feat: add Gemini support (#142)

Co-authored-by: Jihun Kim <jihun.kim.uk@gmail.com>

lua/avante/config.lua

@@ -7,9 +7,9 @@ local M = {}
 ---@class avante.Config
 M.defaults = {
   debug = false,
-  ---Currently, default supported providers include "claude", "openai", "azure", "deepseek", "groq"
+  ---Currently, default supported providers include "claude", "openai", "azure", "deepseek", "groq", "gemini"
   ---For custom provider, see README.md
-  ---@alias Provider "openai" | "claude" | "azure" | "deepseek" | "groq" | "copilot" | string
+  ---@alias Provider "openai" | "claude" | "azure" | "deepseek" | "groq" | "copilot" | "gemini" | string
   provider = "claude",
   ---@type AvanteSupportedProvider
   openai = {
@@ -62,6 +62,13 @@ M.defaults = {
     max_tokens = 4096,
     ["local"] = false,
   },
+  ---@type AvanteGeminiProvider
+  gemini = {
+    endpoint = "",
+    type = "gemini",
+    model = "gemini-1.5-pro",
+    options = {},
+  },
   ---To add support for custom provider, follow the format below
   ---See https://github.com/yetone/avante.nvim/README.md#custom-providers for more details
   ---@type {[string]: AvanteProvider}

lua/avante/llm.lua

@@ -54,6 +54,7 @@ local E = {
     azure = "AZURE_OPENAI_API_KEY",
     deepseek = "DEEPSEEK_API_KEY",
     groq = "GROQ_API_KEY",
+    gemini = "GEMINI_API_KEY",
     copilot = function()
       if Utils.has("copilot.lua") or Utils.has("copilot.vim") or Utils.copilot.find_config_path() then
         return true
@@ -270,7 +271,11 @@ Remember: Accurate line numbers are CRITICAL. The range start_line to end_line m
 ---
 ---@alias AvanteOpenAIMessage AvanteBaseMessage
 ---
----@alias AvanteChatMessage AvanteClaudeMessage | AvanteOpenAIMessage
+---@class AvanteGeminiMessage
+---@field role "user"
+---@field parts { text: string }[]
+---
+---@alias AvanteChatMessage AvanteClaudeMessage | AvanteOpenAIMessage | AvanteGeminiMessage
 ---
 ---@alias AvanteAiMessageBuilder fun(opts: AvantePromptOptions): AvanteChatMessage[]
 ---
@@ -302,6 +307,11 @@ Remember: Accurate line numbers are CRITICAL. The range start_line to end_line m
 ---@field allow_insecure boolean
 ---@field timeout number
 ---
+---@class AvanteGeminiProvider: AvanteDefaultBaseProvider
+---@field model string
+---@field type string
+---@field options table
+---
 ---@class AvanteProvider: AvanteDefaultBaseProvider
 ---@field model? string
 ---@field api_key_name string
@@ -636,6 +646,93 @@ M.make_groq_curl_args = function(code_opts)
   }
 end
 
+------------------------------Gemini------------------------------
+
+---@param opts AvantePromptOptions
+---@return AvanteGeminiMessage[]
+M.make_gemini_message = function(opts)
+  local code_prompt_obj = {
+    text = string.format("<code>```%s\n%s```</code>", opts.code_lang, opts.code_content),
+  }
+
+  if opts.selected_code_content then
+    code_prompt_obj.text = string.format("<code_context>```%s\n%s```</code_context>", opts.code_lang, opts.code_content)
+  end
+
+  -- parts ready
+  local message_content = {
+    code_prompt_obj,
+  }
+
+  if opts.selected_code_content then
+    local selected_code_obj = {
+      text = string.format("<code>```%s\n%s```</code>", opts.code_lang, opts.selected_code_content),
+    }
+
+    table.insert(message_content, selected_code_obj)
+  end
+
+  -- insert a part into parts
+  table.insert(message_content, {
+    text = string.format("<question>%s</question>", opts.question),
+  })
+
+  -- local user_prompt_obj = {
+  --   text = base_user_prompt,
+  -- }
+
+  -- insert another part into parts
+  -- table.insert(message_content, user_prompt_obj)
+
+  return {
+    {
+      role = "user",
+      parts = message_content,
+    },
+  }
+end
+
+---@type AvanteResponseParser
+M.parse_gemini_response = function(data_stream, event_state, opts)
+  local json = vim.json.decode(data_stream)
+  opts.on_chunk(json.candidates[1].content.parts[1].text)
+end
+
+---@type AvanteCurlArgsBuilder
+M.make_gemini_curl_args = function(code_opts)
+  local endpoint = ""
+  if Config.gemini.endpoint == "" then
+    endpoint = "https://generativelanguage.googleapis.com/v1beta/models/"
+      .. Config.gemini.model
+      .. ":streamGenerateContent?alt=sse&key="
+      .. E.value("gemini")
+  end
+  -- Prepare the body with contents and options (only if options are not empty)
+  local body = {
+    systemInstruction = {
+      role = "user",
+      parts = {
+        {
+          text = system_prompt .. base_user_prompt,
+        },
+      },
+    },
+    contents = M.make_gemini_message(code_opts),
+  }
+  if next(Config.gemini.options) ~= nil then -- Check if options table is not empty
+    for k, v in pairs(Config.gemini.options) do
+      body[k] = v
+    end
+  end
+  return {
+    url = endpoint,
+    headers = {
+      ["Content-Type"] = "application/json",
+    },
+    body = body,
+  }
+end
+
 ------------------------------Logic------------------------------
 
 local group = vim.api.nvim_create_augroup("AvanteLLM", { clear = true })