// Storage for the options that the server gives us. This will define our filters.
var options = {};
// Last time we updated the spots/alerts list on display.
var lastUpdateTime;
// Whether "embedded mode" is being used. This removes headers and footers, maximises the remaining content, and
// uses URL params to configure the interface options rather than using the user's localstorage.
var embeddedMode = false;

// Load and apply any URL params. This is used for "embedded mode" where another site can embed a version of
// Spothole and provide its own interface options rather than using the user's saved ones. These may select things
// from the various filter & display options, so this function needs to be called after these are set up, but if
// the URL params ask for "embedded mode", this will suppress loading settings, so this needs to be called before
// that occurs..
function loadURLParams() {
    let params = new URLSearchParams(document.location.search);

    // Handle embedded mode. We set a global to e.g. suppress loading/saving settings, and apply an attribute to the
    // top-level html element to use CSS selectors to remove bits of UI.
    let embedded = params.get("embedded");
    if (embedded != null && embedded === "true") {
        embeddedMode = true;
        $("html").attr("embedded-mode", "true");
    }

    // Handle other params
    updateCheckboxFromParam(params, "dark-mode", "darkMode");
    updateSelectFromParam(params, "time-zone", "timeZone"); // Only on Spots and Alerts pages
    updateSelectFromParam(params, "limit", "spots-to-fetch"); // Only on Spots page
    updateSelectFromParam(params, "limit", "alerts-to-fetch"); // Only on Alerts page
    updateSelectFromParam(params, "max_age", "max-spot-age"); // Only on Map & Bands pages
    updateFilterFromParam(params, "band", "band");
    updateFilterFromParam(params, "sig", "sig");
    updateFilterFromParam(params, "source", "source");
    updateFilterFromParam(params, "mode_type", "mode_type");
    updateFilterFromParam(params, "dx_continent", "dx_continent");
    updateFilterFromParam(params, "de_continent", "de_continent");
}

// Update an HTML checkbox element so that its selected matches the given parameter (which must have a true or false value)
function updateCheckboxFromParam(params, paramName, checkboxID) {
    let v = params.get(paramName);
    if (v != null) {
        $("#" + checkboxID).prop("checked", (v === "true") ? true : false);
        // Extra check if this is the "dark mode" toggle
        if (checkboxID == "darkMode") {
            enableDarkMode((v === "true") ? true : false);
        }
    }
}

// Update an HTML select element so that its value matches the given parameter
function updateSelectFromParam(params, paramName, selectID) {
    let v = params.get(paramName);
    if (v != null) {
        $("#" + selectID).prop("value", v);
    }
}

// Update a set of HTML checkbox elements describing a filter of the given name, so that any items named in the
// parameter (as a comma-separated list) will be enabled, and all others disabled. e.g. if paramName is
// "filter-band" and the params contain "filter-band=20m,40m", and prefix is "band", then #filter-button-band-30m
// would be disabled but #filter-button-band-20m and #filter-button-band-40m would be enabled.
function updateFilterFromParam(params, paramName, filterName) {
    let v = params.get(paramName);
    if (v != null) {
        // First uncheck all options for the filter
        $(".filter-button-" + filterName).prop("checked", false);
        // Now find out which ones should be enabled
        let s = v.split(",");
        s.forEach(val => $("#filter-button-" + filterName + "-" + val).prop("checked", true));
    }
}

// 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;
}


// Generate a filter card with multiple toggle buttons plus All/None buttons.
function generateMultiToggleFilterCard(elementID, filterQuery, options) {
    // Create a button for each option
    options.forEach(o => {
        $(elementID).append(`<input type="checkbox" class="btn-check filter-button-${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
    $(elementID).append(` <span style="display: inline-block"><button id="filter-button-${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>`);
}

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

// 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) {
                var number = count.toFixed(0);
                updatingString = "<span class='nowrap'>Updating in " + number + " second" + (number != "1" ? "s" : "") + ".</span>";
            } else {
                var number = Math.round(count / 60.0).toFixed(0);
                updatingString = "<span class='nowrap'>Updating in " + number + " minute" + (number != "1" ? "s" : "") + ".</span>";
            }
        }
        $("#timing-container").html("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);
}

// When the "use local time" field is changed, reload the table and save settings
function timeZoneUpdated() {
    updateTable();
    saveSettings();
}

// When one of the column toggle checkboxes are changed, reload the table and save settings
function columnsUpdated() {
    updateTable();
    saveSettings();
}

// Calculate great circle bearing between two lat/lon points.
function calcBearing(lat1, lon1, lat2, lon2) {
    lat1 *= Math.PI / 180;
    lon1 *= Math.PI / 180;
    lat2 *= Math.PI / 180;
    lon2 *= Math.PI / 180;
    var lonDelta = lon2 - lon1;
    var y = Math.sin(lonDelta) * Math.cos(lat2);
    var x = Math.cos(lat1) * Math.sin(lat2) - Math.sin(lat1) * Math.cos(lat2) * Math.cos(lonDelta);
    var bearing = Math.atan2(y, x);
    bearing = bearing * (180 / Math.PI);
    if ( bearing < 0 ) { bearing += 360; }
    return bearing;
}

// Convert a Maidenhead grid reference of arbitrary precision to the lat/long of the centre point of the square.
// Returns null if the grid format is invalid.
function latLonForGridCentre(grid) {
    let [lat, lon, latCellSize, lonCellSize] = latLonForGridSWCornerPlusSize(grid);
    if (lat != null && lon != null && latCellSize != null && lonCellSize != null) {
        return [lat + latCellSize / 2.0, lon + lonCellSize / 2.0];
    } else {
        return null;
    }
}

// Convert a Maidenhead grid reference of arbitrary precision to lat/long, including in the result the size of the
// lowest grid square. This is a utility method used by the main methods that return the centre, southwest, and
// northeast coordinates of a grid square.
// The return type is always an array of size 4. The elements in it are null if the grid format is invalid.
function latLonForGridSWCornerPlusSize(grid) {
    // Make sure we are in upper case so our maths works. Case is arbitrary for Maidenhead references
    grid = grid.toUpperCase();

    // Return null if our Maidenhead string is invalid or too short
    let len = grid.length;
    if (len <= 0 || (len % 2) !== 0) {
        return [null, null, null, null];
    }

    let lat = 0.0; // aggregated latitude
    let lon = 0.0; // aggregated longitude
    let latCellSize = 10; // Size in degrees latitude of the current cell. Starts at 20 and gets smaller as the calculation progresses
    let lonCellSize = 20; // Size in degrees longitude of the current cell. Starts at 20 and gets smaller as the calculation progresses
    let latCellNo; // grid latitude cell number this time
    let lonCellNo; // grid longitude cell number this time

    // Iterate through blocks (two-character sections)
    for (let block = 0; block * 2 < len; block += 1) {
        if (block % 2 === 0) {
            // Letters in this block
            lonCellNo = grid.charCodeAt(block * 2) - 'A'.charCodeAt(0);
            latCellNo = grid.charCodeAt(block * 2 + 1) - 'A'.charCodeAt(0);
            // Bail if the values aren't in range. Allowed values are A-R (0-17) for the first letter block, or
            // A-X (0-23) thereafter.
            let maxCellNo = (block === 0) ? 17 : 23;
            if (latCellNo < 0 || latCellNo > maxCellNo || lonCellNo < 0 || lonCellNo > maxCellNo) {
                return [null, null, null, null];
            }
        } else {
            // Numbers in this block
            lonCellNo = parseInt(grid.charAt(block * 2));
            latCellNo = parseInt(grid.charAt(block * 2 + 1));
            // Bail if the values aren't in range 0-9..
            if (latCellNo < 0 || latCellNo > 9 || lonCellNo < 0 || lonCellNo > 9) {
                return [null, null, null, null];
            }
        }

        // Aggregate the angles
        lat += latCellNo * latCellSize;
        lon += lonCellNo * lonCellSize;

        // Reduce the cell size for the next block, unless we are on the last cell.
        if (block * 2 < len - 2) {
            // Still have more work to do, so reduce the cell size
            if (block % 2 === 0) {
                // Just dealt with letters, next block will be numbers so cells will be 1/10 the current size
                latCellSize = latCellSize / 10.0;
                lonCellSize = lonCellSize / 10.0;
            } else {
                // Just dealt with numbers, next block will be letters so cells will be 1/24 the current size
                latCellSize = latCellSize / 24.0;
                lonCellSize = lonCellSize / 24.0;
            }
        }
    }

    // Offset back to (-180, -90) where the grid starts
    lon -= 180.0;
    lat -= 90.0;

    // Return nulls on maths errors
    if (isNaN(lat) || isNaN(lon) || isNaN(latCellSize) ||  isNaN(lonCellSize)) {
        return [null, null, null, null];
    }

    return [lat, lon, latCellSize, lonCellSize];
}

// Function to set dark mode on or off
function enableDarkMode(dark) {
    $("html").attr("data-bs-theme", dark ? "dark" : "light");
    const metaThemeColor = document.querySelector("meta[name=theme-color]");
    metaThemeColor.setAttribute("content", dark ? "black" : "white");
    const metaAppleStatusBarStyle = document.querySelector("meta[name=apple-mobile-web-app-status-bar-style]");
    metaAppleStatusBarStyle.setAttribute("content", dark ? "black-translucent" : "white-translucent");
}

// Startup function to determine whether to use light or dark mode
function usePreferredTheme() {
    // First, work out if we have ever explicitly saved the value of our toggle
    let val = localStorage.getItem("#darkMode:checked");
    if (val != null) {
        enableDarkMode(JSON.parse(val));
    } else {
        // Never set it before, so use the system default theme and set the toggle up to match
        let dark = window.matchMedia && window.matchMedia('(prefers-color-scheme: dark)').matches;
        enableDarkMode(dark);
        $("#darkMode").prop('checked', dark);
    }
}

// Save settings to local storage. Suppressed if "embedded mode" is in use.
function saveSettings() {
    if (!embeddedMode) {
        // 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("#" + $(this)[0].id + ":checked", JSON.stringify($(this)[0].checked));
        });
        $(".storeable-select").each(function() {
            localStorage.setItem("#" + $(this)[0].id + ":value", JSON.stringify($(this)[0].value));
        });
        $(".storeable-text").each(function() {
            localStorage.setItem("#" + $(this)[0].id + ":value", JSON.stringify($(this)[0].value));
        });
    }
}

// Load settings from local storage and set up the filter selectors. Suppressed if "embedded mode" is in use.
function loadSettings() {
    if (!embeddedMode) {
        // Find all local storage entries and push their data to the corresponding UI element
        Object.keys(localStorage).forEach(function(key) {
            if (key.startsWith("#") && key.includes(":")) {
                // 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)));
            }
        });
    }
}

// Startup
$(document).ready(function() {
    usePreferredTheme();
});