package web

import (
	"encoding/json"
	"fmt"
	"html/template"
	"io"
	"log"
	"math"
	"net/http"
	"strconv"
	"strings"
	"time"

	"gitea.dooplex.hu/admin/felhom-hub/internal/store"
	"golang.org/x/crypto/bcrypt"
)

// Server handles the dashboard web UI.
type Server struct {
	store           *store.Store
	passwordHash    string
	apiKey          string // report API key — used for controller callbacks
	logger          *log.Logger
	templates       *template.Template
	staleThreshold  time.Duration
	versionChecker  *VersionChecker
	templateFetcher *TemplateFetcher
}

// New creates a new web server.
func New(store *store.Store, passwordHash, apiKey string, staleThreshold time.Duration, logger *log.Logger) *Server {
	funcMap := template.FuncMap{
		"timeAgo":     timeAgo,
		"statusColor": statusColor,
		"statusIcon":  statusIcon,
		"formatFloat": func(f float64) string { return fmt.Sprintf("%.0f", f) },
		"joinStrings": func(s []string, sep string) string { return strings.Join(s, sep) },
		"json": func(v interface{}) template.JS {
			b, _ := json.Marshal(v)
			return template.JS(b)
		},
	}

	tmpl := template.Must(template.New("").Funcs(funcMap).ParseFS(templateFS, "templates/*.html"))

	return &Server{
		store:          store,
		passwordHash:   passwordHash,
		apiKey:         apiKey,
		logger:         logger,
		templates:      tmpl,
		staleThreshold: staleThreshold,
	}
}

// SetVersionChecker sets the version checker (optional, may be nil if no registry credentials).
func (s *Server) SetVersionChecker(vc *VersionChecker) {
	s.versionChecker = vc
}

// SetTemplateFetcher sets the template fetcher for config generation (optional).
func (s *Server) SetTemplateFetcher(tf *TemplateFetcher) {
	s.templateFetcher = tf
}

// ServeHTTP routes web requests.
func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	path := r.URL.Path

	switch {
	case path == "/":
		s.handleDashboard(w, r)
	case path == "/style.css":
		s.handleCSS(w, r)
	case path == "/login":
		s.handleLogin(w, r)
	case strings.HasPrefix(path, "/customers/") && strings.HasSuffix(path, "/trigger-update"):
		customerID := strings.TrimPrefix(path, "/customers/")
		customerID = strings.TrimSuffix(customerID, "/trigger-update")
		if r.Method == http.MethodPost {
			s.handleTriggerUpdate(w, r, customerID)
		} else {
			http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		}
	case strings.HasPrefix(path, "/customers/") && strings.HasSuffix(path, "/block"):
		customerID := strings.TrimPrefix(path, "/customers/")
		customerID = strings.TrimSuffix(customerID, "/block")
		if r.Method == http.MethodPost {
			s.handleBlockCustomer(w, r, customerID)
		} else {
			http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		}
	case strings.HasPrefix(path, "/customers/") && strings.HasSuffix(path, "/unblock"):
		customerID := strings.TrimPrefix(path, "/customers/")
		customerID = strings.TrimSuffix(customerID, "/unblock")
		if r.Method == http.MethodPost {
			s.handleUnblockCustomer(w, r, customerID)
		} else {
			http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		}
	case strings.HasPrefix(path, "/customers/") && strings.HasSuffix(path, "/push-config"):
		customerID := strings.TrimPrefix(path, "/customers/")
		customerID = strings.TrimSuffix(customerID, "/push-config")
		if r.Method == http.MethodPost {
			s.handlePushConfig(w, r, customerID)
		} else {
			http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		}
	case strings.HasPrefix(path, "/customers/") && strings.HasSuffix(path, "/create-config"):
		customerID := strings.TrimPrefix(path, "/customers/")
		customerID = strings.TrimSuffix(customerID, "/create-config")
		if r.Method == http.MethodPost {
			s.handleCreateConfigFromReport(w, r, customerID)
		} else {
			http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		}
	case strings.HasPrefix(path, "/customers/"):
		customerID := strings.TrimPrefix(path, "/customers/")
		s.handleCustomerUnified(w, r, customerID)
	// Config management routes — exact matches first, then prefix matches
	case path == "/configs":
		s.handleConfigList(w, r)
	case path == "/configs/new":
		if r.Method == http.MethodPost {
			s.handleConfigCreate(w, r)
		} else {
			s.handleConfigNewForm(w, r)
		}
	case strings.HasPrefix(path, "/configs/") && strings.HasSuffix(path, "/delete"):
		customerID := strings.TrimPrefix(path, "/configs/")
		customerID = strings.TrimSuffix(customerID, "/delete")
		if r.Method == http.MethodPost {
			s.handleConfigDelete(w, r, customerID)
		} else {
			http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		}
	case strings.HasPrefix(path, "/configs/") && strings.HasSuffix(path, "/edit"):
		customerID := strings.TrimPrefix(path, "/configs/")
		customerID = strings.TrimSuffix(customerID, "/edit")
		if r.Method == http.MethodPost {
			s.handleConfigUpdate(w, r, customerID)
		} else {
			s.handleConfigEditForm(w, r, customerID)
		}
	case strings.HasPrefix(path, "/configs/") && strings.HasSuffix(path, "/preview"):
		customerID := strings.TrimPrefix(path, "/configs/")
		customerID = strings.TrimSuffix(customerID, "/preview")
		s.handleConfigPreview(w, r, customerID)
	case strings.HasPrefix(path, "/configs/") && strings.HasSuffix(path, "/regen-password"):
		customerID := strings.TrimPrefix(path, "/configs/")
		customerID = strings.TrimSuffix(customerID, "/regen-password")
		if r.Method == http.MethodPost {
			s.handleConfigRegenPassword(w, r, customerID)
		} else {
			http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		}
	case strings.HasPrefix(path, "/configs/"):
		// Redirect old config detail URL to unified customer page
		customerID := strings.TrimPrefix(path, "/configs/")
		http.Redirect(w, r, "/customers/"+customerID, http.StatusSeeOther)
	default:
		http.NotFound(w, r)
	}
}

// RequireAuth wraps a handler with basic authentication.
func (s *Server) RequireAuth(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// Skip auth if no password configured
		if s.passwordHash == "" {
			next.ServeHTTP(w, r)
			return
		}

		// Check session cookie
		if cookie, err := r.Cookie("hub_session"); err == nil && cookie.Value == "authenticated" {
			next.ServeHTTP(w, r)
			return
		}

		// Check basic auth
		_, password, ok := r.BasicAuth()
		if ok && bcrypt.CompareHashAndPassword([]byte(s.passwordHash), []byte(password)) == nil {
			next.ServeHTTP(w, r)
			return
		}

		// Show login page for browser requests
		if r.URL.Path == "/login" && r.Method == http.MethodPost {
			s.handleLogin(w, r)
			return
		}

		w.Header().Set("WWW-Authenticate", `Basic realm="Felhom Hub"`)
		http.Error(w, "Unauthorized", http.StatusUnauthorized)
	})
}

func (s *Server) handleLogin(w http.ResponseWriter, r *http.Request) {
	if r.Method == http.MethodPost {
		password := r.FormValue("password")
		if bcrypt.CompareHashAndPassword([]byte(s.passwordHash), []byte(password)) == nil {
			http.SetCookie(w, &http.Cookie{
				Name:     "hub_session",
				Value:    "authenticated",
				Path:     "/",
				HttpOnly: true,
				MaxAge:   86400 * 7, // 7 days
			})
			http.Redirect(w, r, "/", http.StatusSeeOther)
			return
		}
		http.Error(w, "Invalid password", http.StatusUnauthorized)
		return
	}
	w.WriteHeader(http.StatusOK)
	w.Write([]byte(`<html><body><form method="post"><input type="password" name="password"><button>Login</button></form></body></html>`))
}

func (s *Server) handleDashboard(w http.ResponseWriter, r *http.Request) {
	customers, err := s.store.GetCustomers()
	if err != nil {
		s.logger.Printf("[ERROR] Dashboard: %v", err)
		http.Error(w, "Internal error", http.StatusInternalServerError)
		return
	}

	configs, _ := s.store.ListCustomerConfigs()

	type dashboardCustomer struct {
		store.CustomerSummary
		OverallStatus string // "ok", "warn", "down", "pending"
		BackupAge     string
	}

	// Build map of report customers keyed by ID
	seen := make(map[string]bool)
	var data []dashboardCustomer
	for _, c := range customers {
		// Skip blocked customers
		if s.store.IsCustomerBlocked(c.CustomerID) {
			continue
		}

		seen[c.CustomerID] = true
		dc := dashboardCustomer{CustomerSummary: c}

		// Determine overall status
		if c.HealthStatus == "disabled" {
			dc.OverallStatus = "disabled"
		} else if c.TimeSinceReport > time.Hour {
			dc.OverallStatus = "down"
		} else if c.TimeSinceReport > 30*time.Minute || c.HealthStatus == "warn" {
			dc.OverallStatus = "warn"
		} else if c.HealthStatus == "fail" {
			dc.OverallStatus = "down"
		} else {
			dc.OverallStatus = "ok"
		}

		// Backup age
		if c.BackupLastSnapshot != nil {
			dc.BackupAge = timeAgo(*c.BackupLastSnapshot)
		} else {
			dc.BackupAge = "–"
		}

		data = append(data, dc)
	}

	// Add config-only customers (no reports yet) as "pending"
	for _, cfg := range configs {
		if seen[cfg.CustomerID] || cfg.Status == "blocked" {
			continue
		}
		dc := dashboardCustomer{
			CustomerSummary: store.CustomerSummary{
				CustomerID:   cfg.CustomerID,
				CustomerName: cfg.CustomerName,
			},
			OverallStatus: "pending",
			BackupAge:     "–",
		}
		data = append(data, dc)
	}

	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	if err := s.templates.ExecuteTemplate(w, "dashboard.html", data); err != nil {
		s.logger.Printf("[ERROR] Template render: %v", err)
	}
}

func (s *Server) handleTriggerUpdate(w http.ResponseWriter, r *http.Request, customerID string) {
	customer, err := s.store.GetCustomer(customerID)
	if err != nil {
		s.logger.Printf("[ERROR] Trigger update — get customer %s: %v", customerID, err)
		http.Error(w, "Internal error", http.StatusInternalServerError)
		return
	}
	if customer == nil {
		http.NotFound(w, r)
		return
	}

	// Get controller URL — from denormalized field or report JSON fallback
	controllerURL := customer.ControllerURL
	if controllerURL == "" {
		var rpt struct {
			ControllerURL string `json:"controller_url"`
		}
		json.Unmarshal([]byte(customer.ReportJSON), &rpt)
		controllerURL = rpt.ControllerURL
	}
	if controllerURL == "" {
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusBadRequest)
		w.Write([]byte(`{"ok":false,"error":"Controller URL not available — waiting for next report"}`))
		return
	}

	if s.apiKey == "" {
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusInternalServerError)
		w.Write([]byte(`{"ok":false,"error":"API key not configured"}`))
		return
	}

	// POST to controller's self-update endpoint
	updateURL := controllerURL + "/api/selfupdate/update"
	req, err := http.NewRequest("POST", updateURL, nil)
	if err != nil {
		s.logger.Printf("[ERROR] Trigger update — create request for %s: %v", updateURL, err)
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusInternalServerError)
		w.Write([]byte(`{"ok":false,"error":"Failed to create request"}`))
		return
	}
	req.Header.Set("Authorization", "Bearer "+s.apiKey)

	client := &http.Client{Timeout: 30 * time.Second}
	resp, err := client.Do(req)
	if err != nil {
		s.logger.Printf("[ERROR] Trigger update — request to %s failed: %v", updateURL, err)
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusBadGateway)
		json.NewEncoder(w).Encode(map[string]interface{}{"ok": false, "error": fmt.Sprintf("Controller unreachable: %v", err)})
		return
	}
	defer resp.Body.Close()

	// Forward the controller's response
	body, _ := io.ReadAll(io.LimitReader(resp.Body, 1<<16))
	s.logger.Printf("[INFO] Trigger update for %s — controller responded %d: %s", customerID, resp.StatusCode, string(body))

	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(resp.StatusCode)
	w.Write(body)
}

// compareVersions returns >0 if a > b, 0 if equal, <0 if a < b.
// Accepts "X.Y.Z" format. Returns 0 on parse error.
func compareVersions(a, b string) int {
	a = strings.TrimPrefix(a, "v")
	b = strings.TrimPrefix(b, "v")
	aParts := strings.SplitN(a, ".", 3)
	bParts := strings.SplitN(b, ".", 3)
	if len(aParts) != 3 || len(bParts) != 3 {
		return 0
	}
	for i := 0; i < 3; i++ {
		ai, e1 := strconv.Atoi(aParts[i])
		bi, e2 := strconv.Atoi(bParts[i])
		if e1 != nil || e2 != nil {
			return 0
		}
		if ai != bi {
			return ai - bi
		}
	}
	return 0
}

func (s *Server) handleCSS(w http.ResponseWriter, r *http.Request) {
	data, err := templateFS.ReadFile("templates/style.css")
	if err != nil {
		http.NotFound(w, r)
		return
	}
	w.Header().Set("Content-Type", "text/css")
	w.Header().Set("Cache-Control", "public, max-age=3600")
	w.Write(data)
}

func timeAgo(t time.Time) string {
	d := time.Since(t)

	if d < time.Minute {
		return "just now"
	}
	if d < time.Hour {
		m := int(math.Round(d.Minutes()))
		return fmt.Sprintf("%d min ago", m)
	}
	if d < 24*time.Hour {
		h := int(math.Round(d.Hours()))
		return fmt.Sprintf("%dh ago", h)
	}
	days := int(d.Hours() / 24)
	return fmt.Sprintf("%dd ago", days)
}

func statusColor(status string) string {
	switch status {
	case "ok":
		return "#4ade80" // green
	case "warn":
		return "#facc15" // yellow
	case "down", "fail":
		return "#f87171" // red
	case "disabled", "pending", "blocked":
		return "#94a3b8" // gray
	default:
		return "#94a3b8" // gray
	}
}

func statusIcon(status string) string {
	return "●"
}