var path    = require("path");
var fs      = require("fs");
var lunr    = require("lunr");
var cheerio = require("cheerio");

// don't modify this, it'll be modified on the fly by lunr() in Franklin
const PATH_PREPEND = "..";

const HTML_FOLDER  = "../../__site";
const OUTPUT_INDEX = "lunr_index.js";

function isHtml(filename) {
    lower = filename.toLowerCase();
    return (lower.endsWith(".htm") || lower.endsWith(".html"));
}

function findHtml(folder) {
    if (!fs.existsSync(folder)) {
        console.log("Could not find folder: ", folder);
        return;
    }
    var files = fs.readdirSync(folder);
    var htmls = [];
    for (var i = 0; i < files.length; i++) {
        var filename = path.join(folder, files[i]);
        var stat = fs.lstatSync(filename);
        if (stat.isDirectory()) {
            if (stat == "assets" || stat == "css" || stat == "libs" ) {
                continue
            }
            var recursed = findHtml(filename);
            for (var j = 0; j < recursed.length; j++) {
                recursed[j] = path.join(files[i], recursed[j]).replace(/\\/g, "/");
            }
            htmls.push.apply(htmls, recursed);
        }
        else if (isHtml(filename)){
            htmls.push(files[i]);
        };
    };
    return htmls;
};

function readHtml(root, file, fileId) {
    var filename = path.join(root, file);
    var txt = fs.readFileSync(filename).toString();
    var $ = cheerio.load(txt);
    var title = $("title").text();
    if (typeof title == 'undefined') title = file;
    var body = $("body").text()
    if (typeof body == 'undefined') body = "";

    var data = {
        "id": fileId,
        "l": filename,
        "t": title,
        "b": body
    }
    return data;
}

function buildIndex(docs) {
    var idx = lunr(function () {
        this.ref('id');
        this.field('t'); // title
        this.field('b'); // body
        docs.forEach(function (doc) {
                this.add(doc);
            }, this);
        });
    return idx;
}

function buildPreviews(docs) {
    var result = {};
    for (var i = 0; i < docs.length; i++) {
        var doc = docs[i];
        result[doc["id"]] = {
            "t": doc["t"],
            "l": doc["l"].replace(/^\.\.\/\.\.\/__site/gi, '/' + PATH_PREPEND)
        }
    }
    return result;
}

function main() {
    files = findHtml(HTML_FOLDER);
    var docs = [];
    for (var i = 0; i < files.length; i++) {
        docs.push(readHtml(HTML_FOLDER, files[i], i));
    }
    var idx  = buildIndex(docs);
    var prev = buildPreviews(docs);
    var js = "const LUNR_DATA = " + JSON.stringify(idx) + ";\n" +
             "const PREVIEW_LOOKUP = " + JSON.stringify(prev) + ";";
    fs.writeFile(OUTPUT_INDEX, js, function(err) {
        if(err) {
            return console.log(err);
        }
    });
}

main();