import { createError } from '@cirrusct/error';
import { fsStatSync } from '@cirrusct/fs';
import * as fs from 'fs';
import { merge } from 'lodash';
import * as nodePath from 'path';
import * as ts from 'typescript';
import { TsConfig } from './types';

export const findTsConfigFilePath = (path: string): string | undefined => {
    const stats = fsStatSync(path);
    let entryFilePath: string;
    if (stats) {
        entryFilePath = stats.isDirectory() ? ts.findConfigFile(path, ts.sys.fileExists) : path;
    }
    return entryFilePath;
};

const readJsonFile = (filePath: string): TsConfig => {
    try {
        const content = fs.readFileSync(filePath, { encoding: 'utf8' }).toString();
        return JSON.parse(content);
    } catch (e) {
        throw createError(`loadJsonFile '${filePath}' failed: ${e.message}`);
    }
};

const _load = (filePath: string): TsConfig | undefined => {
    const tsConfig = readJsonFile(filePath);
    if (tsConfig.extends) {
        const extendedFilePath = nodePath.resolve(nodePath.dirname(filePath), tsConfig.extends);
        if (!fs.existsSync(extendedFilePath)) {
            throw createError(`TsConfig file '${filePath}' extends file '${extendedFilePath}' which does not exist`);
        }
        const extendsTsConfig = _load(extendedFilePath);
        delete tsConfig.extends;
        return merge(extendsTsConfig, tsConfig);
    }
    return tsConfig;
};

export const loadTsConfig = (path: string): TsConfig | undefined => {
    const entryFilePath = findTsConfigFilePath(path);
    if (entryFilePath) {
        const tsConfig = _load(entryFilePath);
        return tsConfig;
    }
    return undefined;
};