package scheduler

import (
	"context"
	"fmt"
	"log/slog"
	"strconv"
	"strings"
	"sync"
	"time"

	"github.com/robfig/cron/v3"

	"veola/internal/apify"
	"veola/internal/config"
	"veola/internal/db"
	"veola/internal/ebay"
	"veola/internal/models"
	"veola/internal/ntfy"
)

// Provider labels distinguish how a plan is executed: through an Apify actor
// run, or through eBay's official Browse API.
const (
	providerApify = "apify"
	providerEbay  = "ebay"
)

type Scheduler struct {
	cfg      *config.Config
	store    *db.Store
	apify    *apify.Client
	ebay     *ebay.Client
	ntfy     *ntfy.Client
	cron     *cron.Cron

	mu      sync.Mutex
	entries map[int64]cron.EntryID

	rootCtx context.Context
	cancel  context.CancelFunc
}

func New(cfg *config.Config, store *db.Store, ap *apify.Client, nt *ntfy.Client) *Scheduler {
	rootCtx, cancel := context.WithCancel(context.Background())
	return &Scheduler{
		cfg:     cfg,
		store:   store,
		apify:   ap,
		ebay:    ebay.New(cfg.Ebay.ClientID, cfg.Ebay.ClientSecret, cfg.Ebay.Environment),
		ntfy:    nt,
		cron:    cron.New(),
		entries: make(map[int64]cron.EntryID),
		rootCtx: rootCtx,
		cancel:  cancel,
	}
}

func (s *Scheduler) Start(ctx context.Context) error {
	items, err := s.store.ListActiveItems(ctx)
	if err != nil {
		return err
	}
	for _, it := range items {
		s.register(it)
	}
	s.cron.Start()
	slog.Info("scheduler started", "items", len(items))
	return nil
}

// Stop blocks until running jobs complete.
func (s *Scheduler) Stop() {
	s.cancel()
	stopCtx := s.cron.Stop()
	<-stopCtx.Done()
	slog.Info("scheduler stopped")
}

// SyncItem registers, re-registers, or removes the cron job for an item based
// on its current Active flag. Call after create/update/toggle/delete.
func (s *Scheduler) SyncItem(it models.Item) {
	s.mu.Lock()
	defer s.mu.Unlock()
	if existing, ok := s.entries[it.ID]; ok {
		s.cron.Remove(existing)
		delete(s.entries, it.ID)
	}
	if !it.Active {
		return
	}
	s.registerLocked(it)
}

func (s *Scheduler) RemoveItem(id int64) {
	s.mu.Lock()
	defer s.mu.Unlock()
	if existing, ok := s.entries[id]; ok {
		s.cron.Remove(existing)
		delete(s.entries, id)
	}
}

func (s *Scheduler) register(it models.Item) {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.registerLocked(it)
}

func (s *Scheduler) registerLocked(it models.Item) {
	mins := it.PollIntervalMinutes
	if mins <= 0 {
		mins = s.cfg.Scheduler.GlobalPollIntervalMinutes
	}
	if mins <= 0 {
		mins = 60
	}
	spec := fmt.Sprintf("@every %dm", mins)
	id := it.ID
	entryID, err := s.cron.AddFunc(spec, func() {
		ctx, cancel := context.WithTimeout(s.rootCtx, 10*time.Minute)
		defer cancel()
		fresh, err := s.store.GetItem(ctx, id)
		if err != nil || fresh == nil || !fresh.Active {
			return
		}
		s.RunPoll(ctx, *fresh)
	})
	if err != nil {
		slog.Error("schedule failed", "item_id", it.ID, "err", err)
		return
	}
	s.entries[it.ID] = entryID
}

// RunPoll executes one poll cycle for an item. Public so handlers can trigger
// "Run Now" without going through cron. Iterates over each (alias × marketplace)
// pair; a single failing combo does not poison the others.
func (s *Scheduler) RunPoll(ctx context.Context, it models.Item) {
	plans := s.buildAllInputs(it)
	if len(plans) == 0 {
		s.recordError(ctx, it.ID, "no marketplaces configured for this item")
		return
	}
	apifyClient := s.apifyClient(ctx)
	var results []apify.UnifiedResult
	var errs []string
	successes := 0
	for _, p := range plans {
		decoded, err := s.ExecutePlan(ctx, p)
		if err != nil {
			label := p.marketplace
			if p.query != "" {
				label = fmt.Sprintf("query %q on %s", p.query, p.marketplace)
			}
			errs = append(errs, fmt.Sprintf("%s: %s", label, err.Error()))
			slog.Error("plan failed", "item_id", it.ID, "provider", p.provider, "marketplace", p.marketplace, "query", p.query, "err", err)
			continue
		}
		results = append(results, decoded...)
		successes++
	}
	if successes == 0 {
		s.recordError(ctx, it.ID, strings.Join(errs, "; "))
		return
	}

	if it.UsePriceComparison {
		pcID := it.ActorPriceCompare
		if pcID == "" {
			pcID = s.cfg.Apify.Actors.PriceComparison
		}
		if pcID != "" {
			pcQueries := it.SearchQueries()
			if len(pcQueries) == 0 && it.URL != "" {
				pcQueries = []string{""}
			}
			for _, q := range pcQueries {
				pcRaw, err := apifyClient.Run(ctx, pcID, apify.PriceComparisonInput{
					Query: q, URL: it.URL,
					ProxyConfiguration: s.proxyConfig(),
				})
				if err == nil {
					pc, _ := apify.Decode(pcRaw, apify.SourcePriceCompare)
					for i := range pc {
						pc[i].MatchedQuery = q
					}
					results = append(results, pc...)
				} else {
					slog.Warn("price comparison failed", "item_id", it.ID, "query", q, "err", err)
				}
			}
		}
	}

	beforeDedup := len(results)
	results = DedupByURL(results)

	threshold := s.cfg.Scheduler.MatchConfidenceThreshold
	beforeFilter := len(results)
	results = FilterResults(results, threshold, it.IncludeOutOfStock)
	results = ApplyItemFilters(results, it.MinPrice, it.ExcludeKeywordsList())
	slog.Info("filter applied",
		"item_id", it.ID,
		"before_dedup", beforeDedup,
		"before_filter", beforeFilter,
		"after", len(results),
		"min_confidence", threshold,
		"min_price", it.MinPrice,
		"exclude_count", len(it.ExcludeKeywordsList()),
		"include_out_of_stock", it.IncludeOutOfStock,
	)

	bestIdx := PickBest(results)
	alertsSent := 0
	for _, r := range results {
		exists, err := s.store.ResultExists(ctx, it.ID, r.URL)
		if err != nil {
			slog.Error("dedup check failed", "err", err)
			continue
		}
		if exists {
			// Row already stored — but if this poll surfaced an end time we
			// didn't have before (or the row predates the ends_at column),
			// backfill it so countdowns light up for known auctions.
			if r.EndsAt != nil {
				if err := s.store.BackfillResultEndsAt(ctx, it.ID, r.URL, *r.EndsAt); err != nil {
					slog.Error("backfill ends_at failed", "err", err)
				}
			}
			continue
		}
		alerted := false
		if ShouldAlert(it.TargetPrice, r.Price) {
			if err := s.sendNotification(ctx, it, r); err != nil {
				slog.Error("ntfy send failed", "err", err)
			} else {
				alerted = true
				alertsSent++
			}
		}
		price := r.Price
		_, err = s.store.InsertResult(ctx, &models.Result{
			ItemID:       it.ID,
			Title:        r.Title,
			Price:        &price,
			Currency:     r.Currency,
			URL:          r.URL,
			Source:       r.Source,
			ImageURL:     r.ImageURL,
			MatchedQuery: r.MatchedQuery,
			Alerted:      alerted,
			EndsAt:       r.EndsAt,
		})
		if err != nil {
			slog.Error("insert result failed", "err", err)
		}
	}

	errMsg := ""
	if len(errs) > 0 {
		errMsg = strings.Join(errs, "; ")
	}
	if bestIdx >= 0 {
		best := results[bestIdx]
		bp := best.Price
		_ = s.store.UpdateItemPollResult(ctx, it.ID, &models.Item{
			BestPrice:         &bp,
			BestPriceCurrency: best.Currency,
			BestPriceStore:    best.Store,
			BestPriceURL:      best.URL,
			BestPriceImageURL: best.ImageURL,
			BestPriceTitle:    best.Title,
		}, errMsg)
		_ = s.store.InsertPricePoint(ctx, &models.PricePoint{
			ItemID: it.ID,
			Price:  bp,
			Store:  best.Store,
		})
	} else {
		_ = s.store.UpdateItemPollResult(ctx, it.ID, nil, errMsg)
	}

	slog.Info("poll completed",
		"item_id", it.ID,
		"item_name", it.Name,
		"marketplaces", len(plans),
		"successes", successes,
		"results", len(results),
		"alerts_sent", alertsSent,
	)
}

func (s *Scheduler) recordError(ctx context.Context, id int64, msg string) {
	if err := s.store.UpdateItemPollResult(ctx, id, nil, msg); err != nil {
		slog.Error("record error failed", "err", err)
	}
}

// apifyClient returns an apify.Client whose API key reflects the latest
// value from settings, falling back to config.toml.
func (s *Scheduler) apifyClient(ctx context.Context) *apify.Client {
	key := s.cfg.Apify.APIKey
	if v, _ := s.store.GetSetting(ctx, "apify_api_key"); v != "" {
		key = v
	}
	return apify.New(key)
}

// ebayClient returns the shared eBay client with credentials refreshed from
// settings (falling back to config.toml). The client caches its OAuth token
// in memory, so the same instance is reused across polls; credentials are
// only re-applied when they actually change.
func (s *Scheduler) ebayClient(ctx context.Context) *ebay.Client {
	id := s.cfg.Ebay.ClientID
	secret := s.cfg.Ebay.ClientSecret
	if v, _ := s.store.GetSetting(ctx, "ebay_client_id"); v != "" {
		id = v
	}
	if v, _ := s.store.GetSetting(ctx, "ebay_client_secret"); v != "" {
		secret = v
	}
	s.ebay.EnsureCredentials(id, secret)
	return s.ebay
}

// EbayUsage returns the number of eBay Browse API calls made so far today and
// the configured daily limit. A limit <= 0 means uncapped. Settings override
// config.toml for the limit, mirroring how credentials are resolved.
func (s *Scheduler) EbayUsage(ctx context.Context) (used, limit int) {
	used, _ = s.store.EbayUsageToday(ctx)
	limit = s.cfg.Ebay.DailyCallLimit
	if v, _ := s.store.GetSetting(ctx, "ebay_daily_call_limit"); v != "" {
		if n, err := strconv.Atoi(strings.TrimSpace(v)); err == nil {
			limit = n
		}
	}
	return used, limit
}

// ExecutePlan runs one plan and returns decoded, provider-agnostic results
// with MatchedQuery already stamped. eBay plans go through the official
// Browse API; all other plans run an Apify actor. Callers handle per-plan
// errors without poisoning sibling plans.
func (s *Scheduler) ExecutePlan(ctx context.Context, p actorPlan) ([]apify.UnifiedResult, error) {
	var decoded []apify.UnifiedResult
	switch p.provider {
	case providerEbay:
		sp, ok := p.input.(ebay.SearchParams)
		if !ok {
			return nil, fmt.Errorf("ebay plan has wrong input type %T", p.input)
		}
		used, limit := s.EbayUsage(ctx)
		if limit > 0 && used >= limit {
			return nil, fmt.Errorf("ebay daily API call limit reached (%d/%d); polling halted until the next reset (midnight US Pacific)", used, limit)
		}
		listings, err := s.ebayClient(ctx).Search(ctx, sp)
		// The call hit eBay (or at least was attempted against it) whether
		// or not it succeeded, so it counts against the daily allowance.
		if n, incErr := s.store.IncrementEbayUsage(ctx); incErr != nil {
			slog.Error("ebay usage increment failed", "err", incErr)
		} else if limit > 0 && n >= limit {
			slog.Warn("ebay daily API call limit reached", "used", n, "limit", limit)
		}
		if err != nil {
			return nil, err
		}
		decoded = make([]apify.UnifiedResult, 0, len(listings))
		for _, l := range listings {
			decoded = append(decoded, apify.UnifiedResult{
				Title:    l.Title,
				Price:    l.Price,
				Currency: l.Currency,
				URL:      l.URL,
				Store:    l.Store,
				ImageURL: l.ImageURL,
				Source:   apify.SourceActiveEbay,
				EndsAt:   l.EndsAt,
			})
		}
	default:
		if p.actorID == "" {
			return nil, fmt.Errorf("no actor configured for %s", p.marketplace)
		}
		raw, err := s.apifyClient(ctx).Run(ctx, p.actorID, p.input)
		if err != nil {
			return nil, err
		}
		decoded, _ = apify.Decode(raw, p.source)
	}
	usable := 0
	for i := range decoded {
		decoded[i].MatchedQuery = p.query
		if decoded[i].URL != "" && decoded[i].Price > 0 {
			usable++
		}
	}
	slog.Info("plan executed",
		"provider", p.provider,
		"marketplace", p.marketplace,
		"query", p.query,
		"decoded", len(decoded),
		"usable", usable,
	)
	return decoded, nil
}

func (s *Scheduler) sendNotification(ctx context.Context, it models.Item, r apify.UnifiedResult) error {
	tags := []string{"mag"}
	if it.TargetPrice != nil && r.Price <= *it.TargetPrice {
		tags = []string{"shopping_cart", "tada"}
	}
	priority := it.NtfyPriority
	if priority == "" {
		priority = "default"
	}
	topic := it.NtfyTopic
	if topic == "" {
		if v, _ := s.store.GetSetting(ctx, "ntfy_default_topic"); v != "" {
			topic = v
		} else {
			topic = s.cfg.Ntfy.DefaultTopic
		}
	}
	msg := fmt.Sprintf("%s %s%.2f", r.Store, currencyPrefix(r.Currency), r.Price)
	if it.TargetPrice != nil {
		msg += fmt.Sprintf(" (target: %s%.2f)", currencyPrefix(r.Currency), *it.TargetPrice)
	}
	if r.Title != "" {
		msg += "\n" + r.Title
	}
	baseURL := s.cfg.Ntfy.BaseURL
	if v, _ := s.store.GetSetting(ctx, "ntfy_base_url"); v != "" {
		baseURL = v
	}
	token, _ := s.store.GetSetting(ctx, "ntfy_token")
	client := ntfy.NewWithToken(baseURL, token)
	return client.Send(ctx, ntfy.Notification{
		Topic:    topic,
		Title:    fmt.Sprintf("Veola Alert: %s", it.Name),
		Message:  msg,
		Priority: priority,
		Tags:     tags,
		Click:    r.URL,
	})
}

func currencyPrefix(c string) string {
	switch c {
	case "USD", "":
		return "$"
	case "GBP":
		return "£"
	case "EUR":
		return "€"
	case "JPY":
		return "¥"
	}
	return c + " "
}

// BuildPreviewInputs returns one actor plan per alias for the first marketplace
// on the item. Preview deliberately uses only one marketplace to limit actor
// runs, but exercises every alias so the operator sees the full result set.
func (s *Scheduler) BuildPreviewInputs(it models.Item) []actorPlan {
	queries := it.SearchQueries()
	if len(queries) == 0 {
		queries = []string{""}
	}
	markets := it.Marketplaces
	if len(markets) > 1 {
		markets = markets[:1]
	}
	var out []actorPlan
	for _, q := range queries {
		out = append(out, s.buildInputsForQuery(it, q, markets)...)
	}
	return out
}

type actorPlan struct {
	marketplace string
	source      string
	provider    string
	actorID     string
	query       string
	input       any
}

// Marketplace returns the marketplace for this plan.
func (p actorPlan) Marketplace() string { return p.marketplace }

// Source returns the result-source label (used to pick a decoder).
func (p actorPlan) Source() string { return p.source }

// ActorID returns the Apify actor ID this plan will invoke.
func (p actorPlan) ActorID() string { return p.actorID }

// Query returns the alias string this plan searches for. Empty for URL-only items.
func (p actorPlan) Query() string { return p.query }

// Input returns the actor input payload as expected by apify.Client.Run.
func (p actorPlan) Input() any { return p.input }

// Provider returns "apify" or "ebay" — how this plan is executed.
func (p actorPlan) Provider() string { return p.provider }

// buildAllInputs returns one actor plan per (alias × marketplace) for the item.
// For URL-only items (no aliases), produces one plan per marketplace with an
// empty query string.
func (s *Scheduler) buildAllInputs(it models.Item) []actorPlan {
	queries := it.SearchQueries()
	if len(queries) == 0 {
		queries = []string{""}
	}
	markets := it.Marketplaces
	if len(markets) == 0 {
		markets = []string{"ebay.com"}
	}
	var out []actorPlan
	for _, q := range queries {
		out = append(out, s.buildInputsForQuery(it, q, markets)...)
	}
	return out
}

// buildInputsForQuery returns one actor plan per marketplace, all using the
// same query string. Used by both the scheduler and the preview path.
func (s *Scheduler) buildInputsForQuery(it models.Item, query string, markets []string) []actorPlan {
	url := strings.ToLower(it.URL)
	plans := make([]actorPlan, 0, len(markets))
	for _, m := range markets {
		mk := strings.ToLower(m)
		switch {
		case strings.Contains(mk, "yahoo") || strings.Contains(url, "yahoo.co.jp"):
			actorID := firstNonEmpty(it.ActorActive, s.cfg.Apify.Actors.YahooAuctionsJP)
			plans = append(plans, actorPlan{
				marketplace: m, source: apify.SourceYahooJP, provider: providerApify,
				actorID: actorID, query: query,
				input: apify.YahooAuctionsJPInput{SearchTerm: query, MaxPages: 1},
			})
		case strings.Contains(mk, "mercari") || strings.Contains(url, "mercari"):
			actorID := firstNonEmpty(it.ActorActive, s.cfg.Apify.Actors.MercariJP)
			plans = append(plans, actorPlan{
				marketplace: m, source: apify.SourceMercariJP, provider: providerApify,
				actorID: actorID, query: query,
				input: apify.MercariJPInput{
					SearchKeywords: []string{query},
					Status:         "on_sale",
					MaxResults:     30,
				},
			})
		case ebay.IsEbayMarketplace(mk):
			// eBay marketplaces are polled through eBay's official Browse
			// API, not an Apify scraper actor.
			plans = append(plans, actorPlan{
				marketplace: m, source: apify.SourceActiveEbay, provider: providerEbay,
				query: query,
				input: ebay.SearchParams{
					MarketplaceID: ebay.MarketplaceID(mk),
					Query:         query,
					ListingType:   it.ListingType,
					Condition:     it.Condition,
					Region:        it.Region,
					Limit:         30,
				},
			})
		default:
			// Non-eBay custom marketplaces still fall back to the Apify
			// active-listings actor.
			actorID := firstNonEmpty(it.ActorActive, s.cfg.Apify.Actors.ActiveListings)
			plans = append(plans, actorPlan{
				marketplace: m, source: apify.SourceActiveEbay, provider: providerApify,
				actorID: actorID, query: query,
				input: apify.ActiveListingInput{
					SearchQueries:        []string{query},
					MaxProductsPerSearch: 30,
					MaxSearchPages:       1,
					Sort:                 "best_match",
					ListingType:          mapListingType(it.ListingType),
					ProxyConfiguration:   s.proxyConfig(),
				},
			})
		}
	}
	return plans
}

// DedupByURL collapses duplicates within a single result set. When the same
// listing matches multiple aliases the first occurrence wins, including its
// MatchedQuery tag.
func DedupByURL(in []apify.UnifiedResult) []apify.UnifiedResult {
	seen := map[string]bool{}
	out := make([]apify.UnifiedResult, 0, len(in))
	for _, r := range in {
		if r.URL == "" {
			out = append(out, r)
			continue
		}
		key := r.Source + "|" + r.URL
		if seen[key] {
			continue
		}
		seen[key] = true
		out = append(out, r)
	}
	return out
}

// proxyConfig returns the apify proxyConfiguration block built from
// config.toml. Returns nil — meaning omit the field from actor input
// entirely — if use_apify_proxy is false. Group and country are ignored when
// use_apify_proxy is false to prevent contradictory input.
func (s *Scheduler) proxyConfig() *apify.ProxyConfiguration {
	p := s.cfg.Apify.Proxy
	if !p.UseApifyProxy {
		return nil
	}
	return &apify.ProxyConfiguration{
		UseApifyProxy:     true,
		ApifyProxyGroups:  p.Groups,
		ApifyProxyCountry: p.Country,
	}
}

// mapListingType translates Veola's listing-type vocabulary ("all", "BIN",
// "auction") into the automation-lab/ebay-scraper input vocabulary
// ("all", "buy_it_now", "auction"). Unrecognized values fall through as-is
// in case the user pasted a value the actor accepts but we don't.
func mapListingType(s string) string {
	switch strings.ToLower(s) {
	case "", "all":
		return "all"
	case "bin", "buy_it_now":
		return "buy_it_now"
	case "auction":
		return "auction"
	}
	return s
}

func firstNonEmpty(vs ...string) string {
	for _, v := range vs {
		if v != "" {
			return v
		}
	}
	return ""
}

// SeedSoldHistory runs the sold-listings actor and writes price_history rows
// for an item just added. Errors are logged and swallowed: a missing baseline
// is not fatal.
func (s *Scheduler) SeedSoldHistory(ctx context.Context, it models.Item) {
	queries := it.SearchQueries()
	if len(queries) == 0 {
		return
	}
	markets := it.Marketplaces
	if len(markets) == 0 {
		markets = []string{"ebay.com"}
	}
	for _, q := range queries {
		for _, m := range markets {
			s.seedSoldHistoryFor(ctx, it, q, m)
		}
	}
}

func (s *Scheduler) seedSoldHistoryFor(ctx context.Context, it models.Item, query, marketplace string) {
	actorID := firstNonEmpty(it.ActorSold, s.cfg.Apify.Actors.SoldListings)
	source := apify.SourceSoldEbay
	if strings.Contains(strings.ToLower(marketplace), "yahoo") {
		actorID = firstNonEmpty(it.ActorSold, s.cfg.Apify.Actors.YahooAuctionsJPSold)
		source = apify.SourceSoldYahooJP
	}
	if actorID == "" {
		return
	}
	raw, err := s.apifyClient(ctx).Run(ctx, actorID, apify.SoldListingInput{
		Query: query, Marketplace: marketplace, MaxResults: 50, DaysBack: 30,
		ProxyConfiguration: s.proxyConfig(),
	})
	if err != nil {
		slog.Warn("sold history seed failed", "item_id", it.ID, "marketplace", marketplace, "query", query, "err", err)
		return
	}
	for _, r := range raw {
		var sold apify.SoldListingResult
		if err := jsonUnmarshal(r, &sold); err != nil || sold.SoldPrice <= 0 {
			continue
		}
		t, _ := time.Parse(time.RFC3339, sold.SoldAt)
		if t.IsZero() {
			t = time.Now()
		}
		_ = s.store.InsertPricePoint(ctx, &models.PricePoint{
			ItemID:   it.ID,
			Price:    sold.SoldPrice,
			Store:    sourceLabelToStore(source),
			PolledAt: t,
		})
	}
}

func sourceLabelToStore(src string) string {
	switch src {
	case apify.SourceSoldYahooJP:
		return "yahoo-auctions-jp-sold"
	}
	return "ebay-sold"
}