local M = {}

local state = {
  win = nil,
}

local config = {
  bin = "slides",
  fullscreen = true,
  style = "minimal",
  border = "shadow",
}

function M.close()
  if state.win ~= nil then
    vim.api.nvim_win_close(state.win, true)
  end
end

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

  vim.cmd(
    [[command! -nargs=? -complete=file Slides :lua require"slides".show('<f-args>')]]
  )
  vim.cmd([[command! SlidesClose :lua require"slides".close()]])
end

function M.show(file)
  local window = vim.api.nvim_get_current_win()

  local opts = {
    style = config.style,
    relative = "editor",
    width = config.fullscreen and vim.api.nvim_get_option("columns")
      or vim.api.nvim_win_get_width(window),
    height = config.fullscreen and vim.api.nvim_get_option("lines")
      or vim.api.nvim_win_get_height(window),
    row = 1,
    col = 1,
    border = config.border,
  }

  local input = string.len(file) == 0 and vim.api.nvim_get_current_buf() or file
  local is_file = type(input) == "string"
  local filetype = is_file and vim.fn.fnamemodify(input, ":e"):gsub('"', "")
    or vim.api.nvim_buf_get_option(input, "filetype")

  if not vim.tbl_contains({ "md", "markdown" }, filetype) then
    vim.api.nvim_err_writeln("Invalid filetype")
    return
  end

  if vim.fn.executable(config.bin) ~= 1 then
    vim.api.nvim_err_writeln("Executable not found")
    return
  end

  local bufnr = vim.api.nvim_create_buf(false, true)
  local win = vim.api.nvim_open_win(bufnr, true, opts)

  state.win = win

  vim.cmd("startinsert!")

  vim.fn.termopen(
    config.bin .. " " .. (is_file and input or vim.api.nvim_buf_get_name(input)),
    {
      on_exit = function()
        M.close()
      end,
    }
  )
end

return M