add web service

internal/storage/history.go

@@ -0,0 +1,77 @@
+package storage
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"time"
+)
+
+// GetCooldownMemoNames returns memo names shown within the last cooldownDays.
+func (s *Storage) GetCooldownMemoNames(ctx context.Context, cooldownDays int) (map[string]struct{}, error) {
+	cutoff := time.Now().Unix() - int64(cooldownDays)*86400
+
+	rows, err := s.db.QueryContext(ctx,
+		`SELECT DISTINCT memo_name FROM show_history WHERE shown_at > ?`, cutoff)
+	if err != nil {
+		return nil, fmt.Errorf("query cooldown memos: %w", err)
+	}
+	defer rows.Close()
+
+	result := make(map[string]struct{})
+	for rows.Next() {
+		var name string
+		if err := rows.Scan(&name); err != nil {
+			return nil, fmt.Errorf("scan memo_name: %w", err)
+		}
+		result[name] = struct{}{}
+	}
+	return result, rows.Err()
+}
+
+// GetShowCounts returns show_count for each of the given memo names.
+// Memos not present in history will be absent from the result (count = 0).
+func (s *Storage) GetShowCounts(ctx context.Context, memoNames []string) (map[string]int, error) {
+	if len(memoNames) == 0 {
+		return nil, nil
+	}
+
+	placeholders := make([]string, len(memoNames))
+	args := make([]any, len(memoNames))
+	for i, name := range memoNames {
+		placeholders[i] = "?"
+		args[i] = name
+	}
+
+	query := fmt.Sprintf(
+		`SELECT memo_name, COUNT(*) FROM show_history WHERE memo_name IN (%s) GROUP BY memo_name`,
+		strings.Join(placeholders, ","))
+
+	rows, err := s.db.QueryContext(ctx, query, args...)
+	if err != nil {
+		return nil, fmt.Errorf("query show counts: %w", err)
+	}
+	defer rows.Close()
+
+	result := make(map[string]int)
+	for rows.Next() {
+		var name string
+		var count int
+		if err := rows.Scan(&name, &count); err != nil {
+			return nil, fmt.Errorf("scan show count: %w", err)
+		}
+		result[name] = count
+	}
+	return result, rows.Err()
+}
+
+// RecordShow records that a memo was shown.
+func (s *Storage) RecordShow(ctx context.Context, memoName string, tier int) error {
+	_, err := s.db.ExecContext(ctx,
+		`INSERT INTO show_history (memo_name, shown_at, tier) VALUES (?, ?, ?)`,
+		memoName, time.Now().Unix(), tier)
+	if err != nil {
+		return fmt.Errorf("insert show history: %w", err)
+	}
+	return nil
+}