PostgreSQLConnection+SimpleQuery.swift

import Async

extension PostgreSQLConnection {
    /// Sends a simple PostgreSQL query command, collecting the parsed results.
    public func simpleQuery(_ string: String) -> Future<[[PostgreSQLColumn: PostgreSQLData]]> {
        var rows: [[PostgreSQLColumn: PostgreSQLData]] = []
        return simpleQuery(string) { row in
            rows.append(row)
        }.map(to: [[PostgreSQLColumn: PostgreSQLData]].self) {
            return rows
        }
    }
    /// Sends a simple PostgreSQL query command, returning the parsed results to
    /// the supplied closure.
    public func simpleQuery(_ string: String, onRow: @escaping ([PostgreSQLColumn: PostgreSQLData]) -> ()) -> Future<Void> {
        return operation { self._simpleQuery(string, onRow: onRow) }
    }

    /// Non-operation bounded simple query.
    private func _simpleQuery(_ string: String, onRow: @escaping ([PostgreSQLColumn: PostgreSQLData]) -> ()) -> Future<Void> {
        logger?.log(query: string, parameters: [])
        var currentRow: PostgreSQLRowDescription?
        let query = PostgreSQLQuery(query: string)
        return send([.query(query)]) { message in
            switch message {
            case .rowDescription(let row):
                currentRow = row
            case .dataRow(let data):
                guard let row = currentRow else {
                    throw PostgreSQLError(identifier: "simpleQuery", reason: "Unexpected PostgreSQLDataRow without preceding PostgreSQLRowDescription.", source: .capture())
                }
                let parsed = try row.parse(data: data, formatCodes: row.fields.map { $0.formatCode })
                onRow(parsed)
            case .close: break // query over, waiting for `readyForQuery`
            default: throw PostgreSQLError(identifier: "simpleQuery", reason: "Unexpected message during PostgreSQLQuery: \(message)", source: .capture())
            }
        }
    }
}