package prolog

import org.junit.jupiter.api.Assertions.assertFalse
import org.junit.jupiter.api.Assertions.assertTrue
import org.junit.jupiter.api.BeforeEach
import org.junit.jupiter.api.Test
import prolog.builtins.Conjunction
import prolog.builtins.Disjunction
import prolog.components.Program
import prolog.components.expressions.Fact
import prolog.components.expressions.Rule
import prolog.components.terms.Atom
import prolog.components.terms.Structure

class EvaluationTest {
    @BeforeEach
    fun setUp() {
        Program.clear()
    }

    @Test
    fun successful_single_fact_query() {
        val fact = Fact(Atom("a"))
        Program.load(listOf(fact))

        assertTrue(Program.query(Atom("a")))
    }

    @Test
    fun failing_single_fact_query() {
        val fact = Fact(Atom("a"))
        Program.load(listOf(fact))

        val result = Program.query(Atom("b"))

        assertFalse(result)
    }

    @Test
    fun multiple_fact_query() {
        val fact1 = Fact(Atom("a"))
        val fact2 = Fact(Atom("b"))
        Program.load(listOf(fact1, fact2))

        assertTrue(Program.query(Atom("a")))
        assertTrue(Program.query(Atom("b")))
        assertFalse(Program.query(Atom("c")))
    }

    @Test
    fun single_compound_query() {
        val structure = Structure(Atom("f"), listOf(Atom("a"), Atom("b")))
        Program.load(listOf(Fact(structure)))

        assertTrue(Program.query(Structure(Atom("f"), listOf(Atom("a"), Atom("b")))))
    }

    @Test
    fun multiple_compound_query() {
        val structure1 = Structure(Atom("f"), listOf(Atom("a"), Atom("b")))
        val structure2 = Structure(Atom("g"), listOf(Atom("c"), Atom("d")))
        Program.load(listOf(Fact(structure1), Fact(structure2)))

        assertTrue(Program.query(Structure(Atom("f"), listOf(Atom("a"), Atom("b")))))
        assertTrue(Program.query(Structure(Atom("g"), listOf(Atom("c"), Atom("d")))))
        assertFalse(Program.query(Structure(Atom("h"), listOf(Atom("e")))))
    }

    /**
     * John and Jane are Jimmy's parents.
     */
    @Test
    fun parents_prolog_way() {
        val father = Fact(Structure(Atom("father"), listOf(Atom("john"), Atom("jimmy"))))
        val mother = Fact(Structure(Atom("mother"), listOf(Atom("jane"), Atom("jimmy"))))

        val parent1 = Rule(
            Structure(Atom("parent"), listOf(Atom("X"), Atom("Y"))),
            /* :- */
            Structure(Atom("father"), listOf(Atom("X"), Atom("Y")))
        )
        val parent2 = Rule(
            Structure(Atom("parent"), listOf(Atom("X"), Atom("Y"))),
            /* :- */
            Structure(Atom("mother"), listOf(Atom("X"), Atom("Y")))
        )

        Program.load(listOf(father, mother, parent1, parent2))

        assertTrue(Program.query(Structure(Atom("parent"), listOf(Atom("john"), Atom("jimmy")))))
        assertTrue(Program.query(Structure(Atom("parent"), listOf(Atom("jane"), Atom("jimmy")))))
    }

    /**
     * John and Jane are Jimmy's parents.
     */
    @Test
    fun parents_disjunction_way() {
        val father = Fact(Structure(Atom("father"), listOf(Atom("john"), Atom("jimmy"))))
        val mother = Fact(Structure(Atom("mother"), listOf(Atom("jane"), Atom("jimmy"))))

        val parent = Rule(
            Structure(Atom("parent"), listOf(Atom("X"), Atom("Y"))),
            /* :- */ Disjunction(
            Structure(Atom("father"), listOf(Atom("X"), Atom("Y"))),
            /* ; */
            Structure(Atom("mother"), listOf(Atom("X"), Atom("Y")))
            ))

        Program.load(listOf(father, mother, parent))

        assertTrue(Program.query(Structure(Atom("parent"), listOf(Atom("john"), Atom("jimmy")))))
        assertTrue(Program.query(Structure(Atom("parent"), listOf(Atom("jane"), Atom("jimmy")))))

        assertFalse(Program.query(Structure(Atom("parent"), listOf(Atom("john"), Atom("jane")))))
        assertFalse(Program.query(Structure(Atom("father"), listOf(Atom("john"), Atom("jane")))))
    }

    /**
     * John is Jimmy's father.
     * Jane is Jimmy's mother.
     */
    @Test
    fun father_or_mother() {
        val male = Fact(Structure(Atom("male"), listOf(Atom("john"))))
        val female = Fact(Structure(Atom("female"), listOf(Atom("jane"))))

        val parent1 = Fact(Structure(Atom("parent"), listOf(Atom("john"), Atom("jimmy"))))
        val parent2 = Fact(Structure(Atom("parent"), listOf(Atom("jane"), Atom("jimmy"))))

        val isFather = Rule(
            Structure(Atom("isFather"), listOf(Atom("X"), Atom("Y"))),
            Conjunction(
                Structure(Atom("parent"), listOf(Atom("X"), Atom("Y"))),
                Structure(Atom("male"), listOf(Atom("X")))
            )
        )
        val isMother = Rule(
            Structure(Atom("isMother"), listOf(Atom("X"), Atom("Y"))),
            Conjunction(
                Structure(Atom("parent"), listOf(Atom("X"), Atom("Y"))),
                Structure(Atom("female"), listOf(Atom("X")))
            )
        )

        Program.load(listOf(male, female, parent1, parent2, isFather, isMother))

        val result1 = Program.query(Structure(Atom("isFather"), listOf(Atom("john"), Atom("jimmy"))))
        assertTrue(result1)

        val result2 = Program.query(Structure(Atom("isMother"), listOf(Atom("jane"), Atom("jimmy"))))
        assertTrue(result2)

        val result3 = Program.query(Structure(Atom("isFather"), listOf(Atom("jane"), Atom("jimmy"))))
        assertFalse(result3)

        val result4 = Program.query(Structure(Atom("isMother"), listOf(Atom("john"), Atom("jimmy"))))
        assertFalse(result4)

        val result5 = Program.query(Structure(Atom("parent"), listOf(Atom("trudy"), Atom("jimmy"))))
        assertFalse(result5)
    }
}