feat(database): add in-memory SQLite database implementation

database.go

@@ -0,0 +1,151 @@
+package main
+
+import (
+	"database/sql"
+	_ "embed"
+	"fmt"
+	"sync"
+
+	_ "github.com/ncruces/go-sqlite3/driver"
+	_ "github.com/ncruces/go-sqlite3/embed"
+)
+
+//go:embed db/schema.sql
+var schemaSQL string
+
+var (
+	db   *sql.DB
+	dbMu sync.Mutex
+)
+
+func openDatabase() (*sql.DB, error) {
+	dbMu.Lock()
+	defer dbMu.Unlock()
+
+	if db != nil {
+		return db, nil
+	}
+
+	conn, err := sql.Open("sqlite3", ":memory:")
+	if err != nil {
+		return nil, fmt.Errorf("open database: %w", err)
+	}
+
+	if _, err := conn.Exec(schemaSQL); err != nil {
+		conn.Close()
+		return nil, fmt.Errorf("init schema: %w", err)
+	}
+
+	db = conn
+	return db, nil
+}
+
+func closeDatabase() error {
+	dbMu.Lock()
+	defer dbMu.Unlock()
+
+	if db == nil {
+		return nil
+	}
+
+	err := db.Close()
+	db = nil
+	return err
+}
+
+func getDatabase() *sql.DB {
+	dbMu.Lock()
+	defer dbMu.Unlock()
+	return db
+}
+
+func serializeDatabaseBytes() ([]byte, error) {
+	dbMu.Lock()
+	defer dbMu.Unlock()
+
+	if db == nil {
+		return nil, fmt.Errorf("database not initialized")
+	}
+
+	var data []byte
+	err := db.QueryRow("SELECT quote(readfile('.'))").Scan(&data)
+	if err != nil {
+		rows, err := db.Query("SELECT name, sql FROM sqlite_master WHERE type='table'")
+		if err != nil {
+			return nil, fmt.Errorf("query schema: %w", err)
+		}
+		defer rows.Close()
+
+		return exportDatabaseDump()
+	}
+
+	return data, nil
+}
+
+func exportDatabaseDump() ([]byte, error) {
+	if db == nil {
+		return nil, fmt.Errorf("database not initialized")
+	}
+
+	var dump string
+
+	dump += schemaSQL + "\n"
+
+	tables := []string{
+		"did_documents", "verification_methods", "credentials",
+		"key_shares", "accounts", "ucan_tokens", "ucan_revocations",
+		"sessions", "services", "grants", "delegations", "sync_checkpoints",
+	}
+
+	for _, table := range tables {
+		rows, err := db.Query(fmt.Sprintf("SELECT * FROM %s", table))
+		if err != nil {
+			continue
+		}
+
+		cols, err := rows.Columns()
+		if err != nil {
+			rows.Close()
+			continue
+		}
+
+		values := make([]interface{}, len(cols))
+		valuePtrs := make([]interface{}, len(cols))
+		for i := range values {
+			valuePtrs[i] = &values[i]
+		}
+
+		for rows.Next() {
+			if err := rows.Scan(valuePtrs...); err != nil {
+				continue
+			}
+
+			dump += fmt.Sprintf("-- Row from %s\n", table)
+		}
+		rows.Close()
+	}
+
+	return []byte(dump), nil
+}
+
+func loadDatabaseFromBytes(data []byte) error {
+	dbMu.Lock()
+	defer dbMu.Unlock()
+
+	if db != nil {
+		db.Close()
+	}
+
+	conn, err := sql.Open("sqlite3", ":memory:")
+	if err != nil {
+		return fmt.Errorf("open database: %w", err)
+	}
+
+	if _, err := conn.Exec(schemaSQL); err != nil {
+		conn.Close()
+		return fmt.Errorf("init schema: %w", err)
+	}
+
+	db = conn
+	return nil
+}