// Copyright 2023 The Dawn & Tint Authors
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package cnf_test

import (
	"reflect"
	"testing"

	"dawn.googlesource.com/dawn/tools/src/cnf"
)

func TestAssumeTrue(t *testing.T) {
	for _, test := range []struct {
		expr   string
		isTrue string
		expect string
	}{
		{expr: ``, isTrue: ``, expect: ``},
		{expr: `a`, isTrue: ``, expect: `a`},
		{expr: `a`, isTrue: `!a`, expect: `a`},
		{expr: `a`, isTrue: `!b`, expect: `a`},
		{expr: `a`, isTrue: `c`, expect: `a`},
		{expr: `a`, isTrue: `c`, expect: `a`},
		{expr: `a || b`, isTrue: ``, expect: `a || b`},
		{expr: `a || b`, isTrue: `!a`, expect: `a || b`},
		{expr: `a || b`, isTrue: `!b`, expect: `a || b`},
		{expr: `a || b`, isTrue: `c`, expect: `a || b`},
		{expr: `a || b`, isTrue: `c`, expect: `a || b`},
		{expr: `a && b`, isTrue: ``, expect: `a && b`},
		{expr: `a && b`, isTrue: `!a`, expect: `a && b`},
		{expr: `a && b`, isTrue: `!b`, expect: `a && b`},
		{expr: `a && b`, isTrue: `c`, expect: `a && b`},
		{expr: `a && b`, isTrue: `c`, expect: `a && b`},

		{expr: `a`, isTrue: `a`, expect: ``},
		{expr: `a || b`, isTrue: `a`, expect: ``},
		{expr: `a || b`, isTrue: `b`, expect: ``},
		{expr: `a && b`, isTrue: `a`, expect: `b`},
		{expr: `a && b`, isTrue: `b`, expect: `a`},

		{expr: `a`, isTrue: `a && b`, expect: ``},
		{expr: `a || b`, isTrue: `a && b`, expect: ``},
		{expr: `a || b`, isTrue: `b && b`, expect: ``},
		{expr: `a && b`, isTrue: `a && b`, expect: ``},

		{expr: `a && c`, isTrue: `a && b`, expect: `c`},
		{expr: `(a || b) && c`, isTrue: `a && b`, expect: `c`},
		{expr: `(a || b) && c`, isTrue: `b && c`, expect: ``},
		{expr: `a && b && c`, isTrue: `a && b`, expect: `c`},
	} {
		expr, err := cnf.Parse(test.expr)
		if err != nil {
			t.Errorf(`unexpected error returned from Parse('%v'): %v`, test.expr, err)
			continue
		}
		isTrue, err := cnf.Parse(test.isTrue)
		if err != nil {
			t.Errorf(`unexpected error returned from Parse('%v'): %v`, test.isTrue, err)
			continue
		}
		got := expr.AssumeTrue(isTrue).String()
		if test.expect != got {
			t.Errorf("('%v').AssumeTrue('%v') returned '%v', expected '%v'", expr, isTrue, got, test.expect)
		}
	}
}

func TestIsNegative(t *testing.T) {
	test := func(expression string, expected bool) {
		t.Run(expression, func(t *testing.T) {
			expr, err := cnf.Parse(expression)
			if err != nil {
				t.Fatalf("unexpected error Parse('%v'): %v", expression, err)
			}
			got := expr.IsNegative()
			if got != expected {
				t.Errorf("IsNegative() returned %v, expected %v", got, expected)
			}
		})
	}

	test("!a", true)
	test("!a && !b", true)
	test("a", false)
	test("!a && b", false)
}

func TestPositiveVarsOfNegative(t *testing.T) {
	test := func(expression string, expected []string) {
		t.Run(expression, func(t *testing.T) {
			expr, err := cnf.Parse(expression)
			if err != nil {
				t.Fatalf("unexpected error Parse('%v'): %v", expression, err)
			}
			got := expr.PositiveVarsOfNegative()
			if !reflect.DeepEqual(got, expected) {
				t.Errorf("PositiveVarsOfNegative() returned %v, expected %v", got, expected)
			}
		})
	}

	test("!a", []string{"a"})
	test("!a && !b", []string{"a", "b"})
	test("a", []string{})
	test("!a && b", []string{"a"})
}