feat: add url shortner

internal/repository/shorturl_repo.go

@@ -0,0 +1,157 @@
+package repository
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"time"
+
+	"github.com/jackc/pgx/v5"
+	"github.com/jackc/pgx/v5/pgconn"
+	"github.com/prabhupadasays/spsays-bff/pkg/shorturl"
+)
+
+// ShortenedURLRow mirrors the analytics-relevant columns of shortened_urls.
+type ShortenedURLRow struct {
+	ID         int64
+	Code       string
+	LongURL    string
+	Disabled   bool
+	ExpiresAt  *time.Time
+	ClickCount int64
+}
+
+// ShortURLRepo wraps Postgres CRUD for the shortener.
+type ShortURLRepo struct {
+	pg *Postgres
+}
+
+func NewShortURLRepo(pg *Postgres) *ShortURLRepo {
+	return &ShortURLRepo{pg: pg}
+}
+
+// Insert persists a new short URL. Returns the new row's id. If a unique
+// violation occurs (race: another worker already inserted this code) the
+// caller can detect via IsUniqueViolation(err).
+func (r *ShortURLRepo) Insert(
+	ctx context.Context,
+	code string,
+	payload shorturl.PendingPayload,
+	parsed shorturl.Parsed,
+) (int64, error) {
+	const q = `
+		INSERT INTO shortened_urls (
+			code, long_url,
+			path, content_type, book_code, division, chapter, verse, slug,
+			has_highlight, highlight_param,
+			creator_ip, creator_ua, creator_referer, creator_country,
+			created_at
+		) VALUES (
+			$1, $2,
+			$3, $4, $5, $6, $7, $8, $9,
+			$10, $11,
+			NULLIF($12,'')::inet, NULLIF($13,''), NULLIF($14,''), NULLIF($15,''),
+			$16
+		)
+		RETURNING id
+	`
+	var id int64
+	err := r.pg.Pool.QueryRow(ctx, q,
+		code, payload.URL,
+		parsed.Path, parsed.ContentType,
+		nullableStr(parsed.BookCode),
+		nullableStr(parsed.Division),
+		nullableStr(parsed.Chapter),
+		nullableStr(parsed.Verse),
+		nullableStr(parsed.Slug),
+		parsed.HasHighlight, nullableStr(parsed.HighlightParam),
+		payload.CreatorIP, payload.CreatorUA, payload.CreatorReferer, payload.CreatorCountry,
+		payload.CreatedAt,
+	).Scan(&id)
+	if err != nil {
+		return 0, fmt.Errorf("insert shortened_url: %w", err)
+	}
+	return id, nil
+}
+
+// GetByCode returns the row for code, or pgx.ErrNoRows if missing.
+func (r *ShortURLRepo) GetByCode(ctx context.Context, code string) (*ShortenedURLRow, error) {
+	const q = `
+		SELECT id, code, long_url, disabled, expires_at, click_count
+		FROM shortened_urls
+		WHERE code = $1
+		LIMIT 1
+	`
+	var row ShortenedURLRow
+	err := r.pg.Pool.QueryRow(ctx, q, code).Scan(
+		&row.ID, &row.Code, &row.LongURL, &row.Disabled, &row.ExpiresAt, &row.ClickCount,
+	)
+	if err != nil {
+		return nil, err
+	}
+	return &row, nil
+}
+
+// RecordClick inserts a row in shortened_url_clicks and bumps the aggregate
+// counters on the parent row in a single transaction. The parent lookup uses
+// the code (not id) so this works even if the click worker is processing an
+// event for a URL inserted by a different process.
+func (r *ShortURLRepo) RecordClick(ctx context.Context, ev shorturl.ClickEvent) error {
+	tx, err := r.pg.Pool.Begin(ctx)
+	if err != nil {
+		return err
+	}
+	defer func() { _ = tx.Rollback(ctx) }()
+
+	var id int64
+	err = tx.QueryRow(ctx, `SELECT id FROM shortened_urls WHERE code = $1`, ev.Code).Scan(&id)
+	if err != nil {
+		if errors.Is(err, pgx.ErrNoRows) {
+			// Parent row hasn't landed in PG yet (still pending). Skip silently;
+			// the click is lost. (Rare: only when a resolution and the parent
+			// insert race within the worker drain interval.)
+			return nil
+		}
+		return err
+	}
+
+	if _, err := tx.Exec(ctx, `
+		INSERT INTO shortened_url_clicks (
+			short_url_id, code, clicked_at, client_ip, client_ua, referer, country, is_bot
+		) VALUES (
+			$1, $2, $3, NULLIF($4,'')::inet, NULLIF($5,''), NULLIF($6,''), NULLIF($7,''), $8
+		)`,
+		id, ev.Code, ev.ClickedAt, ev.IP, ev.UA, ev.Referer, ev.Country, ev.IsBot,
+	); err != nil {
+		return err
+	}
+
+	if _, err := tx.Exec(ctx, `
+		UPDATE shortened_urls
+		   SET click_count       = click_count + 1,
+		       human_click_count = human_click_count + CASE WHEN $2 THEN 0 ELSE 1 END,
+		       last_clicked_at   = $1,
+		       first_clicked_at  = COALESCE(first_clicked_at, $1)
+		 WHERE id = $3
+	`, ev.ClickedAt, ev.IsBot, id); err != nil {
+		return err
+	}
+
+	return tx.Commit(ctx)
+}
+
+// IsUniqueViolation reports whether err is a Postgres unique constraint error.
+func IsUniqueViolation(err error) bool {
+	var pgErr *pgconn.PgError
+	if errors.As(err, &pgErr) {
+		return pgErr.Code == "23505"
+	}
+	return false
+}
+
+func nullableStr(s string) any {
+	if s == "" {
+		return nil
+	}
+	return s
+}