From 69b5046bc09582e233d620062e81c4a48c2ba350 Mon Sep 17 00:00:00 2001
From: Kasun Herath <kasunh01@gmail.com>
Date: Sat, 19 Nov 2016 22:15:11 +0530
Subject: [PATCH] aggregate fields

---
 beesql/aggregation.py | 44 +++++++++++++++++++++++++++++++++++++
 beesql/query/base.py  | 51 ++++++++++++++++++++++++++++++-------------
 2 files changed, 80 insertions(+), 15 deletions(-)
 create mode 100644 beesql/aggregation.py

diff --git a/beesql/aggregation.py b/beesql/aggregation.py
new file mode 100644
index 0000000..c7c049d
--- /dev/null
+++ b/beesql/aggregation.py
@@ -0,0 +1,44 @@
+class AggregationField(object):
+    def __init__(self, column_name, as_name=None):
+        self.column_name = column_name
+        self.as_name = as_name
+
+
+class SumAggregationField(AggregationField):
+    QUERY_PART_NAME = 'sum_aggregation'
+
+
+class AvgAggregationField(AggregationField):
+    QUERY_PART_NAME = 'avg_aggregation'
+
+
+class CountAggregationField(AggregationField):
+    QUERY_PART_NAME = 'count_aggregation'
+
+
+class MaxAggregationField(AggregationField):
+    QUERY_PART_NAME = 'max_aggregation'
+
+
+class MinAggregationField(AggregationField):
+    QUERY_PART_NAME = 'min_aggregation'
+
+
+def _sum(column_name, as_name=None):
+    return SumAggregationField(column_name, as_name)
+
+
+def avg(column_name, as_name=None):
+    return AvgAggregationField(column_name, as_name)
+
+
+def count(column_name, as_name=None):
+    return CountAggregationField(column_name, as_name)
+
+
+def _max(column_name, as_name=None):
+    return MaxAggregationField(column_name, as_name)
+
+
+def _min(column_name, as_name=None):
+    return MinAggregationField(column_name, as_name)
diff --git a/beesql/query/base.py b/beesql/query/base.py
index 977ca5f..8a68095 100644
--- a/beesql/query/base.py
+++ b/beesql/query/base.py
@@ -2,6 +2,7 @@
 
 from .mixins import DataOperatorFuncs, AggregationFuncs
 from ..exceptions import BeeSQLError
+from ..aggregation import AggregationField
 from .decorators import primary_keyword, secondary_keyword, logical_operator, complete_condition
 from .decorators import aggregation
 
@@ -257,6 +258,14 @@ class AvgAggregation(AggregationFuncs, Aggregation):
     FUNCTION_NAME = 'AVG'
 
 
+class MaxAggregation(AggregationFuncs, Aggregation):
+    FUNCTION_NAME = 'MAX'
+
+
+class MinAggregation(AggregationFuncs, Aggregation):
+    FUNCTION_NAME = 'MIN'
+
+
 class Statement(object):
 
     def __init__(self, query, **kwargs):
@@ -295,26 +304,24 @@ def get_sql(self):
 
 class Select(StatementWithCondition, Statement):
 
-    def __init__(self, query, all=False, *args):
+    def __init__(self, query, aggregations=None, *args):
         super().__init__(query)
-        self.aggregations = []
+        self.aggregations = aggregations or []
         self.all = all
         self.fields = list(set(args))
 
     def select(self, *args):
-        fields = list(args)
-        if self.all:
-            return
-
-        all = True if len(fields) == 0 else False
-        if all:
-            self.all = all
-            return
-
+        q_maker = self.query.get_query_maker()
+        fields = filter(lambda x: isinstance(x, str), args)
         fields_set = set(self.fields)
         fields_set.update(fields)
         self.fields = list(fields_set)
 
+        agg_fields = filter(lambda x: isinstance(x, AggregationField), args)
+        aggregation_queries = [q_maker.make(agg.QUERY_PART_NAME)(agg.column_name, agg.as_name) for agg in agg_fields]
+        for agg_query in aggregation_queries:
+            self.add_aggregation(agg_query)
+
         return self
 
     @secondary_keyword
@@ -364,11 +371,21 @@ def count(self, column_name, as_name=None):
         AggregationClass = self.query.get_query_maker().make('count_aggregation')
         return AggregationClass(column_name, as_name)
 
+    @aggregation
+    def max(self, column_name, as_name=None):
+        AggregationClass = self.query.get_query_maker().make('max_aggregation')
+        return AggregationClass(column_name, as_name)
+
+    @aggregation
+    def min(self, column_name, as_name=None):
+        AggregationClass = self.query.get_query_maker().make('min_aggregation')
+        return AggregationClass(column_name, as_name)
+
     def add_aggregation(self, aggregation):
         self.aggregations.append(aggregation)
 
     def _get_sql(self):
-        if self.all:
+        if not self.fields and not self.aggregations:
             fields = '*'
         else:
             fields = self.fields[:]
@@ -542,9 +559,11 @@ def on(self, table):
 
     @primary_keyword
     def select(self, *args):
-        fields = args[:]
-        all = True if len(fields) == 0 else False
-        select = self.get_query_maker().make('select')(self, all, *fields)
+        q_maker = self.get_query_maker()
+        fields = filter(lambda x: isinstance(x, str), args)
+        agg_fields = filter(lambda x: isinstance(x, AggregationField), args)
+        aggregation_queries = [q_maker.make(agg.QUERY_PART_NAME)(agg.column_name, agg.as_name) for agg in agg_fields]
+        select = self.get_query_maker().make('select')(self, aggregation_queries, *fields)
         return select
 
     @primary_keyword
@@ -623,6 +642,8 @@ class QueryMaker(metaclass=QueryRegistry):
         'count_aggregation': CountAggregation,
         'sum_aggregation': SumAggregation,
         'avg_aggregation': AvgAggregation,
+        'max_aggregation': MaxAggregation,
+        'min_aggregation': MinAggregation,
     }
 
     @classmethod