var _ = require("lodash");
var kramed = require("kramed");
var annotate = require("kramed/lib/annotate/");

var RAW_START = "{% raw %}";
var RAW_END = "{% endraw %}";

/**
    Escape a code block's content using raw blocks

    @param {String}
    @return {String}
*/
function escape(str) {
    return RAW_START + str + RAW_END;
}

/**
    Combines annotated nodes

    @param {Array}
    @return {String}
*/
function combine(nodes) {
    return _.map(nodes, "raw").join("");
}

/**
    Add templating "raw" to code blocks to
    avoid nunjucks processing their content.

    @param {String} src
    @return {String}
*/
function preparePage(src) {
    // annotate.blocks does not normalize the following characters
    var normalizedSource = src
        .replace(/\r\n|\r|\u2424/g, "\n")
        .replace(/\t/g, "    ")
        .replace(/\u00a0/g, " ");
    var lexed = annotate.blocks(normalizedSource);
    var levelRaw = 0;

    function escapeCodeElement(el) {
        if (el.type == "code" && levelRaw == 0) {
            el.raw = escape(el.raw);
        } else if (el.type == "tplexpr") {
            var expr = el.matches[0];
            if (expr === "raw") {
                levelRaw = levelRaw + 1;
            } else if (expr === "endraw") {
                levelRaw = 0;
            }
        }
        return el;
    }

    var escaped = _.map(lexed, function (el) {
        // Only escape paragraphs and headings
        if (el.type == "paragraph" || el.type == "heading") {
            var line = annotate.inline(el.raw);

            // Escape inline code blocks
            line = line.map(escapeCodeElement);

            // Change raw source code
            el.raw = combine(line);

            return el;
        } else {
            return escapeCodeElement(el);
        }
    });

    return combine(escaped);
}

module.exports = {
    prepare: preparePage,
};