#include "catch/catch.hpp"
#include <iostream>

#include "JMath/JMatrixND.hh"

using Catch::Matchers::Contains;  // a nice "substr" checker


TEST_CASE( "JMatrixND class", "[math]" ) {

    // This is our setup, which is executed before each SECTION
    size_t n = 4;
    JMATH::JMatrixND A(n);
    JMATH::JMatrixND B(n);

    for(size_t i = 0; i < n*n; ++i) {
        // A = [[0,1,2,3], [4,5,6,7], [8,9,10,11], [12,13,14,15]]
        A.at(i/n, i%n) = i;
        // B = [[1,2,3,4], [5,6,7,8], [9,10,11,12], [13,14,15,16]]
        B.at(i/n, i%n) = i + 1;
    }


    // The actual tests:

    SECTION("setIdentity sets diagonals to 1 and everything else to 0") {
        A.setIdentity(); 

        for(size_t i = 0; i != n; ++i) {

            REQUIRE( A.at(i, i) == 1 );  // diagonals

            for(size_t j = 0; j != i; ++j) {
                REQUIRE( A.at(i, j) == 0 );  // everything else
            }
        }
    }

    SECTION("multiplication with a scalar") {
        int s = 3;
        JMATH::JMatrixND C = A * s;
        for (size_t i = 0; i != C.size(); ++i) {
            for (size_t j = 0; j != C.size(); ++j) {
                REQUIRE( C.at(i, j) == A.at(i, j) * s );
            }
        }
    }

    SECTION("multiplication with a matrix") {
        JMATH::JMatrixND C = A * B;
        // not a complete check, but it's a demo
        REQUIRE( C.at(0, 0) == Approx(62) );  // float comparisons, epsilon can be adjusted
        REQUIRE( C.at(3, 3) == Approx(560) );
        REQUIRE( C.at(2, 0) == Approx(286) );
    }

    SECTION("multiplication of two matrices with incompatible dimensions throws") {
        JMATH::JMatrixND C(n*2);

        REQUIRE_THROWS_WITH( A * C, Contains("inconsistent") && Contains("dimensions") );
    }

    SECTION("addition of two matrices with incompatible dimensions throws") {
        JMATH::JMatrixND C(n*2);

        REQUIRE_THROWS_WITH( A + C, Contains("inconsistent") && Contains("dimensions") );
    }
    /*
    SECTION("determinant") {
        JMATH::JMatrixND C(3);
        C.at(0, 0) = 6;
        C.at(0, 1) = 1;
        C.at(0, 2) = 1;
        C.at(1, 0) = 4;
        C.at(1, 1) = -2;
        C.at(1, 2) = 5;
        C.at(2, 0) = 2;
        C.at(2, 1) = 8;
        C.at(2, 2) = 7;

        REQUIRE( C.getDeterminant() == Approx(-306) );
    }

    SECTION("determinant throws when zero pivot") {
        REQUIRE_THROWS_WITH( A.getDeterminant(), Contains("zero pivot") );
    }
    */
}