package handlers

import (
	"context"
	"net/http"
	"strconv"
	"sync"
	"time"

	"github.com/go-chi/chi/v5"

	"git.georgsen.dk/hwlab/internal/labels"
	"git.georgsen.dk/hwlab/internal/netbox"
	"git.georgsen.dk/hwlab/internal/printer"
)

// LabelNetBoxClient is the narrow interface LabelHandler needs from NetBox.
// *netbox.Client satisfies this interface.
type LabelNetBoxClient interface {
	GetDevice(ctx context.Context, id int) (*netbox.Device, error)
}

// LabelPrinter is the narrow interface over printer.PrinterDriver that the
// label handler requires. Allows mock injection in tests.
type LabelPrinter interface {
	Print(bitmap []byte, width, height int) error
}

// LabelHandler handles POST /api/labels/:deviceID/print.
// T-04-09 mitigation: print calls are rate-limited to 1/second per instance
// to prevent runaway label waste.
type LabelHandler struct {
	nb      LabelNetBoxClient
	printer LabelPrinter

	// rate limiting (T-04-09 — DoS / label waste mitigation)
	mu            sync.Mutex
	lastPrintTime time.Time
	printCooldown time.Duration
}

// NewLabelHandler constructs a LabelHandler with a 1-second print cooldown.
func NewLabelHandler(nb LabelNetBoxClient, p LabelPrinter) *LabelHandler {
	return &LabelHandler{
		nb:            nb,
		printer:       p,
		printCooldown: time.Second,
	}
}

// PrintLabel handles POST /api/labels/:deviceID/print.
//
// Flow:
//  1. Parse deviceID path param
//  2. Rate-limit check (1/second — T-04-09)
//  3. Fetch device from NetBox
//  4. Render label via labels.RenderCable or labels.RenderStandard
//  5. Convert to 1-bit bitmap via printer.ImageToRawBitmap
//  6. Send to printer
//  7. Return 200 {"status":"printed"}
func (h *LabelHandler) PrintLabel(w http.ResponseWriter, r *http.Request) {
	idStr := chi.URLParam(r, "deviceID")
	id, err := strconv.Atoi(idStr)
	if err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid device ID"})
		return
	}

	// T-04-09: rate limit — reject if last print was less than 1 second ago.
	h.mu.Lock()
	now := time.Now()
	if !h.lastPrintTime.IsZero() && now.Sub(h.lastPrintTime) < h.printCooldown {
		h.mu.Unlock()
		writeJSON(w, http.StatusTooManyRequests, map[string]string{"error": "print rate limit: wait 1 second between prints"})
		return
	}
	h.lastPrintTime = now
	h.mu.Unlock()

	device, err := h.nb.GetDevice(r.Context(), id)
	if err != nil {
		writeJSON(w, http.StatusNotFound, map[string]string{"error": "device not found"})
		return
	}

	// Choose renderer based on device type.
	var bitmap []byte
	var bWidth, bHeight int

	if labels.IsCableDevice(*device) {
		d := labels.CableLabelData{
			HWID:       device.CustomFields.HWID,
			Name:       device.Name,
			TestDate:   device.CustomFields.TestDate,
			// USBVersion/MaxSpeedGbps/MaxWatts: parsed from TestData in Phase 5.
			// Default values allow label to render without error before that.
			USBVersion: "Unknown",
		}
		labelImg, err := labels.RenderCable(d)
		if err != nil {
			writeJSON(w, http.StatusInternalServerError, map[string]string{"error": "render failed: " + err.Error()})
			return
		}
		bitmap, bWidth, bHeight = printer.ImageToRawBitmap(labelImg)
	} else {
		d := labels.LabelData{
			HWID:     device.CustomFields.HWID,
			Name:     device.Name,
			SpecLine: device.CustomFields.AINotes,
		}
		labelImg, err := labels.RenderStandard(d)
		if err != nil {
			writeJSON(w, http.StatusInternalServerError, map[string]string{"error": "render failed: " + err.Error()})
			return
		}
		bitmap, bWidth, bHeight = printer.ImageToRawBitmap(labelImg)
	}

	if err := h.printer.Print(bitmap, bWidth, bHeight); err != nil {
		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": "print failed: " + err.Error()})
		return
	}

	writeJSON(w, http.StatusOK, map[string]string{"status": "printed"})
}