From 3a89bc588f59024618eae0adff79ecd12b7db882 Mon Sep 17 00:00:00 2001
From: Ira Rosen <irar@il.ibm.com>
Date: Mon, 5 Jun 2017 11:29:23 +0300
Subject: [PATCH] IBM-Swift/Swift-Kuery#82 Support prepared statements with
 connection pooling (#19)

---
 .../PostgreSQLConnection.swift                | 29 +++++++++++++++----
 .../PostgreSQLPreparedStatement.swift         |  2 ++
 2 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/Sources/SwiftKueryPostgreSQL/PostgreSQLConnection.swift b/Sources/SwiftKueryPostgreSQL/PostgreSQLConnection.swift
index 6ccabbe..a175a89 100644
--- a/Sources/SwiftKueryPostgreSQL/PostgreSQLConnection.swift
+++ b/Sources/SwiftKueryPostgreSQL/PostgreSQLConnection.swift
@@ -29,6 +29,8 @@ public class PostgreSQLConnection: Connection {
     private var connectionParameters: String = ""
     private var inTransaction = false
     
+    private var preparedStatements = Set<String>()
+    
     /// An indication whether there is a connection to the database.
     public var isConnected: Bool {
         return connection != nil
@@ -39,7 +41,7 @@ public class PostgreSQLConnection: Connection {
     
     init(connectionParameters: String) {
         self.connectionParameters = connectionParameters
-        queryBuilder = PostgreSQLConnection.createQuryBuilder()
+        queryBuilder = PostgreSQLConnection.createQueryBuilder()
     }
     
     /// Initialize an instance of PostgreSQLConnection.
@@ -110,7 +112,7 @@ public class PostgreSQLConnection: Connection {
         }
     }
     
-    private static func createQuryBuilder() -> QueryBuilder {
+    private static func createQueryBuilder() -> QueryBuilder {
         let queryBuilder = QueryBuilder(withDeleteRequiresUsing: true, withUpdateRequiresFrom: true, createAutoIncrement: createAutoIncrement)
         queryBuilder.updateSubstitutions([QueryBuilder.QuerySubstitutionNames.ucase : "UPPER",
                                           QueryBuilder.QuerySubstitutionNames.lcase : "LOWER",
@@ -277,16 +279,23 @@ public class PostgreSQLConnection: Connection {
     /// - Throws: QueryError.syntaxError if query build fails, or a database error if it fails to prepare statement.
     public func prepareStatement(_ raw: String) throws -> PreparedStatement  {
         let statementName = String.randomString()
-        guard let result = PQprepare(connection, statementName, raw, 0, nil),
+        if let error = prepareStatement(name: statementName, for: raw) {
+            throw QueryError.noResult(error)
+        }
+        return PostgreSQLPreparedStatement(name: statementName, query: raw)
+    }
+    
+    private func prepareStatement(name: String, for query: String) -> String? {
+        guard let result = PQprepare(connection, name, query, 0, nil),
             PQresultStatus(result) == PGRES_COMMAND_OK else {
                 var errorMessage = "Failed to create prepared statement."
                 if let error = String(validatingUTF8: PQerrorMessage(connection)) {
                     errorMessage += " Error: \(error)."
                 }
-                throw QueryError.noResult(errorMessage)
+                return errorMessage
         }
-        
-        return PostgreSQLPreparedStatement(name: statementName)
+        preparedStatements.insert(name)
+        return nil
     }
 
     /// Execute a prepared statement.
@@ -356,6 +365,14 @@ public class PostgreSQLConnection: Connection {
                 onCompletion(.error(QueryError.unsupported("Failed to execute unsupported prepared statement")))
                 return
             }
+            
+            if !preparedStatements.contains(statement.name) {
+                if let error = prepareStatement(name: statement.name, for: statement.query) {
+                    onCompletion(.error(QueryError.databaseError(error)))
+                    return
+
+                }
+            }
 
             _ = parameterData.withUnsafeBufferPointer { buffer in
                 PQsendQueryPrepared(connection, statement.name, Int32(parameters.count), buffer.isEmpty ? nil : buffer.baseAddress, nil, nil, 1)
diff --git a/Sources/SwiftKueryPostgreSQL/PostgreSQLPreparedStatement.swift b/Sources/SwiftKueryPostgreSQL/PostgreSQLPreparedStatement.swift
index db6dd00..639f1a6 100644
--- a/Sources/SwiftKueryPostgreSQL/PostgreSQLPreparedStatement.swift
+++ b/Sources/SwiftKueryPostgreSQL/PostgreSQLPreparedStatement.swift
@@ -23,4 +23,6 @@ public struct PostgreSQLPreparedStatement: PreparedStatement {
     
     /// The name of the prepared statement.
     public let name: String
+    
+    let query: String
 }