package db

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"log/slog"
	"strings"
	"time"

	"veola/internal/crypto"
	"veola/internal/models"
)

// Store wraps a *sql.DB with the encryption key used for column-level crypto.
type Store struct {
	DB  *sql.DB
	Key []byte
}

func NewStore(db *sql.DB, key []byte) *Store {
	return &Store{DB: db, Key: key}
}

// enc encrypts plaintext, logging and returning empty string on failure.
func (s *Store) enc(plain string) string {
	if plain == "" {
		return ""
	}
	v, err := crypto.Encrypt(s.Key, plain)
	if err != nil {
		slog.Error("encrypt failed", "err", err)
		return ""
	}
	return v
}

// dec decrypts a value; on failure returns "" per spec line 333.
func (s *Store) dec(v string) string {
	if v == "" {
		return ""
	}
	out, err := crypto.Decrypt(s.Key, v)
	if err != nil {
		slog.Error("decrypt failed", "err", err)
		return ""
	}
	return out
}

func nullStr(s string) sql.NullString {
	if s == "" {
		return sql.NullString{}
	}
	return sql.NullString{String: s, Valid: true}
}

func nullFloat(f *float64) sql.NullFloat64 {
	if f == nil {
		return sql.NullFloat64{}
	}
	return sql.NullFloat64{Float64: *f, Valid: true}
}

func nullTime(t *time.Time) sql.NullTime {
	if t == nil {
		return sql.NullTime{}
	}
	return sql.NullTime{Time: *t, Valid: true}
}

func ptrFloat(f sql.NullFloat64) *float64 {
	if !f.Valid {
		return nil
	}
	v := f.Float64
	return &v
}

func ptrTime(t sql.NullTime) *time.Time {
	if !t.Valid {
		return nil
	}
	v := t.Time
	return &v
}

// ============ users ============

func (s *Store) UserCount(ctx context.Context) (int, error) {
	var n int
	err := s.DB.QueryRowContext(ctx, `SELECT COUNT(*) FROM users`).Scan(&n)
	return n, err
}

func (s *Store) CreateUser(ctx context.Context, username, hash string, role models.Role) (int64, error) {
	res, err := s.DB.ExecContext(ctx,
		`INSERT INTO users (username, password_hash, role) VALUES (?, ?, ?)`,
		username, hash, string(role))
	if err != nil {
		return 0, err
	}
	return res.LastInsertId()
}

func (s *Store) GetUserByUsername(ctx context.Context, username string) (*models.User, error) {
	row := s.DB.QueryRowContext(ctx,
		`SELECT id, username, password_hash, role, created_at FROM users WHERE username = ?`,
		username)
	var u models.User
	var role string
	if err := row.Scan(&u.ID, &u.Username, &u.PasswordHash, &role, &u.CreatedAt); err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return nil, nil
		}
		return nil, err
	}
	u.Role = models.Role(role)
	return &u, nil
}

func (s *Store) GetUserByID(ctx context.Context, id int64) (*models.User, error) {
	row := s.DB.QueryRowContext(ctx,
		`SELECT id, username, password_hash, role, created_at FROM users WHERE id = ?`, id)
	var u models.User
	var role string
	if err := row.Scan(&u.ID, &u.Username, &u.PasswordHash, &role, &u.CreatedAt); err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return nil, nil
		}
		return nil, err
	}
	u.Role = models.Role(role)
	return &u, nil
}

func (s *Store) ListUsers(ctx context.Context) ([]models.User, error) {
	rows, err := s.DB.QueryContext(ctx,
		`SELECT id, username, password_hash, role, created_at FROM users ORDER BY id`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []models.User
	for rows.Next() {
		var u models.User
		var role string
		if err := rows.Scan(&u.ID, &u.Username, &u.PasswordHash, &role, &u.CreatedAt); err != nil {
			return nil, err
		}
		u.Role = models.Role(role)
		out = append(out, u)
	}
	return out, rows.Err()
}

func (s *Store) UpdateUserPassword(ctx context.Context, id int64, hash string) error {
	_, err := s.DB.ExecContext(ctx, `UPDATE users SET password_hash = ? WHERE id = ?`, hash, id)
	return err
}

func (s *Store) DeleteUser(ctx context.Context, id int64) error {
	_, err := s.DB.ExecContext(ctx, `DELETE FROM users WHERE id = ?`, id)
	return err
}

// ============ settings ============

func (s *Store) GetSetting(ctx context.Context, key string) (string, error) {
	var v sql.NullString
	err := s.DB.QueryRowContext(ctx, `SELECT value FROM settings WHERE key = ?`, key).Scan(&v)
	if errors.Is(err, sql.ErrNoRows) {
		return "", nil
	}
	if err != nil {
		return "", err
	}
	if !v.Valid {
		return "", nil
	}
	return s.dec(v.String), nil
}

func (s *Store) GetAllSettings(ctx context.Context) (map[string]string, error) {
	rows, err := s.DB.QueryContext(ctx, `SELECT key, value FROM settings`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	out := make(map[string]string)
	for rows.Next() {
		var k string
		var v sql.NullString
		if err := rows.Scan(&k, &v); err != nil {
			return nil, err
		}
		if v.Valid {
			out[k] = s.dec(v.String)
		} else {
			out[k] = ""
		}
	}
	return out, rows.Err()
}

func (s *Store) SetSetting(ctx context.Context, key, value string) error {
	enc := s.enc(value)
	_, err := s.DB.ExecContext(ctx, `
		INSERT INTO settings (key, value, updated_at) VALUES (?, ?, CURRENT_TIMESTAMP)
		ON CONFLICT(key) DO UPDATE SET value = excluded.value, updated_at = CURRENT_TIMESTAMP
	`, key, enc)
	return err
}

// ============ items ============

func (s *Store) CreateItem(ctx context.Context, it *models.Item) (int64, error) {
	res, err := s.DB.ExecContext(ctx, `
		INSERT INTO items (
			name, search_query, url, category, target_price, ntfy_topic, ntfy_priority,
			poll_interval_minutes, include_out_of_stock, min_price, exclude_keywords,
			listing_type,
			actor_active, actor_sold, actor_price_compare, use_price_comparison,
			active, best_price, best_price_store, best_price_url, best_price_image_url,
			best_price_title, last_polled_at
		) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
	`,
		it.Name, s.enc(it.SearchQuery), nullStr(it.URL), nullStr(it.Category),
		nullFloat(it.TargetPrice), s.enc(it.NtfyTopic), it.NtfyPriority,
		it.PollIntervalMinutes, boolToInt(it.IncludeOutOfStock),
		nullFloat(it.MinPrice), nullStr(s.enc(it.ExcludeKeywords)),
		nullStr(it.ListingType),
		nullStr(it.ActorActive), nullStr(it.ActorSold), nullStr(it.ActorPriceCompare),
		boolToInt(it.UsePriceComparison), boolToInt(it.Active),
		nullFloat(it.BestPrice), nullStr(it.BestPriceStore),
		nullStr(s.enc(it.BestPriceURL)), nullStr(s.enc(it.BestPriceImageURL)),
		nullStr(s.enc(it.BestPriceTitle)), nullTime(it.LastPolledAt),
	)
	if err != nil {
		return 0, err
	}
	id, err := res.LastInsertId()
	if err != nil {
		return 0, err
	}
	if err := s.SetItemMarketplaces(ctx, id, it.Marketplaces); err != nil {
		return 0, err
	}
	return id, nil
}

func (s *Store) UpdateItem(ctx context.Context, it *models.Item) error {
	if _, err := s.DB.ExecContext(ctx, `
		UPDATE items SET
			name = ?, search_query = ?, url = ?, category = ?, target_price = ?,
			ntfy_topic = ?, ntfy_priority = ?, poll_interval_minutes = ?,
			include_out_of_stock = ?, min_price = ?, exclude_keywords = ?,
			listing_type = ?,
			actor_active = ?, actor_sold = ?, actor_price_compare = ?,
			use_price_comparison = ?, active = ?, updated_at = CURRENT_TIMESTAMP
		WHERE id = ?
	`,
		it.Name, s.enc(it.SearchQuery), nullStr(it.URL), nullStr(it.Category),
		nullFloat(it.TargetPrice), s.enc(it.NtfyTopic), it.NtfyPriority,
		it.PollIntervalMinutes, boolToInt(it.IncludeOutOfStock),
		nullFloat(it.MinPrice), nullStr(s.enc(it.ExcludeKeywords)),
		nullStr(it.ListingType),
		nullStr(it.ActorActive), nullStr(it.ActorSold), nullStr(it.ActorPriceCompare),
		boolToInt(it.UsePriceComparison), boolToInt(it.Active),
		it.ID,
	); err != nil {
		return err
	}
	return s.SetItemMarketplaces(ctx, it.ID, it.Marketplaces)
}

// SetItemMarketplaces replaces the marketplace list for an item. Order is
// preserved via the `position` column.
func (s *Store) SetItemMarketplaces(ctx context.Context, itemID int64, markets []string) error {
	tx, err := s.DB.BeginTx(ctx, nil)
	if err != nil {
		return err
	}
	defer tx.Rollback()
	if _, err := tx.ExecContext(ctx, `DELETE FROM item_marketplaces WHERE item_id = ?`, itemID); err != nil {
		return err
	}
	for i, m := range markets {
		if m == "" {
			continue
		}
		if _, err := tx.ExecContext(ctx,
			`INSERT INTO item_marketplaces (item_id, position, marketplace) VALUES (?, ?, ?)`,
			itemID, i, m); err != nil {
			return err
		}
	}
	return tx.Commit()
}

// getItemMarketplaces returns the ordered marketplace list for one item.
func (s *Store) getItemMarketplaces(ctx context.Context, itemID int64) ([]string, error) {
	rows, err := s.DB.QueryContext(ctx,
		`SELECT marketplace FROM item_marketplaces WHERE item_id = ? ORDER BY position`, itemID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []string
	for rows.Next() {
		var m string
		if err := rows.Scan(&m); err != nil {
			return nil, err
		}
		out = append(out, m)
	}
	return out, rows.Err()
}

// loadMarketplacesForItems bulk-loads marketplaces for a list of items in one
// query. Returns a map keyed by item ID.
func (s *Store) loadMarketplacesForItems(ctx context.Context, ids []int64) (map[int64][]string, error) {
	out := make(map[int64][]string, len(ids))
	if len(ids) == 0 {
		return out, nil
	}
	placeholders := make([]string, len(ids))
	args := make([]any, len(ids))
	for i, id := range ids {
		placeholders[i] = "?"
		args[i] = id
	}
	q := `SELECT item_id, marketplace FROM item_marketplaces WHERE item_id IN (` +
		strings.Join(placeholders, ",") + `) ORDER BY item_id, position`
	rows, err := s.DB.QueryContext(ctx, q, args...)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	for rows.Next() {
		var id int64
		var m string
		if err := rows.Scan(&id, &m); err != nil {
			return nil, err
		}
		out[id] = append(out[id], m)
	}
	return out, rows.Err()
}

func (s *Store) SetItemActive(ctx context.Context, id int64, active bool) error {
	_, err := s.DB.ExecContext(ctx,
		`UPDATE items SET active = ?, updated_at = CURRENT_TIMESTAMP WHERE id = ?`,
		boolToInt(active), id)
	return err
}

func (s *Store) DeleteItem(ctx context.Context, id int64) error {
	_, err := s.DB.ExecContext(ctx, `DELETE FROM items WHERE id = ?`, id)
	return err
}

func (s *Store) GetItem(ctx context.Context, id int64) (*models.Item, error) {
	row := s.DB.QueryRowContext(ctx, itemSelect+` WHERE id = ?`, id)
	it, err := scanItem(row)
	if err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return nil, nil
		}
		return nil, err
	}
	s.decryptItem(it)
	markets, err := s.getItemMarketplaces(ctx, id)
	if err != nil {
		return nil, err
	}
	it.Marketplaces = markets
	return it, nil
}

func (s *Store) ListItems(ctx context.Context) ([]models.Item, error) {
	return s.listItemsWhere(ctx, itemSelect+` ORDER BY name COLLATE NOCASE`)
}

func (s *Store) ListActiveItems(ctx context.Context) ([]models.Item, error) {
	return s.listItemsWhere(ctx, itemSelect+` WHERE active = 1 ORDER BY id`)
}

func (s *Store) listItemsWhere(ctx context.Context, q string, args ...any) ([]models.Item, error) {
	rows, err := s.DB.QueryContext(ctx, q, args...)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []models.Item
	var ids []int64
	for rows.Next() {
		it, err := scanItem(rows)
		if err != nil {
			return nil, err
		}
		s.decryptItem(it)
		out = append(out, *it)
		ids = append(ids, it.ID)
	}
	if err := rows.Err(); err != nil {
		return nil, err
	}
	markets, err := s.loadMarketplacesForItems(ctx, ids)
	if err != nil {
		return nil, err
	}
	for i := range out {
		out[i].Marketplaces = markets[out[i].ID]
	}
	return out, nil
}

func (s *Store) ListCategories(ctx context.Context) ([]string, error) {
	rows, err := s.DB.QueryContext(ctx, `SELECT DISTINCT category FROM items WHERE category IS NOT NULL AND category != '' ORDER BY category COLLATE NOCASE`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []string
	for rows.Next() {
		var c string
		if err := rows.Scan(&c); err != nil {
			return nil, err
		}
		out = append(out, c)
	}
	return out, rows.Err()
}

// UpdateItemPollResult writes best-price fields, last_polled_at, last_poll_error.
func (s *Store) UpdateItemPollResult(ctx context.Context, id int64, best *models.Item, errMsg string) error {
	var (
		bestPrice                                          sql.NullFloat64
		bestStore, bestURL, bestImage, bestTitle, errField sql.NullString
	)
	if best != nil {
		bestPrice = nullFloat(best.BestPrice)
		bestStore = nullStr(best.BestPriceStore)
		bestURL = nullStr(s.enc(best.BestPriceURL))
		bestImage = nullStr(s.enc(best.BestPriceImageURL))
		bestTitle = nullStr(s.enc(best.BestPriceTitle))
	}
	if errMsg != "" {
		errField = nullStr(s.enc(errMsg))
	}
	_, err := s.DB.ExecContext(ctx, `
		UPDATE items SET
			best_price = ?, best_price_store = ?, best_price_url = ?,
			best_price_image_url = ?, best_price_title = ?,
			last_polled_at = CURRENT_TIMESTAMP, last_poll_error = ?
		WHERE id = ?
	`, bestPrice, bestStore, bestURL, bestImage, bestTitle, errField, id)
	return err
}

const itemSelect = `
	SELECT id, name, search_query, url, category, target_price, ntfy_topic, ntfy_priority,
	       poll_interval_minutes, include_out_of_stock, min_price, exclude_keywords,
	       listing_type,
	       actor_active, actor_sold, actor_price_compare, use_price_comparison,
	       active, last_polled_at, last_poll_error, best_price, best_price_store,
	       best_price_url, best_price_image_url, best_price_title, created_at, updated_at
	FROM items
`

type rowScanner interface {
	Scan(dest ...any) error
}

func scanItem(r rowScanner) (*models.Item, error) {
	var (
		it                                       models.Item
		searchQuery, urlS, category, listingType sql.NullString
		excludeKw                                sql.NullString
		actorA, actorS, actorP                   sql.NullString
		ntfyTopic, lastPollErr                   sql.NullString
		bestStore, bestURL, bestImage, bestTitle sql.NullString
		targetPrice, minPrice, bestPrice         sql.NullFloat64
		includeOOS, usePC, active                int
		lastPolledAt                             sql.NullTime
	)
	if err := r.Scan(
		&it.ID, &it.Name, &searchQuery, &urlS, &category, &targetPrice, &ntfyTopic, &it.NtfyPriority,
		&it.PollIntervalMinutes, &includeOOS, &minPrice, &excludeKw,
		&listingType,
		&actorA, &actorS, &actorP, &usePC,
		&active, &lastPolledAt, &lastPollErr, &bestPrice, &bestStore,
		&bestURL, &bestImage, &bestTitle, &it.CreatedAt, &it.UpdatedAt,
	); err != nil {
		return nil, err
	}
	it.ExcludeKeywords = excludeKw.String
	it.MinPrice = ptrFloat(minPrice)
	it.SearchQuery = searchQuery.String
	it.URL = urlS.String
	it.Category = category.String
	it.ListingType = listingType.String
	it.ActorActive = actorA.String
	it.ActorSold = actorS.String
	it.ActorPriceCompare = actorP.String
	it.NtfyTopic = ntfyTopic.String
	it.LastPollError = lastPollErr.String
	it.BestPriceStore = bestStore.String
	it.BestPriceURL = bestURL.String
	it.BestPriceImageURL = bestImage.String
	it.BestPriceTitle = bestTitle.String
	it.TargetPrice = ptrFloat(targetPrice)
	it.BestPrice = ptrFloat(bestPrice)
	it.IncludeOutOfStock = includeOOS != 0
	it.UsePriceComparison = usePC != 0
	it.Active = active != 0
	it.LastPolledAt = ptrTime(lastPolledAt)
	return &it, nil
}

func (s *Store) decryptItem(it *models.Item) *models.Item {
	it.SearchQuery = s.dec(it.SearchQuery)
	it.ExcludeKeywords = s.dec(it.ExcludeKeywords)
	it.NtfyTopic = s.dec(it.NtfyTopic)
	it.LastPollError = s.dec(it.LastPollError)
	it.BestPriceURL = s.dec(it.BestPriceURL)
	it.BestPriceImageURL = s.dec(it.BestPriceImageURL)
	it.BestPriceTitle = s.dec(it.BestPriceTitle)
	return it
}

// ============ results ============

func (s *Store) InsertResult(ctx context.Context, r *models.Result) (int64, error) {
	res, err := s.DB.ExecContext(ctx, `
		INSERT INTO results (item_id, title, price, currency, url, source, image_url, matched_query, alerted, found_at)
		VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, CURRENT_TIMESTAMP)
	`,
		r.ItemID, s.enc(r.Title), nullFloat(r.Price), r.Currency,
		nullStr(r.URL), nullStr(r.Source), s.enc(r.ImageURL),
		nullStr(s.enc(r.MatchedQuery)),
		boolToInt(r.Alerted),
	)
	if err != nil {
		return 0, err
	}
	return res.LastInsertId()
}

// ResultExists returns true if a row with this item_id and url already exists.
// URL is stored as plaintext per agreed deviation #1, so equality works.
func (s *Store) ResultExists(ctx context.Context, itemID int64, url string) (bool, error) {
	if url == "" {
		return false, nil
	}
	var n int
	err := s.DB.QueryRowContext(ctx,
		`SELECT COUNT(*) FROM results WHERE item_id = ? AND url = ?`, itemID, url,
	).Scan(&n)
	if err != nil {
		return false, err
	}
	return n > 0, nil
}

func (s *Store) MarkResultAlerted(ctx context.Context, id int64) error {
	_, err := s.DB.ExecContext(ctx, `UPDATE results SET alerted = 1 WHERE id = ?`, id)
	return err
}

type ResultsQuery struct {
	ItemID int64 // 0 = all items
	Limit  int
	Offset int
	Order  string // "price_asc", "price_desc", "found_desc" (default), "found_asc"
}

func (s *Store) ListResults(ctx context.Context, q ResultsQuery) ([]models.Result, error) {
	order := `found_at DESC`
	switch q.Order {
	case "price_asc":
		order = `price ASC NULLS LAST`
	case "price_desc":
		order = `price DESC NULLS LAST`
	case "found_asc":
		order = `found_at ASC`
	}
	limit := q.Limit
	if limit <= 0 {
		limit = 20
	}
	args := []any{}
	where := ""
	if q.ItemID != 0 {
		where = `WHERE item_id = ?`
		args = append(args, q.ItemID)
	}
	args = append(args, limit, q.Offset)
	rows, err := s.DB.QueryContext(ctx, fmt.Sprintf(`
		SELECT id, item_id, title, price, currency, url, source, image_url, matched_query, alerted, found_at
		FROM results %s ORDER BY %s LIMIT ? OFFSET ?
	`, where, order), args...)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []models.Result
	for rows.Next() {
		var (
			r                                  models.Result
			title, urlS, source, imageS, matchQ sql.NullString
			price                              sql.NullFloat64
			alerted                            int
		)
		if err := rows.Scan(&r.ID, &r.ItemID, &title, &price, &r.Currency, &urlS, &source, &imageS, &matchQ, &alerted, &r.FoundAt); err != nil {
			return nil, err
		}
		r.Title = s.dec(title.String)
		r.URL = urlS.String
		r.Source = source.String
		r.ImageURL = s.dec(imageS.String)
		r.MatchedQuery = s.dec(matchQ.String)
		r.Price = ptrFloat(price)
		r.Alerted = alerted != 0
		out = append(out, r)
	}
	return out, rows.Err()
}

func (s *Store) CountResults(ctx context.Context, itemID int64) (int, error) {
	var n int
	q := `SELECT COUNT(*) FROM results`
	args := []any{}
	if itemID != 0 {
		q += ` WHERE item_id = ?`
		args = append(args, itemID)
	}
	err := s.DB.QueryRowContext(ctx, q, args...).Scan(&n)
	return n, err
}

// ============ price_history ============

func (s *Store) InsertPricePoint(ctx context.Context, p *models.PricePoint) error {
	if p.PolledAt.IsZero() {
		_, err := s.DB.ExecContext(ctx,
			`INSERT INTO price_history (item_id, price, store) VALUES (?, ?, ?)`,
			p.ItemID, p.Price, s.enc(p.Store))
		return err
	}
	_, err := s.DB.ExecContext(ctx,
		`INSERT INTO price_history (item_id, price, store, polled_at) VALUES (?, ?, ?, ?)`,
		p.ItemID, p.Price, s.enc(p.Store), p.PolledAt)
	return err
}

func (s *Store) ListPriceHistory(ctx context.Context, itemID int64) ([]models.PricePoint, error) {
	rows, err := s.DB.QueryContext(ctx,
		`SELECT id, item_id, price, store, polled_at FROM price_history WHERE item_id = ? ORDER BY polled_at ASC`,
		itemID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []models.PricePoint
	for rows.Next() {
		var p models.PricePoint
		var store sql.NullString
		if err := rows.Scan(&p.ID, &p.ItemID, &p.Price, &store, &p.PolledAt); err != nil {
			return nil, err
		}
		p.Store = s.dec(store.String)
		out = append(out, p)
	}
	return out, rows.Err()
}

// ============ stats ============

type DashboardStats struct {
	TotalItems      int
	ActiveItems     int
	ResultsToday    int
	AlertsToday     int
	PotentialSpend  float64
	PricedItemCount int
	UnpricedCount   int
	MoneySaved      float64
	SavedItemCount  int
}

func (s *Store) GetDashboardStats(ctx context.Context) (*DashboardStats, error) {
	d := &DashboardStats{}
	queries := map[string]any{
		`SELECT COUNT(*) FROM items`:                                                                 &d.TotalItems,
		`SELECT COUNT(*) FROM items WHERE active = 1`:                                                &d.ActiveItems,
		`SELECT COUNT(*) FROM results WHERE found_at >= datetime('now', '-1 day')`:                    &d.ResultsToday,
		`SELECT COUNT(*) FROM results WHERE alerted = 1 AND found_at >= datetime('now', '-1 day')`:   &d.AlertsToday,
	}
	for q, dst := range queries {
		if err := s.DB.QueryRowContext(ctx, q).Scan(dst); err != nil {
			return nil, err
		}
	}
	if err := s.DB.QueryRowContext(ctx, `
		SELECT COALESCE(SUM(best_price), 0), COUNT(*)
		FROM items WHERE active = 1 AND best_price IS NOT NULL
	`).Scan(&d.PotentialSpend, &d.PricedItemCount); err != nil {
		return nil, err
	}
	if err := s.DB.QueryRowContext(ctx, `
		SELECT COUNT(*) FROM items WHERE active = 1 AND best_price IS NULL
	`).Scan(&d.UnpricedCount); err != nil {
		return nil, err
	}
	rows, err := s.DB.QueryContext(ctx, `
		SELECT i.best_price, AVG(p.price) AS avg_price
		FROM items i
		JOIN price_history p ON p.item_id = i.id
		WHERE i.active = 1 AND i.best_price IS NOT NULL
		GROUP BY i.id
	`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	for rows.Next() {
		var bp, avg float64
		if err := rows.Scan(&bp, &avg); err != nil {
			return nil, err
		}
		if bp < avg {
			d.MoneySaved += avg - bp
			d.SavedItemCount++
		}
	}
	return d, rows.Err()
}

func boolToInt(b bool) int {
	if b {
		return 1
	}
	return 0
}