import Q from 'q';

export default class AutocompleteProvider {
    constructor(commandRegex?: RegExp, fuseOpts?: any) {
        if(commandRegex) {
            if(!commandRegex.global) {
                throw new Error('commandRegex must have global flag set');
            }
            this.commandRegex = commandRegex;
        }
    }

    /**
     * Of the matched commands in the query, returns the first that contains or is contained by the selection, or null.
     */
    getCurrentCommand(query: string, selection: {start: number, end: number}): ?Array<string> {
        if(this.commandRegex == null)
            return null;

        let match = null;
        while((match = this.commandRegex.exec(query)) != null) {
            let matchStart = match.index,
                matchEnd = matchStart + match[0].length;

            console.log(match);
            
            if(selection.start <= matchEnd && selection.end >= matchStart) {
                return match;
            }
        }
        this.commandRegex.lastIndex = 0;
        return null;
    }

    getCompletions(query: String, selection: {start: number, end: number}) {
        return Q.when([]);
    }

    getName(): string {
        return 'Default Provider';
    }
}