import fs from 'fs';
import path from 'path';
import vscode, { WorkspaceFolder } from 'vscode';

export class TestTemplateManager {
	private workspace: WorkspaceFolder | undefined = vscode.workspace.workspaceFolders?.[0];

	// singleton
	private static instance: TestTemplateManager;

	static getInstance(): TestTemplateManager {
		if (!TestTemplateManager.instance) {
			TestTemplateManager.instance = new TestTemplateManager();
		}
		return TestTemplateManager.instance;
	}

	lookupByRegex(fileName: string): string | null {
		let promptsDir = path.join(this.workspace?.uri.fsPath || '', 'prompts');
		if (!fs.existsSync(promptsDir)) {
			return null;
		}

		let templateFile = path.join(promptsDir, 'templates');
		if (!fs.existsSync(templateFile)) {
			return null;
		}

		const files = fs.readdirSync(templateFile);
		const matchedFile = files.find(file => new RegExp(file).test(fileName));
		if (matchedFile) {
			const matchedFilePath = path.join(templateFile, matchedFile);
			return fs.readFileSync(matchedFilePath, { encoding: 'utf-8' });
		}

		return null;
	}

	/**
	 * Looks up a template file by its name and returns its content as a string.
	 *
	 * @param templateFileName the name of the template file to look up
	 * @return the content of the template file as a string, or null if the file is not found
	 *
	 * 1. Find the prompts directory
	 */
	lookup(templateFileName: string): string | null {
		let promptsDir = path.join(this.workspace?.uri.fsPath || '', 'prompts');
		if (!fs.existsSync(promptsDir)) {
			return null;
		}

		let templateFile = path.join(promptsDir, 'templates');
		if (!fs.existsSync(templateFile)) {
			return null;
		}

		const templateFilePath = path.join(templateFile, templateFileName);
		if (fs.existsSync(templateFilePath)) {
			return fs.readFileSync(templateFilePath, { encoding: 'utf-8' });
		}

		const vmTemplateFilePath = path.join(templateFile, `${templateFileName}.vm`);
		if (fs.existsSync(vmTemplateFilePath)) {
			return fs.readFileSync(vmTemplateFilePath, { encoding: 'utf-8' });
		}

		const files = fs.readdirSync(templateFile);
		const endSuffixFile = files.find(file => file.endsWith(templateFileName));
		if (endSuffixFile) {
			const endSuffixFilePath = path.join(templateFile, endSuffixFile);
			return fs.readFileSync(endSuffixFilePath, { encoding: 'utf-8' });
		}

		return null;
	}
}