refactor: remove db package and move database logic to service layer

service/node_service_sqlite.go

@@ -3,10 +3,16 @@ package service
 import (
 	"axolotl/models"
 	"database/sql"
+	"errors"
+	"fmt"
 	"math/rand"
+	"os"
+	"path/filepath"
 	"slices"
 	"strings"
 	"time"
+
+	_ "modernc.org/sqlite"
 )
 
 type sqliteNodeService struct {
@@ -14,8 +20,50 @@ type sqliteNodeService struct {
 	userID string
 }
 
-func NewSQLiteNodeService(db *sql.DB, userID string) NodeService {
-	return &sqliteNodeService{db: db, userID: userID}
+var migrations = []string{
+	`CREATE TABLE IF NOT EXISTS nodes (id TEXT PRIMARY KEY, title TEXT NOT NULL, content TEXT, due_date TEXT, created_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP, updated_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP)`,
+	`CREATE TABLE IF NOT EXISTS tags (node_id TEXT NOT NULL, tag TEXT NOT NULL, PRIMARY KEY (node_id, tag), FOREIGN KEY (node_id) REFERENCES nodes(id) ON DELETE CASCADE)`,
+	`CREATE TABLE IF NOT EXISTS rels (from_id TEXT NOT NULL, to_id TEXT NOT NULL, rel_type TEXT NOT NULL, PRIMARY KEY (from_id, to_id, rel_type), FOREIGN KEY (from_id) REFERENCES nodes(id) ON DELETE CASCADE, FOREIGN KEY (to_id) REFERENCES nodes(id) ON DELETE CASCADE)`,
+	`CREATE INDEX IF NOT EXISTS idx_tags_tag ON tags(tag)`, `CREATE INDEX IF NOT EXISTS idx_rels_from ON rels(from_id)`, `CREATE INDEX IF NOT EXISTS idx_rels_to ON rels(to_id)`,
+}
+
+func InitSqliteDB(path string) error {
+	if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
+		return err
+	}
+	var err error
+	db, err := sql.Open("sqlite", path)
+	if err != nil {
+		return err
+	}
+	for _, q := range append([]string{"PRAGMA journal_mode=WAL", "PRAGMA busy_timeout=5000", "PRAGMA foreign_keys=ON"}, migrations...) {
+		if _, err := db.Exec(q); err != nil {
+			return err
+		}
+	}
+	return err
+}
+
+func GetSqliteDB(cfg Config) (*sql.DB, error) {
+	dir, err := filepath.Abs(".")
+	if err != nil {
+		return nil, err
+	}
+	for {
+		dbpath := filepath.Join(dir, ".ax.db")
+		if _, err := os.Stat(dbpath); err == nil {
+			db, err := sql.Open("sqlite", dbpath)
+			if err != nil {
+				return nil, fmt.Errorf("failed to open database: %w", err)
+			}
+			return db, nil
+		}
+		if parent := filepath.Dir(dir); parent == dir {
+			return nil, errors.New("no .ax.db found (run 'ax init' first)")
+		} else {
+			dir = parent
+		}
+	}
 }
 
 func (s *sqliteNodeService) GetByID(id string) (*models.Node, error) {