From ffea7e88a28d2809563bd366944ff71a3e217c1e Mon Sep 17 00:00:00 2001
From: Manu Mtz-Almeida <manu.valladolid@gmail.com>
Date: Sat, 30 Aug 2014 22:22:57 +0200
Subject: [PATCH] Working on content type negotiation API

---
 CHANGELOG.md |  5 ++++
 context.go   | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 utils.go     | 26 +++++++++++++++++++
 3 files changed, 104 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5ec8c5a..c89a3c2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 #Changelog
 
+###Gin 0.5 (Aug 21, 2014)
+
+- [NEW] Content Negotiation
+
+
 ###Gin 0.4 (Aug 21, 2014)
 
 - [NEW] Development mode
diff --git a/context.go b/context.go
index 294d1cc..570314b 100644
--- a/context.go
+++ b/context.go
@@ -67,6 +67,7 @@ type Context struct {
 	Engine    *Engine
 	handlers  []HandlerFunc
 	index     int8
+	accepted  []string
 }
 
 /************************************/
@@ -275,3 +276,75 @@ func (c *Context) Data(code int, contentType string, data []byte) {
 func (c *Context) File(filepath string) {
 	http.ServeFile(c.Writer, c.Request, filepath)
 }
+
+/************************************/
+/******** CONTENT NEGOTIATION *******/
+/************************************/
+type Negotiate struct {
+	Offered  []string
+	Data     interface{}
+	JsonData interface{}
+	XMLData  interface{}
+	HTMLData interface{}
+	HTMLPath string
+}
+
+func (c *Context) Negotiate2(code int, config Negotiate) {
+	result := c.NegotiateFormat(config.Offered...)
+	switch result {
+	case MIMEJSON:
+		c.JSON(code, config.Data)
+
+	case MIMEHTML:
+		name := config.HTMLPath
+		c.HTML(code, name, config.Data)
+
+	case MIMEXML:
+		c.XML(code, config.Data)
+	default:
+		c.Fail(400, errors.New("m"))
+	}
+}
+
+func (c *Context) Negotiate(code int, config map[string]interface{}, offerts ...string) {
+	result := c.NegotiateFormat(offerts...)
+	switch result {
+	case MIMEJSON:
+		data := readData("json.data", config)
+		c.JSON(code, data)
+
+	case MIMEHTML:
+		data := readData("html.data", config)
+		name := config["html.path"].(string)
+		c.HTML(code, name, data)
+
+	case MIMEXML:
+		data := readData("xml.data", config)
+		c.XML(code, data)
+	default:
+		c.Fail(400, errors.New("m"))
+	}
+}
+
+func (c *Context) NegotiateFormat(offered ...string) string {
+	if c.accepted == nil {
+		c.accepted = parseAccept(c.Request.Header.Get("Accept"))
+	}
+	if len(c.accepted) == 0 {
+		return offered[0]
+
+	} else {
+		for _, accepted := range c.accepted {
+			for _, offert := range offered {
+				if accepted == offert {
+					return offert
+				}
+			}
+		}
+		return ""
+	}
+}
+
+func (c *Context) SetAccepted(formats ...string) {
+	c.accepted = formats
+}
diff --git a/utils.go b/utils.go
index f58097a..96d403f 100644
--- a/utils.go
+++ b/utils.go
@@ -8,6 +8,7 @@ import (
 	"encoding/xml"
 	"reflect"
 	"runtime"
+	"strings"
 )
 
 type H map[string]interface{}
@@ -45,6 +46,31 @@ func filterFlags(content string) string {
 	return content
 }
 
+func readData(key string, config map[string]interface{}) interface{} {
+	data, ok := config[key]
+	if ok {
+		return data
+	}
+	data, ok = config["*.data"]
+	if !ok {
+		panic("negotiation config is invalid")
+	}
+	return data
+}
+
+func parseAccept(accept string) []string {
+	parts := strings.Split(accept, ",")
+	for i, part := range parts {
+		index := strings.IndexByte(part, ';')
+		if index >= 0 {
+			part = part[0:index]
+		}
+		part = strings.TrimSpace(part)
+		parts[i] = part
+	}
+	return parts
+}
+
 func funcName(f interface{}) string {
 	return runtime.FuncForPC(reflect.ValueOf(f).Pointer()).Name()
 }