import { assertEquals } from "https://deno.land/std@0.224.0/testing/asserts.ts";
import { parse as yamlParse } from "https://deno.land/std@0.224.0/yaml/mod.ts";

/**
 * Generation 2 Proof of Concept: Declarative Frontmatter (YAML UUIDs)
 *
 * This module demonstrates extracting strict UUIDv7 identifiers from
 * Markdown YAML frontmatter using production-ready YAML parsing,
 * ensuring precise artifact identification.
 */

// A helper to test if a string matches UUIDv7 structure
// (8-4-4-4-12, where the 13th hex char is '7')
function isUUIDv7(uuid: string): boolean {
  const uuidV7Regex =
    /^[0-9a-f]{8}-[0-9a-f]{4}-7[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i;
  return uuidV7Regex.test(uuid);
}

export function extractArtifactId(markdownContent: string): string {
  // Extract YAML block strictly
  const match = markdownContent.match(/^---\n([\s\S]*?)\n---/);
  if (!match || !match[1]) {
    throw new Error("No YAML frontmatter found");
  }

  // Parse YAML block with std/yaml
  const metadata = yamlParse(match[1]) as Record<string, unknown>;

  const id = metadata["Artifact-ID"];
  if (!id || typeof id !== "string") {
    throw new Error("Missing or invalid Artifact-ID in frontmatter");
  }

  if (!isUUIDv7(id)) {
    throw new Error(`Artifact-ID ${id} is not a valid UUIDv7`);
  }

  return id;
}

if (import.meta.main) {
  console.log("Running Gen 2 Declarative Frontmatter PoC tests...");

  // Mock UUIDv7: 018fa031-6e3e-7a2e-8c4d-91b5a6c7d8e9
  const validMarkdown = `---
Artifact-ID: 018fa031-6e3e-7a2e-8c4d-91b5a6c7d8e9
Title: Authentication Architecture
Status: Draft
---

# Authentication Architecture
This document details the auth system...
`;

  const invalidMarkdown = `---
Artifact-ID: task-123
Title: Legacy Task
---

# Legacy System
`;

  try {
    const id = extractArtifactId(validMarkdown);
    assertEquals(id, "018fa031-6e3e-7a2e-8c4d-91b5a6c7d8e9");
    console.log(
      "✅ Gen 2 Frontmatter PoC successful: Correctly extracted UUIDv7 using std/yaml.",
    );

    // Test rejection of non-UUIDv7
    let failedAsExpected = false;
    try {
      extractArtifactId(invalidMarkdown);
    } catch (e: any) {
      if (e.message.includes("not a valid UUIDv7")) {
        failedAsExpected = true;
      }
    }
    assertEquals(failedAsExpected, true, "Should have rejected invalid UUID");

    console.log(
      "✅ Gen 2 Frontmatter PoC successful: Successfully rejected non-UUIDv7 artifact.",
    );
  } catch (err) {
    console.error("❌ Gen 2 Frontmatter PoC failed:", err);
    Deno.exit(1);
  }
}