import {
    AbstractNode, Cursor,
    TemplateElement,
    keyword
} from "abstract-lang";
import { Expression, Operand } from "../expression";
import { Name } from "../base";

export interface SetConfigRow {
    session?: boolean;
    local?: boolean;
    key: string;
    value: Operand;
}

export class SetConfig extends AbstractNode<SetConfigRow> {

    static entry(cursor: Cursor): boolean {
        return cursor.beforeWord("set");
    }

    static parse(cursor: Cursor): SetConfigRow {
        cursor.readWord("set");

        let session = false;
        let local = false;
        if ( cursor.beforeWord("session") ) {
            cursor.readWord("session");
            session = true;
        }
        else if ( cursor.beforeWord("local") ) {
            cursor.readWord("local");
            local = true;
        }

        if ( cursor.beforePhrase("time", "zone") ) {
            cursor.readPhrase("time", "zone");

            const key = "time zone";
            const value = cursor.parse(Expression).operand();
            return {session, local, key, value};
        }

        const key = cursor.parse(Name).toString();
        cursor.skipSpaces();

        if ( cursor.beforeWord("to") ) {
            cursor.readWord("to");
        }
        else {
            cursor.readValue("=");
            cursor.skipSpaces();
        }

        const value = cursor.parse(Expression).operand();
        return {session, local, key, value};
    }

    template(): TemplateElement[] {
        const set = this.row;

        const output: TemplateElement[] = [
            keyword("set")
        ];

        if ( set.session ) {
            output.push(keyword("session"));
        }
        else if ( set.local ) {
            output.push(keyword("local"));
        }

        if ( set.key === "time zone" ) {
            output.push(
                keyword("time"),
                keyword("zone")
            );
        }
        else {
            output.push(set.key);
            output.push(keyword("to"));
        }

        output.push(set.value);

        return output;
    }
}