/* Module definition */

/* Variable Definition */
const Discord = require('discord.js'),
    args = require('args-parser')(process.argv),
    config = require('../config.json'),
    gcmdTempl = require('../commands/globalcommands'),
    scmdTempl = require('../commands/servercommands');

let logger = require('winston'),
    globCommands = {};

/**
 * @type {Servant}
 */
exports.Servant = class {
    constructor(prefix) {
        this.commands = {};
        this.prefix = prefix;
        // show all commands (except the owner commands if the user is not an owner)
        this.createCommand(gcmdTempl.utils.help, (msg, kwargs) => {
            if (kwargs.command) {
                let cmd = kwargs.command;
                let allCommands = {...globCommands, ...this.commands};
                if (cmd.charAt(0) !== prefix)
                    cmd = this.prefix + cmd;
                if (allCommands[cmd])
                    return new Discord.RichEmbed()
                        .setTitle(`Help for ${cmd}`)
                        .addField('Usage', `\`${cmd} [${allCommands[cmd].args.join('] [')}]\``.replace('[]', ''))
                        .addField('Description', allCommands[cmd].description)
                        .addField('Permission Role', allCommands[cmd].role || 'all');
                 else
                    return 'Command not found :(';

            } else {
                let helpEmbed = new Discord.RichEmbed()
                    .setTitle('Commands')
                    .setDescription('Create a sequence of commands with `;` (semicolon).')
                    .setTimestamp();
                let globHelp = '';
                Object.entries(globCommands).sort().forEach(([key, value]) => {
                    if (value.role !== 'owner' || checkPermission(msg, 'owner'))
                        globHelp += `\`${key}\` \t`;

                });
                helpEmbed.addField('Global Commands', globHelp);
                let categories = [];
                let catCommands = {};
                Object.entries(this.commands).sort().forEach(([key, value]) => {
                    if (value.role !== 'owner' || checkPermission(msg, 'owner'))
                        if (!categories.includes(value.category)) {
                            categories.push(value.category);
                            catCommands[value.category] = `\`${key}\` \t`;
                        } else {
                            catCommands[value.category] += `\`${key}\` \t`;
                        }

                });
                for (let cat of categories)
                    helpEmbed.addField(cat, catCommands[cat]);

                helpEmbed.setFooter(prefix + 'help [command] for more info to each command');
                return helpEmbed;
            }
        });

        // show all roles that are used by commands
        this.createCommand(scmdTempl.utils.roles, () => {
            let roles = [];
            Object.values(globCommands).concat(Object.values(this.commands)).sort().forEach((value) => {
                roles.push(value.role || 'all');
            });
            return `**Roles**\n${[...new Set(roles)].join('\n')}`;
        });
    }

    /**
     * Creates a command entry in the private commands dict
     * @param template
     * @param call
     */
    createCommand(template, call) {
        if (!template.name) {
            logger.debug(`Name of command template is null or undef. Failed creating command.`);
            return;
        }
        this.commands[this.prefix + template.name] = {
            'args': template.args || [],
            'description': template.description,
            'callback': call,
            'role': template.permission,
            'category': template.category || 'Other'
        };
        logger.debug(`Created server command: ${this.prefix + template.name}, args: ${template.args}`);
    }

    /**
     * Removes a command
     * @param command
     * @deprecated Why would you want to remove a command?
     */
    removeCommand(command) {
        delete this.commands[command];
    }

    /**
     * Processes the command
     * @param msg
     * @param globResult
     * @param content
     * @param returnFunction Boolean if the return value should be a function.
     * @param fallback
     * @returns {*}
     */
    processCommand(msg, globResult, content, returnFunction, fallback) {
        let command = (content.match(/^.\w+/) || [])[0];
        if (!command || !this.commands[command])
            if (fallback && !globResult) {
                command = fallback;
                content = `${fallback} ${content}`;
            } else {
                return globResult;
            }
        let cmd = this.commands[command];
        if (!checkPermission(msg, cmd.role))
            return 'No Permission';
        logger.debug(`Permission <${cmd.role || 'all'}> granted for command ${command} for user <${msg.author.tag}>`);
        let argvars = content.match(/(?<= )\S+/g) || [];
        let kwargs = {};
        let nLength = Math.min(cmd.args.length, argvars.length);
        for (let i = 0; i < nLength; i++)
            kwargs[cmd.args[i]] = argvars[i];

        let argv = argvars.slice(nLength);
        logger.debug(`Executing callback for command: ${command}, kwargs: ${kwargs}, argv: ${argv}`);
        try {
            let locResult = returnFunction? () => cmd.callback(msg, kwargs, argv) : cmd.callback(msg, kwargs, argv);
            return locResult || globResult;
        } catch (err) {
            logger.error(err.message);
            return `The command \`${command}\`  has thrown an error.`;
        }
    }

    /**
     * Parses the message and executes the command callback for the found command entry in the commands dict
     * @param msg
     * @returns {*}
     */
    parseCommand(msg) {
        let globResult = parseGlobalCommand(msg);
        logger.debug(`Global command result is ${globResult}`);
        let content = msg.content;
        let commands = content.split(/(?<!\\);/).map(x => x.replace(/^ +/, ''));
        if (commands.length === 1) {
            return this.processCommand(msg, globResult, content);
        } else  if (commands.length < (config.maxCmdSequenceLength  || 5)) {
            let answers = [];
            let previousCommand = (commands[0].match(/^.\w+/) || [])[0];;
            for (let i = 0; i < commands.length; i++) {
                answers.push(this.processCommand(msg, globResult[i], commands[i],
                    true, previousCommand)); // return function to avoid "race conditions"
                let commandMatch = (commands[i].match(/^.\w+/) || [])[0];
                previousCommand = this.commands[commandMatch]? commandMatch : previousCommand;
            }

            return answers;
        } else {
            return 'This command sequence is too long!';
        }
    }

};

/**
 * Getting the logger
 * @param {Object} newLogger
 */
exports.setLogger = function (newLogger) {
    logger = newLogger;
};

/**
 * Creates a global command that can be executed in every channel.
 * @param prefix
 * @param template
 * @param call
 */
exports.createGlobalCommand = function (prefix, template, call) {
    if (!template.name) {
        logger.debug(`Name of command template is null or undef. Failed to create command.`);
        return;
    }
    globCommands[prefix + template.name] = {
        'args': template.args || [],
        'description': template.description,
        'callback': call,
        'role': template.permission,
        'name': template.name,
        'category': template.category || 'Other'
    };
    logger.debug(`Created global command: ${prefix + template.name}, args: ${template.args}`);
};


/**
 * Parses a message for a global command
 * @param msg
 * @returns {boolean|*}
 */
exports.parseMessage = function (msg) {
    return parseGlobalCommand(msg);
};

/**
 * Initializes the module by creating a help command
 */
exports.init = function (prefix) {
    logger.verbose("Created help command");
    this.createGlobalCommand((prefix || config.prefix), gcmdTempl.utils.help, (msg, kwargs) => {
        if (kwargs.command) {
            let cmd = kwargs.command;
            if (cmd.charAt(0) !== prefix)
                cmd = prefix + cmd;
            if (globCommands[cmd])
                return new Discord.RichEmbed()
                    .setTitle(`Help for ${cmd}`)
                    .addField('Usage', `\`${cmd} [${globCommands[cmd].args.join('] [')}]\``.replace('[]', ''))
                    .addField('Description', globCommands[cmd].description)
                    .addField('Permission Role', globCommands[cmd].role || 'all');

        } else {
            let helpEmbed = new Discord.RichEmbed()
                .setTitle('Global Commands')
                .setDescription('Create a sequence of commands with `;` (semicolon).')
                .setTimestamp();
            let description = '';
            Object.entries(globCommands).sort().forEach(([key, value]) => {
                if (value.role === 'owner' && checkPermission(msg, 'owner'))
                    description += `\`${key}\` \t`;
                 else if (value.role !== 'owner')
                    description += `\`${key}\` \t`;

            });
            helpEmbed.setFooter(prefix + 'help [command] for more info to each command');
            helpEmbed.setDescription(description);
            return helpEmbed;
        }
    });
};

function processCommand(cmd, msg, content, returnFunction) {
    let argvars = content.match(/(?<= )\S+/g) || [];
    let kwargs = {};
    let nLength = Math.min(cmd.args.length, argvars.length);
    for (let i = 0; i < nLength; i++)
        kwargs[cmd.args[i]] = argvars[i];
    let argv = argvars.slice(nLength);
    logger.debug(`Executing callback for command: ${cmd.name}, kwargs: ${JSON.stringify(kwargs)}, argv: ${argv}`);
    return returnFunction? () => cmd.callback(msg, kwargs, argv) : cmd.callback(msg, kwargs, argv);
}

/**
 * Parses the message by calling the assigned function for the command with arguments
 * @param msg
 */
function parseGlobalCommand(msg) {
    let content = msg.content;
    let commands = content.split(/(?<!\\);/).map(x => x.replace(/^ +/, ''));
    if (commands.length === 1) {
        let command = (content.match(/^.\w+/) || [])[0];
        if (!command || !globCommands[command])
            return false;
        let cmd = globCommands[command];
        if (!checkPermission(msg, cmd.role))
            return false;
        logger.debug(`Permission <${cmd.role}> granted for command ${command} for user <${msg.author.tag}>`);
        return processCommand(cmd, msg, content);
    } else if (commands.length < (config.maxCmdSequenceLength  || 5)) {
        let answers = [];
        let previousCommand = '';
        for (let commandPart of commands) {
            let command = (commandPart.match(/^.\w+/) || [])[0] || previousCommand;
            previousCommand = globCommands[command]? command : previousCommand;
            if (!commandPart || !globCommands[command]) {
                commandPart = `${previousCommand} ${commandPart}`;
                command = previousCommand;
            }
            if (command && globCommands[command]) {
                let cmd = globCommands[command];
                if (checkPermission(msg, cmd.role)) {
                    logger.debug(`Permission <${cmd.role}> granted for command ${command} for user <${msg.author.tag}>`);
                    answers.push(processCommand(cmd, msg, commandPart,
                        true));  // return an function to avoid "race conditions"
                } else {
                    answers.push(false);
                }
            } else {
                answers.push(false);
            }
        }
        return answers;
    } else {
        return 'This command sequence is too long!';
    }
}

/**
 * @param msg
 * @param rolePerm {String}
 * @returns {boolean}
 */
function checkPermission(msg, rolePerm) {
    if (!rolePerm || ['all', 'any', 'everyone'].includes(rolePerm))
        return true;
    if (msg.author.tag === args.owner || config.owners.includes(msg.author.tag))
        return true;
    else
        if (msg.member && rolePerm && rolePerm !== 'owner' && msg.member.roles
            .some(role => (role.name.toLowerCase() === rolePerm.toLowerCase() || role.name.toLowerCase() === 'botcommander')))
            return true;

    return false;
}