import { fetchQuery } from "./contentUtility.js";
import Dataset from "./dataset.js";

export const DATASET_ENDPOINT = "/api/v1/datasets";
export const getBaseURL = () => location.origin;

const defaultPagingValue = 20;
export const lastQuery = {
    totalPages: 0,
    currentPage: 0,
};
const loadedCategories = new Set;

// definition of all buttons & sections
const addButton = document.getElementById("add-btn");
const filterButton = document.getElementById("filter-btn");
const searchButton = document.getElementById("search-btn");
const searchBar = document.getElementById("search-entry");
const sortButton = document.getElementById("sort-btn");
const resetButton = document.getElementById("reset-tools-btn");
const upvoteButtons = document.getElementsByClassName("upvote-btn");
const downvoteButtons = document.getElementsByClassName("downvote-btn");
export const searchSection = document.getElementById("search");
const recentSection = document.getElementById("recents");
const mostLikedSection = document.getElementById("top");

// ID of the timeout, because we need to cancel it at some point
export let searchBarTimeout;
const searchDelay = 500;

// Event listeners
addButton.addEventListener("click", () => {
    navigateToAdd();
});

filterButton.addEventListener("change", () => {
    fetchQuery(createQuery(), true);
});

filterButton.addEventListener("click", () => {
    fetchCategories();
})

searchButton.addEventListener("click", () => {
    fetchQuery(createQuery(), true);

});

searchBar.addEventListener("input", () => {
    clearTimeout(searchBarTimeout);
    searchBarTimeout = setTimeout(() => {
        fetchQuery(createQuery(), true);
        updateSections();
    }, searchDelay);
});

searchBar.addEventListener('keypress', function (e) {
    if (e.key === 'Enter') {
        fetchQuery(createQuery(), true);
    }
});

sortButton.addEventListener("change", () => {
    fetchQuery(createQuery(), true);
});

resetButton.addEventListener("click", () => {
    searchBar.value = "";
    filterButton.value = filterButton.querySelector("#default-filter").value;
    sortButton.value = sortButton.querySelector("#default-sort").value;
    updateSections();
});

// functions of the main page
function navigateToAdd() {
    window.location.href = "/add.html"; //TODO: move to EventListener?
}

function getFilterQuery() {
    let filterString = filterButton.value.toUpperCase();
    if (filterString === "NONE") {
        return ["type", "%"]
    } else if (document.querySelector('#filter-btn option:checked').parentElement.label === "Standard categories") {
        return ["type", filterString];
    } else {
        return ["category", filterButton.options[filterButton.selectedIndex].value]
    }
}

function getSearchQuery() {
    let searchString = searchBar.value;
    return (searchString.length === 0 ? "%" : ("%" + searchString + "%"));
}

function getSortQuery() {
    let sortString = sortButton.value.toLowerCase().split(" ");
    if (sortString[1] === "a-z" || sortString[1] === "↑" || sortString[1] === "oldest-newest") {
        sortString[1] = "asc";
    } else {
        sortString[1] = "desc";
    }
    return sortString
}

// creates query for the whole toolbar, so that searching, sorting and filtering are always combined
function createQuery() {
    updateSections();
    let queryURL = new URL(DATASET_ENDPOINT + "/search", getBaseURL());
    queryURL.searchParams.append("search", getSearchQuery());

    let filterQuery = getFilterQuery();
    queryURL.searchParams.append(filterQuery[0], filterQuery[1]);

    let sortQuery = getSortQuery();
    queryURL.searchParams.append("sort", sortQuery[0]);
    queryURL.searchParams.append("direction", sortQuery[1]);
    queryURL.searchParams.append("size", defaultPagingValue.toString(10));

    return queryURL;
}

// updates the page display. If no query is present, the initial page is shown, otherwise the search results.
function updateSections() {
    if (searchBar.value === "" && sortButton.value === sortButton.querySelector("#default-sort").value
        && filterButton.value === filterButton.querySelector("#default-filter").value) {
        searchSection.classList.add("hidden");
        recentSection.classList.remove("hidden");
        mostLikedSection.classList.remove("hidden");
        resetButton.classList.add("hidden");
    } else {
        searchSection.classList.remove("hidden");
        recentSection.classList.add("hidden");
        mostLikedSection.classList.add("hidden");
        resetButton.classList.remove("hidden");
    }
}

// fetches the further categories used in the filter function
function fetchCategories() {
    const fetchURL = new URL("api/v1/categories", getBaseURL());
    fetch(fetchURL)
        .then(resp => resp.json())
        .then((data) => {
            for (let i = 0; i < data.length; i++) {
                let categoryName = data[i].name.toLowerCase();
                categoryName = categoryName.charAt(0).toUpperCase() + categoryName.slice(1);
                if (!loadedCategories.has(categoryName)) {
                    let newCategory = new Option(categoryName, data[i].id);
                    document.getElementById("other-categories").appendChild(newCategory);
                    loadedCategories.add(categoryName);
                }
            }
        });
}

// fetches entries for the initial page
async function fetchInitialEntries() {
    let recentsQueryURL = new URL(DATASET_ENDPOINT + "/search", getBaseURL());
    recentsQueryURL.searchParams.append("sort", "date");
    recentsQueryURL.searchParams.append("direction", "desc");
    recentsQueryURL.searchParams.append("size", "6");

    const recentsResponse = await fetch(recentsQueryURL);
    const recentsData = await recentsResponse.json();

    const recentsDatasets = recentsData.content.map(dataset => new Dataset(dataset));
    for (const recentDataset of recentsDatasets) {
        document.querySelector("#recents .datasets").appendChild(recentDataset.createDatasetHTMLElement());
    }

    let topVotedQueryURL = new URL(DATASET_ENDPOINT + "/search", getBaseURL());
    topVotedQueryURL.searchParams.append("sort", "upvotes");
    topVotedQueryURL.searchParams.append("direction", "desc");
    topVotedQueryURL.searchParams.append("size", "1");
    
    const topVotedResponse = await fetch(topVotedQueryURL);
    const topVotedData = await topVotedResponse.json();
    const topVotedDataset = new Dataset(topVotedData.content[0]);

    document.querySelector("#top .datasets").appendChild(topVotedDataset.createDatasetHTMLElement());
}

window.onload = function () {
    fetchCategories();
    fetchInitialEntries();
    updateSections();
    if (searchBar.value !== "") {
        fetchQuery(createQuery(), true);
    }
    let observer = new IntersectionObserver(() => {
        if (!searchSection.classList.contains("hidden")) {
            fetchPagingResults();
        }
    }, {root: null, rootMargin: "0px", threshold: .9});
    observer.observe(document.getElementById("observable"));
}

function fetchPagingResults() {
    lastQuery.currentPage++
    if (lastQuery.currentPage < lastQuery.totalPages) {
        let pagingQuery = new URL(createQuery());
        pagingQuery.searchParams.append("page", lastQuery.currentPage.toString(10));
        fetchQuery(pagingQuery, false);
    }
}