feat: allow custom input provider, removing dressing.nvim (#2173)

Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>
Co-authored-by: yetone <yetoneful@gmail.com>

lua/avante/ui/input/providers/dressing.lua

@@ -0,0 +1,66 @@
+local api = vim.api
+local fn = vim.fn
+
+local M = {}
+
+---@param input avante.ui.Input
+function M.show(input)
+  local ok, dressing_input = pcall(require, "dressing.input")
+  if not ok then
+    vim.notify("dressing.nvim not found, falling back to native input", vim.log.levels.WARN)
+    require("avante.ui.input.providers.native").show(input)
+    return
+  end
+
+  -- Store state for concealing functionality
+  local state = { winid = nil, input_winid = nil, input_bufnr = nil }
+
+  local function setup_concealing()
+    if not input.conceal then return end
+
+    vim.defer_fn(function()
+      -- Find the dressing input window
+      for _, winid in ipairs(api.nvim_list_wins()) do
+        local bufnr = api.nvim_win_get_buf(winid)
+        if vim.bo[bufnr].filetype == "DressingInput" then
+          state.input_winid = winid
+          state.input_bufnr = bufnr
+          vim.wo[winid].conceallevel = 2
+          vim.wo[winid].concealcursor = "nvi"
+
+          -- Set up concealing syntax
+          local prompt_length = api.nvim_strwidth(fn.prompt_getprompt(state.input_bufnr))
+          api.nvim_buf_call(
+            state.input_bufnr,
+            function()
+              vim.cmd(string.format(
+                [[
+              syn region SecretValue start=/^/ms=s+%s end=/$/ contains=SecretChar
+              syn match SecretChar /./ contained conceal cchar=*
+            ]],
+                prompt_length
+              ))
+            end
+          )
+          break
+        end
+      end
+    end, 50)
+  end
+
+  -- Enhanced functionality for concealed input
+  vim.ui.input({
+    prompt = input.title,
+    default = input.default,
+    completion = input.completion,
+  }, function(result)
+    input.on_submit(result)
+    -- Close the dressing input window after submission if we have concealing
+    if input.conceal then pcall(dressing_input.close) end
+  end)
+
+  -- Set up concealing if needed
+  setup_concealing()
+end
+
+return M