package handler

import (
	"database/sql"
	"log"
	"net/http"
	"strconv"
	"strings"
	"time"

	"vidarchive/internal/models"
)

func (h *Handler) Subscriptions(w http.ResponseWriter, r *http.Request) {
	subscriptions, err := h.subscriptionSvc.GetAll()
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	presets, err := h.presetSvc.GetAll()
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	h.renderWithRequest(w, r, "subscriptions", PageData{
		Title:     "Subscriptions",
		ActiveTab: "subscriptions",
		Data: struct {
			Subscriptions []*models.Subscription
			Presets       []*models.Preset
		}{
			Subscriptions: subscriptions,
			Presets:       presets,
		},
	})
}

// subscriptionFromForm builds and validates a Subscription from form values,
// shared by create and update. It resolves/validates the schedule into a canonical
// cron expression and requires an output directory (the subscription owns it).
func (h *Handler) subscriptionFromForm(r *http.Request) (*models.Subscription, error) {
	name := strings.TrimSpace(r.FormValue("name"))
	url := strings.TrimSpace(r.FormValue("url"))
	if name == "" {
		return nil, errBadRequest("a name is required")
	}
	if url == "" {
		return nil, errBadRequest("URL is required")
	}

	outputDir := strings.TrimSpace(r.FormValue("output_dir"))
	if outputDir == "" {
		return nil, errBadRequest("an output directory is required — the subscription owns this folder")
	}

	refreshMode := r.FormValue("refresh_mode")
	switch refreshMode {
	case "overwrite", "skip", "metadata":
	default:
		refreshMode = "overwrite"
	}

	scheduleKind := r.FormValue("schedule_kind")
	cronExpr, err := h.subscriptionSvc.CronExprFor(scheduleKind, strings.TrimSpace(r.FormValue("cron_expr")))
	if err != nil {
		return nil, errBadRequest(err.Error())
	}

	sub := &models.Subscription{
		Name:           name,
		URL:            url,
		Enabled:        true,
		RefreshMode:    refreshMode,
		ScheduleKind:   scheduleKind,
		CronExpr:       cronExpr,
		FormatOverride: r.FormValue("format_override"),
		CustomFlags:    r.FormValue("custom_flags"),
		OutputDir:      outputDir,
		PruneRemoved:   r.FormValue("prune_removed") == "1",
	}
	if pid := r.FormValue("preset_id"); pid != "" {
		if id, err := strconv.ParseInt(pid, 10, 64); err == nil {
			sub.PresetID = sql.NullInt64{Int64: id, Valid: true}
		}
	}
	return sub, nil
}

func (h *Handler) CreateSubscription(w http.ResponseWriter, r *http.Request) {
	if err := r.ParseForm(); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	sub, err := h.subscriptionFromForm(r)
	if err != nil {
		redirectWithError(w, r, "/subscriptions", err.Error(), nil)
		return
	}

	if next, err := h.subscriptionSvc.ComputeNextRun(sub, time.Now()); err == nil {
		sub.NextRunAt = sql.NullTime{Time: next, Valid: true}
	}

	if err := h.subscriptionSvc.Create(sub); err != nil {
		redirectWithError(w, r, "/subscriptions", "Couldn't create this subscription.", err)
		return
	}
	redirectWithSuccess(w, r, "/subscriptions", "Subscription created.")
}

func (h *Handler) UpdateSubscription(w http.ResponseWriter, r *http.Request) {
	id, ok := parseID(w, r)
	if !ok {
		return
	}
	if err := r.ParseForm(); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	existing, err := h.subscriptionSvc.GetByID(id)
	if err != nil {
		http.Error(w, "Not found", http.StatusNotFound)
		return
	}

	sub, err := h.subscriptionFromForm(r)
	if err != nil {
		redirectWithError(w, r, "/subscriptions", err.Error(), nil)
		return
	}
	sub.ID = id
	sub.Enabled = existing.Enabled
	// Recompute the next run from the (possibly changed) schedule.
	if next, err := h.subscriptionSvc.ComputeNextRun(sub, time.Now()); err == nil {
		sub.NextRunAt = sql.NullTime{Time: next, Valid: true}
	}

	if err := h.subscriptionSvc.Update(sub); err != nil {
		redirectWithError(w, r, "/subscriptions", "Couldn't update this subscription.", err)
		return
	}
	redirectWithSuccess(w, r, "/subscriptions", "Subscription updated.")
}

func (h *Handler) ToggleSubscription(w http.ResponseWriter, r *http.Request) {
	id, ok := parseID(w, r)
	if !ok {
		return
	}
	sub, err := h.subscriptionSvc.GetByID(id)
	if err != nil {
		http.Error(w, "Not found", http.StatusNotFound)
		return
	}
	if err := h.subscriptionSvc.SetEnabled(id, !sub.Enabled); err != nil {
		redirectWithError(w, r, "/subscriptions", "Couldn't change this subscription.", err)
		return
	}
	message := "Subscription resumed."
	if sub.Enabled {
		message = "Subscription paused."
	}
	redirectWithSuccess(w, r, "/subscriptions", message)
}

func (h *Handler) RunSubscription(w http.ResponseWriter, r *http.Request) {
	id, ok := parseID(w, r)
	if !ok {
		return
	}
	sub, err := h.subscriptionSvc.GetByID(id)
	if err != nil {
		http.Error(w, "Not found", http.StatusNotFound)
		return
	}

	// Refuse a second run while one is still in flight, the same guard the
	// scheduler applies. Two runs of one subscription share an output directory,
	// so in overwrite mode they race: one deletes the item the other just wrote.
	active, err := h.downloadSvc.HasActiveForSubscription(id)
	if err != nil {
		redirectWithError(w, r, "/subscriptions", "Couldn't start this subscription run.", err)
		return
	}
	if active {
		redirectWithError(w, r, "/subscriptions", "This subscription already has a run in progress.", nil)
		return
	}

	download, err := h.downloadSvc.CreateForSubscription(sub)
	if err != nil {
		redirectWithError(w, r, "/subscriptions", "Couldn't start this subscription run.", err)
		return
	}
	h.workerPool.Submit(download)

	// Record the manual run so the subscriptions page shows it. The schedule's
	// next run time is deliberately left alone.
	if err := h.subscriptionSvc.MarkManualRun(id, time.Now(), "queued"); err != nil {
		log.Printf("subscription %d: failed to record manual run: %v", id, err)
	}

	redirectWithSuccess(w, r, "/queue", "Subscription run queued.")
}

func (h *Handler) DeleteSubscription(w http.ResponseWriter, r *http.Request) {
	id, ok := parseID(w, r)
	if !ok {
		return
	}
	if err := h.subscriptionSvc.Delete(id); err != nil {
		redirectWithError(w, r, "/subscriptions", "Couldn't delete this subscription.", err)
		return
	}
	redirectWithSuccess(w, r, "/subscriptions", "Subscription deleted.")
}

// errBadRequest is a small sentinel-style error carrying a user-facing message.
type errBadRequest string

func (e errBadRequest) Error() string { return string(e) }