{#- Based on https://github.com/getzola/zola/blob/1ac1231de1e342bbaf4d7a51a8a9a40ea152e246/docs/static/search.js -#}

<script type="text/javascript">
    function debounce(func, wait) {
        var timeout;

        return function () {
            var context = this;
            var args = arguments;
            clearTimeout(timeout);

            timeout = setTimeout(function () {
                timeout = null;
                func.apply(context, args);
            }, wait);
        };
    }

    // Taken from mdbook
    // The strategy is as follows:
    // First, assign a value to each word in the document:
    //  Words that correspond to search terms (stemmer aware): 40
    //  Normal words: 2
    //  First word in a sentence: 8
    // Then use a sliding window with a constant number of words and count the
    // sum of the values of the words within the window. Then use the window that got the
    // maximum sum. If there are multiple maximas, then get the last one.
    // Enclose the terms in <b>.
    function makeTeaser(body, terms) {
        var TERM_WEIGHT = 40;
        var NORMAL_WORD_WEIGHT = 2;
        var FIRST_WORD_WEIGHT = 8;
        var TEASER_MAX_WORDS = 30;

        var stemmedTerms = terms.map(function (w) {
            return elasticlunr.stemmer(w.toLowerCase());
        });
        var termFound = false;
        var index = 0;
        var weighted = []; // contains elements of ["word", weight, index_in_document]

        // split in sentences, then words
        var sentences = body.toLowerCase().split(". ");

        for (var i in sentences) {
            var words = sentences[i].split(" ");
            var value = FIRST_WORD_WEIGHT;

            for (var j in words) {
                var word = words[j];

                if (word.length > 0) {
                    for (var k in stemmedTerms) {
                        if (elasticlunr.stemmer(word).startsWith(stemmedTerms[k])) {
                            value = TERM_WEIGHT;
                            termFound = true;
                        }
                    }
                    weighted.push([word, value, index]);
                    value = NORMAL_WORD_WEIGHT;
                }

                index += word.length;
                index += 1;  // ' ' or '.' if last word in sentence
            }

            index += 1;  // because we split at a two-char boundary '. '
        }

        if (weighted.length === 0) {
            return body;
        }

        var windowWeights = [];
        var windowSize = Math.min(weighted.length, TEASER_MAX_WORDS);
        // We add a window with all the weights first
        var curSum = 0;
        for (var i = 0; i < windowSize; i++) {
            curSum += weighted[i][1];
        }
        windowWeights.push(curSum);

        for (var i = 0; i < weighted.length - windowSize; i++) {
            curSum -= weighted[i][1];
            curSum += weighted[i + windowSize][1];
            windowWeights.push(curSum);
        }

        // If we didn't find the term, just pick the first window
        var maxSumIndex = 0;
        if (termFound) {
            var maxFound = 0;
            // backwards
            for (var i = windowWeights.length - 1; i >= 0; i--) {
                if (windowWeights[i] > maxFound) {
                    maxFound = windowWeights[i];
                    maxSumIndex = i;
                }
            }
        }

        var teaser = [];
        var startIndex = weighted[maxSumIndex][2];
        for (var i = maxSumIndex; i < maxSumIndex + windowSize; i++) {
            var word = weighted[i];
            if (startIndex < word[2]) {
                // missing text from index to start of `word`
                teaser.push(body.substring(startIndex, word[2]));
                startIndex = word[2];
            }

            // add <strong> around search terms
            if (word[1] === TERM_WEIGHT) {
                teaser.push("<strong>");
            }
            startIndex = word[2] + word[0].length;
            teaser.push(body.substring(word[2], startIndex));

            if (word[1] === TERM_WEIGHT) {
                teaser.push("</strong>");
            }
        }
        teaser.push("…");
        return teaser.join("");
    }

    function formatSearchResultItem(item, terms) {
        return '<div class="item">'
            + `<a href="${item.ref}">${item.doc.title}</a>`
            + `<span>${makeTeaser(item.doc.body, terms)}</span>`
            + '</div>';
    }

    function initSearch() {
        var $searchInput = document.getElementById("search-bar");
        var $searchResults = document.getElementById("search-results");
        var MAX_ITEMS = 10;

        var options = {
            bool: "AND",
            fields: {
                title: { boost: 2 },
                body: { boost: 1 },
            }
        };
        var currentTerm = "";
        var index;

        var initIndex = async function () {
            if (index === undefined) {
                index = fetch("{{ get_url(path='/', lang=lang) }}/search_index.{{ config.default_language }}.json")
                    .then(
                        async function (response) {
                            return await elasticlunr.Index.load(await response.json());
                        }
                    );
            }
            let res = await index;
            return res;
        }

        $searchInput.addEventListener("keyup", debounce(async function () {
            var term = $searchInput.value.trim();
            if (term === currentTerm) {
                return;
            }
            $searchResults.style.display = term === "" ? "none" : "flex";
            $searchResults.innerHTML = "";
            currentTerm = term;
            if (term === "") {
                return;
            }

            var results = (await initIndex()).search(term, options);
            if (results.length === 0) {
                $searchResults.style.display = "none";
                return;
            }

            for (var i = 0; i < Math.min(results.length, MAX_ITEMS); i++) {
                $searchResults.innerHTML += formatSearchResultItem(results[i], term.split(" "));
            }
        }, 150));

        window.addEventListener('click', function (e) {
            if ($searchResults.style.display == "flex" && !$searchResults.contains(e.target)) {
                $searchResults.style.display = "none";
            }
        });
    }

    function toggleSearch() {
        var searchContainer = document.getElementById("search-container");
        var searchBar = document.getElementById("search-bar");
        searchContainer.classList.toggle("active");
        searchBar.toggleAttribute("disabled");
    }

    if (document.readyState === "complete" ||
        (document.readyState !== "loading" && !document.documentElement.doScroll)
    ) {
        initSearch();
    } else {
        document.addEventListener("DOMContentLoaded", initSearch);
    }
</script>
