import { cachedProcessFile, FileProcessor, MinimalFS } from './cached-process-file';
import { Diagnostics } from './diagnostics';
import { safeParse } from './parser';
import { create } from './runtime';
import { process, StylableMeta } from './stylable-processor';
import { StylableTransformer } from './stylable-transformer';
import { RuntimeStylesheet } from './types';

export function createGenerator(
    fs: MinimalFS = {
        readFileSync(_path: string) {
            return '';
        },
        statSync(_path: string) {
            return { mtime: new Date(0) };
        }
    },
    requireModule: (moduleId: string) => any = (_path: string): any => ({}),
    delimiter: string = '--'
) {
    const fileProcessor: FileProcessor<StylableMeta> = cachedProcessFile<StylableMeta>(
        (from, content) => {
            return process(safeParse(content, { from }));
        },
        fs,
        x => x
    );

    function output(meta: StylableMeta) {
        const diagnostics = new Diagnostics();

        const transformer = new StylableTransformer({
            fileProcessor,
            requireModule,
            diagnostics,
            delimiter
        });

        const { exports } = transformer.transform(meta);

        return {
            meta,
            transformer,
            diagnostics,
            runtime: create(
                meta.root,
                meta.namespace,
                exports,
                '',
                meta.source
            ) as RuntimeStylesheet
        };
    }

    return {
        fileProcessor,
        delimiter,
        scope: StylableTransformer.prototype.scope,
        fromCSS(source: string, path: string = '/unknown.st.css') {
            const root = safeParse(source, { from: path });
            const meta = process(root);
            fileProcessor.add(meta.source, meta);
            return output(meta);
        },
        fromFile(path: string) {
            const meta = fileProcessor.process(path);
            return output(meta);
        }
    };
}