[Feature] Encapsulate interface logic (#1320)

* Provide a utility function for aligning text

* Replace lvim banner with one using only ASCII chars

* Use strings.format instead of .. operator

* Center text in the popup based on its dimentions

* Minor improvements

* Provide a popup factory function

* Add function documentation

* Improve text alignment

* Print marker only if provider list is not empty

* Format client capabilities as list

* Pretty format lsp client capabilities

* Add a metatable to popup.lua

* Improve rendering when no lsp is available

* Take cmdheight into acount when computing popup size and pos

Co-authored-by: kylo252 <[email protected]>

2 files changed, 141 insertions, 0 deletions

diff --git a/lua/interface/popup.lua b/lua/interface/popup.lua
new file mode 100644
index 00000000..b628125c
--- /dev/null
+++ b/lua/interface/popup.lua
@@ -0,0 +1,62 @@
+local Popup = {}
+
+--- Create a new floating window
+-- @param config The configuration passed to vim.api.nvim_open_win
+-- @param win_opts The options registered with vim.api.nvim_win_set_option
+-- @param buf_opts The options registered with vim.api.nvim_buf_set_option
+-- @return A new popup
+function Popup:new(opts)
+  opts = opts or {}
+  opts.layout = opts.layout or {}
+  opts.win_opts = opts.win_opts or {}
+  opts.buf_opts = opts.buf_opts or {}
+
+  Popup.__index = Popup
+
+  local editor_layout = {
+    height = vim.o.lines - vim.o.cmdheight - 2, -- Add margin for status and buffer line
+    width = vim.o.columns,
+  }
+  local popup_layout = {
+    relative = "editor",
+    height = math.floor(editor_layout.height * 0.9),
+    width = math.floor(editor_layout.width * 0.8),
+    style = "minimal",
+    border = "rounded",
+  }
+  popup_layout.row = math.floor((editor_layout.height - popup_layout.height) / 2)
+  popup_layout.col = math.floor((editor_layout.width - popup_layout.width) / 2)
+
+  local obj = {
+    buffer = vim.api.nvim_create_buf(false, true),
+    layout = vim.tbl_deep_extend("force", popup_layout, opts.layout),
+    win_opts = opts.win_opts,
+    buf_opts = opts.buf_opts,
+  }
+
+  setmetatable(obj, Popup)
+
+  return obj
+end
+
+--- Display the popup with the provided content
+-- @param content_provider A function accepting the popup's layout and returning the content to display
+function Popup:display(content_provider)
+  self.win_id = vim.api.nvim_open_win(self.buffer, true, self.layout)
+  vim.lsp.util.close_preview_autocmd({ "BufHidden", "BufLeave" }, self.win_id)
+
+  local lines = content_provider(self.layout)
+  vim.api.nvim_buf_set_lines(self.bufnr, 0, -1, false, lines)
+
+  -- window options
+  for key, value in pairs(self.win_opts) do
+    vim.api.nvim_win_set_option(self.win_id, key, value)
+  end
+
+  -- buffer options
+  for key, value in pairs(self.buf_opts) do
+    vim.api.nvim_buf_set_option(self.buffer, key, value)
+  end
+end
+
+return Popup
diff --git a/lua/interface/text.lua b/lua/interface/text.lua
new file mode 100644
index 00000000..f68cc491
--- /dev/null
+++ b/lua/interface/text.lua
@@ -0,0 +1,79 @@
+local M = {}
+
+local function max_len_line(lines)
+  local max_len = 0
+
+  for _, line in ipairs(lines) do
+    local line_len = line:len()
+    if line_len > max_len then
+      max_len = line_len
+    end
+  end
+
+  return max_len
+end
+
+--- Center align lines relatively to the parent container
+-- @param container The container where lines will be displayed
+-- @param lines The text to align
+-- @param alignment The alignment value, range: [0-1]
+function M.align(container, lines, alignment)
+  local max_len = max_len_line(lines)
+  local indent_amount = math.ceil(math.max(container.width - max_len, 0) * alignment)
+  return M.shift_left(lines, indent_amount)
+end
+
+--- Shift lines by a given amount
+-- @params lines The lines the shift
+-- @param amount The amount of spaces to add
+function M.shift_left(lines, amount)
+  local output = {}
+  local padding = string.rep(" ", amount)
+
+  for _, line in ipairs(lines) do
+    table.insert(output, padding .. line)
+  end
+
+  return output
+end
+
+--- Pretty format tables
+-- @param entries The table to format
+-- @param col_count The number of column to span the table on
+-- @param col_sep The separator between each colummn, default: " "
+function M.format_table(entries, col_count, col_sep)
+  col_sep = col_sep or " "
+
+  local col_rows = math.ceil(vim.tbl_count(entries) / col_count)
+  local cols = {}
+  local count = 0
+
+  for i, entry in ipairs(entries) do
+    if ((i - 1) % col_rows) == 0 then
+      table.insert(cols, {})
+      count = count + 1
+    end
+    table.insert(cols[count], entry)
+  end
+
+  local col_max_len = {}
+  for _, col in ipairs(cols) do
+    table.insert(col_max_len, max_len_line(col))
+  end
+
+  local output = {}
+  for i, col in ipairs(cols) do
+    for j, entry in ipairs(col) do
+      if not output[j] then
+        output[j] = entry
+      else
+        local padding = string.rep(" ", col_max_len[i - 1] - cols[i - 1][j]:len())
+        output[j] = output[j] .. padding .. col_sep .. entry
+      end
+    end
+  end
+
+  return output
+end
+
+return M