From e548425b188b4ef242f837b8a53b21ae12e2376a Mon Sep 17 00:00:00 2001
From: ngfrolov <ng.frolov@autodrilling.ru>
Date: Fri, 3 Feb 2023 16:00:45 +0500
Subject: [PATCH] Add PredicateBuilder to build complex predicate expressions

---
 AsbCloudInfrastructure/PredicateBuilder.cs    | 80 +++++++++++++++++++
 .../Repository/ProcessMapRepository.cs        | 36 +++++----
 2 files changed, 99 insertions(+), 17 deletions(-)
 create mode 100644 AsbCloudInfrastructure/PredicateBuilder.cs

diff --git a/AsbCloudInfrastructure/PredicateBuilder.cs b/AsbCloudInfrastructure/PredicateBuilder.cs
new file mode 100644
index 00000000..ff0bf720
--- /dev/null
+++ b/AsbCloudInfrastructure/PredicateBuilder.cs
@@ -0,0 +1,80 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Linq.Expressions;
+
+namespace AsbCloudInfrastructure
+{
+#nullable enable
+    /// <summary>
+    /// stolen from https://github.com/lotosbin/BinbinPredicateBuilder
+    /// </summary>
+    public static class PredicateBuilder
+    {
+        /// <summary>
+        ///     Combines the first predicate with the second using the logical "and".
+        /// </summary>
+        public static Expression<Func<T, bool>> And<T>(this Expression<Func<T, bool>> first, Expression<Func<T, bool>> second)
+        {
+            return first.Compose(second, Expression.AndAlso);
+        }
+
+        /// <summary>
+        ///     Combines the first predicate with the second using the logical "or".
+        /// </summary>
+        public static Expression<Func<T, bool>> Or<T>(this Expression<Func<T, bool>> first, Expression<Func<T, bool>> second)
+        {
+            return first.Compose(second, Expression.OrElse);
+        }
+
+        /// <summary>
+        ///     Negates the predicate.
+        /// </summary>
+        public static Expression<Func<T, bool>> Not<T>(this Expression<Func<T, bool>> expression)
+        {
+            var negated = Expression.Not(expression.Body);
+            return Expression.Lambda<Func<T, bool>>(negated, expression.Parameters);
+        }
+
+        private static Expression<T> Compose<T>(this Expression<T> first, Expression<T> second, Func<Expression, Expression, Expression> merge)
+        {
+            var map = first.Parameters
+                .Select((f, i) => new { f, s = second.Parameters[i] })
+                .ToDictionary(p => p.s, p => p.f);
+
+            var tryReplaceParametr = (Expression node) => 
+            {
+                if (node is ParameterExpression parameter)
+                    if (map.TryGetValue(parameter, out ParameterExpression? replacement))
+                        return replacement;
+                return node;
+            };
+
+            var secondBody = ParameterRebinder.ReplaceParameters(map, second.Body);
+            return Expression.Lambda<T>(merge(first.Body, secondBody), first.Parameters);
+        }
+
+        class ParameterRebinder : ExpressionVisitor
+        {
+            private readonly Dictionary<ParameterExpression, ParameterExpression> map;
+
+            private ParameterRebinder(Dictionary<ParameterExpression, ParameterExpression> map)
+            {
+                this.map = map;
+            }
+
+            public static Expression ReplaceParameters(Dictionary<ParameterExpression, ParameterExpression> map, Expression exp)
+            {
+                return new ParameterRebinder(map).Visit(exp);
+            }
+
+            protected override Expression VisitParameter(ParameterExpression parametr)
+            {
+                if (map.TryGetValue(parametr, out ParameterExpression? replacement))
+                    parametr = replacement;
+                return parametr;
+            }
+        }
+    }
+}
+#nullable disable
\ No newline at end of file
diff --git a/AsbCloudInfrastructure/Repository/ProcessMapRepository.cs b/AsbCloudInfrastructure/Repository/ProcessMapRepository.cs
index 95330293..09f1f0a4 100644
--- a/AsbCloudInfrastructure/Repository/ProcessMapRepository.cs
+++ b/AsbCloudInfrastructure/Repository/ProcessMapRepository.cs
@@ -11,6 +11,7 @@ using Org.BouncyCastle.Asn1.Ocsp;
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Linq.Expressions;
 using System.Threading;
 using System.Threading.Tasks;
 
@@ -80,27 +81,28 @@ namespace AsbCloudInfrastructure.Repository
         private IQueryable<ProcessMap> BuildQuery(IEnumerable<ProcessMapRequest> requests)
         {
             var query = GetQuery();
-            Func<ProcessMap, bool>? p = null;
-            foreach (var request in requests)
+            if (requests.Any())
             {
-                var p2 = (ProcessMap map) => map.IdWell == request.IdWell;
-
-                if (request.IdWellSectionType is not null)
-                    p2 = (ProcessMap map) => p2(map) && map.IdWellSectionType == request.IdWellSectionType;
-
-                if (request.UpdateFrom is not null)
+                Expression<Func<ProcessMap, bool>> predicate = map => false;
+                foreach (var request in requests)
                 {
-                    var timezone = wellService.GetTimezone(request.IdWell);
-                    var updateFromUtc = request.UpdateFrom?.ToUtcDateTimeOffset(timezone.Hours);
-                    p2 = (ProcessMap map) => p2(map) && map.LastUpdate >= updateFromUtc;
+                    Expression<Func<ProcessMap, bool>> predicate2 = map => map.IdWell == request.IdWell;
+
+                    if (request.IdWellSectionType is not null)
+                        predicate2 = predicate2.And(map => map.IdWellSectionType == request.IdWellSectionType);
+
+                    if (request.UpdateFrom is not null)
+                    {
+                        var timezone = wellService.GetTimezone(request.IdWell);
+                        var updateFromUtc = request.UpdateFrom?.ToUtcDateTimeOffset(timezone.Hours);
+                        predicate2 = predicate2.And(map => map.LastUpdate >= updateFromUtc);
+                    }
+
+                    predicate = predicate.Or(predicate2);
                 }
-               
-                p = p is null 
-                    ? p2
-                    : (ProcessMap map) => p(map) || p2(map);
+                query = query.Where(predicate);
+
             }
-            if(p is not null)
-                query.Where(p);
             return query;
         }
         protected override ProcessMapDto Convert(ProcessMap entity)