(* Copyright (c) 2008-2009, Adam Chlipala
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * - The names of contributors may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *)

structure Postgres :> POSTGRES = struct

open Settings
open Print.PD
open Print

fun init (dbstring, ss) =
    box [if #persistent (currentProtocol ()) then
             box [string "static void uw_db_prepare(uw_context ctx) {",
                  newline,
                  string "PGconn *conn = uw_get_db(ctx);",
                  newline,
                  string "PGresult *res;",
                  newline,
                  newline,

                  p_list_sepi newline (fn i => fn (s, n) =>
                                                  box [string "res = PQprepare(conn, \"uw",
                                                       string (Int.toString i),
                                                       string "\", \"",
                                                       string (String.toString s),
                                                       string "\", ",
                                                       string (Int.toString n),
                                                       string ", NULL);",
                                                       newline,
                                                       string "if (PQresultStatus(res) != PGRES_COMMAND_OK) {",
                                                       newline,
                                                       box [string "char msg[1024];",
                                                            newline,
                                                            string "strncpy(msg, PQerrorMessage(conn), 1024);",
                                                            newline,
                                                            string "msg[1023] = 0;",
                                                            newline,
                                                            string "PQclear(res);",
                                                            newline,
                                                            string "PQfinish(conn);",
                                                            newline,
                                                            string "uw_error(ctx, FATAL, \"Unable to create prepared statement:\\n",
                                                            string (String.toString s),
                                                            string "\\n%s\", msg);",
                                                            newline],
                                                       string "}",
                                                       newline,
                                                       string "PQclear(res);",
                                                       newline])
                              ss,

                  string "}",
                  newline,
                  newline,

                  string "void uw_db_close(uw_context ctx) {",
                  newline,
                  string "PQfinish(uw_get_db(ctx));",
                  newline,
                  string "}",
                  newline,
                  newline,

                  string "int uw_db_begin(uw_context ctx) {",
                  newline,
                  string "PGconn *conn = uw_get_db(ctx);",
                  newline,
                  string "PGresult *res = PQexec(conn, \"BEGIN ISOLATION LEVEL SERIALIZABLE\");",
                  newline,
                  newline,
                  string "if (res == NULL) return 1;",
                  newline,
                  newline,
                  string "if (PQresultStatus(res) != PGRES_COMMAND_OK) {",
                  box [string "PQclear(res);",
                       newline,
                       string "return 1;",
                       newline],
                  string "}",
                  newline,
                  string "return 0;",
                  newline,
                  string "}",
                  newline,
                  newline,

                  string "int uw_db_commit(uw_context ctx) {",
                  newline,
                  string "PGconn *conn = uw_get_db(ctx);",
                  newline,
                  string "PGresult *res = PQexec(conn, \"COMMIT\");",
                  newline,
                  newline,
                  string "if (res == NULL) return 1;",
                  newline,
                  newline,
                  string "if (PQresultStatus(res) != PGRES_COMMAND_OK) {",
                  box [string "PQclear(res);",
                       newline,
                       string "return 1;",
                       newline],
                  string "}",
                  newline,
                  string "return 0;",
                  newline,
                  string "}",
                  newline,
                  newline,

                  string "int uw_db_rollback(uw_context ctx) {",
                  newline,
                  string "PGconn *conn = uw_get_db(ctx);",
                  newline,
                  string "PGresult *res = PQexec(conn, \"ROLLBACK\");",
                  newline,
                  newline,
                  string "if (res == NULL) return 1;",
                  newline,
                  newline,
                  string "if (PQresultStatus(res) != PGRES_COMMAND_OK) {",
                  box [string "PQclear(res);",
                       newline,
                       string "return 1;",
                       newline],
                  string "}",
                  newline,
                  string "return 0;",
                  newline,
                  string "}",
                  newline,
                  newline]
         else
             string "static void uw_db_prepare(uw_context ctx) { }",
         newline,
         newline,

         string "void uw_db_init(uw_context ctx) {",
         newline,
         string "PGconn *conn = PQconnectdb(\"",
         string (String.toString dbstring),
         string "\");",
         newline,
         string "if (conn == NULL) uw_error(ctx, FATAL, ",
         string "\"libpq can't allocate a connection.\");",
         newline,
         string "if (PQstatus(conn) != CONNECTION_OK) {",
         newline,
         box [string "char msg[1024];",
              newline,
              string "strncpy(msg, PQerrorMessage(conn), 1024);",
              newline,
              string "msg[1023] = 0;",
              newline,
              string "PQfinish(conn);",
              newline,
              string "uw_error(ctx, BOUNDED_RETRY, ",
              string "\"Connection to Postgres server failed: %s\", msg);"],
         newline,
         string "}",
         newline,
         string "uw_set_db(ctx, conn);",
         newline,
         string "uw_db_validate(ctx);",
         newline,
         string "uw_db_prepare(ctx);",
         newline,
         string "}"]

fun p_getcol {wontLeakStrings, col = i, typ = t} =
    let
        fun p_unsql t e eLen =
            case t of
                Int => box [string "uw_Basis_stringToInt_error(ctx, ", e, string ")"]
              | Float => box [string "uw_Basis_stringToFloat_error(ctx, ", e, string ")"]
              | String =>
                if wontLeakStrings then
                    e
                else
                    box [string "uw_strdup(ctx, ", e, string ")"]
              | Bool => box [string "uw_Basis_stringToBool_error(ctx, ", e, string ")"]
              | Time => box [string "uw_Basis_stringToTime_error(ctx, ", e, string ")"]
              | Blob => box [string "uw_Basis_stringToBlob_error(ctx, ",
                             e,
                             string ", ",
                             eLen,
                             string ")"]
              | Channel => box [string "uw_Basis_stringToChannel_error(ctx, ", e, string ")"]
              | Client => box [string "uw_Basis_stringToClient_error(ctx, ", e, string ")"]

              | Nullable _ => raise Fail "Postgres: Recursive Nullable"

        fun getter t =
            case t of
                Nullable t =>
                box [string "(PQgetisnull(res, i, ",
                     string (Int.toString i),
                     string ") ? NULL : ",
                     case t of
                         String => getter t
                       | _ => box [string "({",
                                   newline,
                                   p_sql_type t,
                                   space,
                                   string "*tmp = uw_malloc(ctx, sizeof(",
                                   p_sql_type t,
                                   string "));",
                                   newline,
                                   string "*tmp = ",
                                   getter t,
                                   string ";",
                                   newline,
                                   string "tmp;",
                                   newline,
                                   string "})"],
                     string ")"]
              | _ =>
                box [string "(PQgetisnull(res, i, ",
                     string (Int.toString i),
                     string ") ? ",
                     box [string "({",
                          p_sql_type t,
                          space,
                          string "tmp;",
                          newline,
                          string "uw_error(ctx, FATAL, \"Unexpectedly NULL field #",
                          string (Int.toString i),
                          string "\");",
                          newline,
                          string "tmp;",
                          newline,
                          string "})"],
                     string " : ",
                     p_unsql t
                             (box [string "PQgetvalue(res, i, ",
                                   string (Int.toString i),
                                   string ")"])
                             (box [string "PQgetlength(res, i, ",
                                   string (Int.toString i),
                                   string ")"]),
                     string ")"]
    in
        getter t
    end

fun queryCommon {loc, query, numCols, doCols} =
    box [string "int n, i;",
         newline,
         newline,

         string "if (res == NULL) uw_error(ctx, FATAL, \"Out of memory allocating query result.\");",
         newline,
         newline,

         string "if (PQresultStatus(res) != PGRES_TUPLES_OK) {",
         newline,
         box [string "PQclear(res);",
              newline,
              string "uw_error(ctx, FATAL, \"",
              string (ErrorMsg.spanToString loc),
              string ": Query failed:\\n%s\\n%s\", ",
              query,
              string ", PQerrorMessage(conn));",
              newline],
         string "}",
         newline,
         newline,

         string "if (PQnfields(res) != ",
         string (Int.toString numCols),
         string ") {",
         newline,
         box [string "int nf = PQnfields(res);",
              newline,
              string "PQclear(res);",
              newline,
              string "uw_error(ctx, FATAL, \"",
              string (ErrorMsg.spanToString loc),
              string ": Query returned %d columns instead of ",
              string (Int.toString numCols),
              string ":\\n%s\\n%s\", nf, ",
              query,
              string ", PQerrorMessage(conn));",
              newline],
         string "}",
         newline,
         newline,

         string "uw_end_region(ctx);",
         newline,
         string "uw_push_cleanup(ctx, (void (*)(void *))PQclear, res);",
         newline,
         string "n = PQntuples(res);",
         newline,
         string "for (i = 0; i < n; ++i) {",
         newline,
         doCols p_getcol,
         string "}",
         newline,
         newline,
         string "uw_pop_cleanup(ctx);",
         newline]    

fun query {loc, numCols, doCols} =
    box [string "PGconn *conn = uw_get_db(ctx);",
         newline,
         string "PGresult *res = PQexecParams(conn, query, 0, NULL, NULL, NULL, NULL, 0);",
         newline,
         newline,
         queryCommon {loc = loc, numCols = numCols, doCols = doCols, query = string "query"}]

fun p_ensql t e =
    case t of
        Int => box [string "uw_Basis_attrifyInt(ctx, ", e, string ")"]
      | Float => box [string "uw_Basis_attrifyFloat(ctx, ", e, string ")"]
      | String => e
      | Bool => box [string "(", e, string " ? \"TRUE\" : \"FALSE\")"]
      | Time => box [string "uw_Basis_attrifyTime(ctx, ", e, string ")"]
      | Blob => box [e, string ".data"]
      | Channel => box [string "uw_Basis_attrifyChannel(ctx, ", e, string ")"]
      | Client => box [string "uw_Basis_attrifyClient(ctx, ", e, string ")"]
      | Nullable String => e
      | Nullable t => box [string "(",
                           e,
                           string " == NULL ? NULL : ",
                           p_ensql t (box [string "(*", e, string ")"]),
                           string ")"]

fun queryPrepared {loc, id, query, inputs, numCols, doCols} =
    box [string "PGconn *conn = uw_get_db(ctx);",
         newline,
         string "const int paramFormats[] = { ",
         p_list_sep (box [string ",", space])
                    (fn t => if isBlob t then string "1" else string "0") inputs,
         string " };",
         newline,
         string "const int paramLengths[] = { ",
         p_list_sepi (box [string ",", space])
                     (fn i => fn Blob => string ("arg" ^ Int.toString (i + 1) ^ ".size")
                               | Nullable Blob => string ("arg" ^ Int.toString (i + 1)
                                                          ^ "?arg" ^ Int.toString (i + 1) ^ "->size:0")
                               | _ => string "0") inputs,
         string " };",
         newline,
         string "const char *paramValues[] = { ",
         p_list_sepi (box [string ",", space])
                     (fn i => fn t => p_ensql t (box [string "arg",
                                                      string (Int.toString (i + 1))]))
                     inputs,
         string " };",
         newline,
         newline,
         string "PGresult *res = ",
         if #persistent (Settings.currentProtocol ()) then
             box [string "PQexecPrepared(conn, \"uw",
                  string (Int.toString id),
                  string "\", ",
                  string (Int.toString (length inputs)),
                  string ", paramValues, paramLengths, paramFormats, 0);"]
         else
             box [string "PQexecParams(conn, \"",
                  string (String.toString query),
                  string "\", ",
                  string (Int.toString (length inputs)),
                  string ", NULL, paramValues, paramLengths, paramFormats, 0);"],
         newline,
         newline,
         queryCommon {loc = loc, numCols = numCols, doCols = doCols, query = box [string "\"",
                                                                                  string (String.toString query),
                                                                                  string "\""]}]

val () = addDbms {name = "postgres",
                  header = "postgresql/libpq-fe.h",
                  link = "-lpq",
                  global_init = box [string "void uw_client_init() { }",
                                     newline],
                  init = init,
                  query = query,
                  queryPrepared = queryPrepared}
val () = setDbms "postgres"

end