/*
 * Strawberry Music Player
 * This file was part of Clementine.
 * Copyright 2010, David Sansome <me@davidsansome.com>
 *
 * Strawberry is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Strawberry 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 Strawberry.  If not, see <http://www.gnu.org/licenses/>.
 * 
 */

#include "config.h"

#include <QtGlobal>
#include <QDateTime>
#include <QVariant>
#include <QString>
#include <QStringList>
#include <QStringBuilder>
#include <QRegExp>
#include <QSqlDatabase>
#include <QSqlQuery>

#include "collectionquery.h"
#include "core/song.h"

QueryOptions::QueryOptions() : max_age_(-1), query_mode_(QueryMode_All) {}

CollectionQuery::CollectionQuery(const QueryOptions& options)
    : include_unavailable_(false), join_with_fts_(false), limit_(-1) {

  if (!options.filter().isEmpty()) {
    // We need to munge the filter text a little bit to get it to work as expected with sqlite's FTS3:
    //  1) Append * to all tokens.
    //  2) Prefix "fts" to column names.
    //  3) Remove colons which don't correspond to column names.

    // Split on whitespace
    QStringList tokens(options.filter().split(QRegExp("\\s+"), QString::SkipEmptyParts));
    QString query;
    for (QString token : tokens) {
      token.remove('(');
      token.remove(')');
      token.remove('"');
      token.replace('-', ' ');

      if (token.contains(':')) {
        // Only prefix fts if the token is a valid column name.
        if (Song::kFtsColumns.contains("fts" + token.section(':', 0, 0), Qt::CaseInsensitive)) {
          // Account for multiple colons.
          QString columntoken = token.section(':', 0, 0, QString::SectionIncludeTrailingSep);
          QString subtoken = token.section(':', 1, -1);
          subtoken.replace(":", " ");
          subtoken = subtoken.trimmed();
          query += "fts" + columntoken + subtoken + "* ";
        }
        else {
          token.replace(":", " ");
          token = token.trimmed();
          query += token + "* ";
        }
      }
      else {
        query += token + "* ";
      }
    }

    where_clauses_ << "fts.%fts_table_noprefix MATCH ?";
    bound_values_ << query;
    join_with_fts_ = true;
  }

  if (options.max_age() != -1) {
    int cutoff = QDateTime::currentDateTime().toTime_t() - options.max_age();

    where_clauses_ << "ctime > ?";
    bound_values_ << cutoff;
  }

  // TODO: Currently you cannot use any QueryMode other than All and fts at the same time.
  // Joining songs, duplicated_songs and songs_fts all together takes a huge amount of time.
  // The query takes about 20 seconds on my machine then. Why?
  // Untagged mode could work with additional filtering but I'm disabling it just to be consistent
  // this way filtering is available only in the All mode.
  // Remember though that when you fix the Duplicates + FTS cooperation, enable the filtering in both Duplicates and Untagged modes.
  duplicates_only_ = options.query_mode() == QueryOptions::QueryMode_Duplicates;

  if (options.query_mode() == QueryOptions::QueryMode_Untagged) {
    where_clauses_ << "(artist = '' OR album = '' OR title ='')";
  }

}

QString CollectionQuery::GetInnerQuery() {
  return duplicates_only_
             ? QString(" INNER JOIN (select * from duplicated_songs) dsongs        "
                   "ON (%songs_table.artist = dsongs.dup_artist       "
                   "AND %songs_table.album = dsongs.dup_album     "
                   "AND %songs_table.title = dsongs.dup_title)    ")
             : QString();
}

void CollectionQuery::AddWhere(const QString &column, const QVariant &value, const QString &op) {

  // ignore 'literal' for IN
  if (!op.compare("IN", Qt::CaseInsensitive)) {
    QStringList final;
    for (const QString &single_value : value.toStringList()) {
      final.append("?");
      bound_values_ << single_value;
    }

    where_clauses_ << QString("%1 IN (" + final.join(",") + ")").arg(column);
  }
  else {
    // Do integers inline - sqlite seems to get confused when you pass integers to bound parameters
    if (value.type() == QVariant::Int) {
      where_clauses_ << QString("%1 %2 %3").arg(column, op, value.toString());
    }
    else {
      where_clauses_ << QString("%1 %2 ?").arg(column, op);
      bound_values_ << value;
    }
  }

}

void CollectionQuery::AddCompilationRequirement(bool compilation) {
  // The unary + is added to prevent sqlite from using the index idx_comp_artist.
  // When joining with fts, sqlite 3.8 has a tendency to use this index and thereby nesting the tables in an order which gives very poor performance

  where_clauses_ << QString("+compilation_effective = %1").arg(compilation ? 1 : 0);

}

QSqlQuery CollectionQuery::Exec(QSqlDatabase db, const QString &songs_table, const QString &fts_table) {

  QString sql;

  if (join_with_fts_) {
    sql = QString("SELECT %1 FROM %2 INNER JOIN %3 AS fts ON %2.ROWID = fts.ROWID").arg(column_spec_, songs_table, fts_table);
  }
  else {
    sql = QString("SELECT %1 FROM %2 %3").arg(column_spec_, songs_table, GetInnerQuery());
  }

  QStringList where_clauses(where_clauses_);
  if (!include_unavailable_) {
    where_clauses << "unavailable = 0";
  }

  if (!where_clauses.isEmpty()) sql += " WHERE " + where_clauses.join(" AND ");

  if (!order_by_.isEmpty()) sql += " ORDER BY " + order_by_;

  if (limit_ != -1) sql += " LIMIT " + QString::number(limit_);

  sql.replace("%songs_table", songs_table);
  sql.replace("%fts_table_noprefix", fts_table.section('.', -1, -1));
  sql.replace("%fts_table", fts_table);

  query_ = QSqlQuery(db);
  query_.prepare(sql);

  // Bind values
  for (const QVariant &value : bound_values_) {
    query_.addBindValue(value);
  }

  query_.exec();
  return query_;

}

bool CollectionQuery::Next() { return query_.next(); }

QVariant CollectionQuery::Value(int column) const { return query_.value(column); }

bool QueryOptions::Matches(const Song &song) const {

  if (max_age_ != -1) {
    const uint cutoff = QDateTime::currentDateTime().toTime_t() - max_age_;
    if (song.ctime() <= cutoff) return false;
  }

  if (!filter_.isNull()) {
    return song.artist().contains(filter_, Qt::CaseInsensitive) || song.album().contains(filter_, Qt::CaseInsensitive) || song.title().contains(filter_, Qt::CaseInsensitive);
  }

  return true;

}