import Handlebars from "handlebars";
import type { TemplateData } from "./types.ts";

/**
 * Default template for generating filenames
 */
export const DEFAULT_FILENAME_TEMPLATE = `{{dateFormat publishedAt "YYYY-MM-DD"}}_{{slug (default path title)}}.md`;

/**
 * Default template for generating file content
 */
export const DEFAULT_CONTENT_TEMPLATE = `---
title: "{{title}}"
date: {{publishedAt}}
{{#if tags.length}}
tags:
{{#each tags}}
  - {{this}}
{{/each}}
{{/if}}
---

{{content}}
`;

/**
 * Convert a string to a URL-safe slug
 */
export function slugify(text: string): string {
	return text
		.toString()
		.toLowerCase()
		.trim()
		.replace(/^\/+/, "") // Remove leading slashes
		.replace(/\/+$/, "") // Remove trailing slashes
		.replace(/\s+/g, "-") // Replace spaces with -
		.replace(/[^\w-]+/g, "") // Remove non-word chars (except -)
		.replace(/--+/g, "-") // Replace multiple - with single -
		.replace(/^-+/, "") // Trim - from start
		.replace(/-+$/, ""); // Trim - from end
}

/**
 * Format a date string
 */
function formatDate(dateStr: string | undefined, format: string): string {
	if (!dateStr) {
		return "";
	}

	const date = new Date(dateStr);
	if (Number.isNaN(date.getTime())) {
		return "";
	}

	// Simple format replacements
	const year = date.getFullYear();
	const month = String(date.getMonth() + 1).padStart(2, "0");
	const day = String(date.getDate()).padStart(2, "0");

	return format
		.replace("YYYY", String(year))
		.replace("MM", month)
		.replace("DD", day);
}

/**
 * Register custom Handlebars helpers
 */
function registerHelpers(hbs: typeof Handlebars): void {
	// Slug helper: {{slug text}}
	hbs.registerHelper("slug", (text: unknown) => {
		if (typeof text !== "string") {
			return "";
		}
		return slugify(text);
	});

	// Date format helper: {{dateFormat date "YYYY-MM-DD"}}
	hbs.registerHelper("dateFormat", (date: unknown, format: unknown) => {
		if (typeof date !== "string" || typeof format !== "string") {
			return "";
		}
		return formatDate(date, format);
	});

	// Default helper: {{default value fallback}}
	hbs.registerHelper("default", (value: unknown, fallback: unknown) => {
		if (value !== undefined && value !== null && value !== "") {
			return value;
		}
		return fallback;
	});
}

/**
 * Create a configured Handlebars instance with helpers registered
 */
export function createHandlebars(): typeof Handlebars {
	const hbs = Handlebars.create();
	registerHelpers(hbs);
	return hbs;
}

/**
 * Compile and render a template with the given data
 */
export function renderTemplate(
	hbs: typeof Handlebars,
	template: string,
	data: TemplateData,
): string {
	const compiled = hbs.compile(template);
	return compiled(data);
}

/**
 * Generate a filename from template and data
 */
export function generateFilename(
	hbs: typeof Handlebars,
	template: string,
	data: TemplateData,
): string {
	const filename = renderTemplate(hbs, template, data);
	// Sanitize filename - remove any path traversal attempts
	return filename.replace(/\.\./g, "").replace(/[<>:"|?*]/g, "");
}

/**
 * Generate file content from template and data
 */
export function generateContent(
	hbs: typeof Handlebars,
	template: string,
	data: TemplateData,
): string {
	return renderTemplate(hbs, template, data);
}