"use strict";

let query = (new URL(location)).searchParams.get("query")
    , epoch = Math.floor(Date.now() / 1000)
;
let orderBy, ascending;  // use `setOrderBy()` to modify orderBy
let lastOrderedValue, lastID;

window.onload = function () {
    if (query !== null && query !== "") {
        orderBy = "RELEVANCE";
    } else {
        document.getElementById("query").value = query;
    }

    const title = document.getElementsByTagName("title")[0];
    if (query) {
        title.textContent = query + " - magneticow";
        const input = document.getElementsByTagName("input")[0];
        input.setAttribute("value", query);

        setOrderBy("RELEVANCE");
        ascending = false;
    } else {
        title.textContent = "Most recent torrents - magneticow";

        ascending = false;
        setOrderBy("DISCOVERED_ON");
    }

    const feedAnchor = document.getElementById("feed-anchor");
    const sortDropdown = document.getElementById("sort-dropdown");
    if (query) {
        feedAnchor.setAttribute("href", "/feed?query=" + encodeURIComponent(query));
    } else {
        sortDropdown.selectedIndex = 3
    }

    const queryInput = document.getElementById("query");
    queryInput.onchange = sortDropdown.onchange = function () {
        const ul = document.querySelector("main ul");

        query = queryInput.value

        const newurl = window.location.protocol + "//" + window.location.host + window.location.pathname + '?query=' + query;
        window.history.pushState({path: newurl}, '', newurl);

        switch (sortDropdown.selectedIndex) {
            case 0:
                setOrderBy("RELEVANCE")
                break;
            case 1:
            case 2:
                setOrderBy("TOTAL_SIZE")
                break;
            case 3:
            case 4:
                setOrderBy("DISCOVERED_ON")
                break;
            case 5:
            case 6:
                setOrderBy("N_FILES")
                break;
        }

        ascending = sortDropdown.selectedIndex % 2 === 1

        ul.innerHTML = ""
        lastID = lastOrderedValue = null
        load(queryInput.value);
    };

    load(query);
};


function setOrderBy(x) {
    const validValues = [
        "TOTAL_SIZE",
        "DISCOVERED_ON",
        "UPDATED_ON",
        "N_FILES",
        "N_SEEDERS",
        "N_LEECHERS",
        "RELEVANCE"
    ];
    if (!validValues.includes(x)) {
        throw new Error("invalid value for @orderBy");
    }
    orderBy = x;
}

function orderedValue(torrent) {
    if (orderBy === "TOTAL_SIZE") return torrent.size;
    else if (orderBy === "DISCOVERED_ON") return torrent.discoveredOn;
    else if (orderBy === "UPDATED_ON") alert("implement it server side first!");
    else if (orderBy === "N_FILES") return torrent.nFiles;
    else if (orderBy === "N_SEEDERS") alert("implement it server side first!");
    else if (orderBy === "N_LEECHERS") alert("implement it server side first!");
    else if (orderBy === "RELEVANCE") return torrent.relevance;
}


function load(queryParam) {
    const button = document.getElementsByTagName("button")[0];
    button.textContent = "Loading More Results...";
    button.setAttribute("disabled", "");  // disable the button whilst loading...

    if (queryParam == null) {
        queryParam = query
    }

    const ul = document.querySelector("main ul");
    const template = document.getElementById("item-template").innerHTML;
    const reqURL = "/api/v0.1/torrents?" + encodeQueryData({
        query: queryParam,
        epoch: epoch,
        lastID: lastID,
        lastOrderedValue: lastOrderedValue,
        orderBy: orderBy,
        ascending: ascending
    });

    console.log("reqURL", reqURL);

    let req = new XMLHttpRequest();

    function disableButtonWithMsg(msg) {
        button.textContent = msg;
        button.setAttribute("disabled", "");
    }

    req.onreadystatechange = function () {
        if (req.readyState !== 4)
            return;

        button.textContent = "Load More Results";
        button.removeAttribute("disabled");

        if (req.status !== 200)
            alert(req.responseText);

        let torrents = JSON.parse(req.responseText);
        if (torrents.length === 0) {
            disableButtonWithMsg("No More Results")
            return;
        }

        const last = torrents[torrents.length - 1];
        lastID = last.id;
        lastOrderedValue = orderedValue(last);

        for (let t of torrents) {
            t.size = fileSize(t.size);
            t.discoveredOn = humaniseDate(t.discoveredOn);

            ul.innerHTML += Mustache.render(template, t);
        }

        if (torrents.length < 20) {
            disableButtonWithMsg("No More Results");
        }
    };

    req.open("GET", reqURL);
    req.send();
}