// Solution 1
function extractMatrixColumn(matrix, column) {
    let result = []
    matrix.forEach(inner => {
        inner.forEach((colValue, index) => {
            if(index === column) {
                result.push(colValue)
            }
        })
    })
    return result
}

// Solution 2
//  function extractMatrixColumn(matrix, column) {
//     let result = []
//     matrix.map( x => {
//         if(x[column] !== undefined) {
//             result.push(x[column])
//         }
//     })
//     return result
// }


/**
* Test Suite 
*/
describe('extractMatrixColumn()', () => {
    it('returns largest positive integer possible for digit count', () => {
        const matrix = [[1, 1, 1, 2], [0, 5, 0, 4], [2, 1, 3, 6]];
        const column = 2;
        const result = extractMatrixColumn(matrix, column);
        console.log("result: ", result);
        expect(result).toEqual([1, 0, 3]);
    });
    
    it('returns empty array in case of index out of limit', () => {
        // arrange
        const matrix = [[1, 1, 1, 2], [0, 5, 0, 4], [2, 1, 3, 6]];
        const column = 4;
        const result = extractMatrixColumn(matrix, column);
        console.log("result1: ", result);
        expect(result).toEqual([]);
    });
    
    it('returns empty array in case of negative index', () => {
        const matrix = [[1, 1, 1, 2], [0, 5, 0, 4], [2, 1, 3, 6]];
        const column = -4;
        const result = extractMatrixColumn(matrix, column);
        console.log("result2: ", result);
        expect(result).toEqual([]);
    });

    it('returns largest positive integer possible in case of mixed length inner arrays', () => {
        const matrix = [[1, 1, 1, 2], [0, 5, 0, 4], [2, 1, 3]];
        const column = 3;   
        const result = extractMatrixColumn(matrix, column);
        console.log("result3: ", result);
        expect(result).toEqual([2,4]);
    });
});