import type { PromptTemplate } from "./types.js";

export function parseCommandArgs(argsString: string): string[] {
	const args: string[] = [];
	let current = "";
	let inQuote: string | null = null;

	for (let i = 0; i < argsString.length; i++) {
		const char = argsString[i]!;
		if (inQuote) {
			if (char === inQuote) inQuote = null;
			else current += char;
		} else if (char === '"' || char === "'") {
			inQuote = char;
		} else if (char === " " || char === "\t") {
			if (current) {
				args.push(current);
				current = "";
			}
		} else {
			current += char;
		}
	}
	if (current) args.push(current);
	return args;
}

export function substituteArgs(content: string, args: string[]): string {
	let result = content;
	result = result.replace(/\$(\d+)/g, (_, num: string) => args[parseInt(num, 10) - 1] ?? "");
	result = result.replace(/\$\{@:(\d+)(?::(\d+))?\}/g, (_, startStr: string, lengthStr?: string) => {
		let start = parseInt(startStr, 10) - 1;
		if (start < 0) start = 0;
		if (lengthStr) return args.slice(start, start + parseInt(lengthStr, 10)).join(" ");
		return args.slice(start).join(" ");
	});
	const allArgs = args.join(" ");
	result = result.replace(/\$ARGUMENTS/g, allArgs);
	result = result.replace(/\$@/g, allArgs);
	return result;
}

export function expandPromptTemplate(text: string, templates: PromptTemplate[]): string {
	if (!text.startsWith("/")) return text;
	const spaceIndex = text.indexOf(" ");
	const commandName = spaceIndex === -1 ? text.slice(1) : text.slice(1, spaceIndex);
	const argsString = spaceIndex === -1 ? "" : text.slice(spaceIndex + 1);
	const template = templates.find((candidate) => candidate.name === commandName);
	if (!template) return text;
	return substituteArgs(template.content, parseCommandArgs(argsString));
}