From 86ac331681ad7ece11688d4c1b0f18c67ba252d4 Mon Sep 17 00:00:00 2001
From: alexpantyukhin <apantykhin@gmail.com>
Date: Fri, 1 Sep 2017 15:53:14 +0400
Subject: [PATCH 1/2] add facade pattern

---
 README.md            |  2 +-
 structural/facade.md | 83 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 84 insertions(+), 1 deletion(-)
 create mode 100644 structural/facade.md

diff --git a/README.md b/README.md
index 7d9f5f7..5874630 100644
--- a/README.md
+++ b/README.md
@@ -28,7 +28,7 @@ A curated collection of idiomatic design & application patterns for Go language.
 | [Bridge](/structural/bridge.md) | Decouples an interface from its implementation so that the two can vary independently | ✘ |
 | [Composite](/structural/composite.md) | Encapsulates and provides access to a number of different objects | ✘ |
 | [Decorator](/structural/decorator.md) | Adds behavior to an object, statically or dynamically | ✔ |
-| [Facade](/structural/facade.md) | Uses one type as an API to a number of others | ✘ |
+| [Facade](/structural/facade.md) | Uses one type as an API to a number of others | ✔ |
 | [Flyweight](/structural/flyweight.md) | Reuses existing instances of objects with similar/identical state to minimize resource usage | ✘ |
 | [Proxy](/structural/proxy.md) | Provides a surrogate for an object to control it's actions | ✔ |
 
diff --git a/structural/facade.md b/structural/facade.md
new file mode 100644
index 0000000..817340f
--- /dev/null
+++ b/structural/facade.md
@@ -0,0 +1,83 @@
+# Facade Pattern
+
+Facade design pattern provides a unified interface to a set
+of interfaces in a subsystem. Facade defines a higher-level
+interface that makes the subsystem easier to use
+
+## Implementation
+
+```go
+package facade
+
+// Models
+type Product struct {
+    name string
+    cost float64
+    discount float64
+}
+
+type User struct {
+    name string
+    discount float64
+}
+
+// Storages
+type ProductStorage struct {
+    storageMap map[string]Product
+}
+
+func (storage ProductStorage) GetProductByName(name string) Product{
+    product, ok := storage.storageMap[name]
+    if (!ok){
+        panic("Product is absent")
+    }
+
+    return product
+}
+
+type UserStorage struct {
+    storageMap map[string]User
+}
+
+func (storage UserStorage) GetUserByName(name string) User{
+    user, ok := storage.storageMap[name]
+    if (!ok){
+        panic("User is absent")
+    }
+
+    return user
+}
+
+// Facade
+type ProductFacade struct {
+    productStorage ProductStorage
+    userStorage UserStorage
+}
+
+func (productFacade ProductFacade) GetDiscountedCost(userName string, productName string) float64 {
+    product := productFacade.productStorage.GetProductByName(productName)
+    user := productFacade.userStorage.GetUserByName(userName)
+
+    return product.cost * (1 - product.discount) * (1 - user.discount)
+}
+
+```
+
+## Usage
+
+```go
+    user := User{name: "Alex", discount: 0.2}
+    product := Product{name: "Car", cost:10.50, discount: 0.1 }
+
+    userStorage := UserStorage{storageMap: make(map[string]User)}
+    //userStorage.storageMap = make(map[string]User)
+    userStorage.storageMap[user.name] = user
+
+    productStorage := ProductStorage{storageMap: make(map[string]Product)}
+    //productStorage.storageMap = make(map[string]Product)
+    productStorage.storageMap[product.name] = product
+
+    facade := ProductFacade{productStorage: productStorage, userStorage: userStorage}
+    discount := facade.GetDiscountedCost("Alex", "Car")
+    fmt.Printf("Cost with discount is: %f", discount)
+```
\ No newline at end of file

From 708e69df8876b4ddb22ac64361492a20e5746df8 Mon Sep 17 00:00:00 2001
From: alexpantyukhin <apantykhin@gmail.com>
Date: Fri, 1 Sep 2017 17:52:07 +0400
Subject: [PATCH 2/2] remove comments

---
 structural/facade.md | 2 --
 1 file changed, 2 deletions(-)

diff --git a/structural/facade.md b/structural/facade.md
index 817340f..b674508 100644
--- a/structural/facade.md
+++ b/structural/facade.md
@@ -70,11 +70,9 @@ func (productFacade ProductFacade) GetDiscountedCost(userName string, productNam
     product := Product{name: "Car", cost:10.50, discount: 0.1 }
 
     userStorage := UserStorage{storageMap: make(map[string]User)}
-    //userStorage.storageMap = make(map[string]User)
     userStorage.storageMap[user.name] = user
 
     productStorage := ProductStorage{storageMap: make(map[string]Product)}
-    //productStorage.storageMap = make(map[string]Product)
     productStorage.storageMap[product.name] = product
 
     facade := ProductFacade{productStorage: productStorage, userStorage: userStorage}