package handlers

import (
	"context"
	"fmt"
	"log/slog"
	"net/http"
	"sort"
	"strconv"
	"strings"
	"time"

	"veola/internal/apify"
	"veola/internal/models"
	"veola/internal/scheduler"
	"veola/templates"
)

func (a *App) GetItems(w http.ResponseWriter, r *http.Request) {
	cat := r.URL.Query().Get("category")
	all, err := a.Store.ListItems(r.Context())
	if err != nil {
		http.Error(w, "db error", http.StatusInternalServerError)
		return
	}
	var items []models.Item
	for _, it := range all {
		if cat == "" || it.Category == cat {
			items = append(items, it)
		}
	}
	cats, _ := a.Store.ListCategories(r.Context())

	// Bulk-load recent price history so each row can render a sparkline
	// without N+1 queries. 20 points is enough for a meaningful trend line
	// at 80px wide and stays cheap on the largest realistic watchlists.
	ids := make([]int64, 0, len(items))
	for _, it := range items {
		ids = append(ids, it.ID)
	}
	history, _ := a.Store.LoadRecentPriceHistory(r.Context(), ids, 20)

	render(w, r, templates.Items(templates.ItemsData{
		Page:             a.page(r, "Items", "items"),
		Items:            items,
		Categories:       cats,
		SelectedCategory: cat,
		PriceHistory:     history,
	}))
}

func (a *App) GetNewItem(w http.ResponseWriter, r *http.Request) {
	cats, _ := a.Store.ListCategories(r.Context())
	render(w, r, templates.ItemForm(templates.ItemFormData{
		Page:       a.page(r, "Add Item", "items"),
		IsEdit:     false,
		Categories: cats,
		Item: models.Item{
			NtfyPriority:        "default",
			PollIntervalMinutes: a.Cfg.Scheduler.GlobalPollIntervalMinutes,
			Marketplaces:        []string{"ebay.com"},
			ListingType:         "all",
		},
	}))
}

func (a *App) GetEditItem(w http.ResponseWriter, r *http.Request) {
	id := intParam(r, "id")
	it, err := a.Store.GetItem(r.Context(), id)
	if err != nil || it == nil {
		http.NotFound(w, r)
		return
	}
	cats, _ := a.Store.ListCategories(r.Context())
	render(w, r, templates.ItemForm(templates.ItemFormData{
		Page:       a.page(r, "Edit "+it.Name, "items"),
		IsEdit:     true,
		Item:       *it,
		Categories: cats,
	}))
}

// parseItemForm pulls form fields into a models.Item plus a list of validation
// errors. Used by preview, create, and update.
func parseItemForm(r *http.Request) (models.Item, []string) {
	var it models.Item
	var errs []string
	if err := r.ParseForm(); err != nil {
		return it, []string{"could not parse form"}
	}
	it.Name = strings.TrimSpace(r.PostFormValue("name"))
	it.SearchQuery = strings.Join(models.SplitList(r.PostFormValue("search_query"), 10), "\n")
	it.ExcludeKeywords = strings.Join(models.SplitList(r.PostFormValue("exclude_keywords"), 20), "\n")
	it.URL = strings.TrimSpace(r.PostFormValue("url"))
	if newCat := strings.TrimSpace(r.PostFormValue("category_new")); newCat != "" {
		it.Category = newCat
	} else {
		it.Category = strings.TrimSpace(r.PostFormValue("category"))
	}
	it.NtfyTopic = strings.TrimSpace(r.PostFormValue("ntfy_topic"))
	it.NtfyPriority = strings.TrimSpace(r.PostFormValue("ntfy_priority"))
	if it.NtfyPriority == "" {
		it.NtfyPriority = "default"
	}
	it.Marketplaces = collectMarketplaces(r.PostForm["marketplace"], r.PostFormValue("marketplace_custom"))
	it.ListingType = strings.TrimSpace(r.PostFormValue("listing_type"))
	it.Condition = strings.TrimSpace(r.PostFormValue("condition"))
	it.Region = strings.ToUpper(strings.TrimSpace(r.PostFormValue("region")))
	it.ActorActive = strings.TrimSpace(r.PostFormValue("actor_active"))
	it.ActorSold = strings.TrimSpace(r.PostFormValue("actor_sold"))
	it.ActorPriceCompare = strings.TrimSpace(r.PostFormValue("actor_price_compare"))
	it.IncludeOutOfStock = r.PostFormValue("include_out_of_stock") == "1"
	it.UsePriceComparison = r.PostFormValue("use_price_comparison") == "1"
	it.Active = true

	if tp := strings.TrimSpace(r.PostFormValue("target_price")); tp != "" {
		if v, err := strconv.ParseFloat(tp, 64); err == nil && v >= 0 {
			it.TargetPrice = &v
		}
	}
	if mp := strings.TrimSpace(r.PostFormValue("min_price")); mp != "" {
		if v, err := strconv.ParseFloat(mp, 64); err == nil && v >= 0 {
			it.MinPrice = &v
		}
	}
	if pi := strings.TrimSpace(r.PostFormValue("poll_interval_minutes")); pi != "" {
		if v, err := strconv.Atoi(pi); err == nil && v > 0 {
			it.PollIntervalMinutes = v
		}
	}
	if it.PollIntervalMinutes == 0 {
		it.PollIntervalMinutes = 60
	}

	if it.Name == "" {
		errs = append(errs, "name is required")
	}
	if it.SearchQuery == "" && it.URL == "" {
		errs = append(errs, "either search query or product URL is required")
	}
	if it.NtfyTopic == "" {
		// Default to a slug of the name.
		it.NtfyTopic = slugify(it.Name)
	}
	return it, errs
}

// collectMarketplaces dedupes the checkbox values + custom CSV input into an
// ordered slice. Checkbox order first, then custom entries in the order the
// user typed them.
func collectMarketplaces(checked []string, custom string) []string {
	seen := map[string]bool{}
	var out []string
	add := func(v string) {
		v = strings.TrimSpace(v)
		if v == "" || seen[v] {
			return
		}
		seen[v] = true
		out = append(out, v)
	}
	for _, v := range checked {
		add(v)
	}
	for _, v := range strings.Split(custom, ",") {
		add(v)
	}
	return out
}

func slugify(s string) string {
	s = strings.ToLower(strings.TrimSpace(s))
	var b strings.Builder
	for _, r := range s {
		switch {
		case r >= 'a' && r <= 'z', r >= '0' && r <= '9':
			b.WriteRune(r)
		case r == ' ', r == '_', r == '-':
			b.WriteRune('-')
		}
	}
	out := b.String()
	if out == "" {
		return "veola-item"
	}
	return out
}

func (a *App) PostPreview(w http.ResponseWriter, r *http.Request) {
	it, errs := parseItemForm(r)
	if len(errs) > 0 {
		render(w, r, templates.ItemPreview(templates.PreviewData{
			CSRFToken: a.Auth.CSRFToken(r.Context()),
			Form:      formValuesFromItem(it, r),
			Error:     strings.Join(errs, "; "),
		}))
		return
	}
	results, source, cached, err := a.runPreview(r.Context(), it)
	if err != nil {
		render(w, r, templates.ItemPreview(templates.PreviewData{
			CSRFToken: a.Auth.CSRFToken(r.Context()),
			Form:      formValuesFromItem(it, r),
			Error:     err.Error(),
		}))
		return
	}
	results = scheduler.FilterResults(results, a.Cfg.Scheduler.MatchConfidenceThreshold, it.IncludeOutOfStock)
	results = scheduler.ApplyItemFilters(results, it.MinPrice, it.ExcludeKeywordsList())
	if len(results) == 0 {
		render(w, r, templates.ItemPreview(templates.PreviewData{
			CSRFToken: a.Auth.CSRFToken(r.Context()),
			Form:      formValuesFromItem(it, r),
			Empty:     true,
		}))
		return
	}
	bestIdx := scheduler.PickBest(results)
	minP, maxP := results[0].Price, results[0].Price
	stores := map[string]struct{}{}
	cur := results[0].Currency
	for _, r := range results {
		if r.Price < minP {
			minP = r.Price
		}
		if r.Price > maxP {
			maxP = r.Price
		}
		stores[r.Store] = struct{}{}
	}
	render(w, r, templates.ItemPreview(templates.PreviewData{
		CSRFToken:  a.Auth.CSRFToken(r.Context()),
		Form:       formValuesFromItem(it, r),
		Results:    results,
		BestIndex:  bestIdx,
		MinPrice:   minP,
		MaxPrice:   maxP,
		StoreCount: len(stores),
		Cached:     cached,
		Currency:   cur,
	}))
	_ = source
}

func (a *App) runPreview(ctx context.Context, it models.Item) ([]apify.UnifiedResult, string, bool, error) {
	plans := a.Scheduler.BuildPreviewInputs(it)
	if len(plans) == 0 {
		return nil, "", false, fmt.Errorf("no actor configured for this item")
	}
	previewMarket := ""
	if len(it.Marketplaces) > 0 {
		previewMarket = it.Marketplaces[0]
	}
	queries := it.SearchQueries()
	sortedQ := make([]string, len(queries))
	copy(sortedQ, queries)
	sort.Strings(sortedQ)
	actorIDs := make([]string, 0, len(plans))
	for _, p := range plans {
		actorIDs = append(actorIDs, p.ActorID())
	}
	sort.Strings(actorIDs)
	key := previewKey{
		Queries:     strings.Join(sortedQ, "\n"),
		URL:         it.URL,
		Marketplace: previewMarket,
		ListingType: it.ListingType,
		ActorIDs:    strings.Join(actorIDs, ","),
		Condition:   it.Condition,
		Region:      it.Region,
		MaxResults:  30,
	}
	if cached, src, ok := a.Preview.Get(key); ok {
		return cached, src, true, nil
	}
	var merged []apify.UnifiedResult
	primarySource := ""
	for _, p := range plans {
		decoded, err := a.Scheduler.ExecutePlan(ctx, p)
		if err != nil {
			slog.Warn("preview plan failed",
				"provider", p.Provider(),
				"marketplace", p.Marketplace(),
				"query", p.Query(),
				"err", err,
			)
			continue
		}
		merged = append(merged, decoded...)
		if primarySource == "" {
			primarySource = p.Source()
		}
	}
	merged = scheduler.DedupByURL(merged)
	a.Preview.Put(key, merged, primarySource)
	return merged, primarySource, false, nil
}

func formValuesFromItem(it models.Item, r *http.Request) templates.FormValues {
	tp := ""
	if it.TargetPrice != nil {
		tp = fmt.Sprintf("%.2f", *it.TargetPrice)
	}
	mp := ""
	if it.MinPrice != nil {
		mp = fmt.Sprintf("%.2f", *it.MinPrice)
	}
	return templates.FormValues{
		Name:                it.Name,
		SearchQuery:         it.SearchQuery,
		URL:                 it.URL,
		Category:            it.Category,
		TargetPrice:         tp,
		MinPrice:            mp,
		ExcludeKeywords:     it.ExcludeKeywords,
		NtfyTopic:           it.NtfyTopic,
		NtfyPriority:        it.NtfyPriority,
		PollIntervalMinutes: fmt.Sprintf("%d", it.PollIntervalMinutes),
		IncludeOutOfStock:   it.IncludeOutOfStock,
		Marketplaces:        it.Marketplaces,
		ListingType:         it.ListingType,
		Condition:           it.Condition,
		Region:              it.Region,
		ActorActive:         it.ActorActive,
		ActorSold:           it.ActorSold,
		ActorPriceCompare:   it.ActorPriceCompare,
		UsePriceComparison:  it.UsePriceComparison,
	}
}

func (a *App) PostCreateItem(w http.ResponseWriter, r *http.Request) {
	it, errs := parseItemForm(r)
	if len(errs) > 0 {
		http.Error(w, strings.Join(errs, "; "), http.StatusBadRequest)
		return
	}
	id, err := a.Store.CreateItem(r.Context(), &it)
	if err != nil {
		a.serverError(w, r, err)
		return
	}
	it.ID = id
	a.Scheduler.SyncItem(it)

	go func() {
		bg := context.Background()
		fresh, err := a.Store.GetItem(bg, id)
		if err != nil || fresh == nil {
			return
		}
		a.Scheduler.SeedSoldHistory(bg, *fresh)
		a.Scheduler.RunPoll(bg, *fresh)
	}()

	http.Redirect(w, r, fmt.Sprintf("/items/%d/results", id), http.StatusSeeOther)
}

func (a *App) PostUpdateItem(w http.ResponseWriter, r *http.Request) {
	id := intParam(r, "id")
	existing, err := a.Store.GetItem(r.Context(), id)
	if err != nil || existing == nil {
		http.NotFound(w, r)
		return
	}
	updated, errs := parseItemForm(r)
	if len(errs) > 0 {
		cats, _ := a.Store.ListCategories(r.Context())
		updated.ID = id
		render(w, r, templates.ItemForm(templates.ItemFormData{
			Page:       a.page(r, "Edit "+updated.Name, "items"),
			IsEdit:     true,
			Item:       updated,
			Errors:     errs,
			Categories: cats,
		}))
		return
	}
	updated.ID = id
	updated.Active = existing.Active
	if err := a.Store.UpdateItem(r.Context(), &updated); err != nil {
		a.serverError(w, r, err)
		return
	}
	a.Scheduler.SyncItem(updated)
	http.Redirect(w, r, "/items", http.StatusSeeOther)
}

func (a *App) PostToggleItem(w http.ResponseWriter, r *http.Request) {
	id := intParam(r, "id")
	it, err := a.Store.GetItem(r.Context(), id)
	if err != nil || it == nil {
		http.NotFound(w, r)
		return
	}
	it.Active = !it.Active
	if err := a.Store.SetItemActive(r.Context(), id, it.Active); err != nil {
		a.serverError(w, r, err)
		return
	}
	a.Scheduler.SyncItem(*it)
	hist, _ := a.Store.LoadRecentPriceHistory(r.Context(), []int64{id}, 20)
	render(w, r, templates.ItemRow(*it, a.Auth.CSRFToken(r.Context()), hist[id]))
}

func (a *App) PostDeleteItem(w http.ResponseWriter, r *http.Request) {
	id := intParam(r, "id")
	if err := a.Store.DeleteItem(r.Context(), id); err != nil {
		a.serverError(w, r, err)
		return
	}
	a.Scheduler.RemoveItem(id)
	render(w, r, templates.EmptyRow())
}

func (a *App) PostRunItem(w http.ResponseWriter, r *http.Request) {
	id := intParam(r, "id")
	it, err := a.Store.GetItem(r.Context(), id)
	if err != nil || it == nil {
		http.NotFound(w, r)
		return
	}

	// Run synchronously so the response reflects the finished poll. Bounded so
	// a slow Apify actor run can't tie the request up indefinitely (eBay
	// Browse API polls finish in seconds, well within this). Detached from the
	// request context so a client disconnect mid-run doesn't abort DB writes.
	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Minute)
	defer cancel()
	a.Scheduler.RunPoll(ctx, *it)

	// A partial swap (single row or just the results table) leaves the rest
	// of the page — best-price card, price chart, "last polled" time, badge —
	// looking stale, so the run reads as a no-op. Tell htmx to do a full
	// reload so every derived view picks up the post-poll state.
	if r.Header.Get("HX-Request") != "" {
		w.Header().Set("HX-Refresh", "true")
		w.WriteHeader(http.StatusNoContent)
		return
	}

	// Non-htmx fallback: redirect back to the originating page.
	target := "/items"
	if r.PostFormValue("from") == "results" {
		target = fmt.Sprintf("/items/%d/results", id)
	}
	http.Redirect(w, r, target, http.StatusSeeOther)
}

func (a *App) GetItemError(w http.ResponseWriter, r *http.Request) {
	id := intParam(r, "id")
	it, err := a.Store.GetItem(r.Context(), id)
	if err != nil || it == nil {
		http.NotFound(w, r)
		return
	}
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	fmt.Fprintf(w, "<span>%s</span>", htmlEscape(it.LastPollError))
}

func htmlEscape(s string) string {
	r := strings.NewReplacer("&", "&amp;", "<", "&lt;", ">", "&gt;", "\"", "&quot;")
	return r.Replace(s)
}