util.lua

-- Nursery for random things that may later find their way into stdlib if they mature.

local M = {}

--- Adds one or more blank lines above or below the cursor.
-- TODO: move to _core/defaults.lua once it is possible to assign a Lua function to options #25672
--- @param above? boolean Place blank line(s) above the cursor
local function add_blank(above)
  local offset = above and 1 or 0
  local repeated = vim.fn['repeat']({ '' }, vim.v.count1)
  local linenr = vim.api.nvim_win_get_cursor(0)[1]
  vim.api.nvim_buf_set_lines(0, linenr - offset, linenr - offset, true, repeated)
end

-- TODO: move to _core/defaults.lua once it is possible to assign a Lua function to options #25672
function M.space_above()
  add_blank(true)
end

-- TODO: move to _core/defaults.lua once it is possible to assign a Lua function to options #25672
function M.space_below()
  add_blank()
end

--- Edit a file in a specific window
--- @param winnr number
--- @param file string
--- @return number buffer number of the edited buffer
M.edit_in = function(winnr, file)
  local function resolved_path(path)
    if not path or path == '' then
      return ''
    end
    return vim.fn.resolve(vim.fs.abspath(path))
  end

  return vim.api.nvim_win_call(winnr, function()
    local current_buf = vim.api.nvim_win_get_buf(winnr)
    local current = resolved_path(vim.api.nvim_buf_get_name(current_buf))

    -- Check if the current buffer is already the target file
    if current == resolved_path(file) then
      return current_buf
    end

    -- Read the file into the buffer
    vim.cmd.edit(vim.fn.fnameescape(file))
    return vim.api.nvim_get_current_buf()
  end)
end

--- Read a chunk of data from a file
--- @param file string
--- @param size number
--- @return string? chunk or nil on error
function M.read_chunk(file, size)
  local fd = io.open(file, 'rb')
  if not fd then
    return nil
  end
  local chunk = fd:read(size)
  fd:close()
  return tostring(chunk)
end

--- Check if a range in a buffer is inside a Lua codeblock via treesitter injection.
--- Used by :source to detect Lua code in non-Lua files (e.g., vimdoc).
--- @param bufnr integer Buffer number
--- @param line1 integer Start line (1-indexed)
--- @param line2 integer End line (1-indexed)
--- @return boolean True if the range is in a Lua injection
function M.source_is_lua(bufnr, line1, line2)
  local ok, parser = pcall(vim.treesitter.get_parser, bufnr)
  if not ok or not parser then
    return false
  end
  -- Parse from buffer start through one line past line2 to include injection closing markers
  local range = { line1 - 1, 0, line2 - 1, -1 }
  parser:parse({ 0, 0, line2, -1 })
  local lang_tree = parser:language_for_range(range)
  return lang_tree:lang() == 'lua'
end

--- Returns the exit code string for the current buffer, given:
--- - Channel is attached to the current buffer
--- - Current buffer is a terminal buffer
---
--- @return string
function M.term_exitcode()
  local chan_id = vim.bo.channel
  if chan_id == 0 or vim.bo.buftype ~= 'terminal' then
    return ''
  end

  local info = vim.api.nvim_get_chan_info(chan_id)
  if info.exitcode and info.exitcode >= 0 then
    return string.format('[Exit: %d]', info.exitcode)
  end
  return ''
end

return M