/* jslint node: true */
'use strict';

//  ENiGMA½
const userDb        = require('./database.js').dbs.user;
const Config        = require('./config.js').get;
const userGroup     = require('./user_group.js');
const {
    Errors,
    ErrorReasons
}                   = require('./enig_error.js');
const Events        = require('./events.js');
const UserProps     = require('./user_property.js');
const Log           = require('./logger.js').log;
const StatLog       = require('./stat_log.js');

//  deps
const crypto        = require('crypto');
const assert        = require('assert');
const async         = require('async');
const _             = require('lodash');
const moment        = require('moment');

exports.isRootUserId = function(id) { return 1 === id; };

module.exports = class User {
    constructor() {
        this.userId     = 0;
        this.username   = '';
        this.properties = {};   //  name:value
        this.groups     = [];   //  group membership(s)
    }

    //  static property accessors
    static get RootUserID() {
        return 1;
    }

    static get PBKDF2() {
        return {
            iterations  : 1000,
            keyLen      : 128,
            saltLen     : 32,
        };
    }

    static get StandardPropertyGroups() {
        return {
            password    : [ UserProps.PassPbkdf2Salt, UserProps.PassPbkdf2Dk ],
        };
    }

    static get AccountStatus() {
        return {
            disabled    : 0,    //  +op disabled
            inactive    : 1,    //  inactive, aka requires +op approval/activation
            active      : 2,    //  standard, active
            locked      : 3,    //  locked out (too many bad login attempts, etc.)
        };
    }

    static isSamePasswordSlowCompare(passBuf1, passBuf2) {
        if(passBuf1.length !== passBuf2.length) {
            return false;
        }

        let c = 0;
        for(let i = 0; i < passBuf1.length; i++) {
            c |= passBuf1[i] ^ passBuf2[i];
        }
        return 0 === c;
    }

    isAuthenticated() {
        return true === this.authenticated;
    }

    isValid() {
        if(this.userId <= 0 || this.username.length < Config().users.usernameMin) {
            return false;
        }

        return this.hasValidPasswordProperties();
    }

    hasValidPasswordProperties() {
        const salt  = this.getProperty(UserProps.PassPbkdf2Salt);
        const dk    = this.getProperty(UserProps.PassPbkdf2Dk);

        if(!salt || !dk ||
            (salt.length !== User.PBKDF2.saltLen * 2) ||
            (dk.length !== User.PBKDF2.keyLen * 2))
        {
            return false;
        }

        return true;
    }

    isRoot() {
        return User.isRootUserId(this.userId);
    }

    isSysOp() { //  alias to isRoot()
        return this.isRoot();
    }

    isGroupMember(groupNames) {
        if(_.isString(groupNames)) {
            groupNames = [ groupNames ];
        }

        const isMember = groupNames.some(gn => (-1 !== this.groups.indexOf(gn)));
        return isMember;
    }

    getLegacySecurityLevel() {
        if(this.isRoot() || this.isGroupMember('sysops')) {
            return 100;
        }

        if(this.isGroupMember('users')) {
            return 30;
        }

        return 10;  //  :TODO: Is this what we want?
    }

    processFailedLogin(userId, cb) {
        async.waterfall(
            [
                (callback) => {
                    return User.getUser(userId, callback);
                },
                (tempUser, callback) => {
                    return StatLog.incrementUserStat(
                        tempUser,
                        UserProps.FailedLoginAttempts,
                        1,
                        (err, failedAttempts) => {
                            return callback(null, tempUser, failedAttempts);
                        }
                    );
                },
                (tempUser, failedAttempts, callback) => {
                    const lockAccount = _.get(Config(), 'users.failedLogin.lockAccount');
                    if(lockAccount > 0 && failedAttempts >= lockAccount) {
                        const props = {
                            [ UserProps.AccountStatus ]     : User.AccountStatus.locked,
                            [ UserProps.AccountLockedTs ]   : StatLog.now,
                        };
                        if(!_.has(tempUser.properties, UserProps.AccountLockedPrevStatus)) {
                            props[UserProps.AccountLockedPrevStatus] = tempUser.getProperty(UserProps.AccountStatus);
                        }
                        Log.info( { userId, failedAttempts }, '(Re)setting account to locked due to failed logins');
                        return tempUser.persistProperties(props, callback);
                    }

                    return cb(null);
                }
            ],
            err => {
                return cb(err);
            }
        );
    }

    unlockAccount(cb) {
        const prevStatus = this.getProperty(UserProps.AccountLockedPrevStatus);
        if(!prevStatus) {
            return cb(null);    //  nothing to do
        }

        this.persistProperty(UserProps.AccountStatus, prevStatus, err => {
            if(err) {
                return cb(err);
            }

            return this.removeProperties( [ UserProps.AccountLockedPrevStatus, UserProps.AccountLockedTs ], cb);
        });
    }

    authenticate(username, password, cb) {
        const self = this;
        const tempAuthInfo = {};

        async.waterfall(
            [
                function fetchUserId(callback) {
                    //  get user ID
                    User.getUserIdAndName(username, (err, uid, un) => {
                        tempAuthInfo.userId   = uid;
                        tempAuthInfo.username = un;

                        return callback(err);
                    });
                },
                function getRequiredAuthProperties(callback) {
                    //  fetch properties required for authentication
                    User.loadProperties(tempAuthInfo.userId, { names : User.StandardPropertyGroups.password }, (err, props) => {
                        return callback(err, props);
                    });
                },
                function getDkWithSalt(props, callback) {
                    //  get DK from stored salt and password provided
                    User.generatePasswordDerivedKey(password, props[UserProps.PassPbkdf2Salt], (err, dk) => {
                        return callback(err, dk, props[UserProps.PassPbkdf2Dk]);
                    });
                },
                function validateAuth(passDk, propsDk, callback) {
                    //
                    //  Use constant time comparison here for security feel-goods
                    //
                    const passDkBuf     = Buffer.from(passDk,   'hex');
                    const propsDkBuf    = Buffer.from(propsDk,  'hex');

                    return callback(User.isSamePasswordSlowCompare(passDkBuf, propsDkBuf) ?
                        null :
                        Errors.AccessDenied('Invalid password')
                    );
                },
                function initProps(callback) {
                    User.loadProperties(tempAuthInfo.userId, (err, allProps) => {
                        if(!err) {
                            tempAuthInfo.properties = allProps;
                        }

                        return callback(err);
                    });
                },
                function checkAccountStatus(callback) {
                    const accountStatus = parseInt(tempAuthInfo.properties[UserProps.AccountStatus], 10);
                    if(User.AccountStatus.disabled === accountStatus) {
                        return callback(Errors.AccessDenied('Account disabled', ErrorReasons.Disabled));
                    }
                    if(User.AccountStatus.inactive === accountStatus) {
                        return callback(Errors.AccessDenied('Account inactive', ErrorReasons.Inactive));
                    }

                    if(User.AccountStatus.locked === accountStatus) {
                        const autoUnlockMinutes = _.get(Config(), 'users.failedLogin.autoUnlockMinutes');
                        const lockedTs          = moment(tempAuthInfo.properties[UserProps.AccountLockedTs]);
                        if(autoUnlockMinutes && lockedTs.isValid()) {
                            const minutesSinceLocked = moment().diff(lockedTs, 'minutes');
                            if(minutesSinceLocked >= autoUnlockMinutes) {
                                //  allow the login - we will clear any lock there
                                Log.info(
                                    { username, userId : tempAuthInfo.userId, lockedAt : lockedTs.format() },
                                    'Locked account will now be unlocked due to auto-unlock minutes policy'
                                );
                                return callback(null);
                            }
                        }
                        return callback(Errors.AccessDenied('Account is locked', ErrorReasons.Locked));
                    }

                    //  anything else besides active is still not allowed
                    if(User.AccountStatus.active !== accountStatus) {
                        return callback(Errors.AccessDenied('Account is not active'));
                    }

                    return callback(null);
                },
                function initGroups(callback) {
                    userGroup.getGroupsForUser(tempAuthInfo.userId, (err, groups) => {
                        if(!err) {
                            tempAuthInfo.groups = groups;
                        }

                        return callback(err);
                    });
                }
            ],
            err => {
                if(err) {
                    //
                    //  If we failed login due to something besides an inactive or disabled account,
                    //  we need to update failure status and possibly lock the account.
                    //
                    //  If locked already, update the lock timestamp -- ie, extend the lockout period.
                    //
                    if(![ErrorReasons.Disabled, ErrorReasons.Inactive].includes(err.reasonCode) && tempAuthInfo.userId) {
                        self.processFailedLogin(tempAuthInfo.userId, persistErr => {
                            if(persistErr) {
                                Log.warn( { error : persistErr.message }, 'Failed to persist failed login information');
                            }
                            return cb(err); //  pass along original error
                        });
                    } else {
                        return cb(err);
                    }
                } else {
                    //  everything checks out - load up info
                    self.userId         = tempAuthInfo.userId;
                    self.username       = tempAuthInfo.username;
                    self.properties     = tempAuthInfo.properties;
                    self.groups         = tempAuthInfo.groups;
                    self.authenticated  = true;

                    self.removeProperty(UserProps.FailedLoginAttempts);

                    //
                    //  We need to *revert* any locked status back to
                    //  the user's previous status & clean up props.
                    //
                    self.unlockAccount(unlockErr => {
                        if(unlockErr) {
                            Log.warn( { error : unlockErr.message }, 'Failed to unlock account');
                        }
                        return cb(null);
                    });
                }
            }
        );
    }

    create(createUserInfo , cb) {
        assert(0 === this.userId);
        const config = Config();

        if(this.username.length < config.users.usernameMin || this.username.length > config.users.usernameMax) {
            return cb(Errors.Invalid('Invalid username length'));
        }

        const self = this;

        //  :TODO: set various defaults, e.g. default activation status, etc.
        self.properties[UserProps.AccountStatus] = config.users.requireActivation ? User.AccountStatus.inactive : User.AccountStatus.active;

        async.waterfall(
            [
                function beginTransaction(callback) {
                    return userDb.beginTransaction(callback);
                },
                function createUserRec(trans, callback) {
                    trans.run(
                        `INSERT INTO user (user_name)
                        VALUES (?);`,
                        [ self.username ],
                        function inserted(err) {    //  use classic function for |this|
                            if(err) {
                                return callback(err);
                            }

                            self.userId = this.lastID;

                            //  Do not require activation for userId 1 (root/admin)
                            if(User.RootUserID === self.userId) {
                                self.properties[UserProps.AccountStatus] = User.AccountStatus.active;
                            }

                            return callback(null, trans);
                        }
                    );
                },
                function genAuthCredentials(trans, callback) {
                    User.generatePasswordDerivedKeyAndSalt(createUserInfo.password, (err, info) => {
                        if(err) {
                            return callback(err);
                        }

                        self.properties[UserProps.PassPbkdf2Salt]   = info.salt;
                        self.properties[UserProps.PassPbkdf2Dk]     = info.dk;
                        return callback(null, trans);
                    });
                },
                function setInitialGroupMembership(trans, callback) {
                    self.groups = config.users.defaultGroups;

                    if(User.RootUserID === self.userId) {   //  root/SysOp?
                        self.groups.push('sysops');
                    }

                    return callback(null, trans);
                },
                function saveAll(trans, callback) {
                    self.persistWithTransaction(trans, err => {
                        return callback(err, trans);
                    });
                },
                function sendEvent(trans, callback) {
                    Events.emit(
                        Events.getSystemEvents().NewUser,
                        {
                            user : Object.assign({}, self, { sessionId : createUserInfo.sessionId } )
                        }
                    );
                    return callback(null, trans);
                }
            ],
            (err, trans) => {
                if(trans) {
                    trans[err ? 'rollback' : 'commit'](transErr => {
                        return cb(err ? err : transErr);
                    });
                } else {
                    return cb(err);
                }
            }
        );
    }

    persistWithTransaction(trans, cb) {
        assert(this.userId > 0);

        const self = this;

        async.series(
            [
                function saveProps(callback) {
                    self.persistProperties(self.properties, trans, err => {
                        return callback(err);
                    });
                },
                function saveGroups(callback) {
                    userGroup.addUserToGroups(self.userId, self.groups, trans, err => {
                        return callback(err);
                    });
                }
            ],
            err => {
                return cb(err);
            }
        );
    }

    static persistPropertyByUserId(userId, propName, propValue, cb) {
        userDb.run(
            `REPLACE INTO user_property (user_id, prop_name, prop_value)
            VALUES (?, ?, ?);`,
            [ userId, propName, propValue ],
            err => {
                if(cb) {
                    return cb(err, propValue);
                }
            }
        );
    }

    getProperty(propName) {
        return this.properties[propName];
    }

    getPropertyAsNumber(propName) {
        return parseInt(this.getProperty(propName), 10);
    }

    persistProperty(propName, propValue, cb) {
        //  update live props
        this.properties[propName] = propValue;

        return User.persistPropertyByUserId(this.userId, propName, propValue, cb);
    }

    removeProperty(propName, cb) {
        //  update live
        delete this.properties[propName];

        userDb.run(
            `DELETE FROM user_property
            WHERE user_id = ? AND prop_name = ?;`,
            [ this.userId, propName ],
            err => {
                if(cb) {
                    return cb(err);
                }
            }
        );
    }

    removeProperties(propNames, cb) {
        async.each(propNames, (name, next) => {
            return this.removeProperty(name, next);
        },
        err => {
            if(cb) {
                return cb(err);
            }
        });
    }

    persistProperties(properties, transOrDb, cb) {
        if(!_.isFunction(cb) && _.isFunction(transOrDb)) {
            cb = transOrDb;
            transOrDb = userDb;
        }

        const self = this;

        //  update live props
        _.merge(this.properties, properties);

        const stmt = transOrDb.prepare(
            `REPLACE INTO user_property (user_id, prop_name, prop_value)
            VALUES (?, ?, ?);`
        );

        async.each(Object.keys(properties), (propName, nextProp) => {
            stmt.run(self.userId, propName, properties[propName], err => {
                return nextProp(err);
            });
        },
        err => {
            if(err) {
                return cb(err);
            }

            stmt.finalize( () => {
                return cb(null);
            });
        });
    }

    setNewAuthCredentials(password, cb) {
        User.generatePasswordDerivedKeyAndSalt(password, (err, info) => {
            if(err) {
                return cb(err);
            }

            const newProperties = {
                [ UserProps.PassPbkdf2Salt ]    : info.salt,
                [ UserProps.PassPbkdf2Dk ]      : info.dk,
            };

            this.persistProperties(newProperties, err => {
                return cb(err);
            });
        });
    }

    getAge() {
        const birthdate = this.getProperty(UserProps.Birthdate);
        if(birthdate) {
            return moment().diff(birthdate, 'years');
        }
    }

    static getUser(userId, cb) {
        async.waterfall(
            [
                function fetchUserId(callback) {
                    User.getUserName(userId, (err, userName) => {
                        return callback(null, userName);
                    });
                },
                function initProps(userName, callback) {
                    User.loadProperties(userId, (err, properties) => {
                        return callback(err, userName, properties);
                    });
                },
                function initGroups(userName, properties, callback) {
                    userGroup.getGroupsForUser(userId, (err, groups) => {
                        return callback(null, userName, properties, groups);
                    });
                }
            ],
            (err, userName, properties, groups) => {
                const user = new User();
                user.userId         = userId;
                user.username       = userName;
                user.properties     = properties;
                user.groups         = groups;
                user.authenticated  = false;    //  this is NOT an authenticated user!

                return cb(err, user);
            }
        );
    }

    static isRootUserId(userId) {
        return (User.RootUserID === userId);
    }

    static getUserIdAndName(username, cb) {
        userDb.get(
            `SELECT id, user_name
            FROM user
            WHERE user_name LIKE ?;`,
            [ username ],
            (err, row) => {
                if(err) {
                    return cb(err);
                }

                if(row) {
                    return cb(null, row.id, row.user_name);
                }

                return cb(Errors.DoesNotExist('No matching username'));
            }
        );
    }

    static getUserIdAndNameByRealName(realName, cb) {
        userDb.get(
            `SELECT id, user_name
            FROM user
            WHERE id = (
                SELECT user_id
                FROM user_property
                WHERE prop_name='${UserProps.RealName}' AND prop_value LIKE ?
            );`,
            [ realName ],
            (err, row) => {
                if(err) {
                    return cb(err);
                }

                if(row) {
                    return cb(null, row.id, row.user_name);
                }

                return cb(Errors.DoesNotExist('No matching real name'));
            }
        );
    }

    static getUserIdAndNameByLookup(lookup, cb) {
        User.getUserIdAndName(lookup, (err, userId, userName) => {
            if(err) {
                User.getUserIdAndNameByRealName(lookup, (err, userId, userName) => {
                    return cb(err, userId, userName);
                });
            } else {
                return cb(null, userId, userName);
            }
        });
    }

    static getUserName(userId, cb) {
        userDb.get(
            `SELECT user_name
            FROM user
            WHERE id = ?;`,
            [ userId ],
            (err, row) => {
                if(err) {
                    return cb(err);
                }

                if(row) {
                    return cb(null, row.user_name);
                }

                return cb(Errors.DoesNotExist('No matching user ID'));
            }
        );
    }

    static loadProperties(userId, options, cb) {
        if(!cb && _.isFunction(options)) {
            cb = options;
            options = {};
        }

        let sql =
            `SELECT prop_name, prop_value
            FROM user_property
            WHERE user_id = ?`;

        if(options.names) {
            sql += ` AND prop_name IN("${options.names.join('","')}");`;
        } else {
            sql += ';';
        }

        let properties = {};
        userDb.each(sql, [ userId ], (err, row) => {
            if(err) {
                return cb(err);
            }
            properties[row.prop_name] = row.prop_value;
        }, (err) => {
            return cb(err, err ? null : properties);
        });
    }

    //  :TODO: make this much more flexible - propValue should allow for case-insensitive compare, etc.
    static getUserIdsWithProperty(propName, propValue, cb) {
        let userIds = [];

        userDb.each(
            `SELECT user_id
            FROM user_property
            WHERE prop_name = ? AND prop_value = ?;`,
            [ propName, propValue ],
            (err, row) => {
                if(row) {
                    userIds.push(row.user_id);
                }
            },
            () => {
                return cb(null, userIds);
            }
        );
    }

    static getUserList(options, cb) {
        const userList = [];
        const orderClause = 'ORDER BY ' + (options.order || 'user_name');

        userDb.each(
            `SELECT id, user_name
            FROM user
            ${orderClause};`,
            (err, row) => {
                if(row) {
                    userList.push({
                        userId      : row.id,
                        userName    : row.user_name,
                    });
                }
            },
            () => {
                options.properties = options.properties || [];
                async.map(userList, (user, nextUser) => {
                    userDb.each(
                        `SELECT prop_name, prop_value
                        FROM user_property
                        WHERE user_id = ? AND prop_name IN ("${options.properties.join('","')}");`,
                        [ user.userId ],
                        (err, row) => {
                            if(row) {
                                if(options.propsCamelCase) {
                                    user[_.camelCase(row.prop_name)] = row.prop_value;
                                } else {
                                    user[row.prop_name] = row.prop_value;
                                }
                            }
                        },
                        err => {
                            return nextUser(err, user);
                        }
                    );
                },
                (err, transformed) => {
                    return cb(err, transformed);
                });
            }
        );
    }

    static generatePasswordDerivedKeyAndSalt(password, cb) {
        async.waterfall(
            [
                function getSalt(callback) {
                    User.generatePasswordDerivedKeySalt( (err, salt) => {
                        return callback(err, salt);
                    });
                },
                function getDk(salt, callback) {
                    User.generatePasswordDerivedKey(password, salt, (err, dk) => {
                        return callback(err, salt, dk);
                    });
                }
            ],
            (err, salt, dk) => {
                return cb(err, { salt : salt, dk : dk } );
            }
        );
    }

    static generatePasswordDerivedKeySalt(cb) {
        crypto.randomBytes(User.PBKDF2.saltLen, (err, salt) => {
            if(err) {
                return cb(err);
            }
            return cb(null, salt.toString('hex'));
        });
    }

    static generatePasswordDerivedKey(password, salt, cb) {
        password = Buffer.from(password).toString('hex');

        crypto.pbkdf2(password, salt, User.PBKDF2.iterations, User.PBKDF2.keyLen, 'sha1', (err, dk) => {
            if(err) {
                return cb(err);
            }

            return cb(null, dk.toString('hex'));
        });
    }
};