package econetui

import (
	"bytes"
	"context"
	"encoding/json"
	"net/http"
	"strings"

	pb "gitea.libretechconsulting.com/rmcguire/econet-exporter/api/econet/v1alpha1"
	"gitea.libretechconsulting.com/rmcguire/econet-exporter/pkg/econet/econetgrpc"
)

// cardView is the template model for one device card.
type cardView struct {
	Device  *pb.Device
	Icon    string       // static asset path for the device type
	Modes   []modeOption // settable modes for the dropdown
	Pending string       // pretty label of an in-flight mode change, if any
	Error   string       // last mode-change error, if any
}

type modeOption struct {
	Value    string // proto enum name, e.g. MODE_HEAT_PUMP
	Label    string // display label, e.g. Heat Pump
	Selected bool
}

type pageView struct {
	Devices []cardView
}

func (s *EconetUIServer) handleIndex(w http.ResponseWriter, r *http.Request) {
	// A full page load is a "fresh get": show reported state, ignore pending.
	s.render(w, "layout", pageView{Devices: s.deviceViews(r.Context(), false)})
}

func (s *EconetUIServer) handleDevices(w http.ResponseWriter, r *http.Request) {
	// The polling refresh honors pending so an in-flight change stays visible
	// until it lands or its TTL lapses.
	s.render(w, "devices", pageView{Devices: s.deviceViews(r.Context(), true)})
}

func (s *EconetUIServer) handleSetMode(w http.ResponseWriter, r *http.Request) {
	serial := r.PathValue("serial")
	modeName := r.FormValue("mode")

	modeVal, ok := pb.Mode_value[modeName]
	if !ok || pb.Mode(modeVal) == pb.Mode_MODE_UNSPECIFIED {
		s.renderCard(w, r.Context(), serial, "invalid mode "+modeName)
		return
	}

	_, err := s.econetGRPC.SetMode(r.Context(), &pb.SetModeRequest{
		SerialNumber: serial,
		Mode:         pb.Mode(modeVal),
	})
	if err != nil {
		s.log.Warn().Err(err).Str("serial", serial).Msg("ui: set mode failed")
		s.renderCard(w, r.Context(), serial, err.Error())
		return
	}

	s.pending.set(serial, econetgrpc.ModeSlug(pb.Mode(modeVal)))
	s.renderCard(w, r.Context(), serial, "")
}

// handleDebug returns the raw EcoNet payload for a device, pretty-printed, for
// the bug-icon modal.
func (s *EconetUIServer) handleDebug(w http.ResponseWriter, r *http.Request) {
	serial := r.PathValue("serial")
	raw, ok := s.econetGRPC.DeviceRawJSON(serial)
	if !ok {
		s.render(w, "debug", "No raw payload captured for "+serial+" yet.")
		return
	}
	var buf bytes.Buffer
	if err := json.Indent(&buf, raw, "", "  "); err != nil {
		buf.Write(raw)
	}
	s.render(w, "debug", buf.String())
}

// deviceViews builds card views for all devices. When usePending is true, an
// in-flight mode change is shown as a pending badge (and cleared once the
// reported mode catches up).
func (s *EconetUIServer) deviceViews(ctx context.Context, usePending bool) []cardView {
	resp, err := s.econetGRPC.ListDevices(ctx, &pb.ListDevicesRequest{})
	if err != nil {
		s.log.Error().Err(err).Msg("ui: list devices failed")
		return nil
	}
	views := make([]cardView, 0, len(resp.GetDevices()))
	for _, d := range resp.GetDevices() {
		views = append(views, s.toCardView(d, usePending))
	}
	return views
}

// renderCard re-renders a single device's card, used for the HTMX swap after a
// mode change. A successful change is optimistic (pending badge shown).
func (s *EconetUIServer) renderCard(w http.ResponseWriter, ctx context.Context, serial, errMsg string) {
	resp, err := s.econetGRPC.GetDevice(ctx, &pb.GetDeviceRequest{SerialNumber: serial})
	if err != nil {
		http.Error(w, err.Error(), http.StatusNotFound)
		return
	}
	cv := s.toCardView(resp.GetDevice(), true)
	cv.Error = errMsg
	s.render(w, "card", cv)
}

func (s *EconetUIServer) toCardView(d *pb.Device, usePending bool) cardView {
	cv := cardView{Device: d, Icon: iconFor(d.GetGenericType())}

	for _, m := range d.GetSupportedModes() {
		slug := econetgrpc.ModeSlug(m)
		cv.Modes = append(cv.Modes, modeOption{
			Value:    m.String(),
			Label:    prettyMode(slug),
			Selected: slug == d.GetMode(),
		})
	}

	if usePending {
		if desired, ok := s.pending.get(d.GetSerialNumber()); ok {
			if desired == d.GetMode() {
				s.pending.clear(d.GetSerialNumber()) // reported caught up
			} else {
				cv.Pending = prettyMode(desired)
			}
		}
	}
	return cv
}

func (s *EconetUIServer) render(w http.ResponseWriter, name string, data any) {
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	if err := s.tmpl.ExecuteTemplate(w, name, data); err != nil {
		s.log.Error().Err(err).Str("template", name).Msg("ui: render failed")
	}
}

// iconFor maps a device's generic type to an embedded SVG asset. It matches
// loosely (case/spacing/underscore-insensitive substrings) because the reported
// @TYPE varies in form across firmware (e.g. "heatpumpWaterHeater", "HeatPump",
// "Hybrid Electric"); unrecognized types fall back to a generic icon.
func iconFor(genericType string) string {
	t := strings.NewReplacer(" ", "", "_", "", "-", "").Replace(strings.ToLower(genericType))
	switch {
	case strings.Contains(t, "heatpump"), strings.Contains(t, "hybrid"):
		return "/static/icons/heatpump.svg"
	case strings.Contains(t, "tankless"):
		return "/static/icons/tankless.svg"
	case strings.Contains(t, "gas"):
		return "/static/icons/gas.svg"
	case strings.Contains(t, "electric"):
		return "/static/icons/electric.svg"
	default:
		return "/static/icons/unknown.svg"
	}
}