/* Copyright IBM Corp. 2017 */
import { replace } from 'lodash';
import { join as pathJoin, parse as pathParse, relative as pathRelative, resolve as pathResolve } from 'path';
import { Observable } from 'rxjs';
import { map, mergeMap } from 'rxjs/operators';

import { writeTextFileSafe } from './rx.file';
import { readFile as rxReadFile } from './rx.walk';

const VAR_LAYOUTS = 'LAYOUTS';
const SPREAD_LAYOUTS = '...' + VAR_LAYOUTS;
const PROP_DECLARATIONS = 'declarations';
const PROP_ENTRY_COMPONENTS = 'entryComponents';

function _isEmpty(aValue: string): boolean {
    return !aValue || (aValue.trim().length === 0);
}

function _addToArray(aValue: string, aPrefix: string, aInfix: string, aSuffix: string): string {
    // check
    if (_isEmpty(aInfix)) {
        return `${aPrefix}${aInfix}${SPREAD_LAYOUTS}${aSuffix}`;
    }
    // check
    if (aInfix.includes(SPREAD_LAYOUTS)) {
        return aValue;
    }
    // append
    return `${aPrefix}${aInfix}, ${SPREAD_LAYOUTS}${aSuffix}`;
}

function _replaceModule(aValue: string, aPrefix: string, aInfix: string, aSuffix: string): string {

    // declarations
    const declEx = /(declarations:\s+\[)([^\]]*)(\])/g;
    let infix = aInfix.replace(declEx, _addToArray);
    // check if there exist entry components
    if (!declEx.test(infix)) {
        // insert the declaration
        const sep = _isEmpty(infix) ? '' : ',';
        infix = `\ndeclarations: [${SPREAD_LAYOUTS}]${sep}${infix}`;
    }

    // entry components
    const entryEx = /(entryComponents:\s+\[)([^\]]*)(\])/g;
    infix = infix.replace(entryEx, _addToArray);

    // check if there exist entry components
    if (!entryEx.test(infix)) {
        // insert the declaration
        const sep = _isEmpty(infix) ? '' : ',';
        infix = `\nentryComponents: [${SPREAD_LAYOUTS}]${sep}${infix}`;
    }

    return `${aPrefix}${infix}${aSuffix}`;
}

function _addLayoutViaRegexp(aLayoutExports: string, aModuleFile: string): Observable<string> {
    // get the module directory
    const moduleDir = pathResolve(aModuleFile, '..');
    // load the file
    return rxReadFile(aModuleFile).pipe(
        mergeMap(module => {
            // the modified file
            let mod = module;
            // look for the layouts import
            const layoutImport = /import\s+{\s*LAYOUTS\s*}/g;
            if (!layoutImport.test(mod)) {
                // get the relative name
                const parsed = pathParse(pathRelative(moduleDir, aLayoutExports));
                // relative path
                const relPath = replace(pathJoin(parsed.dir, parsed.name), /\\/g, '/');
                // insert the import
                mod =
                    `import { LAYOUTS } from './${relPath}';
${mod}`;
            }
            // find the module
            const ngModule = /(@NgModule\s*\(\s*{)((?:.|\n|\r)*)(}\)(?:.|\n|\r)*export\s+class)/g;
            mod = mod.replace(ngModule, _replaceModule);

            // save the module
            return writeTextFileSafe(aModuleFile, mod, true);
        }),
        map(() => aModuleFile)
    );
}

export {
    _addLayoutViaRegexp as addLayoutToModule
};