// Strong typedef: using Type = int creates a distinct type
using Meters = int

def measure(Meters m) {
  return m
}

// Constructing a strong typedef value should work
var m = Meters(42)

// Calling with the typedef'd value should succeed
measure(m)

// Calling with a plain int should fail (strong typedef)
try {
  measure(42)
  assert_equal(true, false)
} catch(e) {
  // Expected: type mismatch because int is not Meters
}

// Multiple strong typedefs from the same base type should be distinct
using Seconds = int

def wait(Seconds s) {
  return s
}

var s = Seconds(10)
wait(s)

// Meters and Seconds should not be interchangeable
try {
  wait(m)
  assert_equal(true, false)
} catch(e) {
  // Expected: Meters is not Seconds
}

try {
  measure(s)
  assert_equal(true, false)
} catch(e) {
  // Expected: Seconds is not Meters
}

// to_underlying should return the base value
assert_equal(to_underlying(m), 42)
assert_equal(to_underlying(s), 10)

// to_underlying result should be a plain value, not a strong typedef
def takes_int(int i) {
  return i
}
assert_equal(takes_int(to_underlying(m)), 42)

// --- Arithmetic operators: strongly typed ---
var m2 = Meters(8)
var m_sum = m + m2
assert_equal(to_underlying(m_sum), 50)
measure(m_sum)

var m_diff = m - m2
assert_equal(to_underlying(m_diff), 34)

var m_prod = Meters(3) * Meters(4)
assert_equal(to_underlying(m_prod), 12)

var m_quot = Meters(20) / Meters(5)
assert_equal(to_underlying(m_quot), 4)

var m_rem = Meters(17) % Meters(5)
assert_equal(to_underlying(m_rem), 2)

// Arithmetic result is strongly typed, not plain int
try {
  takes_int(m_sum)
  assert_equal(true, false)
} catch(e) {
  // Expected: m_sum is Meters, not int
}

// --- Comparison operators ---
assert_equal(Meters(5) == Meters(5), true)
assert_equal(Meters(5) != Meters(3), true)
assert_equal(Meters(3) < Meters(5), true)
assert_equal(Meters(5) > Meters(3), true)
assert_equal(Meters(5) <= Meters(5), true)
assert_equal(Meters(3) >= Meters(3), true)
assert_equal(Meters(3) >= Meters(5), false)

// --- Strong typedef over string ---
using StrongString = string

var ss1 = StrongString("hello")
var ss2 = StrongString(" world")
var ss_cat = ss1 + ss2
assert_equal(to_underlying(ss_cat), "hello world")

// StrongString + StrongString -> StrongString (strongly typed)
def takes_strong_string(StrongString ss) {
  return ss
}
takes_strong_string(ss_cat)

// StrongString * StrongString -> error (no * for strings)
try {
  var bad = ss1 * ss2
  assert_equal(true, false)
} catch(e) {
  // Expected: no * operator for strings
}

// Comparison on StrongString
assert_equal(StrongString("abc") < StrongString("def"), true)
assert_equal(StrongString("abc") == StrongString("abc"), true)
assert_equal(StrongString("abc") != StrongString("def"), true)
assert_equal(StrongString("def") > StrongString("abc"), true)
assert_equal(StrongString("abc") <= StrongString("abc"), true)
assert_equal(StrongString("def") >= StrongString("abc"), true)

// --- User-defined extensions on strong typedefs ---
def first_char(StrongString ss) {
  return to_string(to_underlying(ss)[0])
}
assert_equal(first_char(StrongString("hello")), "h")

def double_meters(Meters m) {
  return Meters(to_underlying(m) * 2)
}
assert_equal(to_underlying(double_meters(Meters(21))), 42)

// User-defined operator extension
def `[]`(StrongString ss, int offset) {
  return to_string(to_underlying(ss)[offset])
}
assert_equal(StrongString("hello")[1], "e")