Feature: add Claude support (#29)

* feat: add claude backend

* docs: add Claude docs

doc/cmp-ai.txt

@@ -258,6 +258,32 @@ To use Tabby:
 You will also need to make sure you have the Tabby api key in your environment,
 `TABBY_API_KEY`.
 
+To use Claude:
+
+>lua
+    local cmp_ai = require('cmp_ai.config')
+
+    cmp_ai:setup({
+      max_lines = 1000,
+      provider = 'Claude',
+      provider_options = {
+        model = 'claude-3-5-sonnet-20240620',
+      },
+      notify = true,
+      notify_callback = function(msg)
+        vim.notify(msg)
+      end,
+      run_on_every_keystroke = true,
+      ignored_file_types = {
+        -- default is not to ignore
+        -- uncomment to ignore in lua:
+        -- lua = true
+      },
+    })
+<
+
+You will also need to make sure you have the Anthropic api key in your environment,
+`CLAUDE_API_KEY`.
 
 NOTIFY ~
 

lua/cmp_ai/backends/claude.lua

@@ -0,0 +1,81 @@
+local requests = require('cmp_ai.requests')
+
+Claude = requests:new(nil)
+BASE_URL = 'https://api.anthropic.com/v1/messages'
+
+function Claude:new(o, params)
+  o = o or {}
+  setmetatable(o, self)
+  self.__index = self
+  self.params = vim.tbl_deep_extend('keep', params or {}, {
+    -- Custom params for claude
+  })
+
+  self.api_key = os.getenv('CLAUDE_API_KEY')
+  if not self.api_key then
+    vim.schedule(function()
+      vim.notify('CLAUDE_API_KEY environment variable not set', vim.log.levels.ERROR)
+    end)
+    self.api_key = 'NO_KEY'
+  end
+  self.headers = {
+    'x-api-key: ' .. self.api_key,
+  }
+  return o
+end
+
+function Claude:complete(lines_before, lines_after, cb)
+  if not self.api_key then
+    vim.schedule(function()
+      vim.notify('CLAUDE_API_KEY environment variable not set', vim.log.levels.ERROR)
+    end)
+    return
+  end
+
+  local data = {
+    messages = {
+      {
+        role = 'system',
+        content = [=[You are a coding companion.
+You need to suggest code for the language ]=] .. vim.o.filetype .. [=[
+Given some code prefix and suffix for context, output code which should follow the prefix code.
+You should only output valid code in the language ]=] .. vim.o.filetype .. [=[
+. to clearly define a code block, including white space, we will wrap the code block
+with tags.
+Make sure to respect the white space and indentation rules of the language.
+Do not output anything in plain language, make sure you only use the relevant programming language verbatim.
+For example, consider the following request:
+<begin_code_prefix>def print_hello():<end_code_prefix><begin_code_suffix>\n    return<end_code_suffix><begin_code_middle>
+Your answer should be:
+
+    print("Hello")<end_code_middle>
+]=],
+      },
+      {
+        role = 'user',
+        content = '<begin_code_prefix>' .. lines_before .. '<end_code_prefix>' .. '<begin_code_suffix>' .. lines_after .. '<end_code_suffix><begin_code_middle>',
+      },
+    },
+  }
+
+  data = vim.tbl_deep_extend('keep', data, self.params)
+  self:Get(BASE_URL, self.headers, data, function(answer)
+    local new_data = {}
+    if answer.choices then
+      for _, response in ipairs(answer.choices) do
+        local entry = response.message.content:gsub('<end_code_middle>', '')
+        entry = entry:gsub('```', '')
+        table.insert(new_data, entry)
+      end
+    end
+    cb(new_data)
+  end)
+end
+
+function Claude:test()
+  self:complete('def factorial(n)\n    if', '    return ans\n', function(data)
+    dump(data)
+  end)
+end
+
+return Claude