feat: PostgreSQL driver support

internal/infrastructure/persistence/database/postgresBackup.go

@@ -0,0 +1,189 @@
+package database
+
+import (
+	"fmt"
+	"strings"
+	"time"
+
+	"gorm.io/gorm"
+)
+
+const (
+	postgresSchema = "public"
+
+	postgresTablesQuery = "SELECT table_name FROM information_schema.tables WHERE table_schema = ? AND table_type = 'BASE TABLE' ORDER BY table_name"
+
+	postgresColumnsQuery = `SELECT a.attname AS name, format_type(a.atttypid, a.atttypmod) AS data_type, a.attnotnull AS not_null, COALESCE(pg_get_expr(d.adbin, d.adrelid), '') AS default_value, a.attidentity::text AS identity
+FROM pg_attribute a
+JOIN pg_class c ON c.oid = a.attrelid
+JOIN pg_namespace n ON n.oid = c.relnamespace
+LEFT JOIN pg_attrdef d ON d.adrelid = a.attrelid AND d.adnum = a.attnum
+WHERE n.nspname = ? AND c.relname = ? AND a.attnum > 0 AND NOT a.attisdropped
+ORDER BY a.attnum`
+
+	postgresConstraintsQuery = `SELECT con.conname AS name, pg_get_constraintdef(con.oid) AS definition
+FROM pg_constraint con
+JOIN pg_class c ON c.oid = con.conrelid
+JOIN pg_namespace n ON n.oid = c.relnamespace
+WHERE n.nspname = ? AND c.relname = ? AND con.contype IN ('p', 'u', 'c')
+ORDER BY CASE con.contype WHEN 'p' THEN 0 ELSE 1 END, con.conname`
+
+	postgresIndexesQuery = `SELECT i.indexdef
+FROM pg_indexes i
+WHERE i.schemaname = ? AND i.tablename = ?
+AND i.indexname NOT IN (
+	SELECT con.conname FROM pg_constraint con
+	JOIN pg_class c ON c.oid = con.conrelid
+	JOIN pg_namespace n ON n.oid = c.relnamespace
+	WHERE n.nspname = ? AND c.relname = ?
+)
+ORDER BY i.indexname`
+
+	postgresIdentityColumn = "id"
+	postgresTimeLayout     = "2006-01-02 15:04:05.999999999Z07:00"
+	postgresByteaType      = "BYTEA"
+)
+
+var postgresNumericTypes = map[string]bool{
+	"INT2": true, "INT4": true, "INT8": true, "FLOAT4": true, "FLOAT8": true, "NUMERIC": true, "OID": true,
+}
+
+var postgresSerialTypes = map[string]string{
+	"smallint": "smallserial",
+	"integer":  "serial",
+	"bigint":   "bigserial",
+}
+
+var postgresDumpDialect = dumpDialect{
+	preamble: []string{
+		"SET client_encoding = 'UTF8';",
+		"SET standard_conforming_strings = on;",
+		"SET TimeZone = 'UTC';",
+	},
+	quote:        quotePostgresIdentifier,
+	literal:      postgresLiteral,
+	tableTrailer: postgresSequenceReset,
+}
+
+func NewPostgresBackup(db *gorm.DB, directory string, now func() time.Time) *DumpBackup {
+	backup := NewDumpBackup(func() (DumpSource, error) { return openPostgresDumpSource(db) }, directory, now)
+	backup.dialect = postgresDumpDialect
+	return backup
+}
+
+type postgresDumpSource struct {
+	*txDumpSource
+}
+
+var _ DumpSource = &postgresDumpSource{}
+
+func openPostgresDumpSource(db *gorm.DB) (*postgresDumpSource, error) {
+	source, err := openTxDumpSource(db, quotePostgresIdentifier, postgresDumpBytes)
+	if err != nil {
+		return nil, err
+	}
+	return &postgresDumpSource{source}, nil
+}
+
+func (s *postgresDumpSource) Tables() ([]string, error) {
+	var tables []string
+	err := s.tx.Raw(postgresTablesQuery, postgresSchema).Scan(&tables).Error
+	return tables, err
+}
+
+type postgresColumn struct {
+	Name         string
+	DataType     string
+	NotNull      bool
+	DefaultValue string
+	Identity     string
+}
+
+type postgresConstraint struct {
+	Name       string
+	Definition string
+}
+
+func (s *postgresDumpSource) CreateStatement(table string) (string, error) {
+	var columns []postgresColumn
+	if err := s.tx.Raw(postgresColumnsQuery, postgresSchema, table).Scan(&columns).Error; err != nil {
+		return "", err
+	}
+	var constraints []postgresConstraint
+	if err := s.tx.Raw(postgresConstraintsQuery, postgresSchema, table).Scan(&constraints).Error; err != nil {
+		return "", err
+	}
+	var indexes []string
+	if err := s.tx.Raw(postgresIndexesQuery, postgresSchema, table, postgresSchema, table).Scan(&indexes).Error; err != nil {
+		return "", err
+	}
+	var definitions []string
+	for _, column := range columns {
+		definitions = append(definitions, "  "+postgresColumnDefinition(column))
+	}
+	for _, constraint := range constraints {
+		definitions = append(definitions, fmt.Sprintf("  CONSTRAINT %s %s", quotePostgresIdentifier(constraint.Name), constraint.Definition))
+	}
+	statements := []string{fmt.Sprintf("CREATE TABLE %s (\n%s\n)", quotePostgresIdentifier(table), strings.Join(definitions, ",\n"))}
+	statements = append(statements, indexes...)
+	return strings.Join(statements, ";\n"), nil
+}
+
+func postgresColumnDefinition(column postgresColumn) string {
+	quoted := quotePostgresIdentifier(column.Name)
+	serial, isSerial := postgresSerialTypes[column.DataType]
+	if isSerial && strings.HasPrefix(column.DefaultValue, "nextval(") {
+		return quoted + " " + serial + " NOT NULL"
+	}
+	if column.Identity != "" {
+		return quoted + " " + column.DataType + " GENERATED BY DEFAULT AS IDENTITY NOT NULL"
+	}
+	definition := quoted + " " + column.DataType
+	if column.DefaultValue != "" {
+		definition += " DEFAULT " + column.DefaultValue
+	}
+	if column.NotNull {
+		definition += " NOT NULL"
+	}
+	return definition
+}
+
+func postgresDumpBytes(value any) []byte {
+	if moment, isTime := value.(time.Time); isTime {
+		return []byte(moment.UTC().Format(postgresTimeLayout))
+	}
+	return dumpBytes(value)
+}
+
+func quotePostgresIdentifier(name string) string {
+	return `"` + strings.ReplaceAll(name, `"`, `""`) + `"`
+}
+
+func postgresLiteral(databaseType string, value []byte) string {
+	if value == nil {
+		return "NULL"
+	}
+	upper := strings.ToUpper(databaseType)
+	if postgresNumericTypes[upper] && plainNumber.Match(value) {
+		return string(value)
+	}
+	if upper == postgresByteaType {
+		return fmt.Sprintf(`'\x%x'`, value)
+	}
+	return "'" + strings.ReplaceAll(string(value), "'", "''") + "'"
+}
+
+func postgresSequenceReset(table string, columns []DumpColumn) []string {
+	for _, column := range columns {
+		if column.Name != postgresIdentityColumn {
+			continue
+		}
+		quotedTable, quotedColumn := quotePostgresIdentifier(table), quotePostgresIdentifier(column.Name)
+		sequenceTable := strings.ReplaceAll(quotedTable, "'", "''")
+		return []string{fmt.Sprintf(
+			"SELECT setval(pg_get_serial_sequence('%s', '%s'), COALESCE((SELECT MAX(%s) FROM %s), 1), (SELECT COUNT(*) > 0 FROM %s));",
+			sequenceTable, column.Name, quotedColumn, quotedTable, quotedTable,
+		)}
+	}
+	return nil
+}