// How often to query the server?
const REFRESH_INTERVAL_SEC = 60 * 30;

// Storage for the alert data that the server gives us.
var alerts = []
// Storage for the options that the server gives us. This will define our filters.
var options = {};
// Last time we updated the alerts list on display.
var lastUpdateTime;

// Load alerts and populate the table.
function loadAlerts() {
    $.getJSON('/api/alerts' + buildQueryString(), function(jsonData) {
        // Store last updated time
        lastUpdateTime = moment.utc();
        updateRefreshDisplay();
        // Store data
        alerts = jsonData;
        // Update table
        updateTable();
    });
}

// Build a query string for the API, based on the filters that the user has selected.
function buildQueryString() {
    var str =  "?";
    ["dx_continent", "source"].forEach(fn => {
        if (!allFilterOptionsSelected(fn)) {
            str = str + getQueryStringFor(fn) + "&";
        }
    });
    str = str + "limit=" + $("#alerts-to-fetch option:selected").val();
    str = str + "&max_duration=604800";
    return str;
}

// For a parameter, such as dx_continent, get the query string for the current filter options.
function getQueryStringFor(parameter) {
    return parameter + "=" + encodeURIComponent(getSelectedFilterOptions(parameter));
}

// For a parameter, such as dx_continent, get the filter options that are currently selected in the UI.
function getSelectedFilterOptions(parameter) {
    return $(".filter-button-" + parameter).filter(function() {
        return this.checked;
    }).map(function() {
        return this.value;
    }).get().join(",");
}

// For a parameter, such as dx_continent, return true if all possible options are enabled. (In this case, we don't need
// to bother sending this as one of the query parameters to the API; no parameter provided implies "send everything".)
function allFilterOptionsSelected(parameter) {
    var filter = $(".filter-button-" + parameter).filter(function() {
        return !this.checked;
    }).get();
    return filter.length == 0;
}

// Update the alerts table
function updateTable() {
    // Populate table with headers
    let table = $('<table class="table table-striped-custom table-hover">').append('<thead><tr class="table-primary"></tr></thead><tbody></tbody>');
    table.find('thead tr').append(`<th>Start UTC</th>`);
    table.find('thead tr').append(`<th>End UTC</th>`);
    table.find('thead tr').append(`<th>DX</th>`);
    table.find('thead tr').append(`<th>Freq<span class='hideonmobile'>uencie</span>s & Modes</th>`);
    table.find('thead tr').append(`<th class='hideonmobile'>Comment</th>`);
    table.find('thead tr').append(`<th class='hideonmobile'>Source</th>`);
    table.find('thead tr').append(`<th class='hideonmobile'>Ref.</th>`);

    // Split alerts into three types, each of which will get its own table header: On now, next 24h, and later. "On now"
    // is considered to be events with an end_time where start<now<end, or events with no end time that started in the
    // last hour.
    onNow = alerts.filter(a => (a["end_time"] != null && moment.unix(a["end_time"]).utc().isSameOrAfter() && moment.unix(a["start_time"]).utc().isBefore())
        || (a["end_time"] == null && moment.unix(a["start_time"]).utc().add(1, 'hours').isSameOrAfter() && moment.unix(a["start_time"]).utc().isBefore()));
    next24h = alerts.filter(a => moment.unix(a["start_time"]).utc().isSameOrAfter() && moment.unix(a["start_time"]).utc().subtract(24, 'hours').isBefore());
    later = alerts.filter(a => moment.unix(a["start_time"]).utc().subtract(24, 'hours').isSameOrAfter());

    if (onNow.length > 0) {
        table.find('tbody').append('<tr class="table-primary"><td colspan="100" style="text-align:center;">On Now</td></tr>');
        addAlertRowsToTable(table.find('tbody'), onNow);
    }

    if (next24h.length > 0) {
        table.find('tbody').append('<tr class="table-primary"><td colspan="100" style="text-align:center;">Starting within 24 hours</td></tr>');
        addAlertRowsToTable(table.find('tbody'), next24h);
    }

    if (later.length > 0) {
        table.find('tbody').append('<tr class="table-primary"><td colspan="100" style="text-align:center;">Starting later </td></tr>');
        addAlertRowsToTable(table.find('tbody'), later);
    }

    if (onNow.length == 0 && next24h.length == 0 && later.length == 0) {
        table.find('tbody').append('<tr class="table-danger"><td colspan="100" style="text-align:center;">No alerts match your filters.</td></tr>');
    }

    // Update DOM
    $('#table-container').html(table);
}

// Add a row to tbody for each alert in the provided list
function addAlertRowsToTable(tbody, alerts) {
    alerts.forEach(a => {
        // Create row
        let $tr = $('<tr>');

        // Format UTC times for display
        var start_time = moment.unix(a["start_time"]).utc();
        var start_time_formatted = start_time.format("YYYY-MM-DD HH:mm");
        var end_time = moment.unix(a["end_time"]).utc();
        var end_time_formatted = (end_time != null) ? end_time.format("YYYY-MM-DD HH:mm") : "Not specified";

        // Format dx country
        var dx_country = a["dx_country"]
        if (dx_country == null) {
            dx_country = "Unknown or not a country"
        }

        // Format freqs & modes
        var freqsModesText = "";
        if (a["freqs_modes"] != null) {
            freqsModesText = escapeHtml(a["freqs_modes"]);
        }

        // Format comment
        var commentText = "";
        if (a["comment"] != null) {
            commentText = escapeHtml(a["comment"]);
        }

        // Sig or fallback to source
        var sigSourceText = a["source"];
        if (a["sig"]) {
            sigSourceText = a["sig"];
        }

        // Format sig_refs
        var sig_refs = ""
        if (a["sig_refs"]) {
            sig_refs = a["sig_refs"].join(", ")
        }

        // Populate the row
        $tr.append(`<td class='nowrap'>${start_time_formatted}</td>`);
        $tr.append(`<td class='nowrap'>${end_time_formatted}</td>`);
        $tr.append(`<td class='nowrap'><span class='flag-wrapper hideonmobile' title='${dx_country}'>${a["dx_flag"]}</span><a class='dx-link' href='https://qrz.com/db/${a["dx_call"]}' target='_new'>${a["dx_call"]}</a></td>`);
        $tr.append(`<td class='hideonmobile'>${freqsModesText}</td>`);
        $tr.append(`<td class='hideonmobile'>${commentText}</td>`);
        $tr.append(`<td class='nowrap hideonmobile'><span class='icon-wrapper'><i class='fa-solid fa-${a["icon"]}'></i></span> ${sigSourceText}</td>`);
        $tr.append(`<td class='hideonmobile'>${sig_refs}</td>`);
        tbody.append($tr);

        // Second row for mobile view only, containing source, ref, freqs/modes & comment
        $tr2 = $("<tr class='hidenotonmobile'>");
        $tr2.append(`<td colspan="100"><span class='icon-wrapper'><i class='fa-solid fa-${a["icon"]}'></i></span> ${sig_refs} ${freqsModesText}<br/>${commentText}</td>`);
        tbody.append($tr2);
    });
}

// Load server options. Once a successful callback is made from this, we then query alerts.
function loadOptions() {
    $.getJSON('/api/options', function(jsonData) {
        // Store options
        options = jsonData;

        // Populate the filters panel
        $("#settings-container").append(generateFilterCard("DX Continent", "dx_continent", options["continents"]));
        $("#settings-container").append(generateFilterCard("Sources", "source", options["spot_sources"]));

        // Load settings from settings storage
        loadSettings();

        // Load alerts and set up the timer
        loadAlerts();
        setInterval(loadAlerts, REFRESH_INTERVAL_SEC * 1000);
    });
}

// Generate filter card
function generateFilterCard(displayName, filterQuery, options) {
    let $col = $("<div class='col'>")
    let $card = $("<div class='card'>");
    let $card_body = $("<div class='card-body'>");
    $card_body.append(`<h5 class='card-title'>${displayName}</h5>`);
    $p = $("<p class='card-text filter-card-text'>");
    // Create a button for each option
    options.forEach(o => {
        $p.append(`<input type="checkbox" class="btn-check filter-button-${filterQuery} storeable-checkbox" name="options" id="filter-button-${filterQuery}-${o}" value="${o}" autocomplete="off" onClick="filtersUpdated()" checked><label class="btn btn-outline-primary" for="filter-button-${filterQuery}-${o}">${o}</label> `);
    });
    // Create All/None buttons
    $p.append(` <span style="display: inline-block"><button id="filter-button-${filterQuery}-all" type="button" class="btn btn-outline-secondary" onclick="toggleFilterButtons('${filterQuery}', true);">All</button>&nbsp;<button id="filter-button-${filterQuery}-none" type="button" class="btn btn-outline-secondary" onclick="toggleFilterButtons('${filterQuery}', false);">None</button></span>`);
    // Compile HTML elements to return
    $card_body.append($p);
    $card.append($card_body);
    $col.append($card);
    return $col;
}

// Method called when "All" or "None" is clicked
function toggleFilterButtons(filterQuery, state) {
    $(".filter-button-" + filterQuery).each(function() {
        $(this).prop('checked', state);
    });
    filtersUpdated();
}

// Method called when any filter is changed to reload the alerts and persist the filter settings.
function filtersUpdated() {
    loadAlerts();
    saveSettings();
}

// Update the refresh timing display
function updateRefreshDisplay() {
    if (lastUpdateTime != null) {
        let count = REFRESH_INTERVAL_SEC;
        let secSinceUpdate = moment.duration(moment().diff(lastUpdateTime)).asSeconds();
        updatingString = "Updating..."
        if (secSinceUpdate < REFRESH_INTERVAL_SEC) {
            count = REFRESH_INTERVAL_SEC - secSinceUpdate;
            if (count <= 60) {
                updatingString = "Updating in " + count.toFixed(0) + " seconds...";
            } else {
                updatingString = "Updating in " + Math.floor(count / 60.0).toFixed(0) + " minutes.";
            }
        }
        $("#timing-container").text("Last updated at " + lastUpdateTime.format('HH:mm') + " UTC. " + updatingString);
    }
}

// Utility function to escape HTML characters from a string.
function escapeHtml(str) {
    if (typeof str !== 'string') {
        return '';
    }

    const escapeCharacter = (match) => {
        switch (match) {
            case '&': return '&amp;';
            case '<': return '&lt;';
            case '>': return '&gt;';
            case '"': return '&quot;';
            case '\'': return '&#039;';
            case '`': return '&#096;';
            default: return match;
        }
    };

    return str.replace(/[&<>"'`]/g, escapeCharacter);
}

// Save settings to local storage
function saveSettings() {
    // Find all storeable UI elements, store a key of "element id:property name" mapped to the value of that
    // property. For a checkbox, that's the "checked" property.
    $(".storeable-checkbox").each(function() {
        localStorage.setItem($(this)[0].id + ":checked", $(this)[0].checked);
    });
    $(".storeable-select").each(function() {
        localStorage.setItem($(this)[0].id + ":value", $(this)[0].value);
    });
}

// Load settings from local storage and set up the filter selectors
function loadSettings() {
    // Find all local storage entries and push their data to the corresponding UI element
    Object.keys(localStorage).forEach(function(key) {
        // Split the key back into an element ID and a property
        var split = key.split(":");
        $("#" + split[0]).prop(split[1], JSON.parse(localStorage.getItem(key)));
    });
}

// Set up UI element event listeners, after the document is ready
function setUpEventListeners() {
    $("#settings-button").click(function() {
        $("#settings-area").toggle();
    });
    $("#close-settings-button").click(function() {
        $("#settings-button").button("toggle");
        $("#settings-area").hide();
    });
    $("#alerts-to-fetch").click(function() {
        filtersUpdated();
    });
}

// Startup
$(document).ready(function() {
    // Call loadOptions(), this will then trigger loading alerts and setting up timers.
    loadOptions();
    // Update the refresh timing display every second
    setInterval(updateRefreshDisplay, 1000);
    // Set up event listeners
    setUpEventListeners();
});