/// <summary>
/// Returns a range of elements from the source, if the elements are not local it will fetch them from the interwebs
/// This can take multiple web calls to get the list, so this can be slow. If there aren't enough elements remaining
/// we will return as many as we can get.
/// THIS IS NOT THREAD SAFE
/// </summary>
/// <param name="bottom">The bottom range, inclusive</param>
/// <param name="top">Teh top of the range, exclusive</param>
/// <returns></returns>
public async Task <List <Element <T> > > FetchElements(int bottom, int top)
{
if (top <= bottom)
{
throw new Exception("top can't be larger than bottom!");
}
int santyCheckCount = 0;
while (true)
{
// See if we now have what they asked for, OR the list has elements but we don't have an after.
// (this is the case when we have hit the end of the list)
// #bug!?!? At some point I changed the children count in the after check to santyCheckCount == 0, but I can't remember why
// and it breaks lists that have ends. There is some bug where something doesn't try to refresh or something...
if (m_currentElementList.Children.Count >= top ||
(m_currentElementList.Children.Count != 0 && m_currentElementList.After == null) ||
(santyCheckCount > 25))
{
// Return what they asked for capped at the list size
int length = top - bottom;
int listLength = m_currentElementList.Children.Count - bottom;
length = Math.Min(length, listLength);
// Set what the top was we returned.
m_lastTopGet = bottom + length;
return(m_currentElementList.Children.GetRange(bottom, length));
}
// Figure out how many we need still.
int numberNeeded = top - m_currentElementList.Children.Count;
// Make the request.
string webResult = await MakeRequest(numberNeeded, m_currentElementList.After);
RootElement <T> root = null;
// Special case, see the comment on the bool var
if (m_hasEmptyArrayRoot)
{
// Fix up the json returned.
string namedRootJson = "{\"root\": " + webResult + "}";
ArrayRoot <T> arrayRoot = await Task.Run(() => JsonConvert.DeserializeObject <ArrayRoot <T> >(namedRootJson));
if (m_takeFirstArrayRoot)
{
// Used for forcing a post to load in flipview.
root = arrayRoot.Root[0];
}
else
{
// Used for comments to ignore the post header
root = arrayRoot.Root[1];
}
}
else
{
// Parse the Json
root = await Task.Run(() => JsonConvert.DeserializeObject <RootElement <T> >(webResult));
}
// Copy the new contents into the current cache
m_currentElementList.Children.AddRange(root.Data.Children);
// Update the before and after
m_currentElementList.After = root.Data.After;
m_currentElementList.Before = root.Data.Before;
santyCheckCount++;
}
}
/// <summary>
/// Returns a range of elements from the source, if the elements are not local it will fetch them from the interwebs
/// This can take multiple web calls to get the list, so this can be slow. If there aren't enough elements remaining
/// we will return as many as we can get.
/// THIS IS NOT THREAD SAFE
/// </summary>
/// <param name="bottom">The bottom range, inclusive</param>
/// <param name="top">Teh top of the range, exclusive</param>
/// <returns></returns>
public async Task <List <Element <T> > > FetchElements(int bottom, int top)
{
if (top <= bottom)
{
throw new Exception("top can't be larger than bottom!");
}
int santyCheckCount = 0;
while (true)
{
// See if we now have what they asked for, OR the list has elements but we don't have an after.
// (this is the case when we have hit the end of the list)
// #bug!?!? At some point I changed the children count in the after check to santyCheckCount == 0, but I can't remember why
// and it breaks lists that have ends. There is some bug where something doesn't try to refresh or something...
if (m_currentElementList.Children.Count >= top ||
(m_currentElementList.Children.Count != 0 && m_currentElementList.After == null) ||
(santyCheckCount > 25))
{
// Return what they asked for capped at the list size
int length = top - bottom;
int listLength = m_currentElementList.Children.Count - bottom;
length = Math.Min(length, listLength);
// Set what the top was we returned.
m_lastTopGet = bottom + length;
return(m_currentElementList.Children.GetRange(bottom, length));
}
// Figure out how many we need still.
int numberNeeded = top - m_currentElementList.Children.Count;
// Make the request.
IHttpContent webResult = await MakeRequest(numberNeeded, m_currentElementList.After);
// This will hold the root
RootElement <T> root = null;
// Get the input stream and json reader.
// NOTE!! We are really careful not to use a string here so we don't have to allocate a huge string.
IInputStream inputStream = await webResult.ReadAsInputStreamAsync();
using (StreamReader reader = new StreamReader(inputStream.AsStreamForRead()))
using (JsonReader jsonReader = new JsonTextReader(reader))
{
// Check if we have an array root or a object root
if (m_isArrayRoot)
{
// Parse the Json as an object
JsonSerializer serializer = new JsonSerializer();
List <RootElement <T> > arrayRoot = await Task.Run(() => serializer.Deserialize <List <RootElement <T> > >(jsonReader));
// Use which ever list element we want.
if (m_takeFirstArrayRoot)
{
root = arrayRoot[0];
}
else
{
root = arrayRoot[1];
}
}
else
{
// Parse the Json as an object
JsonSerializer serializer = new JsonSerializer();
root = await Task.Run(() => serializer.Deserialize <RootElement <T> >(jsonReader));
}
}
// Copy the new contents into the current cache
m_currentElementList.Children.AddRange(root.Data.Children);
// Update the before and after
m_currentElementList.After = root.Data.After;
m_currentElementList.Before = root.Data.Before;
santyCheckCount++;
}
}
