feat: add Brave Search as web search engine provider (#1481)

* feat: add Brave Search as web search engine provider

* docs: update README

lua/avante/config.lua

@@ -161,6 +161,28 @@ M._defaults = {
           return "", nil
         end,
       },
+      brave = {
+        api_key_name = "BRAVE_API_KEY",
+        extra_request_body = {
+          count = "10",
+          result_filter = "web",
+        },
+        format_response_body = function(body)
+          if body.web == nil then return "", nil end
+
+          local jsn = vim.iter(body.web.results):map(
+            function(result)
+              return {
+                title = result.title,
+                url = result.url,
+                snippet = result.description,
+              }
+            end
+          )
+
+          return vim.json.encode(jsn), nil
+        end,
+      },
     },
   },
   ---@type AvanteSupportedProvider

lua/avante/llm_tools.lua

@@ -378,6 +378,23 @@ function M.web_search(opts, on_log)
     if resp.status ~= 200 then return nil, "Error: " .. resp.body end
     local jsn = vim.json.decode(resp.body)
     return search_engine.format_response_body(jsn)
+  elseif provider_type == "brave" then
+    local query_params = vim.tbl_deep_extend("force", {
+      q = opts.query,
+    }, search_engine.extra_request_body)
+    local query_string = ""
+    for key, value in pairs(query_params) do
+      query_string = query_string .. key .. "=" .. vim.uri_encode(value) .. "&"
+    end
+    local resp = curl.get("https://api.search.brave.com/res/v1/web/search?" .. query_string, {
+      headers = {
+        ["Content-Type"] = "application/json",
+        ["X-Subscription-Token"] = api_key,
+      },
+    })
+    if resp.status ~= 200 then return nil, "Error: " .. resp.body end
+    local jsn = vim.json.decode(resp.body)
+    return search_engine.format_response_body(jsn)
   end
 end