/**Returns a list of the most viewed pages.*/
private List <DvdInfo> getMostViewedDvdInfos(Customer customer)
{
List <DvdInfo> dvdInfos = new List <DvdInfo>();
try
{
DvdInfoService dvdInfoService = new DvdInfoService();
List <PageVisits> pageVisitsList = new PageVisitsService().getTopPageVisitsForCustomer(customer, 16); //Throws NoRecordException
List <DvdInfo> dvdInfosFinal = new List <DvdInfo>();
foreach (PageVisits pageVisits in pageVisitsList)
{
dvdInfos.Add(dvdInfoService.getByID(pageVisits.dvdInfo.dvd_info_id.ToString())); //Throws NoRecordException
}
//only return dvd's that the user hasn't bought before
foreach (DvdInfo dvdInfo in dvdInfos)
{
if (!orderLinesDvdIds.Contains(dvdInfo.dvd_info_id))
{
dvdInfosFinal.Add(dvdInfo);
}
}
}
catch (DALException ex)
{
throw new NoRecordException("failed to retrieve data", ex);
}
catch (NoRecordException ex)
{
}
return(dvdInfos);
}
public List <DvdInfo> getRelatedDvds(String id, int amount)
{
List <DvdInfo> relatedDvds = new List <DvdInfo>();
DvdInfoService dvdInfoService = new DvdInfoService();
DvdInfo dvdInfo = dvdInfoService.getByID(id); //Throws NoRecordException
foreach (int i in new DvdGenreDAO().findRelatedDvdsBasedOnGenre(dvdInfo, amount)) //Throws NoRecordException
{
relatedDvds.Add(new DvdInfoDAO().getByID(i.ToString())); //Throws NoRecordException
}
return(relatedDvds);
}
/**Returns a list of recommendations based on the user's order history.
* 1) Gets all past orders and determines the user's 3 favourite genres.
* 2) Gets a list of DVDs that have the most matches with the user's favourites.
* A dvd that contains all 3 favourite genres will rank higher than a dvd that only matches 1 favourite genre.
* 3) Removes dvds that the user has already rented or bought before.
* 4) If no dvd's are left (or if the user had no orderlines), a list of DVDs is generated based on the pages the user has visited.
*/
public List <DvdInfo> getRecommendations(Customer customer, int amount)
{
List <DvdInfo> dvdList = new List <DvdInfo>();
List <Genre> genres = new List <Genre>();
List <OrderLine> orderLines;
try
{
orderLines = new OrderLineService().getByCustomer(customer); //Throws NoRecordException
} catch (Exception error)
{
orderLines = new List <OrderLine>();
}
orderLinesDvdIds = new List <String>(); //list that contains the DVDids of the orderlines (=movies that the user has rented before)
GenreService genreService = new GenreService();
DvdInfoService dvdInfoService = new DvdInfoService();
//customer has at least 1 order, base recommendations on orderLines
if (orderLines.Count > 0)
{
foreach (OrderLine line in orderLines)
{
String dvdID = line.dvdInfo.dvd_info_id;
genres.AddRange(genreService.getGenresForDvd(dvdID)); //Throws NoRecordException
//fill orderLinesDvdIds
if (!orderLinesDvdIds.Contains(dvdID))
{
orderLinesDvdIds.Add(dvdID);
}
}
//put genres in a dictionary (genreID, numberOfOccurrances)
Dictionary <int, int> genreCountMap = new Dictionary <int, int>();
foreach (Genre genre in genres)
{
if (genreCountMap.ContainsKey(genre.genre_id))
{
genreCountMap[genre.genre_id]++;
}
else
{
genreCountMap.Add(genre.genre_id, 1);
}
}
//loop over dictionary and find the 3 most occuring genres
int[] maxGenres = { 0, 0, 0 };
int[] maxCounts = { 0, 0, 0 };
foreach (KeyValuePair <int, int> pair in genreCountMap)
{
if (maxCounts[0] < pair.Value)
{
maxCounts[2] = maxCounts[1];
maxCounts[1] = maxCounts[0];
maxCounts[0] = pair.Value;
maxGenres[2] = maxGenres[1];
maxGenres[1] = maxGenres[0];
maxGenres[0] = pair.Key;
}
else if (maxCounts[1] < pair.Value)
{
maxCounts[2] = maxCounts[1];
maxCounts[1] = pair.Value;
maxGenres[2] = maxGenres[1];
maxGenres[1] = pair.Key;
}
else if (maxCounts[2] < pair.Value)
{
maxCounts[2] = pair.Value;
maxGenres[2] = pair.Key;
}
}
//we now have the user's 3 favourite genres in maxGenres, use that info to get the dvds that match those 3 genres the most
//get max 16 dvds. Index will always show maximum 4, but catalog can show up to 16
List <String> dvdIds = dvdInfoService.getRecommendations(maxGenres, 16); //Throws NoRecordException
List <String> dvdTempIds = new List <String>();
//only accept dvd's that the user had not watched yet
foreach (String id in dvdIds)
{
if (!orderLinesDvdIds.Contains(id))
{
dvdTempIds.Add(id);
}
}
if (dvdTempIds.Count > 0)
{
foreach (String id in dvdTempIds)
{
dvdList.Add(dvdInfoService.getByID(id.ToString())); //Throws NoRecordException
}
}
else
{
//customer has already bought or rented every suggestion, recommend the movies whose pages the user has viewed most often
dvdList = getMostViewedDvdInfos(customer); //Throws NoRecordException
}
}
else
{
//customer has no orderlines, recommend the movies whose pages the user has viewed the most
dvdList = getMostViewedDvdInfos(customer); //Throws NoRecordException
}
//remove elements until the list size is the requested size (4 for index row, 16 for catalog page)
//loop deletes a random item until the size is ok so the user gets different recommendations on every visit/refresh
Random rnd = new Random();
while (dvdList.Count > amount)
{
dvdList.RemoveAt(rnd.Next(dvdList.Count));
}
return(dvdList);
}