local M = {}

local defaults = {
  out_waiting = "...",
  out_no_jj_repo = "~no_jj_repo~",
  out_no_desc = "~no_desc~",
  max_desc_length = 47,
}

M.config = vim.deepcopy(defaults)

M.update_jj_status = function(bufnr)
  vim.api.nvim_buf_set_var(bufnr, "jj_desc", M.config.out_waiting)

  local current_file = vim.api.nvim_buf_get_name(bufnr)
  if current_file == "" or current_file == nil then
    vim.api.nvim_buf_del_var(bufnr, "jj_desc")
    return
  end

  if not vim.fn.filereadable(current_file) then
    vim.api.nvim_buf_del_var(bufnr, "jj_desc")
    return
  end

  local jj_root = vim.fs.find(
    ".jj", {
      upward = true,
      stop = vim.loop.os_homedir(),
      path = current_file,
      type = "directory",
    }
  )[1]

  if not jj_root then
    vim.api.nvim_buf_set_var(bufnr, "jj_desc", M.config.out_no_jj_repo)
    return
  end

  local repo_root = vim.fs.dirname(jj_root)
  local _cmd = string.format("jj log -R %s -r @ -T description --no-graph", repo_root)
  
  local cmd = { "jj", "log", "-R", repo_root, "-r", "@", "-T", "description", "--no-graph", }

  vim.system(cmd, { text = true, cwd = vim.fs.dirname(repo_root) }, function(obj)
    if obj.code ~= 0 then
      vim.api.nvim_buf_del_var(bufnr, "jj_desc")
      return
    end

    local output = vim.trim(obj.stdout or "")
    output = output:gsub("\n", ""):gsub("^%s*", ""):gsub("%s*$", "")

    if output == "" then output = M.config.out_no_desc end
    if #output > (M.config.max_desc_length + 3) then 
      output = string.sub(output, 1, M.config.max_desc_length) .. "..."
    end

    vim.schedule(function()
      if vim.api.nvim_buf_is_valid(bufnr) then
        vim.api.nvim_buf_set_var(bufnr, "jj_desc", output)

        if bufnr == vim.api.nvim_get_current_buf() then
          vim.cmd.redrawstatus()
        end
      end
    end)
  end)
end

M.setup = function(opts)
  M.config = vim.tbl_deep_extend("force", M.config, opts or {})

  local group = vim.api.nvim_create_augroup("JJLogPlugin", { clear = true })

  vim.api.nvim_create_autocmd({ "BufEnter", "BufWinEnter", "BufWritePost", "FocusGained" }, {
    group = group,
    pattern = "*",
    callback = function(args)
      M.update_jj_status(args.buf)
    end,
  })
end

return M