feat(picker.scratch): add scratch picker with grep, new and delete keybinds (#1019)

## Description


The scratch module uses `vim.ui.select` which misses the nice things
about the picker.
This implementation adds scratch picker with ability to create, grep and
delete scratch buffers.

Couldn't figure out how to prettify the scratch buffer's name so any
help would be appreciated.
## Related Issue(s)

<!--
  If this PR fixes any issues, please link to the issue here.
  - Fixes #<issue_number>
-->

## Screenshots

<!-- Add screenshots of the changes if applicable. -->

---------

Co-authored-by: Folke Lemaitre <folke.lemaitre@gmail.com>

lua/snacks/picker/config/init.lua

@@ -300,6 +300,19 @@ function M.finder(finder)
   return M.field(finder) or nop
 end
 
+---@param picker snacks.Picker
+---@param action string
+function M.action(picker, action)
+  local ret = (picker.opts.actions or {})[action] or require("snacks.picker.actions")[action]
+  if ret then
+    return ret
+  end
+  local source = action:match("^(.-)_")
+  if source then -- source specific action
+    return (M.field(("%s_actions"):format(source)) or {})[action]
+  end
+end
+
 --- Resolves a module field
 ---@param spec string
 function M.field(spec)

lua/snacks/picker/config/sources.lua

@@ -807,6 +807,21 @@ M.registers = {
 -- Special picker that resumes the last picker
 M.resume = {}
 
+-- Open or create scratch buffers
+M.scratch = {
+  finder = "scratch",
+  format = "scratch_format",
+  confirm = "scratch_open",
+  win = {
+    input = {
+      keys = {
+        ["<c-x>"] = { "scratch_delete", mode = { "n", "i" } },
+        ["<c-n>"] = { "scratch_new", mode = { "n", "i" } },
+      },
+    },
+  },
+}
+
 -- Neovim search history
 ---@type snacks.picker.history.Config
 M.search_history = {

lua/snacks/picker/core/actions.lua

@@ -81,16 +81,8 @@ function M.resolve(action, picker, name, stack)
       end
     end
     stack[#stack + 1] = action
-    return M.resolve(
-      (picker.opts.actions or {})[action]
-        or require("snacks.picker.actions")[action]
-        or require("snacks.explorer.actions").actions[action],
-      picker,
-      action,
-      stack
-    )
+    return M.resolve(Snacks.picker.config.action(picker, action), picker, action, stack)
   elseif type(action) == "table" and svim.islist(action) then
-    ---@type snacks.picker.Action[]
     local actions = vim.tbl_map(function(a)
       return M.resolve(a, picker, nil, stack)
     end, action)

lua/snacks/picker/source/explorer.lua

@@ -4,6 +4,8 @@ local Tree = require("snacks.explorer.tree")
 
 local M = {}
 
+M.actions = Actions.actions
+
 ---@type table<snacks.Picker, snacks.picker.explorer.State>
 M._state = setmetatable({}, { __mode = "k" })
 local uv = vim.uv or vim.loop

lua/snacks/picker/source/scratch.lua

@@ -0,0 +1,62 @@
+local M = {}
+
+---@class snacks.scratch.actions
+---@field [string] snacks.picker.Action.spec
+M.actions = {
+  scratch_open = function(picker, item)
+    picker:close()
+    if not item then
+      return
+    end
+    Snacks.scratch.open({ icon = item.item.icon, file = item.item.file, name = item.item.name, ft = item.item.ft })
+  end,
+  scratch_delete = function(picker, item)
+    local current = item.file
+    os.remove(current)
+    picker.list:set_selected()
+    picker.list:set_target()
+    picker:find()
+  end,
+  scratch_new = function(picker)
+    picker:close()
+    Snacks.scratch.open()
+  end,
+}
+
+---@param opts snacks.picker.proc.Config
+---@type snacks.picker.finder
+function M.scratch(opts)
+  local list = Snacks.scratch.list()
+  local items = {} ---@type snacks.picker.finder.Item[]
+  for _, item in ipairs(list) do
+    items[#items + 1] = {
+      file = item.file,
+      item = item,
+      title = item.name,
+      text = Snacks.picker.util.text(item, { "name", "branch", "ft" }),
+      branch = item.branch and ("branch:%s"):format(item.branch) or "",
+    }
+  end
+  return items
+end
+
+---@type snacks.picker.format
+function M.format(item, picker)
+  local file = item.item
+  local ret = {} ---@type snacks.picker.Highlight[]
+  local a = Snacks.picker.util.align
+  local icon, icon_hl = file.icon, nil
+  if not icon then
+    icon, icon_hl = Snacks.util.icon(file.ft, "filetype")
+  end
+  ret[#ret + 1] = { a(icon, 3), icon_hl }
+  ret[#ret + 1] = { a(file.name, 20, { truncate = true }) }
+  ret[#ret + 1] = { " " }
+  ret[#ret + 1] = { a(item.branch, 20, { truncate = true }), "Number" }
+  ret[#ret + 1] = { " " }
+  ---@diagnostic disable-next-line: missing-fields
+  vim.list_extend(ret, Snacks.picker.format.filename({ text = "", dir = true, file = file.cwd }, picker))
+  return ret
+end
+
+return M

lua/snacks/scratch.lua

@@ -119,32 +119,7 @@ end
 
 --- Select a scratch buffer from a list of scratch buffers.
 function M.select()
-  local widths = { 0, 0, 0, 0 }
-  local items = M.list()
-  for _, item in ipairs(items) do
-    item.icon = item.icon or Snacks.util.icon(item.ft, "filetype")
-    item.branch = item.branch and ("branch:%s"):format(item.branch) or ""
-    item.cwd = item.cwd and vim.fn.fnamemodify(item.cwd, ":p:~") or ""
-    widths[1] = math.max(widths[1], vim.api.nvim_strwidth(item.cwd))
-    widths[2] = math.max(widths[2], vim.api.nvim_strwidth(item.icon))
-    widths[3] = math.max(widths[3], vim.api.nvim_strwidth(item.name))
-    widths[4] = math.max(widths[4], vim.api.nvim_strwidth(item.branch))
-  end
-  vim.ui.select(items, {
-    prompt = "Select Scratch Buffer",
-    ---@param item snacks.scratch.File
-    format_item = function(item)
-      local parts = { item.cwd, item.icon, item.name, item.branch }
-      for i, part in ipairs(parts) do
-        parts[i] = part .. string.rep(" ", widths[i] - vim.api.nvim_strwidth(part))
-      end
-      return table.concat(parts, " ")
-    end,
-  }, function(selected)
-    if selected then
-      M.open({ icon = selected.icon, file = selected.file, name = selected.name, ft = selected.ft })
-    end
-  end)
+  return Snacks.picker.scratch()
 end
 
 --- Open a scratch buffer with the given options.