}
	return err.Error()
}