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using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Text;
using System.Threading.Tasks;
using Tango.Core;
namespace Tango.BL.Builders
{
public class EntityCollectionBuilderBase<T, TBuilder> : IEntityCollectionBuilder<T> where T : ObservableEntity<T> where TBuilder : EntityCollectionBuilderBase<T, TBuilder>
{
private List<KeyValuePair<int, Action>> _steps;
private List<KeyValuePair<int, Func<IQueryable<T>, IQueryable<T>>>> _querySteps;
private bool _entity_set;
protected IEnumerable<T> Entities { get; set; }
protected ObservablesContext Context { get; set; }
public EntityCollectionBuilderBase(ObservablesContext context)
{
Entities = new List<T>();
_steps = new List<KeyValuePair<int, Action>>();
_querySteps = new List<KeyValuePair<int, Func<IQueryable<T>, IQueryable<T>>>>();
Context = context;
}
public virtual TBuilder SetAll()
{
AddStep(0, () =>
{
IQueryable<T> query = Context.Set<T>();
query = OnSetQuery(query);
foreach (var queryStep in _querySteps.ToList().DistinctBy(x => x.Key).OrderBy(x => x.Key))
{
query = queryStep.Value(query);
}
Entities = query.ToList();
});
_entity_set = true;
return this as TBuilder;
}
public virtual TBuilder Set(Expression<Func<T, bool>> condition)
{
AddStep(0, () =>
{
IQueryable<T> query = Context.Set<T>().Where(condition);
query = OnSetQuery(query);
foreach (var queryStep in _querySteps.ToList().DistinctBy(x => x.Key).OrderBy(x => x.Key))
{
query = queryStep.Value(query);
}
Entities = query.ToList();
});
_entity_set = true;
return this as TBuilder;
}
protected virtual IQueryable<T> OnSetQuery(IQueryable<T> query)
{
return query;
}
protected void CommitSteps()
{
foreach (var step in _steps.ToList().DistinctBy(x => x.Key).OrderBy(x => x.Key))
{
step.Value();
_steps.Remove(step);
}
}
protected TBuilder AddStep(int index, Action action)
{
_steps.Add(new KeyValuePair<int, Action>(index, action));
return this as TBuilder;
}
protected TBuilder AddQueryStep(int index, Func<IQueryable<T>, IQueryable<T>> func)
{
_querySteps.Add(new KeyValuePair<int, Func<IQueryable<T>, IQueryable<T>>>(index, func));
return this as TBuilder;
}
public SynchronizedObservableCollection<T> Build()
{
if (!_entity_set)
{
throw new InvalidOperationException("Could not build entity. Entity was not set.");
}
CommitSteps();
return Entities.ToSynchronizedObservableCollection();
}
public Task<SynchronizedObservableCollection<T>> BuildAsync()
{
return Task.Factory.StartNew<SynchronizedObservableCollection<T>>(() =>
{
return Build();
});
}
}
}
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