local M = {}
function M.getVenvSuffix()
  if vim.loop.os_uname().sysname == 'Linux' then
    return 'bin/python'
  elseif vim.loop.os_uname().sysname == 'Windows_NT' then
    return 'Scripts/python.exe'
  end
end

function M.getVenvFromJson(jsonfile)
  if not vim.fn.filereadable(jsonfile) then
    return nil
  end
  local f = io.open(jsonfile, 'r')
  if not f then
    return nil
  end
  local data = f:read('*a')
  f:close()
  if data then
    local jdata = vim.json.decode(data)
    if jdata['venvPath'] ~= nil and jdata['venv'] ~= nil then
      return jdata['venvPath'] .. '/' .. jdata['venv']
    end
  end
  return nil
end

function M.getPythonEnv()
  local venv = os.getenv('VIRTUAL_ENV')
  if venv ~= nil then
    return string.format('%s/%s', venv, M.getVenvSuffix())
  end
  local conda = os.getenv('CONDA_PREFIX')
  if conda ~= nil then
    return string.format('%s/%s', conda, 'python.exe')
  end

  local cwd = vim.fn.getcwd()

  local jsonVenv = M.getVenvFromJson(cwd .. '/pyrightconfig.json')
  if jsonVenv ~= nil then
    return jsonVenv .. '/' .. M.getVenvSuffix()
  end

  if vim.fn.executable(cwd .. '/venv/' .. M.getVenvSuffix()) == 1 then
    return cwd .. '/venv/' .. M.getVenvSuffix()
  elseif vim.fn.executable(cwd .. '/.venv/' .. M.getVenvSuffix()) == 1 then
    return cwd .. '/.venv/' .. M.getVenvSuffix()
  else
    if vim.loop.os_uname().sysname == 'Linux' then
      return '/usr/bin/python'
    elseif vim.loop.os_uname().sysname == 'Windows_NT' then
      return os.getenv('SCOOP') .. '/apps/python/current/python.exe'
    end
  end
end

function M.getPythonEnvs()
  local venvs = {}
  local venv = os.getenv('VIRTUAL_ENV')
  if venv ~= nil then
    table.insert(venvs, {
      name = 'VIRTUAL_ENV',
      path = string.format('%s/%s', venv, M.getVenvSuffix()),
    })
  end
  local conda = os.getenv('CONDA_PREFIX')
  if conda ~= nil then
    table.insert(venvs, {
      name = 'CONDA_PREFIX',
      path = string.format('%s/%s', conda, 'python.exe'),
    })
  end

  local cwd = vim.fn.getcwd()

  local jsonVenv = M.getVenvFromJson(cwd .. '/pyrightconfig.json')
  if jsonVenv ~= nil then
    table.insert(venvs, {
      name = 'pyrightconfig.json',
      path = jsonVenv .. '/' .. M.getVenvSuffix(),
    })
  end

  local venvDirs = { 'venv', '.venv' }
  for _, envDir in pairs(venvDirs) do
    if vim.fn.executable(cwd .. '/' .. envDir .. '/' .. M.getVenvSuffix()) == 1 then
      table.insert(venvs, {
        name = envDir,
        path = cwd .. '/' .. envDir .. '/' .. M.getVenvSuffix(),
      })
    end
  end
  if vim.loop.os_uname().sysname == 'Linux' then
    table.insert(venvs, {
      name = 'system',
      path = '/usr/bin/python',
    })
  end
  if vim.loop.os_uname().sysname == 'Windows_NT' then
    table.insert(venvs, {
      name = 'system',
      path = os.getenv('SCOOP') .. '/apps/python/current/python.exe',
    })
  end
  return venvs
end

M.pick_venv = function()
  vim.ui.select(M.getPythonEnvs(), {
    prompt = 'Select python venv',
    format_item = function(item)
      return string.format('%s (%s)', item.name, item.path)
    end,
  }, function(choice)
    if not choice then
      return
    end
    print(choice.path)
  end)
end

return M