/*
 *  Paglo Crawler
 *  Copyright (C) 2006-2008 Paglo Labs Inc. All rights reserved.
 *  www.paglo.com
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of version 2 of the GNU General Public License as
 *  published by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */
//---------------------------------------------------------------------------
#include "DataStore.h"
#ifdef _WIN32     
#include <io.h>
#else
#include <unistd.h>
#endif

using namespace std;
//---------------------------------------------------------------------------

TDataStore::TDataStore(const char *Filename)
{
  DB = NULL;
  DBFilename = Filename;
  
  if (!access(Filename, 0) == 0) {
    CreateDatabase(Filename);
  }
  OpenDatabase(Filename);
}
//---------------------------------------------------------------------------

TDataStore::~TDataStore()
{
  CloseDatabase();
}
//---------------------------------------------------------------------------

void TDataStore::UpdateScanSummary(int WeekHour, int CompletedScans)
{
  static int LastCompletedScans = 0;
  int Tmp = CompletedScans;
  time_t Now = time(NULL);
  CompletedScans = CompletedScans - LastCompletedScans;
  LastCompletedScans = Tmp;
  string S = "update scanning_summary set completed_scans = " +
    Int2String(CompletedScans) + ", timestamp = " + Int2String(Now) +
    " where week_hour = " + Int2String(WeekHour);
  ExecuteStmt(S.c_str());
}
//---------------------------------------------------------------------------

int *TDataStore::GetScanSummary(void)
{
  int *Data = (int *)malloc(168 * sizeof(int));
  for (int i = 0; i < 168; i++) {
    Data[i] = 0;
  }
  
  CppSQLite3Query Results = ExecuteQuery("select * from scanning_summary order by week_hour");
  for (int i = 0; !Results.eof(); Results.nextRow()) {
    int WeekHour = Results.getIntField("week_hour");
    int CompletedScans = Results.getIntField("completed_scans");
    int Timestamp = Results.getIntField("timestamp");
    Data[i] = CompletedScans;
    i++;
  }

  return Data;
}
//---------------------------------------------------------------------------

void TDataStore::OpenDatabase(const char *Filename)
{
  if (!DB) {
    DB = new CppSQLite3DB();
    DB->open(Filename);

    /*
     * Make sure the schema is up to date.
     */
    Migrate();
  }
}
//---------------------------------------------------------------------------

void TDataStore::CloseDatabase(void)
{
  if (DB) {
    DB->close();
    delete DB;
    DB = NULL;
  }
}
//---------------------------------------------------------------------------

void TDataStore::CreateDatabase(const char *Filename)
{
  /*
   * Create and configure the DB.
   */
  DB = new CppSQLite3DB();
  DB->open(Filename);
  
  /*
   * Create the schema.
   */
  ExecuteStmt("create table scanning_summary ( "
              "week_hour integer not null, "
              "completed_scans integer not null, "
              "timestamp integer not null)");
  
  ExecuteStmt("create index idx_scanning_summary_week_hour "
              "on scanning_summary (week_hour) ");
  
  string S;
  ExecuteStmt("BEGIN");
  for (int i = 0; i < 168; i++) {
    S = "insert into scanning_summary values (";
    S += Int2String(i);
    S += ", 0, 0)";
    ExecuteStmt(S.c_str());
  }
  ExecuteStmt("COMMIT");

  /*
   * Close the DB. We will open it again when we need it.
   */
  CloseDatabase();
}
//---------------------------------------------------------------------------

void TDataStore::ExecuteStmt(string SQL)
{
  TLocker Locker(QueryLock);
  if (!DB) {
    throw CppSQLite3Exception(1, "Attempt to execute statement on a closed database.", false);
  }
  DB->execDML(SQL.c_str());
}
//---------------------------------------------------------------------------

CppSQLite3Query TDataStore::ExecuteQuery(string SQL)
{
  if (!DB) {
    throw CppSQLite3Exception(1, "Attempt to execute query on a closed database.", false);
  }
  
  return DB->execQuery(SQL.c_str());
}
//---------------------------------------------------------------------------


typedef void (*TMigration)(TDataStore *Manager);

void MigrationAddSchema_001(TDataStore *Manager)
{
  /*
   * Create the schema table.
   */
  Manager->ExecuteStmt("create table schema_info ( "
    "version integer not null default 0) ");
  Manager->ExecuteStmt("insert into schema_info (version) values (0) ");
}
//---------------------------------------------------------------------------

void MigrationAddScanStatus_002(TDataStore *Manager)
{
}
//---------------------------------------------------------------------------

/*
 * When a new migration is necessary, simply add it to this list.
 */
TMigration Migrations[] = {
  MigrationAddSchema_001,
  //MigrationAddScanStatus_002
};
//---------------------------------------------------------------------------
              
/*
 * Determine the current schema version. If the schema_info table
 * is not present then the version is 0.
 */
int TDataStore::GetDBVersion()
{
  TLocker Locker(QueryLock);
  try {
    CppSQLite3Query Results = ExecuteQuery("select version from schema_info");
    if (Results.eof()) {
      return 0;
    } else {
      return Results.getIntField("version");
    }
  } catch (...) {
    return 0;
  }
}
//---------------------------------------------------------------------------

void TDataStore::Migrate()
{
  int StartingVersion = GetDBVersion();

  for (unsigned int V = StartingVersion;
    V < sizeof(Migrations)/sizeof(*Migrations);
    V++) {
    LogMesg("Migrating data schema from %d to %d", V, V+1);
    Migrations[V](this);
    ExecuteStmt("update schema_info set version = " + Int2String(V+1));
  }
}
//---------------------------------------------------------------------------