// Device registry and manual lock/unlock handlers (AGENTS.md §5 screens 2–3,
// §11 Phase 2). Only the Control Service writes device state; the dashboard is
// the admin surface.
package web

import (
	"context"
	"errors"
	"fmt"
	"net/http"
	"net/url"
	"strconv"
	"strings"
	"time"

	"gitea.lab.audasmedia.com.au/sam/internet_use_control/internal/store"
)

// deviceView is the display model for one dashboard card.
type deviceView struct {
	ID            int64
	Name          string
	Child         string
	Platform      string
	PlatformLabel string
	Topic         string
	Online        bool
	Locked        bool
	Until         *time.Time
	UntilLocal    string
	TimeLeft      string
	StateLabel    string
	LastSeen      string
	HasLastSeen   bool
}

// auditView is the display model for one audit row.
type auditView struct {
	Action         string
	ActionLabel    string
	Actor          string
	DeviceName     string
	Detail         string
	CreatedAtLocal string
}

func buildDeviceViews(devs []store.Device) []deviceView {
	out := make([]deviceView, 0, len(devs))
	for _, d := range devs {
		v := deviceView{
			ID:            d.ID,
			Name:          d.Name,
			Child:         d.Child,
			Platform:      d.Platform,
			PlatformLabel: platformLabel(d.Platform),
			Topic:         d.Topic,
			Online:        d.Online,
			Locked:        d.Locked,
			Until:         d.Until,
		}
		if d.Locked {
			v.StateLabel = "Locked"
		} else {
			v.StateLabel = "Unlocked"
		}
		if d.Until != nil {
			local := d.Until.Local()
			v.UntilLocal = local.Format("Mon 15:04")
			v.TimeLeft = timeLeft(*d.Until)
		}
		if d.LastSeen != nil {
			v.LastSeen = d.LastSeen.Local().Format("Mon 02 Jan 15:04")
			v.HasLastSeen = true
		}
		out = append(out, v)
	}
	return out
}

func buildAuditViews(entries []store.AuditEntry) []auditView {
	out := make([]auditView, 0, len(entries))
	for _, e := range entries {
		v := auditView{
			Action:      e.Action,
			ActionLabel: auditLabel(e.Action),
			Actor:       e.Actor,
			DeviceName:  e.DeviceName,
			Detail:      e.Detail,
		}
		if !e.CreatedAt.IsZero() {
			v.CreatedAtLocal = e.CreatedAt.Local().Format("02 Jan 15:04:05")
		}
		out = append(out, v)
	}
	return out
}

func platformLabel(p string) string {
	switch p {
	case store.PlatformAndroid:
		return "Android"
	case store.PlatformWindows:
		return "Windows"
	default:
		return p
	}
}

// timeLeft renders how long remains on a timed lock.
func timeLeft(until time.Time) string {
	d := time.Until(until)
	if d <= 0 {
		return "lifting now"
	}
	d = d.Round(time.Minute)
	if d < time.Minute {
		return "under a minute left"
	}
	h := int(d.Hours())
	m := int(d.Minutes()) % 60
	switch {
	case h == 0:
		return fmt.Sprintf("%d min left", m)
	case m == 0:
		return fmt.Sprintf("%dh left", h)
	default:
		return fmt.Sprintf("%dh %dm left", h, m)
	}
}

func auditLabel(action string) string {
	switch action {
	case "device.created":
		return "Device added"
	case "device.updated":
		return "Device edited"
	case "state.locked":
		return "Locked"
	case "state.unlocked":
		return "Unlocked"
	case "state.expired":
		return "Lock expired"
	case "device.online":
		return "Device online"
	case "device.offline":
		return "Device offline"
	case "login.success":
		return "Signed in"
	case "login.failed":
		return "Sign-in failed"
	case "login.csrf_rejected":
		return "Sign-in rejected"
	case "logout":
		return "Signed out"
	default:
		return action
	}
}

// ---------- dashboard data ----------

type deviceFormData struct {
	Title      string
	Heading    string
	Sub        string
	Username   string
	CSRF       string
	Version    string
	AppEnv     string
	FormAction string
	Name       string
	Child      string
	Platform   string
	Error      string
}

// ---------- handlers ----------

func (s *Server) handleDeviceNew(w http.ResponseWriter, r *http.Request) {
	s.render(w, r, "device-form.html", deviceFormData{
		Title:      "Add device",
		Heading:    "Add a device",
		Sub:        "Name the device, assign it to a child, and choose its platform.",
		Username:   s.cfg.AdminUsername,
		CSRF:       s.auth.EnsureCSRF(w, r),
		Version:    s.cfg.Version,
		AppEnv:     s.cfg.AppEnv,
		FormAction: "/devices",
		Platform:   store.PlatformAndroid,
	})
}

func (s *Server) handleDeviceCreate(w http.ResponseWriter, r *http.Request) {
	if !s.requireCSRF(w, r) {
		return
	}
	if err := r.ParseForm(); err != nil {
		http.Error(w, "bad request", http.StatusBadRequest)
		return
	}
	name := r.PostFormValue("name")
	child := r.PostFormValue("child")
	platform := r.PostFormValue("platform")

	ctx, cancel := context.WithTimeout(r.Context(), 3*time.Second)
	defer cancel()

	dev, err := s.store.CreateDevice(ctx, name, child, platform, s.cfg.AdminUsername)
	if err != nil {
		s.log.Warn("device create rejected", "err", err, "remote", r.RemoteAddr)
		s.render(w, r, "device-form.html", deviceFormData{
			Title:      "Add device",
			Heading:    "Add a device",
			Sub:        "Name the device, assign it to a child, and choose its platform.",
			Username:   s.cfg.AdminUsername,
			CSRF:       s.auth.EnsureCSRF(w, r),
			Version:    s.cfg.Version,
			AppEnv:     s.cfg.AppEnv,
			FormAction: "/devices",
			Name:       strings.TrimSpace(name),
			Child:      strings.TrimSpace(child),
			Platform:   strings.ToLower(strings.TrimSpace(platform)),
			Error:      err.Error(),
		})
		return
	}
	s.log.Info("device created", "id", dev.ID, "name", dev.Name, "topic", dev.Topic)
	s.publishConfig(ctx, *dev)
	http.Redirect(w, r, "/?ok="+url.QueryEscape("Added "+dev.Name), http.StatusSeeOther)
}

func (s *Server) handleDeviceEdit(w http.ResponseWriter, r *http.Request) {
	id, ok := s.deviceID(w, r)
	if !ok {
		return
	}
	ctx, cancel := context.WithTimeout(r.Context(), 2*time.Second)
	defer cancel()

	dev, err := s.store.GetDevice(ctx, id)
	if err != nil {
		s.deviceLookupError(w, r, err)
		return
	}
	s.render(w, r, "device-form.html", deviceFormData{
		Title:      "Edit " + dev.Name,
		Heading:    "Edit device",
		Sub:        fmt.Sprintf("%s · %s", platformLabel(dev.Platform), dev.Topic),
		Username:   s.cfg.AdminUsername,
		CSRF:       s.auth.EnsureCSRF(w, r),
		Version:    s.cfg.Version,
		AppEnv:     s.cfg.AppEnv,
		FormAction: fmt.Sprintf("/devices/%d", dev.ID),
		Name:       dev.Name,
		Child:      dev.Child,
		Platform:   dev.Platform,
	})
}

func (s *Server) handleDeviceUpdate(w http.ResponseWriter, r *http.Request) {
	id, ok := s.deviceID(w, r)
	if !ok {
		return
	}
	if !s.requireCSRF(w, r) {
		return
	}
	if err := r.ParseForm(); err != nil {
		http.Error(w, "bad request", http.StatusBadRequest)
		return
	}
	name := r.PostFormValue("name")
	child := r.PostFormValue("child")
	platform := r.PostFormValue("platform")

	ctx, cancel := context.WithTimeout(r.Context(), 3*time.Second)
	defer cancel()

	dev, err := s.store.UpdateDevice(ctx, id, name, child, platform, s.cfg.AdminUsername)
	if err != nil {
		if errors.Is(err, store.ErrNotFound) {
			s.deviceLookupError(w, r, err)
			return
		}
		s.render(w, r, "device-form.html", deviceFormData{
			Title:      "Edit device",
			Heading:    "Edit device",
			Sub:        "Correct the details and save again.",
			Username:   s.cfg.AdminUsername,
			CSRF:       s.auth.EnsureCSRF(w, r),
			Version:    s.cfg.Version,
			AppEnv:     s.cfg.AppEnv,
			FormAction: fmt.Sprintf("/devices/%d", id),
			Name:       strings.TrimSpace(name),
			Child:      strings.TrimSpace(child),
			Platform:   strings.ToLower(strings.TrimSpace(platform)),
			Error:      err.Error(),
		})
		return
	}
	s.log.Info("device updated", "id", dev.ID, "name", dev.Name)
	s.publishConfig(ctx, *dev)
	http.Redirect(w, r, "/?ok="+url.QueryEscape("Saved "+dev.Name), http.StatusSeeOther)
}

func (s *Server) handleDeviceLock(w http.ResponseWriter, r *http.Request) {
	id, ok := s.deviceID(w, r)
	if !ok {
		return
	}
	if !s.requireCSRF(w, r) {
		return
	}
	if err := r.ParseForm(); err != nil {
		http.Error(w, "bad request", http.StatusBadRequest)
		return
	}

	minutes, _ := strconv.Atoi(strings.TrimSpace(r.PostFormValue("minutes")))
	if minutes < 0 || minutes > 24*60 {
		minutes = 0
	}
	var until *time.Time
	if minutes > 0 {
		t := time.Now().Add(time.Duration(minutes) * time.Minute).UTC()
		until = &t
	}

	ctx, cancel := context.WithTimeout(r.Context(), 3*time.Second)
	defer cancel()

	dev, err := s.store.SetDeviceLock(ctx, id, true, until, s.cfg.AdminUsername, "state.locked")
	if err != nil {
		s.deviceLookupError(w, r, err)
		return
	}
	s.log.Info("device locked", "id", dev.ID, "name", dev.Name, "minutes", minutes)
	s.publishConfig(ctx, *dev)
	msg := "Locked " + dev.Name
	if minutes > 0 {
		msg = fmt.Sprintf("Locked %s for %d min", dev.Name, minutes)
	}
	http.Redirect(w, r, "/?ok="+url.QueryEscape(msg), http.StatusSeeOther)
}

func (s *Server) handleDeviceUnlock(w http.ResponseWriter, r *http.Request) {
	id, ok := s.deviceID(w, r)
	if !ok {
		return
	}
	if !s.requireCSRF(w, r) {
		return
	}
	if err := r.ParseForm(); err != nil {
		http.Error(w, "bad request", http.StatusBadRequest)
		return
	}

	ctx, cancel := context.WithTimeout(r.Context(), 3*time.Second)
	defer cancel()

	dev, err := s.store.SetDeviceLock(ctx, id, false, nil, s.cfg.AdminUsername, "state.unlocked")
	if err != nil {
		s.deviceLookupError(w, r, err)
		return
	}
	s.log.Info("device unlocked", "id", dev.ID, "name", dev.Name)
	s.publishConfig(ctx, *dev)
	http.Redirect(w, r, "/?ok="+url.QueryEscape("Unlocked "+dev.Name), http.StatusSeeOther)
}

// ---------- helpers ----------

func (s *Server) deviceID(w http.ResponseWriter, r *http.Request) (int64, bool) {
	id, err := strconv.ParseInt(r.PathValue("id"), 10, 64)
	if err != nil || id <= 0 {
		http.NotFound(w, r)
		return 0, false
	}
	return id, true
}

func (s *Server) deviceLookupError(w http.ResponseWriter, r *http.Request, err error) {
	if errors.Is(err, store.ErrNotFound) {
		http.NotFound(w, r)
		return
	}
	s.log.Error("device handler", "err", err, "path", r.URL.Path)
	http.Error(w, "internal server error", http.StatusInternalServerError)
}

func (s *Server) requireCSRF(w http.ResponseWriter, r *http.Request) bool {
	if err := r.ParseForm(); err != nil {
		http.Error(w, "bad request", http.StatusBadRequest)
		return false
	}
	if !s.auth.CheckCSRF(r) {
		s.log.Warn("rejected: bad csrf token", "path", r.URL.Path, "remote", r.RemoteAddr)
		http.Error(w, "invalid CSRF token", http.StatusForbidden)
		return false
	}
	return true
}