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module Order exposing Order(..), reverse/1, to_int/1, compare/2, max/2, min/2

type Order =
  | LT
  | EQ
  | GT

; // Fix GitHub syntax highlighting

fn reverse(order) {
  case order {
  | LT => GT
  | EQ => EQ
  | GT => LT
  }
}

test reverse {
  reverse(LT) |> Assert.equal(_, GT)
  reverse(EQ) |> Assert.equal(_, EQ)
  reverse(GT) |> Assert.equal(_, LT)
}

fn to_int(order) {
  case order {
  | LT => -1
  | EQ => 0
  | GT => 1
  }
}

test to_int {
  to_int(LT) |> Assert.equal(_, -1)
  to_int(EQ) |> Assert.equal(_, 0)
  to_int(GT) |> Assert.equal(_, 1)
}

fn compare(a, b) {
  case (a, b) {
  | (LT, LT) => EQ
  | (LT, _) => LT
  | (EQ, EQ) => EQ
  | (GT, GT) => EQ
  | (EQ, GT) => LT
  | _ => GT
  }
}

test compare {
  compare(LT, LT) |> Assert.equal(_, EQ)
  compare(LT, EQ) |> Assert.equal(_, LT)
  compare(LT, GT) |> Assert.equal(_, LT)
  compare(EQ, LT) |> Assert.equal(_, GT)
  compare(EQ, EQ) |> Assert.equal(_, EQ)
  compare(EQ, GT) |> Assert.equal(_, LT)
  compare(GT, LT) |> Assert.equal(_, GT)
  compare(GT, EQ) |> Assert.equal(_, GT)
  compare(GT, GT) |> Assert.equal(_, EQ)
}

fn max(a, b) {
  case (a, b) {
  | (GT, _) => GT
  | (EQ, LT) => EQ
  | _ => b
  }
}

test max {
  max(LT, LT) |> Assert.equal(_, LT)
  max(LT, EQ) |> Assert.equal(_, EQ)
  max(LT, GT) |> Assert.equal(_, GT)
  max(EQ, LT) |> Assert.equal(_, EQ)
  max(EQ, EQ) |> Assert.equal(_, EQ)
  max(EQ, GT) |> Assert.equal(_, GT)
  max(GT, LT) |> Assert.equal(_, GT)
  max(GT, EQ) |> Assert.equal(_, GT)
  max(GT, GT) |> Assert.equal(_, GT)
}

fn min(a, b) {
  case (a, b) {
  | (LT, _) => LT
  | (EQ, GT) => EQ
  | _ => b
  }
}

test min {
  min(LT, LT) |> Assert.equal(_, LT)
  min(LT, EQ) |> Assert.equal(_, LT)
  min(LT, GT) |> Assert.equal(_, LT)
  min(EQ, LT) |> Assert.equal(_, LT)
  min(EQ, EQ) |> Assert.equal(_, EQ)
  min(EQ, GT) |> Assert.equal(_, EQ)
  min(GT, LT) |> Assert.equal(_, LT)
  min(GT, EQ) |> Assert.equal(_, EQ)
  min(GT, GT) |> Assert.equal(_, GT)
}