import Utils from "../Utils.js";
import jsesc from "jsesc";


/**
 * String utility operations.
 *
 * @author n1474335 [n1474335@gmail.com]
 * @copyright Crown Copyright 2016
 * @license Apache-2.0
 *
 * @namespace
 */
const StrUtils = {

    /**
     * @constant
     * @default
     */
    CASE_SCOPE: ["All", "Word", "Sentence", "Paragraph"],

    /**
     * To Upper case operation.
     *
     * @param {string} input
     * @param {Object[]} args
     * @returns {string}
     */
    runUpper: function (input, args) {
        const scope = args[0];

        switch (scope) {
            case "Word":
                return input.replace(/(\b\w)/gi, function(m) {
                    return m.toUpperCase();
                });
            case "Sentence":
                return input.replace(/(?:\.|^)\s*(\b\w)/gi, function(m) {
                    return m.toUpperCase();
                });
            case "Paragraph":
                return input.replace(/(?:\n|^)\s*(\b\w)/gi, function(m) {
                    return m.toUpperCase();
                });
            case "All":
                /* falls through */
            default:
                return input.toUpperCase();
        }
    },


    /**
     * To Upper case operation.
     *
     * @param {string} input
     * @param {Object[]} args
     * @returns {string}
     */
    runLower: function (input, args) {
        return input.toLowerCase();
    },


    /**
     * @constant
     * @default
     */
    SPLIT_DELIM_OPTIONS: [
        {name: "Comma", value: ","},
        {name: "Space", value: " "},
        {name: "Line feed", value: "\\n"},
        {name: "CRLF", value: "\\r\\n"},
        {name: "Semi-colon", value: ";"},
        {name: "Colon", value: ":"},
        {name: "Nothing (separate chars)", value: ""}
    ],
    /**
     * @constant
     * @default
     */
    JOIN_DELIM_OPTIONS: [
        {name: "Line feed", value: "\\n"},
        {name: "CRLF", value: "\\r\\n"},
        {name: "Space", value: " "},
        {name: "Comma", value: ","},
        {name: "Semi-colon", value: ";"},
        {name: "Colon", value: ":"},
        {name: "Nothing (join chars)", value: ""}
    ],

    /**
     * Split operation.
     *
     * @param {string} input
     * @param {Object[]} args
     * @returns {string}
     */
    runSplit: function(input, args) {
        let splitDelim = args[0],
            joinDelim = args[1],
            sections = input.split(splitDelim);

        return sections.join(joinDelim);
    },


    /**
     * @constant
     * @default
     */
    DELIMITER_OPTIONS: ["Line feed", "CRLF", "Space", "Comma", "Semi-colon", "Colon", "Nothing (separate chars)"],

    /**
     * Filter operation.
     *
     * @author Mikescher (https://github.com/Mikescher | https://mikescher.com)
     * @param {string} input
     * @param {Object[]} args
     * @returns {string}
     */
    runFilter: function(input, args) {
        let delim = Utils.charRep[args[0]],
            regex,
            reverse = args[2];

        try {
            regex = new RegExp(args[1]);
        } catch (err) {
            return "Invalid regex. Details: " + err.message;
        }

        const regexFilter = function(value) {
            return reverse ^ regex.test(value);
        };

        return input.split(delim).filter(regexFilter).join(delim);
    },


    /**
     * @constant
     * @default
     */
    OFF_CHK_SAMPLE_DELIMITER: "\\n\\n",

    /**
     * Offset checker operation.
     *
     * @param {string} input
     * @param {Object[]} args
     * @returns {html}
     */
    runOffsetChecker: function(input, args) {
        let sampleDelim = args[0],
            samples = input.split(sampleDelim),
            outputs = new Array(samples.length),
            i = 0,
            s = 0,
            match = false,
            inMatch = false,
            chr;

        if (!samples || samples.length < 2) {
            return "Not enough samples, perhaps you need to modify the sample delimiter or add more data?";
        }

        // Initialise output strings
        outputs.fill("", 0, samples.length);

        // Loop through each character in the first sample
        for (i = 0; i < samples[0].length; i++) {
            chr = samples[0][i];
            match = false;

            // Loop through each sample to see if the chars are the same
            for (s = 1; s < samples.length; s++) {
                if (samples[s][i] !== chr) {
                    match = false;
                    break;
                }
                match = true;
            }

            // Write output for each sample
            for (s = 0; s < samples.length; s++) {
                if (samples[s].length <= i) {
                    if (inMatch) outputs[s] += "</span>";
                    if (s === samples.length - 1) inMatch = false;
                    continue;
                }

                if (match && !inMatch) {
                    outputs[s] += "<span class='hl5'>" + Utils.escapeHtml(samples[s][i]);
                    if (samples[s].length === i + 1) outputs[s] += "</span>";
                    if (s === samples.length - 1) inMatch = true;
                } else if (!match && inMatch) {
                    outputs[s] += "</span>" + Utils.escapeHtml(samples[s][i]);
                    if (s === samples.length - 1) inMatch = false;
                } else {
                    outputs[s] += Utils.escapeHtml(samples[s][i]);
                    if (inMatch && samples[s].length === i + 1) {
                        outputs[s] += "</span>";
                        if (samples[s].length - 1 !== i) inMatch = false;
                    }
                }

                if (samples[0].length - 1 === i) {
                    if (inMatch) outputs[s] += "</span>";
                    outputs[s] += Utils.escapeHtml(samples[s].substring(i + 1));
                }
            }
        }

        return outputs.join(sampleDelim);
    },


    /**
     * @constant
     * @default
     */
    QUOTE_TYPES: ["Single", "Double", "Backtick"],
    /**
     * @constant
     * @default
     */
    ESCAPE_LEVEL: ["Special chars", "Everything", "Minimal"],

    /**
     * Escape string operation.
     *
     * @author Vel0x [dalemy@microsoft.com]
     * @author n1474335 [n1474335@gmail.com]
     *
     * @param {string} input
     * @param {Object[]} args
     * @returns {string}
     *
     * @example
     * StrUtils.runEscape("Don't do that", [])
     * > "Don\'t do that"
     * StrUtils.runEscape(`Hello
     * World`, [])
     * > "Hello\nWorld"
     */
    runEscape: function(input, args) {
        const level = args[0],
            quotes = args[1],
            jsonCompat = args[2],
            es6Compat = args[3],
            lowercaseHex = !args[4];

        return jsesc(input, {
            quotes: quotes.toLowerCase(),
            es6: es6Compat,
            escapeEverything: level === "Everything",
            minimal: level === "Minimal",
            json: jsonCompat,
            lowercaseHex: lowercaseHex,
        });
    },


    /**
     * Unescape string operation.
     *
     * @author Vel0x [dalemy@microsoft.com]
     * @author n1474335 [n1474335@gmail.com]
     *
     * @param {string} input
     * @param {Object[]} args
     * @returns {string}
     *
     * @example
     * StrUtils.runUnescape("Don\'t do that", [])
     * > "Don't do that"
     * StrUtils.runUnescape("Hello\nWorld", [])
     * > `Hello
     * World`
     */
    runUnescape: function(input, args) {
        return Utils.parseEscapedChars(input);
    },


    /**
     * Head lines operation.
     *
     * @param {string} input
     * @param {Object[]} args
     * @returns {string}
     */
    runHead: function(input, args) {
        let delimiter = args[0],
            number = args[1];

        delimiter = Utils.charRep[delimiter];
        const splitInput = input.split(delimiter);

        return splitInput
            .filter((line, lineIndex) => {
                lineIndex += 1;

                if (number < 0) {
                    return lineIndex <= splitInput.length + number;
                } else {
                    return lineIndex <= number;
                }
            })
            .join(delimiter);
    },


    /**
     * Tail lines operation.
     *
     * @param {string} input
     * @param {Object[]} args
     * @returns {string}
     */
    runTail: function(input, args) {
        let delimiter = args[0],
            number = args[1];

        delimiter = Utils.charRep[delimiter];
        const splitInput = input.split(delimiter);

        return splitInput
            .filter((line, lineIndex) => {
                lineIndex += 1;

                if (number < 0) {
                    return lineIndex > -number;
                } else {
                    return lineIndex > splitInput.length - number;
                }
            })
            .join(delimiter);
    },


    /**
     * @constant
     * @default
     */
    HAMMING_DELIM: "\\n\\n",
    /**
     * @constant
     * @default
     */
    HAMMING_INPUT_TYPE: ["Raw string", "Hex"],
    /**
     * @constant
     * @default
     */
    HAMMING_UNIT: ["Byte", "Bit"],

    /**
     * Hamming Distance operation.
     *
     * @author GCHQ Contributor [2]
     *
     * @param {string} input
     * @param {Object[]} args
     * @returns {string}
     */
    runHamming: function(input, args) {
        const delim = args[0],
            byByte = args[1] === "Byte",
            inputType = args[2],
            samples = input.split(delim);

        if (samples.length !== 2) {
            return "Error: You can only calculae the edit distance between 2 strings. Please ensure exactly two inputs are provided, separated by the specified delimiter.";
        }

        if (samples[0].length !== samples[1].length) {
            return "Error: Both inputs must be of the same length.";
        }

        if (inputType === "Hex") {
            samples[0] = Utils.fromHex(samples[0]);
            samples[1] = Utils.fromHex(samples[1]);
        } else {
            samples[0] = Utils.strToByteArray(samples[0]);
            samples[1] = Utils.strToByteArray(samples[1]);
        }

        let dist = 0;

        for (let i = 0; i < samples[0].length; i++) {
            const lhs = samples[0][i],
                rhs = samples[1][i];

            if (byByte && lhs !== rhs) {
                dist++;
            } else if (!byByte) {
                let xord = lhs ^ rhs;

                while (xord) {
                    dist++;
                    xord &= xord - 1;
                }
            }
        }

        return dist.toString();
    },
};

export default StrUtils;