import { process_frontmatter } from '@doc-utils/markdown2html';
import { promises as fs } from 'fs';
import { resolve as resolve_path } from 'path';
import { parse as parse_yaml, stringify as to_yaml } from 'yaml';
import { hash_str } from './hash';

export async function load_from_dir(dir: string, file: string) {
	if (! dir) {
		return null;
	}

	const rel_path = resolve_path('/', file);
	const abs_path = resolve_path(dir, '.' + rel_path);
	return await fs.readFile(abs_path, 'utf8');
}

export function mkdirp(dir: string, mode = 0o700) {
	return fs.mkdir(dir, { mode, recursive: true });
}

export async function with_default_if_missing<T>(read_promise: Promise<T>, default_value: T) : Promise<T> {
	try {
		return await read_promise;
	}

	catch (error) {
		if (error?.code === 'ENOENT') {
			return default_value;
		}

		throw error;
	}
}

export async function read_text(file: string, check_for_frontmatter = true, compute_hash = true) {
	const text = await fs.readFile(file, 'utf8');
	const hash = compute_hash ? hash_str(text) : null;

	if (check_for_frontmatter) {
		const { frontmatter, document } = process_frontmatter(text);
		return { frontmatter, text: document, hash };
	}

	return { text, frontmatter: null, hash };
}

export async function read_json(file: string, check_for_frontmatter = true, compute_hash = true) {
	const json = await fs.readFile(file, 'utf8');
	const hash = compute_hash ? hash_str(json) : null;

	if (check_for_frontmatter) {
		const { frontmatter, document } = process_frontmatter(json);
		const parsed = JSON.parse(document);
		return { frontmatter, json: document, parsed, hash };
	}

	const parsed = JSON.parse(json);
	return { json, parsed, frontmatter: null, hash };
}

export async function read_yaml(file: string, check_for_frontmatter = true, compute_hash = true) {
	const yaml = await fs.readFile(file, 'utf8');
	const hash = compute_hash ? hash_str(yaml) : null;

	if (check_for_frontmatter) {
		const { frontmatter, document } = process_frontmatter(yaml);
		const parsed = parse_yaml(document);
		return { frontmatter, yaml: document, parsed, hash };
	}

	const parsed = parse_yaml(yaml);
	return { yaml, parsed, frontmatter: null, hash };
}

export function write_text(file: string, text: string) {
	return fs.writeFile(file, text, 'utf8');
}

export function write_json(file: string, obj: any, pretty = true) {
	const json = JSON.stringify(obj, null, pretty ? '  ' : null);
	return fs.writeFile(file, json, 'utf8');
}

export function write_yaml(file: string, obj: any) {
	const yaml = to_yaml(obj);
	return fs.writeFile(file, yaml, 'utf8');
}