/* Copyright IBM Corp. 2017 */
import { readFile, writeFile } from 'graceful-fs';
import { getType } from 'mime';
import { Observable, Observer } from 'rxjs';
import { VError } from 'verror';

import { FileDescriptor } from './rx.walk';

export interface JsonFile {
    desc: FileDescriptor;
    data: any;
}

function _readJSON(aDesc: FileDescriptor): Observable<JsonFile> {

    return Observable.create((observer: Observer<JsonFile>) => {

        // read the file
        readFile(aDesc.absPath, 'utf-8', (err, data) => {
            if (err) {
                observer.error(err);
            } else {
                try {
                    observer.next({ desc: aDesc, data: JSON.parse(data) });
                    observer.complete();
                } catch (error) {
                    observer.error(new VError(error, 'Unable to parse JSON file %s.', aDesc.absPath));
                }
            }
        });

    });
}

function _writeJSON(aDesc: JsonFile): Observable<FileDescriptor> {
    return Observable.create((observer: Observer<FileDescriptor>) => {
        try {
            // read the file
            writeFile(aDesc.desc.absPath, JSON.stringify(aDesc.data, undefined, 2), (err) => {
                if (err) {
                    observer.error(err);
                } else {
                    observer.next(aDesc.desc);
                    observer.complete();
                }
            });
        } catch (error) {
            observer.error(new VError(error, 'Unable to write JSON file %s.', aDesc.desc.absPath));
        }
    });
}

function _isJSON(aDesc: FileDescriptor): boolean {
    return getType(aDesc.absPath) === 'application/json';
}

export {
    _readJSON as readJSON,
    _writeJSON as writeJSON,
    _isJSON as isJSON
};