const _ = require('lodash');
const Promise = require('bluebird');
const {i18n} = require('../../lib/common');
const logging = require('../../../shared/logging');
const db = require('../db');
const schema = require('./schema');
const clients = require('./clients');

function addTableColumn(tableName, table, columnName, columnSpec = schema[tableName][columnName]) {
    let column;

    // creation distinguishes between text with fieldtype, string with maxlength and all others
    if (columnSpec.type === 'text' && Object.prototype.hasOwnProperty.call(columnSpec, 'fieldtype')) {
        column = table[columnSpec.type](columnName, columnSpec.fieldtype);
    } else if (columnSpec.type === 'string') {
        if (Object.prototype.hasOwnProperty.call(columnSpec, 'maxlength')) {
            column = table[columnSpec.type](columnName, columnSpec.maxlength);
        } else {
            column = table[columnSpec.type](columnName, 191);
        }
    } else {
        column = table[columnSpec.type](columnName);
    }

    if (Object.prototype.hasOwnProperty.call(columnSpec, 'nullable') && columnSpec.nullable === true) {
        column.nullable();
    } else {
        column.nullable(false);
    }
    if (Object.prototype.hasOwnProperty.call(columnSpec, 'primary') && columnSpec.primary === true) {
        column.primary();
    }
    if (Object.prototype.hasOwnProperty.call(columnSpec, 'unique') && columnSpec.unique) {
        column.unique();
    }
    if (Object.prototype.hasOwnProperty.call(columnSpec, 'unsigned') && columnSpec.unsigned) {
        column.unsigned();
    }
    if (Object.prototype.hasOwnProperty.call(columnSpec, 'references')) {
        // check if table exists?
        column.references(columnSpec.references);
    }
    if (Object.prototype.hasOwnProperty.call(columnSpec, 'cascadeDelete') && columnSpec.cascadeDelete === true) {
        column.onDelete('CASCADE');
    }
    if (Object.prototype.hasOwnProperty.call(columnSpec, 'defaultTo')) {
        column.defaultTo(columnSpec.defaultTo);
    }
    if (Object.prototype.hasOwnProperty.call(columnSpec, 'index') && columnSpec.index === true) {
        column.index();
    }
}

function addColumn(tableName, column, transaction, columnSpec) {
    return (transaction || db.knex).schema.table(tableName, function (table) {
        addTableColumn(tableName, table, column, columnSpec);
    });
}

function dropColumn(tableName, column, transaction) {
    return (transaction || db.knex).schema.table(tableName, function (table) {
        table.dropColumn(column);
    });
}

/**
 * Adds an unique index to a table over the given columns.
 *
 * @param {string} tableName - name of the table to add unique constraint to
 * @param {string|[string]} columns - column(s) to form unique constraint with
 * @param {Object} transaction - connnection object containing knex reference
 * @param {Object} transaction.knex - knex instance
 */
function addUnique(tableName, columns, transaction) {
    return (transaction || db.knex).schema.table(tableName, function (table) {
        table.unique(columns);
    });
}

/**
 * Drops a unique key constraint from a table.
 *
 * @param {string} tableName - name of the table to drop unique constraint from
 * @param {string|[string]} columns - column(s) unique constraint was formed
 * @param {Object} transaction - connnection object containing knex reference
 * @param {Object} transaction.knex - knex instance
 */
function dropUnique(tableName, columns, transaction) {
    return (transaction || db.knex).schema.table(tableName, function (table) {
        table.dropUnique(columns);
    });
}

/**
 * https://github.com/tgriesser/knex/issues/1303
 * createTableIfNotExists can throw error if indexes are already in place
 */
function createTable(table, transaction, tableSpec = schema[table]) {
    return (transaction || db.knex).schema.hasTable(table)
        .then(function (exists) {
            if (exists) {
                return;
            }

            return (transaction || db.knex).schema.createTable(table, function (t) {
                let tableIndexes = [];
                let tableUniqueConstraints = [];

                const columnKeys = _.keys(tableSpec);
                _.each(columnKeys, function (column) {
                    if (column === '@@INDEXES@@') {
                        tableIndexes = tableSpec['@@INDEXES@@'];
                        return;
                    }

                    if (column === '@@UNIQUE_CONSTRAINTS@@') {
                        tableUniqueConstraints = tableSpec['@@UNIQUE_CONSTRAINTS@@'];
                        return;
                    }

                    return addTableColumn(table, t, column, tableSpec[column]);
                });

                _.each(tableIndexes, function (index) {
                    t.index(index);
                });

                _.each(tableUniqueConstraints, function (unique) {
                    t.unique(unique);
                });
            });
        });
}

function deleteTable(table, transaction) {
    return (transaction || db.knex).schema.dropTableIfExists(table);
}

function getTables(transaction) {
    const client = (transaction || db.knex).client.config.client;

    if (_.includes(_.keys(clients), client)) {
        return clients[client].getTables(transaction);
    }

    return Promise.reject(i18n.t('notices.data.utils.index.noSupportForDatabase', {client: client}));
}

function getIndexes(table, transaction) {
    const client = (transaction || db.knex).client.config.client;

    if (_.includes(_.keys(clients), client)) {
        return clients[client].getIndexes(table, transaction);
    }

    return Promise.reject(i18n.t('notices.data.utils.index.noSupportForDatabase', {client: client}));
}

function getColumns(table, transaction) {
    const client = (transaction || db.knex).client.config.client;

    if (_.includes(_.keys(clients), client)) {
        return clients[client].getColumns(table);
    }

    return Promise.reject(i18n.t('notices.data.utils.index.noSupportForDatabase', {client: client}));
}

function checkTables(transaction) {
    const client = (transaction || db.knex).client.config.client;

    if (client === 'mysql') {
        return clients[client].checkPostTable();
    }
}

const createLog = type => msg => logging[type](msg);

function createColumnMigration(...migrations) {
    async function runColumnMigration(conn, migration) {
        const {
            table,
            column,
            dbIsInCorrectState,
            operation,
            operationVerb,
            columnDefinition
        } = migration;

        const hasColumn = await conn.schema.hasColumn(table, column);
        const isInCorrectState = dbIsInCorrectState(hasColumn);

        const log = createLog(isInCorrectState ? 'warn' : 'info');

        log(`${operationVerb} ${table}.${column} column`);

        if (!isInCorrectState) {
            await operation(table, column, conn, columnDefinition);
        }
    }

    return async function columnMigration(conn) {
        for (const migration of migrations) {
            await runColumnMigration(conn, migration);
        }
    };
}

module.exports = {
    checkTables: checkTables,
    createTable: createTable,
    deleteTable: deleteTable,
    getTables: getTables,
    getIndexes: getIndexes,
    addUnique: addUnique,
    dropUnique: dropUnique,
    addColumn: addColumn,
    dropColumn: dropColumn,
    getColumns: getColumns,
    createColumnMigration
};