// libWebAssign LOL

function putHelp(solutionSet) {
    title = solutionSet[0]
    solutionSet = solutionSet[1] || {}

    if($$('.bread').getNext()[0].innerHTML.replace(/^\s+/, '') != title) {
        alert("Invalid Solution Set Loaded! I work for '" + title + "'")
    }

    $$('.numSolveButtan').dispose()
    $$('[id^="question"]').each(function(v, k) {
        addSolveButton(v)
    })

    function solve(questionDiv, sol) {
        var elements = []
        questionDiv.getElements('font[color=red]').each(function(v, k) {
            elements.push(
                parseFloat(v.innerHTML)
            )
        })

        var results = sol(elements)
        var inputFields = questionDiv.getElements('input[type=text]')

        try {
            results.each(function(v, k) {
                if(inputFields[k] === undefined) {
                    throw "fail";
                } else {
                    inputFields[k].set('value', round(v))
                }
            })
        } catch(e) {
            alert("Too many results, too few fields.")
        }
    }

    function addSolveButton(div) {
        var key = div.getElement('.qTitleRight > span').innerHTML.substring(16).replace(/\.\s+/, '')
        var sol = solutionSet[key]
        if(sol === undefined) {
            div.getElement('.leftBarTitle').appendChild(
                new Element('span', {
                    'html': 'no logic present',
                    'styles': {
                        'color': 'grey',
                        'padding': '2px 0 2px 20px',
                        'font-weight': 'bold'
                    },
                    'class': 'numSolveButtan'
                })
            )
        } else {
            div.getElement('.leftBarTitle').appendChild(
                new Element('a', {
                    html: 'Solve',
                    events: {
                        click: function(e) {
                            solve(div, sol)
                        }
                    },
                    styles: {
                        'font-weight': 'bold',
                        'color': 'red',
                        'padding': '2px 0 2px 20px'
                    },
                    'class': 'numSolveButtan'
                })
            )
        }
    }
}

var g = -9.80;

function round(num, places) {
    places = Math.pow(10, places || 2)
    return Math.round(num * places)/places
}

function sin(degs) {
    return Math.sin(deg2rad(degs))
}
function cos(degs) {
    return Math.cos(deg2rad(degs))
}

function deg2rad(degs) {
    return degs * Math.PI / 180
}

solutions = ['ch 6 Motion in 2D (Homework)', {
    'GPhys09 6.MP.052': function(elements) { // question 1
        var distanceY = -elements[0], distanceX = elements[1]

        time = Math.sqrt(
            (2 * distanceY) / g
        )
        velocityX = distanceX / time

        return [time, velocityX]

    },
    'GPhys09 6.MP.055': function(elements) { // question 2
        var velocityX = elements[0], time = elements[1]

        distanceY = Math.abs(.5* g * Math.pow(time, 2))
        distanceX = velocityX * time

        return [distanceY, distanceX]

    },
    'GPhys09 6.MP.056': function(elements) { // question 3
        var theta = elements[0], velocity = elements[1];

        height = (Math.pow(velocity * sin(theta), 2)) / (-2 * g)
        range = (Math.pow(velocity, 2) * sin(2 * theta)) / -g

        return [height, range]

    },
    'GPhys09 6.MP.058': function(elements) { // question 4
        var distanceY = -elements[0], velocityX = (elements[1] * 1000 / 3600)

        time = Math.sqrt(
            (2 * distanceY) / g
        )
        distanceX = velocityX * time

        return [time, distanceX]

    },
    'GPhys09 6.MP.059': function(elements) { // question 5
        var distanceY = -elements[0], distanceX = elements[1];

        return [
            distanceX / Math.sqrt((2 * distanceY) / g) // velocityX
        ]

    },
    'GPhys09 6.MP.061': function(elements) { // question 6
        var massKg = elements[0], radius = elements[1];
        var T = 14.3;

        acceleration = (4 * Math.pow(Math.PI, 2) * radius) / Math.pow(T, 2)
        Fnet = massKg * acceleration

        return [acceleration, Fnet]

    }
}]


putHelp(solutions)