/**
 * Output Text Computation
 *
 * Converts a ContentItem array into a single string for test assertions.
 * Joins all text content with newlines and trims whitespace.
 *
 * ## Strategy
 * - Extract text from text-type content items
 * - Extract text from resource items that have a text field
 * - Skip image items (no text representation by default)
 * - Join multiple text items with newlines
 * - Trim leading/trailing whitespace from result
 *
 * ## Edge Cases
 * - Empty content array → empty string
 * - Content with no text items → empty string
 * - Null/undefined text values → skipped
 * - Whitespace-only items → preserved but trimmed at end
 *
 * @example Basic text
 * ```typescript
 * const content = [{ type: "text", text: "Hello" }];
 * computeOutputText(content); // "Hello"
 * ```
 *
 * @example Multiple text items
 * ```typescript
 * const content = [
 *   { type: "text", text: "Hello" },
 *   { type: "text", text: "World" }
 * ];
 * computeOutputText(content); // "Hello\nWorld"
 * ```
 *
 * @example Mixed content with images
 * ```typescript
 * const content = [
 *   { type: "text", text: "Image:" },
 *   { type: "image", data: "...", mimeType: "image/png" },
 *   { type: "text", text: "Done" }
 * ];
 * computeOutputText(content); // "Image:\nDone"
 * ```
 *
 * @example Resource with text
 * ```typescript
 * const content = [
 *   { type: "text", text: "File contents:" },
 *   { type: "resource", data: "file.txt", text: "Hello from file" }
 * ];
 * computeOutputText(content); // "File contents:\nHello from file"
 * ```
 *
 * @module @wavespec/kit/response
 */

import type { ContentItem } from "@wavespec/types";

/**
 * Compute output_text from content array
 *
 * Joins all text content with newlines. Ignores images unless they have
 * text representations. Trims whitespace from the final result.
 *
 * @param content - Array of content items from response
 * @returns Single string for test assertions
 *
 * @example
 * ```typescript
 * const content = [
 *   { type: "text", text: "Hello" },
 *   { type: "text", text: "World" }
 * ];
 * computeOutputText(content); // "Hello\nWorld"
 * ```
 */
export function computeOutputText(content: ContentItem[]): string {
	const textParts: string[] = [];

	for (const item of content) {
		// Handle text items
		if (item.type === "text" && item.text != null) {
			textParts.push(item.text);
			continue;
		}

		// Handle resource items with text field
		if (
			item.type === "resource" &&
			item.text != null
		) {
			textParts.push(item.text);
			continue;
		}

		// Skip images and other types without explicit text representation
	}

	// Join with newlines and trim
	return textParts.join("\n").trim();
}