local M = {}

local state = {
  buf = nil,
  win = nil,
  job = nil,
}

local config = {
  width = 0.2,
}

local function is_valid_window(win)
  return win and vim.api.nvim_win_is_valid(win)
end

local function is_valid_buffer(buf)
  return buf and vim.api.nvim_buf_is_valid(buf)
end

local function terminal_width()
  return math.max(1, math.floor(vim.o.columns * config.width))
end

local function open_side_window()
  vim.cmd("botright vertical " .. terminal_width() .. "new")
  state.win = vim.api.nvim_get_current_win()
  vim.api.nvim_set_option_value("winfixwidth", true, { win = state.win })
end

local function start_terminal()
  state.buf = vim.api.nvim_create_buf(false, true)
  vim.api.nvim_set_option_value("bufhidden", "hide", { buf = state.buf })
  vim.api.nvim_set_option_value("filetype", "opencode", { buf = state.buf })
  vim.api.nvim_buf_set_name(state.buf, "opencode")

  vim.api.nvim_win_set_buf(state.win, state.buf)
  state.job = vim.fn.termopen("opencode", {
    on_exit = function()
      state.job = nil
    end,
  })
end

function M.toggle()
  if is_valid_window(state.win) then
    vim.api.nvim_win_close(state.win, false)
    state.win = nil
    return
  end

  open_side_window()

  if is_valid_buffer(state.buf) then
    vim.api.nvim_win_set_buf(state.win, state.buf)
  else
    start_terminal()
  end

  vim.cmd("startinsert")
end

function M.setup(opts)
  opts = opts or {}

  if opts.width ~= nil then
    assert(
      type(opts.width) == "number" and opts.width > 0 and opts.width <= 1,
      "opencode.nvim: width must be a number between 0 and 1"
    )

    config.width = opts.width
  end

  vim.api.nvim_create_user_command("OpenCodeToggle", function()
    M.toggle()
  end, { force = true })

end

return M