local M = { passed = 0, failed = 0, failures = {} }

local current = '?'

function M.describe(name, fn)
  current = name
  fn()
end

function M.it(name, fn)
  local ok, err = pcall(fn)
  if ok then
    M.passed = M.passed + 1
  else
    M.failed = M.failed + 1
    table.insert(M.failures, string.format('%s > %s\n    %s', current, name, tostring(err)))
  end
end

local function render(v)
  if type(v) == 'table' then
    return vim.inspect(v)
  end
  return string.format('%q', tostring(v))
end

function M.eq(expected, actual, msg)
  if not vim.deep_equal(expected, actual) then
    error(string.format('%sexpected %s, got %s', msg and (msg .. ': ') or '', render(expected), render(actual)), 2)
  end
end

function M.truthy(value, msg)
  if not value then
    error((msg or 'expected a truthy value') .. ', got ' .. render(value), 2)
  end
end

function M.falsy(value, msg)
  if value then
    error((msg or 'expected a falsy value') .. ', got ' .. render(value), 2)
  end
end

function M.matches(pattern, actual, msg)
  if type(actual) ~= 'string' or not actual:find(pattern) then
    error(string.format('%sexpected %s to match %q', msg and (msg .. ': ') or '', render(actual), pattern), 2)
  end
end

function M.report()
  for _, failure in ipairs(M.failures) do
    io.stderr:write('FAIL  ' .. failure .. '\n')
  end
  io.stdout:write(string.format('\n%d passed, %d failed\n', M.passed, M.failed))
  return M.failed == 0
end

return M