package game

import "testing"

// The golden values below were produced by the original C generator
// (seed = seed*11109+13849; rnd(range) = abs(RN) % range) compiled and run
// on this machine. They lock in seed compatibility with the C game.
func TestRndMatchesCImplementation(t *testing.T) {
	golden := map[int32][]int{
		1:          {0, 30, 79, 7, 87, 1, 23, 7, 57, 98},
		12345:      {92, 92, 45, 98, 24, 39, 92, 67, 3, 7},
		2026:       {43, 90, 6, 2, 43, 34, 20, 5, 67, 71},
		1751808000: {61, 51, 56, 99, 68, 45, 88, 50, 46, 88},
	}
	for seed, want := range golden {
		r := &Rng{Seed: seed}
		for i, w := range want {
			if got := r.Rnd(100); got != w {
				t.Errorf("seed %d: rnd(100) call %d = %d, want %d", seed, i, got, w)
			}
		}
	}
}

func TestRollMatchesCImplementation(t *testing.T) {
	golden := map[int32][]int{
		1:          {6, 8, 10},
		12345:      {10, 10, 15},
		2026:       {10, 10, 13},
		1751808000: {7, 9, 9},
	}
	for seed, want := range golden {
		r := &Rng{Seed: seed}
		for i, w := range want {
			if got := r.Roll(3, 6); got != w {
				t.Errorf("seed %d: roll(3,6) call %d = %d, want %d", seed, i, got, w)
			}
		}
	}
}

// rnd(0) must return 0 without stepping the generator: the C macro
// short-circuits before evaluating RN, and BEFORE/AFTER depend on it.
func TestRndZeroDoesNotStep(t *testing.T) {
	r := &Rng{Seed: 42}
	if got := r.Rnd(0); got != 0 {
		t.Fatalf("rnd(0) = %d, want 0", got)
	}

	if r.Seed != 42 {
		t.Fatalf("rnd(0) stepped the generator: seed = %d, want 42", r.Seed)
	}
}

// spread(1)==1 and spread(2)==2 deterministically; the C BEFORE/AFTER
// constants rely on this.
func TestSpreadSmallValues(t *testing.T) {
	g := &RogueGame{Rng: &Rng{Seed: 7}}
	if got := g.spread(1); got != 1 {
		t.Errorf("spread(1) = %d, want 1", got)
	}

	if got := g.spread(2); got != 2 {
		t.Errorf("spread(2) = %d, want 2", got)
	}
}