package webui

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

	"bee/audit/internal/app"
	"bee/audit/internal/runtimeenv"
	gocharts "github.com/go-analyze/charts"
	"reanimator/chart/viewer"
	"reanimator/chart/web"
)

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
}

// metricsRing holds a rolling window of live metric samples.
type metricsRing struct {
	mu     sync.Mutex
	vals   []float64
	labels []string
	size   int
}

func newMetricsRing(size int) *metricsRing {
	return &metricsRing{size: size, vals: make([]float64, 0, size), labels: make([]string, 0, size)}
}

func (r *metricsRing) push(v float64) {
	r.mu.Lock()
	defer r.mu.Unlock()
	if len(r.vals) >= r.size {
		r.vals = r.vals[1:]
		r.labels = r.labels[1:]
	}
	r.vals = append(r.vals, v)
	r.labels = append(r.labels, time.Now().Format("15:04"))
}

func (r *metricsRing) snapshot() ([]float64, []string) {
	r.mu.Lock()
	defer r.mu.Unlock()
	v := make([]float64, len(r.vals))
	l := make([]string, len(r.labels))
	copy(v, r.vals)
	copy(l, r.labels)
	return v, l
}

// gpuRings holds per-GPU ring buffers.
type gpuRings struct {
	Temp    *metricsRing
	Util    *metricsRing
	MemUtil *metricsRing
	Power   *metricsRing
}

// handler is the HTTP handler for the web UI.
type handler struct {
	opts        HandlerOptions
	mux         *http.ServeMux
	// server rings
	ringCPUTemp *metricsRing
	ringCPULoad *metricsRing
	ringMemLoad *metricsRing
	ringPower   *metricsRing
	ringFans    []*metricsRing
	fanNames    []string
	// per-GPU rings (index = GPU index)
	gpuRings    []*gpuRings
	ringsMu     sync.Mutex
	// install job (at most one at a time)
	installJob  *jobState
	installMu   sync.Mutex
}

// 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,
		ringCPUTemp: newMetricsRing(120),
		ringCPULoad: newMetricsRing(120),
		ringMemLoad: newMetricsRing(120),
		ringPower:   newMetricsRing(120),
	}
	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)
	mux.HandleFunc("POST /api/sat/abort", h.handleAPISATAbort)

	// 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)

	// Install
	mux.HandleFunc("GET /api/install/disks", h.handleAPIInstallDisks)
	mux.HandleFunc("POST /api/install/run", h.handleAPIInstallRun)
	mux.HandleFunc("GET /api/install/stream", h.handleAPIInstallStream)

	// Metrics — SSE stream of live sensor data + server-side SVG charts
	mux.HandleFunc("GET /api/metrics/stream", h.handleAPIMetricsStream)
	mux.HandleFunc("GET /api/metrics/chart/", h.handleMetricsChartSVG)

	// Reanimator chart static assets (viewer template expects /static/*)
	mux.Handle("GET /static/", http.StripPrefix("/static/", web.Static()))

	// ── 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, err := viewer.RenderHTML(snapshot, h.opts.Title)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	w.Header().Set("Cache-Control", "no-store")
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	_, _ = w.Write(body)
}

func (h *handler) handleMetricsChartSVG(w http.ResponseWriter, r *http.Request) {
	path := strings.TrimPrefix(r.URL.Path, "/api/metrics/chart/")
	path = strings.TrimSuffix(path, ".svg")

	var datasets [][]float64
	var names []string
	var labels []string
	var title string

	switch {
	case path == "server":
		title = "Server"
		vCPUTemp, l := h.ringCPUTemp.snapshot()
		vCPULoad, _ := h.ringCPULoad.snapshot()
		vMemLoad, _ := h.ringMemLoad.snapshot()
		vPower, _ := h.ringPower.snapshot()
		labels = l
		datasets = [][]float64{vCPUTemp, vCPULoad, vMemLoad, vPower}
		names = []string{"CPU Temp °C", "CPU Load %", "Mem Load %", "Power W"}

		h.ringsMu.Lock()
		for i, fr := range h.ringFans {
			fv, _ := fr.snapshot()
			datasets = append(datasets, fv)
			name := "Fan"
			if i < len(h.fanNames) {
				name = h.fanNames[i]
			}
			names = append(names, name+" RPM")
		}
		h.ringsMu.Unlock()

	case strings.HasPrefix(path, "gpu/"):
		idxStr := strings.TrimPrefix(path, "gpu/")
		idx := 0
		fmt.Sscanf(idxStr, "%d", &idx)
		h.ringsMu.Lock()
		var gr *gpuRings
		if idx < len(h.gpuRings) {
			gr = h.gpuRings[idx]
		}
		h.ringsMu.Unlock()
		if gr == nil {
			http.NotFound(w, r)
			return
		}
		vTemp, l := gr.Temp.snapshot()
		vUtil, _ := gr.Util.snapshot()
		vMemUtil, _ := gr.MemUtil.snapshot()
		vPower, _ := gr.Power.snapshot()
		labels = l
		title = fmt.Sprintf("GPU %d", idx)
		datasets = [][]float64{vTemp, vUtil, vMemUtil, vPower}
		names = []string{"Temp °C", "Load %", "Mem %", "Power W"}

	default:
		http.NotFound(w, r)
		return
	}

	// Ensure all datasets same length as labels
	n := len(labels)
	if n == 0 {
		n = 1
		labels = []string{""}
	}
	for i := range datasets {
		if len(datasets[i]) == 0 {
			datasets[i] = make([]float64, n)
		}
	}

	sparse := sparseLabels(labels, 6)

	opt := gocharts.NewLineChartOptionWithData(datasets)
	opt.Title = gocharts.TitleOption{Text: title}
	opt.XAxis.Labels = sparse
	opt.Legend = gocharts.LegendOption{SeriesNames: names}

	p := gocharts.NewPainter(gocharts.PainterOptions{
		OutputFormat: gocharts.ChartOutputSVG,
		Width:        1400,
		Height:       280,
	}, gocharts.PainterThemeOption(gocharts.GetTheme("grafana")))
	if err := p.LineChart(opt); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	buf, err := p.Bytes()
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	w.Header().Set("Content-Type", "image/svg+xml")
	w.Header().Set("Cache-Control", "no-store")
	_, _ = w.Write(buf)
}

func safeIdx(s []float64, i int) float64 {
	if i < len(s) {
		return s[i]
	}
	return 0
}

func sparseLabels(labels []string, n int) []string {
	out := make([]string, len(labels))
	step := len(labels) / n
	if step < 1 {
		step = 1
	}
	for i, l := range labels {
		if i%step == 0 {
			out[i] = l
		}
	}
	return out
}

// ── 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})
}