Hack to get dadbod auto-complete in sqmeow scratch buffers

lua/plugins/sqmeow.lua

@@ -1,3 +1,46 @@
+-- sqmeow has no completion in scratchpads, so point vim-dadbod-completion (the blink "dadbod"
+-- source from the LazyVim sql extra) at the buffer's sqmeow connection by setting b:db.
+local dadbod_schemes = { postgres = true, mysql = true }
+
+-- The dadbod URL for a sqmeow connection, or nil when dadbod can't use it.
+local function dadbod_url(conn)
+  if conn.state ~= "connected" or conn.ssh or conn.url:find("{{", 1, true) then
+    return nil
+  end
+  local prefix, rest = conn.url:match("^%a[%w+.-]*(://[^/?#]*)(.*)$")
+  if not prefix or not dadbod_schemes[conn.dialect] then
+    return nil
+  end
+  local path, query = rest:match("^([^?#]*)(.*)$")
+  -- A database opened from the drawer's database list shares its parent's URL.
+  if conn.database then
+    path = "/" .. conn.database
+  end
+  return conn.dialect .. prefix .. path .. query
+end
+
+local function sync_dadbod(buf)
+  -- Don't load sqmeow just for this, and leave b:db alone in buffers sqmeow doesn't own.
+  if not package.loaded["sqmeow.state"] or vim.bo[buf].filetype ~= "sql" then
+    return
+  end
+  local b = vim.b[buf]
+  if not (b.sqmeow_editor or b.sqmeow_connection) or (b.db and b.db ~= b.sqmeow_dadbod_url) then
+    return
+  end
+
+  local conn = require("sqmeow.api").target(buf)
+  local url = conn and dadbod_url(conn)
+  if url == b.sqmeow_dadbod_url then
+    return
+  end
+  b.db = url
+  b.sqmeow_dadbod_url = url
+  if url and vim.fn.exists("*vim_dadbod_completion#fetch") == 1 then
+    vim.fn["vim_dadbod_completion#fetch"](buf)
+  end
+end
+
 return {
   "2giosangmitom/sqmeow.nvim",
   dependencies = { "MunifTanjim/nui.nvim" },
@@ -14,4 +57,13 @@ return {
     { "<leader>Da", "<cmd>Sqmeow add<cr>", desc = "Add Connection" },
     { "<leader>Ds", "<cmd>Sqmeow scratch<cr>", desc = "New Scratchpad" },
   },
+  init = function()
+    -- InsertEnter catches connecting, or switching connections with `u`, after the buffer opened.
+    vim.api.nvim_create_autocmd({ "BufEnter", "InsertEnter" }, {
+      group = vim.api.nvim_create_augroup("sqmeow_dadbod", { clear = true }),
+      callback = function(ev)
+        sync_dadbod(ev.buf)
+      end,
+    })
+  end,
 }