// tool-registrar.ts - MCP content transformation
// NOTE: Tools are NOT registered with Pi - only the unified `mcp` proxy tool is registered.
// This keeps the LLM context small (1 tool instead of 100s).

import type { McpContent, ContentBlock } from './_types.ts';

/**
 * Transform MCP content types to Pi content blocks.
 */
export function transformMcpContent(content: McpContent[]): ContentBlock[] {
  return content.map((c) => {
    if (c.type === 'text') {
      return { type: 'text' as const, text: c.text ?? '' };
    }

    if (c.type === 'image') {
      return {
        type: 'image' as const,
        data: c.data ?? '',
        mimeType: c.mimeType ?? 'image/png',
      };
    }

    if (c.type === 'resource') {
      const resourceUri = c.resource?.uri ?? '(no URI)';
      const resourceContent = c.resource?.text ?? (c.resource ? JSON.stringify(c.resource) : '(no content)');

      return {
        type: 'text' as const,
        text: `[Resource: ${resourceUri}]\n${resourceContent}`,
      };
    }

    if (c.type === 'resource_link') {
      const linkName = c.name ?? c.uri ?? 'unknown';
      const linkUri = c.uri ?? '(no URI)';

      return {
        type: 'text' as const,
        text: `[Resource Link: ${linkName}]\nURI: ${linkUri}`,
      };
    }

    if (c.type === 'audio') {
      return {
        type: 'text' as const,
        text: `[Audio content: ${c.mimeType ?? 'audio/*'}]`,
      };
    }

    return { type: 'text' as const, text: JSON.stringify(c) };
  });
}

/**
 * Resolve a tool result's content blocks, falling back to structuredContent
 * when content is empty.
 */
export function resolveMcpResultContent(result: Record<string, unknown>): ContentBlock[] {
  const blocks = transformMcpContent((Array.isArray(result.content) ? result.content : []) as McpContent[]);

  if (blocks.length > 0) {
    return blocks;
  }

  if (result.structuredContent !== undefined && result.structuredContent !== null) {
    return [{ type: 'text' as const, text: stringifyStructuredContent(result.structuredContent) }];
  }

  return [];
}

function stringifyStructuredContent(value: unknown): string {
  try {
    return JSON.stringify(value, null, 2) ?? String(value);
  } catch {
    return String(value);
  }
}