wal

type Column struct {
	// ID is a pgstream assigned immutable column id. Id does not change when column is renamed.
	ID    string `json:"id"`
	Name  string `json:"name"`
	Type  string `json:"type"`
	Value any    `json:"value"`
}

type ColumnDiff struct {
	ColumnName       string
	ColumnPgstreamID string
	NameChange       *ValueChange[string]
	TypeChange       *ValueChange[string]
	UniqueChange     *ValueChange[bool]
	NullChange       *ValueChange[bool]
	DefaultChange    *ValueChange[*string]
	GeneratedChange  *ValueChange[bool]
	IdentityChange   *ValueChange[string]
}

type CommitPosition string

type DDLColumn struct {
	Attnum    int     `json:"attnum"`
	Name      string  `json:"name"`
	Type      string  `json:"type"`
	Nullable  bool    `json:"nullable"`
	Default   *string `json:"default,omitempty"`
	Generated bool    `json:"generated"`
	Identity  *string `json:"identity,omitempty"`
	Unique    bool    `json:"unique"`
}

type DDLEvent struct {
	DDL        string      `json:"ddl"`
	SchemaName string      `json:"schema_name"`
	CommandTag string      `json:"command_tag"`
	Objects    []DDLObject `json:"objects"`
}

type DDLObject struct {
	Type              string      `json:"type"`
	Identity          string      `json:"identity"`
	Schema            string      `json:"schema"`
	OID               string      `json:"oid"`
	PgstreamID        string      `json:"pgstream_id,omitempty"`
	Columns           []DDLColumn `json:"columns,omitempty"`
	PrimaryKeyColumns []string    `json:"primary_key_columns,omitempty"`
}

type Data struct {
	Action    string   `json:"action"`    // "I" -- insert, "U" -- update, "D" -- delete, "T" -- truncate, "M" -- logical message
	Timestamp string   `json:"timestamp"` // ISO8601, i.e. 2019-12-29 04:58:34.806671
	LSN       string   `json:"lsn"`
	Schema    string   `json:"schema"`
	Table     string   `json:"table"`
	Columns   []Column `json:"columns"`
	Identity  []Column `json:"identity"`
	XID       int64    `json:"xid,omitempty"`
	// For logical messages (when Action == "M")
	Prefix  string `json:"prefix,omitempty"`
	Content string `json:"content,omitempty"`
	// pgstream specific metadata
	Metadata Metadata `json:"metadata"`
}

type Event struct {
	Data           *Data
	CommitPosition CommitPosition
}

type Metadata struct {
	SchemaID        xid.ID `json:"schema_id"`         // the schema ID the event was stamped with
	TablePgstreamID string `json:"table_pgstream_id"` // the ID of the table to which the event belongs
	// This is the Pgstream ID of the "id" column(s). We track this specifically, as we extract it from the event
	// in order to use as the ID for the record.
	InternalColIDs []string `json:"id_col_pgstream_id"`
}

type SchemaDiff struct {
	SchemaName    string
	SchemaDropped bool
	TablesAdded   []DDLObject
	TablesRemoved []DDLObject
	TablesChanged []TableDiff
}

type TableDiff struct {
	TableName             string
	TablePgstreamID       string
	TableNameChange       *ValueChange[string]
	TablePrimaryKeyChange *ValueChange[[]string]
	ColumnsAdded          []DDLColumn
	ColumnsRemoved        []DDLColumn
	ColumnsChanged        []ColumnDiff
}

type ValueChange[T any] struct {
	Old, New T
}