'use strict';

const _ = require('lodash')
const async = require('async')
const crypto = require('crypto')
const fs = require('graceful-fs')
const glob = require('glob')

const config = require('../config').config
const ErrorTypes = require('../utils/errorTypes')
const Logger = require('../logger')
const MailService = require('../services/mailService')
const Strings = require('../utils/strings')
const UrlBuilder = require('../utils/urlBuilder')

const MAX_PARALLEL_NODES_PARSING = 10;

const linePrefixes = {
    hostname: '# Knotenname: ',
    nickname: '# Ansprechpartner: ',
    email: '# Kontakt: ',
    coords: '# Koordinaten: ',
    mac: '# MAC: ',
    token: '# Token: ',
    monitoring: '# Monitoring: ',
    monitoringToken: '# Monitoring-Token: '
};

const filenameParts = ['hostname', 'mac', 'key', 'token', 'monitoringToken'];

function generateToken() {
    return crypto.randomBytes(8).toString('hex');
}

function toNodeFilesPattern(filter) {
    const pattern = _.join(
        _.map(filenameParts, function (field) {
            return filter.hasOwnProperty(field) ? filter[field] : '*';
        }),
        '@'
    );

    return config.server.peersPath + '/' + pattern.toLowerCase();
}

function findNodeFiles(filter, callback) {
    glob(toNodeFilesPattern(filter), callback);
}

function findNodeFilesSync(filter) {
    return glob.sync(toNodeFilesPattern(filter));
}

function findFilesInPeersPath(callback) {
    glob(config.server.peersPath + '/*', function (err, files) {
        if (err) {
            return callback(err);
        }

        async.filter(files, function (file, fileCallback) {
            if (file[0] === '.') {
                return fileCallback(null, false);
            }

            fs.lstat(file, function (err, stats) {
                if (err) {
                    return fileCallback(err);
                }

                fileCallback(null, stats.isFile());
            });
        }, callback);
    });
}

function parseNodeFilename(filename) {
    const parts = _.split(filename, '@', filenameParts.length);
    const parsed = {};
    _.each(_.zip(filenameParts, parts), function (part) {
        parsed[part[0]] = part[1];
    });
    return parsed;
}

function isDuplicate(filter, token) {
    const files = findNodeFilesSync(filter);
    if (files.length === 0) {
        return false;
    }

    if (files.length > 1 || !token /* node is being created*/) {
        return true;
    }

    return parseNodeFilename(files[0]).token !== token;
}

function checkNoDuplicates(token, node, nodeSecrets) {
    if (isDuplicate({ hostname: node.hostname }, token)) {
        return {data: {msg: 'Already exists.', field: 'hostname'}, type: ErrorTypes.conflict};
    }

    if (node.key) {
        if (isDuplicate({ key: node.key }, token)) {
            return {data: {msg: 'Already exists.', field: 'key'}, type: ErrorTypes.conflict};
        }
    }

    if (isDuplicate({ mac: node.mac }, token)) {
        return {data: {msg: 'Already exists.', field: 'mac'}, type: ErrorTypes.conflict};
    }

    if (nodeSecrets.monitoringToken && isDuplicate({ monitoringToken: nodeSecrets.monitoringToken }, token)) {
        return {data: {msg: 'Already exists.', field: 'monitoringToken'}, type: ErrorTypes.conflict};
    }

    return null;
}

function toNodeFilename(token, node, nodeSecrets) {
    return config.server.peersPath + '/' +
        (
            (node.hostname || '') + '@' +
            (node.mac || '') + '@' +
            (node.key || '') + '@' +
            (token || '') + '@' +
            (nodeSecrets.monitoringToken || '')
        ).toLowerCase();
}

function writeNodeFile(isUpdate, token, node, nodeSecrets, callback) {
    const filename = toNodeFilename(token, node, nodeSecrets);
    let data = '';
    _.each(linePrefixes, function (prefix, key) {
        let value;
        switch (key) {
            case 'monitoring':
                if (node.monitoring && node.monitoringConfirmed) {
                    value = 'aktiv';
                } else if (node.monitoring && !node.monitoringConfirmed) {
                    value = 'pending';
                } else {
                    value = '';
                }
            break;

            case 'monitoringToken':
                value = nodeSecrets.monitoringToken || '';
            break;

            default:
                value = key === 'token' ? token : node[key];
                if (_.isUndefined(value)) {
                    value = _.isUndefined(nodeSecrets[key]) ? '' : nodeSecrets[key];
                }
            break;
        }
        data += prefix + value + '\n';
    });
    if (node.key) {
        data += 'key "' + node.key + '";\n';
    }

    // since node.js is single threaded we don't need a lock

    let error;

    if (isUpdate) {
        const files = findNodeFilesSync({ token: token });
        if (files.length !== 1) {
            return callback({data: 'Node not found.', type: ErrorTypes.notFound});
        }

        error = checkNoDuplicates(token, node, nodeSecrets);
        if (error) {
            return callback(error);
        }

        const file = files[0];
        try {
            fs.unlinkSync(file);
        }
        catch (error) {
            Logger.tag('node', 'save').error('Could not delete old node file: ' + file, error);
            return callback({data: 'Could not remove old node data.', type: ErrorTypes.internalError});
        }
    } else {
        error = checkNoDuplicates(null, node, nodeSecrets);
        if (error) {
            return callback(error);
        }
    }

    try {
        fs.writeFileSync(filename, data, 'utf8');
    }
    catch (error) {
        Logger.tag('node', 'save').error('Could not write node file: ' + filename, error);
        return callback({data: 'Could not write node data.', type: ErrorTypes.internalError});
    }

    return callback(null, token, node);
}

function deleteNodeFile(token, callback) {
    findNodeFiles({ token: token }, function (err, files) {
        if (err) {
            Logger.tag('node', 'delete').error('Could not find node file: ' + files, err);
            return callback({data: 'Could not delete node.', type: ErrorTypes.internalError});
        }

        if (files.length !== 1) {
            return callback({data: 'Node not found.', type: ErrorTypes.notFound});
        }

        try {
            fs.unlinkSync(files[0]);
        }
        catch (error) {
            Logger.tag('node', 'delete').error('Could not delete node file: ' + files, error);
            return callback({data: 'Could not delete node.', type: ErrorTypes.internalError});
        }

        return callback(null);
    });
}

function parseNodeFile(file, callback) {
    fs.readFile(file, function (err, contents) {
        if (err) {
            return callback(err);
        }

        const lines = contents.toString();

        const node = {};
        const nodeSecrets = {};

        _.each(lines.split('\n'), function (line) {
            const entries = {};

            for (const key in linePrefixes) {
                if (linePrefixes.hasOwnProperty(key)) {
                    const prefix = linePrefixes[key];
                    if (line.substring(0, prefix.length) === prefix) {
                        entries[key] = Strings.normalizeString(line.substr(prefix.length));
                        break;
                    }
                }
            }

            if (_.isEmpty(entries) && line.substring(0, 5) === 'key "') {
                entries.key = Strings.normalizeString(line.split('"')[1]);
            }

            _.each(entries, function (value, key) {
                if (key === 'mac') {
                    node.mac = value;
                    node.mapId = _.toLower(value).replace(/:/g, '');
                } else if (key === 'monitoring') {
                    const active = value === 'aktiv';
                    const pending = value === 'pending';
                    node.monitoring = active || pending;
                    node.monitoringConfirmed = active;
                    node.monitoringState = active ? 'active' : (pending ? 'pending' : 'disabled');
                } else if (key === 'monitoringToken') {
                    nodeSecrets.monitoringToken = value;
                } else {
                    node[key] = value;
                }
            });
        });

        callback(null, node, nodeSecrets);
    });
}

function findNodeDataByFilePattern(filter, callback) {
    findNodeFiles(filter, function (err, files) {
        if (err) {
            return callback(err);
        }

        if (files.length !== 1) {
            return callback(null);
        }

        const file = files[0];
        return parseNodeFile(file, callback);
    });
}

function getNodeDataByFilePattern(filter, callback) {
    findNodeDataByFilePattern(filter, function (err, node, nodeSecrets) {
        if (err) {
            return callback(err);
        }

        if (!node) {
            return callback({data: 'Node not found.', type: ErrorTypes.notFound});
        }

        callback(null, node, nodeSecrets);
    });
}

function sendMonitoringConfirmationMail(node, nodeSecrets, callback) {
    const confirmUrl = UrlBuilder.monitoringConfirmUrl(nodeSecrets);
    const disableUrl = UrlBuilder.monitoringDisableUrl(nodeSecrets);

    MailService.enqueue(
        config.server.email.from,
        node.nickname + ' <' + node.email + '>',
        'monitoring-confirmation',
        {
            node: node,
            confirmUrl: confirmUrl,
            disableUrl: disableUrl
        },
        function (err) {
            if (err) {
                Logger.tag('monitoring', 'confirmation').error('Could not enqueue confirmation mail.', err);
                return callback({data: 'Internal error.', type: ErrorTypes.internalError});
            }

            callback(null);
        }
    );
}

module.exports = {
    createNode: function (node, callback) {
        const token = generateToken();
        const nodeSecrets = {};

        node.monitoringConfirmed = false;

        if (node.monitoring) {
            nodeSecrets.monitoringToken = generateToken();
        }

        writeNodeFile(false, token, node, nodeSecrets, function (err, token, node) {
            if (err) {
                return callback(err);
            }

            if (node.monitoring && !node.monitoringConfirmed) {
                return sendMonitoringConfirmationMail(node, nodeSecrets, function (err) {
                    if (err) {
                        return callback(err);
                    }

                    return callback(null, token, node);
                });
            }

            return callback(null, token, node);
        });
    },

    updateNode: function (token, node, callback) {
        this.getNodeDataByToken(token, function (err, currentNode, nodeSecrets) {
            if (err) {
                return callback(err);
            }

            let monitoringConfirmed = false;
            let monitoringToken = '';

            if (node.monitoring) {
                if (!currentNode.monitoring) {
                    // monitoring just has been enabled
                    monitoringConfirmed = false;
                    monitoringToken = generateToken();

                } else {
                    // monitoring is still enabled

                    if (currentNode.email !== node.email) {
                        // new email so we need a new token and a reconfirmation
                        monitoringConfirmed = false;
                        monitoringToken = generateToken();

                    } else {
                        // email unchanged, keep token (fix if not set) and confirmation state
                        monitoringConfirmed = currentNode.monitoringConfirmed;
                        monitoringToken = nodeSecrets.monitoringToken || generateToken();
                    }
                }
            }

            node.monitoringConfirmed = monitoringConfirmed;
            nodeSecrets.monitoringToken = monitoringToken;

            writeNodeFile(true, token, node, nodeSecrets, function (err, token, node) {
                if (err) {
                    return callback(err);
                }

                if (node.monitoring && !node.monitoringConfirmed) {
                    return sendMonitoringConfirmationMail(node, nodeSecrets, function (err) {
                        if (err) {
                            return callback(err);
                        }

                        return callback(null, token, node);
                    });
                }

                return callback(null, token, node);
            });
        });
    },

    internalUpdateNode: function (token, node, nodeSecrets, callback) {
        writeNodeFile(true, token, node, nodeSecrets, callback);
    },

    deleteNode: function (token, callback) {
        deleteNodeFile(token, callback);
    },

    getAllNodes: function (callback) {
        findNodeFiles({}, function (err, files) {
            if (err) {
                Logger.tag('nodes').error('Error getting all nodes:', err);
                return callback({data: 'Internal error.', type: ErrorTypes.internalError});
            }

            async.mapLimit(
                files,
                MAX_PARALLEL_NODES_PARSING,
                parseNodeFile,
                function (err, nodes) {
                    if (err) {
                        Logger.tag('nodes').error('Error getting all nodes:', err);
                        return callback({data: 'Internal error.', type: ErrorTypes.internalError});
                    }

                    return callback(null, nodes);
                }
            );
        });
    },

    getNodeDataByMac: function (mac, callback) {
        return findNodeDataByFilePattern({ mac: mac }, callback);
    },

    getNodeDataByToken: function (token, callback) {
        return getNodeDataByFilePattern({ token: token }, callback);
    },

    getNodeDataByMonitoringToken: function (monitoringToken, callback) {
        return getNodeDataByFilePattern({ monitoringToken: monitoringToken }, callback);
    },

    fixNodeFilenames: function (callback) {
        findFilesInPeersPath(function (err, files) {
            if (err) {
                return callback(err);
            }

            async.mapLimit(
                files,
                MAX_PARALLEL_NODES_PARSING,
                function (file, fileCallback) {
                    parseNodeFile(file, function (err, node, nodeSecrets) {
                        if (err) {
                            return fileCallback(err);
                        }

                        const expectedFilename = toNodeFilename(node.token, node, nodeSecrets);
                        if (file !== expectedFilename) {
                            return fs.rename(file, expectedFilename, function (err) {
                                if (err) {
                                    return fileCallback(new Error(
                                        'Cannot rename file ' + file + ' to ' + expectedFilename + ' => ' + err
                                    ));
                                }

                                fileCallback(null);
                            });
                        }

                        fileCallback(null);
                    });
                },
                callback
            );
        });
    },

    getNodeStatistics: function (callback) {
        this.getAllNodes(function (err, nodes) {
            if (err) {
                return callback(err);
            }

            const nodeStatistics = {
                registered: _.size(nodes),
                withVPN: 0,
                withCoords: 0,
                monitoring: {
                    active: 0,
                    pending: 0
                }
            };

            _.each(nodes, function (node) {
                if (node.key) {
                    nodeStatistics.withVPN += 1;
                }

                if (node.coords) {
                    nodeStatistics.withCoords += 1;
                }

                switch (node.monitoringState) {
                    case 'active':
                        nodeStatistics.monitoring.active += 1;
                    break;
                    case 'pending':
                        nodeStatistics.monitoring.pending += 1;
                    break;
                }
            });

            callback(null, nodeStatistics);
        });
    }
}