/**
* Simple template rendering engine for prompts
*/
import type { PromptArgument, RenderedPrompt } from "./types.js";
/**
* Render a template string by replacing {{variable}} placeholders with actual values
* @param template Template string with {{variable}} placeholders
* @param args Record of argument values
* @param definitions Argument definitions with defaults
* @returns Rendered template
*/
export function renderTemplate(
template: string,
args: Record<string, string> = {},
definitions: PromptArgument[] = []
): RenderedPrompt {
let rendered = template;
// Create a map of defaults
const defaults = new Map<string, string>();
for (const def of definitions) {
if (def.default !== undefined) {
defaults.set(def.name, def.default);
}
}
// Replace all {{variable}} placeholders
rendered = rendered.replace(/\{\{(\w+)\}\}/g, (match, varName) => {
// Check if value is provided in args
if (args[varName] !== undefined) {
return args[varName];
}
// Check if there's a default value
if (defaults.has(varName)) {
return defaults.get(varName)!;
}
// If no value and no default, keep the placeholder
return match;
});
return { text: rendered };
}
/**
* Validate that all required arguments are provided
* @param args Provided arguments
* @param definitions Argument definitions
* @throws Error if required arguments are missing
*/
export function validateArguments(
args: Record<string, string>,
definitions: PromptArgument[]
): void {
const missing: string[] = [];
for (const def of definitions) {
if (def.required && (args[def.name] === undefined || args[def.name] === "")) {
missing.push(def.name);
}
}
if (missing.length > 0) {
throw new Error(`Missing required arguments: ${missing.join(", ")}`);
}
}
