peek.lua

local M = {
  floating_buf = nil,
  floating_win = nil,
  prev_result = nil,
}

local function create_floating_file(location, opts)
  vim.validate {
    location = { location, "t" },
    opts = { opts, "t", true },
  }

  -- Set some defaults
  opts = opts or {}
  local close_events = opts.close_events or { "CursorMoved", "CursorMovedI", "BufHidden", "InsertCharPre" }

  -- location may be LocationLink or Location
  local uri = location.targetUri or location.uri
  if uri == nil then
    return
  end
  local bufnr = vim.uri_to_bufnr(uri)
  if not vim.api.nvim_buf_is_loaded(bufnr) then
    vim.fn.bufload(bufnr)
  end

  local range = location.targetRange or location.range

  local contents = vim.api.nvim_buf_get_lines(
    bufnr,
    range.start.line,
    math.min(range["end"].line + 1 + (opts.context or 15), range.start.line + (opts.max_height or 15)),
    false
  )
  if next(contents) == nil then
    vim.notify("peek: Unable to get contents of the file!", vim.log.levels.WARN)
    return
  end
  local width, height = vim.lsp.util._make_floating_popup_size(contents, opts)
  local if_nil = vim.F.if_nil
  opts = vim.lsp.util.make_floating_popup_options(if_nil(width, 30), if_nil(height, 15), opts)
  -- Don't make it minimal as it is meant to be fully featured
  opts["style"] = nil

  vim.api.nvim_set_option_value("bufhidden", "wipe", { buf = bufnr })

  local winnr = vim.api.nvim_open_win(bufnr, false, opts)
  vim.api.nvim_set_option_value("winblend", 0, { win = 0, scope = "local" })

  vim.api.nvim_win_set_cursor(winnr, { range.start.line + 1, range.start.character })
  vim.api.nvim_buf_set_var(bufnr, "lsp_floating_window", winnr)

  -- Set some autocmds to close the window
  vim.api.nvim_command(
    string.format("autocmd %s <buffer> ++once lua pcall(vim.api.nvim_win_close, %d, true)", unpack(close_events), winnr)
  )

  return bufnr, winnr
end

local function preview_location_callback(result)
  if result == nil or vim.tbl_isempty(result) then
    return nil
  end

  local opts = {
    border = "rounded",
    context = 10,
  }

  if vim.islist(result) then
    M.prev_result = result[1]
    M.floating_buf, M.floating_win = create_floating_file(result[1], opts)
  else
    M.prev_result = result
    M.floating_buf, M.floating_win = create_floating_file(result, opts)
  end
end

local function preview_location_callback_new_signature(_, result)
  return preview_location_callback(result)
end

function M.open_file()
  -- Get the file currently open in the floating window
  local filepath = vim.fn.expand "%:."

  if not filepath then
    vim.notify("peek: Unable to open the file!", vim.log.levels.ERROR)
    return
  end

  -- Close the floating window
  pcall(vim.api.nvim_win_close, M.floating_win, true)

  -- Edit the file
  vim.cmd("edit " .. filepath)

  local winnr = vim.api.nvim_get_current_win()

  -- Set the cursor at the right position
  M.set_cursor_to_prev_pos(winnr)
end

function M.set_cursor_to_prev_pos(winnr)
  -- Get position of the thing to peek at
  local location = M.prev_result
  local range = location.targetRange or location.range
  local cursor_pos = { range.start.line + 1, range.start.character }

  -- Set the winnr to the floating window if none was passed in
  winnr = winnr or M.floating_win
  -- Set the cursor at the correct position in the floating window
  vim.api.nvim_win_set_cursor(winnr, cursor_pos)
end

function M.Peek(what)
  -- If a window already exists, focus it at the right position!
  if vim.tbl_contains(vim.api.nvim_list_wins(), M.floating_win) then
    local success_1, _ = pcall(vim.api.nvim_set_current_win, M.floating_win)
    if not success_1 then
      vim.notify("peek: You cannot edit the current file in a preview!", vim.log.levels.ERROR)
      return
    end

    -- Set the cursor at the correct position in the floating window
    M.set_cursor_to_prev_pos()

    vim.api.nvim_buf_set_keymap(
      M.floating_buf,
      "n",
      "<CR>",
      ":lua require('user.peek').open_file()<CR>",
      { noremap = true, silent = true }
    )
  else
    -- Make a new request and then create the new window in the callback
    local params = vim.lsp.util.make_position_params(0, "utf-16")
    local preview_callback = preview_location_callback_new_signature
    local success, _ = pcall(vim.lsp.buf_request, 0, "textDocument/" .. what, params, preview_callback)
    if not success then
      vim.notify(
        'peek: Error calling LSP method "textDocument/' .. what .. '". The current language lsp might not support it.',
        vim.log.levels.ERROR
      )
    end
  end
end

return M