Add database schema, ERD, and repository layer

internal/database/artist_repository.go

@@ -0,0 +1,73 @@
+package database
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+type Artist struct {
+	ID         string
+	ExternalID string
+	Name       string
+	ArtistType string
+	Country    string
+	Genres     []string
+	ImageURL   string
+	CreatedAt  time.Time
+	UpdatedAt  time.Time
+}
+
+type ArtistRepository struct {
+	pool *pgxpool.Pool
+}
+
+func NewArtistRepository(pool *pgxpool.Pool) *ArtistRepository {
+	return &ArtistRepository{pool: pool}
+}
+
+func (r *ArtistRepository) Create(ctx context.Context, a *Artist) error {
+	_, err := r.pool.Exec(ctx,
+		`INSERT INTO artists (external_id, name, artist_type, country, genres, image_url)
+		 VALUES ($1, $2, $3, $4, $5, $6)
+		 ON CONFLICT (external_id) DO UPDATE SET
+		   name = EXCLUDED.name,
+		   artist_type = EXCLUDED.artist_type,
+		   country = EXCLUDED.country,
+		   genres = EXCLUDED.genres,
+		   image_url = EXCLUDED.image_url,
+		   updated_at = NOW()
+		 RETURNING id, created_at, updated_at`,
+		a.ExternalID, a.Name, a.ArtistType, a.Country, a.Genres, a.ImageURL,
+	)
+	if err != nil {
+		return fmt.Errorf("creating artist: %w", err)
+	}
+	return nil
+}
+
+func (r *ArtistRepository) GetByExternalID(ctx context.Context, externalID string) (*Artist, error) {
+	a := &Artist{}
+	err := r.pool.QueryRow(ctx,
+		`SELECT id, external_id, name, artist_type, country, genres, image_url, created_at, updated_at
+		 FROM artists WHERE external_id = $1`, externalID,
+	).Scan(&a.ID, &a.ExternalID, &a.Name, &a.ArtistType, &a.Country, &a.Genres, &a.ImageURL, &a.CreatedAt, &a.UpdatedAt)
+	if err != nil {
+		return nil, fmt.Errorf("getting artist: %w", err)
+	}
+	return a, nil
+}
+
+func (r *ArtistRepository) GetByID(ctx context.Context, id string) (*Artist, error) {
+	a := &Artist{}
+	err := r.pool.QueryRow(ctx,
+		`SELECT id, external_id, name, artist_type, country, genres, image_url, created_at, updated_at
+		 FROM artists WHERE id = $1`, id,
+	).Scan(&a.ID, &a.ExternalID, &a.Name, &a.ArtistType, &a.Country, &a.Genres, &a.ImageURL, &a.CreatedAt, &a.UpdatedAt)
+	if err != nil {
+		return nil, fmt.Errorf("getting artist: %w", err)
+	}
+	return a, nil
+}