add support for Baidu yiyan (#2049)

### What problem does this PR solve?

add support for Baidu yiyan

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

---------

Co-authored-by: Zhedong Cen <cenzhedong2@126.com>

rag/llm/chat_model.py

@@ -1185,3 +1185,69 @@ class SparkChat(Base):
         }
         model_version = model2version[model_name]
         super().__init__(key, model_version, base_url)
+
+
+class BaiduYiyanChat(Base):
+    def __init__(self, key, model_name, base_url=None):
+        import qianfan
+        
+        key = json.loads(key)
+        ak = key.get("yiyan_ak","")
+        sk = key.get("yiyan_sk","")
+        self.client = qianfan.ChatCompletion(ak=ak,sk=sk)
+        self.model_name = model_name.lower()
+        self.system = ""
+
+    def chat(self, system, history, gen_conf):
+        if system:
+            self.system = system
+        gen_conf["penalty_score"] = (
+            (gen_conf.get("presence_penalty", 0) + gen_conf.get("frequency_penalty", 0)) / 2
+        ) + 1
+        if "max_tokens" in gen_conf:
+            gen_conf["max_output_tokens"] = gen_conf["max_tokens"]
+        ans = ""
+        
+        try:
+            response = self.client.do(
+                model=self.model_name, 
+                messages=history, 
+                system=self.system,
+                **gen_conf
+            ).body
+            ans = response['result']
+            return ans, response["usage"]["total_tokens"]
+            
+        except Exception as e:
+            return ans + "\n**ERROR**: " + str(e), 0
+
+    def chat_streamly(self, system, history, gen_conf):
+        if system:
+            self.system = system
+        gen_conf["penalty_score"] = (
+            (gen_conf.get("presence_penalty", 0) + gen_conf.get("frequency_penalty", 0)) / 2
+        ) + 1
+        if "max_tokens" in gen_conf:
+            gen_conf["max_output_tokens"] = gen_conf["max_tokens"]
+        ans = ""
+        total_tokens = 0
+        
+        try:
+            response = self.client.do(
+                model=self.model_name, 
+                messages=history, 
+                system=self.system,
+                stream=True,
+                **gen_conf
+            )
+            for resp in response:
+                resp = resp.body
+                ans += resp['result']
+                total_tokens = resp["usage"]["total_tokens"]
+
+                yield ans
+
+        except Exception as e:
+            return ans + "\n**ERROR**: " + str(e), 0
+
+        yield total_tokens