package webui

import (
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"os"
	"path/filepath"
	"strings"

	"bee/audit/internal/app"
	"bee/audit/internal/runtimeenv"
)

const defaultTitle = "Bee Hardware Audit"

// HandlerOptions configures the web UI handler.
type HandlerOptions struct {
	Title       string
	AuditPath   string
	ExportDir   string
	App         *app.App
	RuntimeMode runtimeenv.Mode
}

// handler is the HTTP handler for the web UI.
type handler struct {
	opts HandlerOptions
	mux  *http.ServeMux
}

// NewHandler creates the HTTP mux with all routes.
func NewHandler(opts HandlerOptions) http.Handler {
	if strings.TrimSpace(opts.Title) == "" {
		opts.Title = defaultTitle
	}
	if strings.TrimSpace(opts.ExportDir) == "" {
		opts.ExportDir = app.DefaultExportDir
	}
	if opts.RuntimeMode == "" {
		opts.RuntimeMode = runtimeenv.ModeAuto
	}

	h := &handler{opts: opts}
	mux := http.NewServeMux()

	// ── Infrastructure ──────────────────────────────────────────────────────
	mux.HandleFunc("GET /healthz", h.handleHealthz)

	// ── Existing read-only endpoints (preserved for compatibility) ──────────
	mux.HandleFunc("GET /audit.json", h.handleAuditJSON)
	mux.HandleFunc("GET /runtime-health.json", h.handleRuntimeHealthJSON)
	mux.HandleFunc("GET /export/support.tar.gz", h.handleSupportBundleDownload)
	mux.HandleFunc("GET /export/file", h.handleExportFile)
	mux.HandleFunc("GET /export/", h.handleExportIndex)
	mux.HandleFunc("GET /viewer", h.handleViewer)

	// ── API ──────────────────────────────────────────────────────────────────
	// Audit
	mux.HandleFunc("POST /api/audit/run", h.handleAPIAuditRun)
	mux.HandleFunc("GET /api/audit/stream", h.handleAPIAuditStream)

	// SAT
	mux.HandleFunc("POST /api/sat/nvidia/run", h.handleAPISATRun("nvidia"))
	mux.HandleFunc("POST /api/sat/memory/run", h.handleAPISATRun("memory"))
	mux.HandleFunc("POST /api/sat/storage/run", h.handleAPISATRun("storage"))
	mux.HandleFunc("POST /api/sat/cpu/run", h.handleAPISATRun("cpu"))
	mux.HandleFunc("GET /api/sat/stream", h.handleAPISATStream)

	// Services
	mux.HandleFunc("GET /api/services", h.handleAPIServicesList)
	mux.HandleFunc("POST /api/services/action", h.handleAPIServicesAction)

	// Network
	mux.HandleFunc("GET /api/network", h.handleAPINetworkStatus)
	mux.HandleFunc("POST /api/network/dhcp", h.handleAPINetworkDHCP)
	mux.HandleFunc("POST /api/network/static", h.handleAPINetworkStatic)

	// Export
	mux.HandleFunc("GET /api/export/list", h.handleAPIExportList)
	mux.HandleFunc("POST /api/export/bundle", h.handleAPIExportBundle)

	// Tools
	mux.HandleFunc("GET /api/tools/check", h.handleAPIToolsCheck)

	// Preflight
	mux.HandleFunc("GET /api/preflight", h.handleAPIPreflight)

	// Metrics — SSE stream of live sensor data
	mux.HandleFunc("GET /api/metrics/stream", h.handleAPIMetricsStream)

	// ── Pages ────────────────────────────────────────────────────────────────
	mux.HandleFunc("GET /", h.handlePage)

	h.mux = mux
	return mux
}

// ListenAndServe starts the HTTP server.
func ListenAndServe(addr string, opts HandlerOptions) error {
	return http.ListenAndServe(addr, NewHandler(opts))
}

// ── Infrastructure handlers ──────────────────────────────────────────────────

func (h *handler) handleHealthz(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Cache-Control", "no-store")
	w.WriteHeader(http.StatusOK)
	_, _ = w.Write([]byte("ok"))
}

// ── Compatibility endpoints ──────────────────────────────────────────────────

func (h *handler) handleAuditJSON(w http.ResponseWriter, r *http.Request) {
	data, err := loadSnapshot(h.opts.AuditPath)
	if err != nil {
		if errors.Is(err, os.ErrNotExist) {
			http.Error(w, "audit snapshot not found", http.StatusNotFound)
			return
		}
		http.Error(w, fmt.Sprintf("read audit snapshot: %v", err), http.StatusInternalServerError)
		return
	}
	w.Header().Set("Cache-Control", "no-store")
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	_, _ = w.Write(data)
}

func (h *handler) handleRuntimeHealthJSON(w http.ResponseWriter, r *http.Request) {
	data, err := loadSnapshot(filepath.Join(h.opts.ExportDir, "runtime-health.json"))
	if err != nil {
		if errors.Is(err, os.ErrNotExist) {
			http.Error(w, "runtime health not found", http.StatusNotFound)
			return
		}
		http.Error(w, fmt.Sprintf("read runtime health: %v", err), http.StatusInternalServerError)
		return
	}
	w.Header().Set("Cache-Control", "no-store")
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	_, _ = w.Write(data)
}

func (h *handler) handleSupportBundleDownload(w http.ResponseWriter, r *http.Request) {
	archive, err := app.BuildSupportBundle(h.opts.ExportDir)
	if err != nil {
		http.Error(w, fmt.Sprintf("build support bundle: %v", err), http.StatusInternalServerError)
		return
	}
	w.Header().Set("Cache-Control", "no-store")
	w.Header().Set("Content-Type", "application/gzip")
	w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=%q", filepath.Base(archive)))
	http.ServeFile(w, r, archive)
}

func (h *handler) handleExportFile(w http.ResponseWriter, r *http.Request) {
	rel := strings.TrimSpace(r.URL.Query().Get("path"))
	if rel == "" {
		http.Error(w, "path is required", http.StatusBadRequest)
		return
	}
	clean := filepath.Clean(rel)
	if clean == "." || strings.HasPrefix(clean, "..") {
		http.Error(w, "invalid path", http.StatusBadRequest)
		return
	}
	http.ServeFile(w, r, filepath.Join(h.opts.ExportDir, clean))
}

func (h *handler) handleExportIndex(w http.ResponseWriter, r *http.Request) {
	body, err := renderExportIndex(h.opts.ExportDir)
	if err != nil {
		http.Error(w, fmt.Sprintf("render export index: %v", err), http.StatusInternalServerError)
		return
	}
	w.Header().Set("Cache-Control", "no-store")
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	_, _ = w.Write([]byte(body))
}

func (h *handler) handleViewer(w http.ResponseWriter, r *http.Request) {
	snapshot, _ := loadSnapshot(h.opts.AuditPath)
	body := renderViewerPage(h.opts.Title, snapshot)
	w.Header().Set("Cache-Control", "no-store")
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	_, _ = w.Write([]byte(body))
}

// ── Page handler ─────────────────────────────────────────────────────────────

func (h *handler) handlePage(w http.ResponseWriter, r *http.Request) {
	page := strings.TrimPrefix(r.URL.Path, "/")
	if page == "" {
		page = "dashboard"
	}
	body := renderPage(page, h.opts)
	w.Header().Set("Cache-Control", "no-store")
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	_, _ = w.Write([]byte(body))
}

// ── Helpers ──────────────────────────────────────────────────────────────────

func loadSnapshot(path string) ([]byte, error) {
	if strings.TrimSpace(path) == "" {
		return nil, os.ErrNotExist
	}
	return os.ReadFile(path)
}

// writeJSON sends v as JSON with status 200.
func writeJSON(w http.ResponseWriter, v any) {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	w.Header().Set("Cache-Control", "no-store")
	_ = json.NewEncoder(w).Encode(v)
}

// writeError sends a JSON error response.
func writeError(w http.ResponseWriter, status int, msg string) {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	w.Header().Set("Cache-Control", "no-store")
	w.WriteHeader(status)
	_ = json.NewEncoder(w).Encode(map[string]string{"error": msg})
}