const ParameterizedSQL = require('loopback-connector').ParameterizedSQL;

module.exports = Self => {
    Self.remoteMethod('getLeaves', {
        description: 'Returns the first shipped and landed possible for params',
        accepts: [{
            arg: 'zoneFk',
            type: 'Number',
            required: true,
        },
        {
            arg: 'parentFk',
            type: 'Number',
            default: 1,
            required: false,
        },
        {
            arg: 'filter',
            type: 'Object',
            description: 'Filter defining where, order, offset, and limit - must be a JSON-encoded string',
            http: {source: 'query'}
        }],
        returns: {
            type: ['object'],
            root: true
        },
        http: {
            path: `/getLeaves`,
            verb: 'GET'
        }
    });

    Self.getLeaves = async(zoneFk, parentFk = 1, filter) => {
        let conn = Self.dataSource.connector;
        let stmts = [];

        stmts.push(`DROP TEMPORARY TABLE IF EXISTS tmp.checkedChilds`);
        stmts.push(new ParameterizedSQL(
            `CREATE TEMPORARY TABLE tmp.checkedChilds (
                id INT,
                name VARCHAR(100),
                lft INT,
                rgt INT,
                depth BIGINT(22),
                sons DECIMAL(10, 0),
                isIncluded TINYINT
            ) ENGINE = MEMORY`));

        if (parentFk === 1) {
            stmts.push(new ParameterizedSQL(
                `INSERT INTO tmp.checkedChilds
                        SELECT
                                zg.id,
                                zg.name,
                                zg.lft,
                                zg.rgt,
                                zg.depth,
                                zg.sons,
                                zi.isIncluded
                            FROM zoneGeo zg
                                JOIN zoneIncluded zi ON zi.geoFk = zg.id 
                                    AND zoneFk = ?`, [zoneFk]));
        }

        let stmt = new ParameterizedSQL(
            `SELECT * FROM (
                SELECT 
                        zg.id,
                        zg.name,
                        zg.lft,
                        zg.rgt,
                        zg.depth,
                        zg.sons,
                        IF(ch.id = zg.id, isIncluded, null) selected
                    FROM zoneGeo zg
                        JOIN tmp.checkedChilds ch 
                            ON zg.lft <= ch.lft AND zg.rgt >= ch.rgt
                                AND zg.depth > 0
                UNION ALL
                SELECT 
                        child.id,
                        child.name,
                        child.lft,
                        child.rgt,
                        child.depth,
                        child.sons,
                        zi.isIncluded AS selected
                    FROM zoneGeo parent 
                        JOIN zoneGeo child ON child.lft > parent.lft 
                            AND child.rgt < parent.rgt
                            AND child.depth = parent.depth + 1
                        LEFT JOIN zoneIncluded zi ON zi.geoFk = child.id 
                            AND zoneFk = ?
                        WHERE parent.id = ?) AS nst`, [zoneFk, parentFk]);

        // Get nodes from depth greather than Origin
        stmt.merge(conn.makeSuffix(filter));
        stmt.merge('GROUP BY nst.id');

        const resultIndex = stmts.push(stmt) - 1;

        const sql = ParameterizedSQL.join(stmts, ';');
        const result = await Self.rawStmt(sql);
        const nodes = result[resultIndex];

        if (nodes.length == 0)
            return nodes;

        // Get parent nodes
        const minorDepth = nodes.reduce((a, b) => {
            return b < a ? b : a;
        }).depth;

        const parentNodes = nodes.filter(element => {
            return element.depth === minorDepth;
        });
        const leaves = Object.assign([], sortNodes(parentNodes));

        nestLeaves(leaves);

        function nestLeaves(elements) {
            elements.forEach(element => {
                let childs = Object.assign([], getLeaves(element));
                if (childs.length > 0) {
                    element.childs = childs;
                    nestLeaves(element.childs);
                }
            });
        }

        function getLeaves(parent) {
            let elements = nodes.filter(element => {
                return element.lft > parent.lft && element.rgt < parent.rgt
                    && element.depth === parent.depth + 1;
            });

            return sortNodes(elements);
        }

        return leaves;
    };

    function sortNodes(nodes) {
        return nodes.sort((a, b) => {
            if (b.selected !== a.selected) {
                if (a.selected == null)
                    return 1;
                if (b.selected == null)
                    return -1;
                return b.selected - a.selected;
            }

            return a.name.localeCompare(b.name);
        });
    }
};