// Make the class reference table sortable in ascending or descending order
// when a header is clicked.


// Helper function to return the content from the idx-th cell of row tr
const getCellValue = (tr, idx) => tr.children[idx].textContent;

// Array sorting functions for different columns used by the comparer

// Compares the Desc. and Brief Desc. columns
// "MISSING" comes first in ascending order
const descriptionComparer = function(v1, v2) {
    if(v1 == v2) return 0
    if(v1 == "OK") return 1
    return -1
}

// Compares the Name and Docs URL columns using a basic string sort
const stringComparer = (new Intl.Collator()).compare

// Compares the Overall column by completion percentage
const overallComparer = function(v1, v2) {
    return Number(v1.replace("%", "")) - Number(v2.replace("%", ""))
}

// Compares the other columns (constructors, methods, members, etc.)
// by the percentage they're finished.
// If two have the same percentage, they're compared by denominator size.
const fractionComparer = (asc) => function(v1, v2) {
    if(v1 == v2) return 0
    
    // Always send 0/0 values to the bottom
    // The "asc" parameter is needed for that purpose.
    if(v1 == "0/0") {
        return asc ? 1 : -1
    }

    if(v2 == "0/0") {
        return asc ? -1 : 1
    }

    var v1fraction = v1.split("/")
    var v2fraction = v2.split("/")

    var v1decimal = Number(v1fraction[0]) / Number(v1fraction[1])
    var v2decimal = Number(v2fraction[0]) / Number(v2fraction[1])
    if(v1decimal == v2decimal) return v1fraction[1] - v2fraction[1]

    return v1decimal - v2decimal
}

// Returns a function responsible for sorting a specific table column 
// (column = column object, asc = ascending order?).
const comparer = function(column, asc) { 

    // This is used by the array.sort() function...
    return function(a, b) {
        const colIdx = Array.from(column.parentNode.children).indexOf(column)
        const colName = column.textContent

        // Select a function based on which column is being called.
        var columnComparer
        switch(colName) {
            case "Brief Desc.":
            case "Desc.":
                columnComparer = descriptionComparer
                break
            case "Name":
            case "Docs URL":
                columnComparer = stringComparer
                break
            case "Overall":
                columnComparer = overallComparer
                break
            default:
                columnComparer = fractionComparer(column.asc)
                break
        }

        // Switch the order of the values depending on whether it's an ascending or descending sort.
        return columnComparer(getCellValue(asc ? a : b, colIdx), getCellValue(asc ? b : a, colIdx));
    }
};

const SKIP_END_ROWS = 5 // The number of footer rows generated by doc_status.py

// Set up event listeners that will sort the table when headers are clicked.
window.onload = function()
{
    document.querySelectorAll('th')
        .forEach(th => 
            th.addEventListener('click', (() => 
            {
                const table = th.closest('table');
                const tbody = table.querySelector('tbody')
                const trows = Array.from(tbody.querySelectorAll('tr'))
                trows.slice(0, -SKIP_END_ROWS)
                    .sort(comparer(th, th.asc = !th.asc)) // Give each column an individual sort direction
                    .concat(trows.splice(-SKIP_END_ROWS)) // Don't sort the last rows, as they are not class reference entries.
                    .forEach(tr => tbody.appendChild(tr) );
            })));
}