#!/usr/bin/env bun
/**
 * Validates YAML frontmatter in agent, skill, and command .md files.
 *
 * Usage:
 *   bun validate-frontmatter.ts                    # scan current directory
 *   bun validate-frontmatter.ts /path/to/dir       # scan specific directory
 *   bun validate-frontmatter.ts file1.md file2.md  # validate specific files
 */

import { parse as parseYaml } from "yaml";
import { readdir, readFile } from "fs/promises";
import { basename, join, relative, resolve } from "path";

// Characters that require quoting in YAML values when unquoted:
// {} [] flow indicators, * anchor/alias, & anchor, # comment,
// ! tag, | > block scalars, % directive, @ ` reserved
const YAML_SPECIAL_CHARS = /[{}[\]*&#!|>%@`]/;
const FRONTMATTER_REGEX = /^---\s*\n([\s\S]*?)---\s*\n?/;

/**
 * Pre-process frontmatter text to quote values containing special YAML
 * characters. This allows glob patterns like **\/*.{ts,tsx} to parse.
 */
function quoteSpecialValues(text: string): string {
  const lines = text.split("\n");
  const result: string[] = [];

  for (const line of lines) {
    const match = line.match(/^([a-zA-Z_-]+):\s+(.+)$/);
    if (match) {
      const [, key, value] = match;
      if (!key || !value) {
        result.push(line);
        continue;
      }
      // Skip already-quoted values
      if (
        (value.startsWith('"') && value.endsWith('"')) ||
        (value.startsWith("'") && value.endsWith("'"))
      ) {
        result.push(line);
        continue;
      }
      if (YAML_SPECIAL_CHARS.test(value)) {
        const escaped = value.replace(/\\/g, "\\\\").replace(/"/g, '\\"');
        result.push(`${key}: "${escaped}"`);
        continue;
      }
    }
    result.push(line);
  }

  return result.join("\n");
}

interface ParseResult {
  frontmatter: Record<string, unknown>;
  content: string;
  error?: string;
}

function parseFrontmatter(markdown: string): ParseResult {
  const match = markdown.match(FRONTMATTER_REGEX);

  if (!match) {
    return {
      frontmatter: {},
      content: markdown,
      error: "No frontmatter found",
    };
  }

  const frontmatterText = quoteSpecialValues(match[1] || "");
  const content = markdown.slice(match[0].length);

  try {
    const parsed = parseYaml(frontmatterText);
    if (parsed && typeof parsed === "object" && !Array.isArray(parsed)) {
      return { frontmatter: parsed as Record<string, unknown>, content };
    }
    return {
      frontmatter: {},
      content,
      error: `YAML parsed but result is not an object (got ${typeof parsed}${Array.isArray(parsed) ? " array" : ""})`,
    };
  } catch (err) {
    return {
      frontmatter: {},
      content,
      error: `YAML parse failed: ${err instanceof Error ? err.message : err}`,
    };
  }
}

// --- Validation ---

type FileType = "agent" | "skill" | "command";

interface ValidationIssue {
  level: "error" | "warning";
  message: string;
}

function validateAgent(
  frontmatter: Record<string, unknown>
): ValidationIssue[] {
  const issues: ValidationIssue[] = [];

  if (!frontmatter["name"] || typeof frontmatter["name"] !== "string") {
    issues.push({ level: "error", message: 'Missing required "name" field' });
  }
  if (
    !frontmatter["description"] ||
    typeof frontmatter["description"] !== "string"
  ) {
    issues.push({
      level: "error",
      message: 'Missing required "description" field',
    });
  }

  return issues;
}

function validateSkill(
  frontmatter: Record<string, unknown>
): ValidationIssue[] {
  const issues: ValidationIssue[] = [];

  if (!frontmatter["description"] && !frontmatter["when_to_use"]) {
    issues.push({
      level: "error",
      message: 'Missing required "description" field',
    });
  }

  return issues;
}

function validateCommand(
  frontmatter: Record<string, unknown>
): ValidationIssue[] {
  const issues: ValidationIssue[] = [];

  if (
    !frontmatter["description"] ||
    typeof frontmatter["description"] !== "string"
  ) {
    issues.push({
      level: "error",
      message: 'Missing required "description" field',
    });
  }

  return issues;
}

// --- File type detection ---

function detectFileType(filePath: string): FileType | null {
  if (filePath.includes("/agents/")) return "agent";
  if (filePath.includes("/skills/") && basename(filePath) === "SKILL.md")
    return "skill";
  if (filePath.includes("/commands/")) return "command";
  return null;
}

// --- File discovery ---

async function findMdFiles(
  baseDir: string
): Promise<{ path: string; type: FileType }[]> {
  const results: { path: string; type: FileType }[] = [];

  async function walk(dir: string) {
    const entries = await readdir(dir, { withFileTypes: true });
    for (const entry of entries) {
      const fullPath = join(dir, entry.name);
      if (entry.isDirectory()) {
        await walk(fullPath);
      } else if (entry.name.endsWith(".md")) {
        const type = detectFileType(fullPath);
        if (type) {
          results.push({ path: fullPath, type });
        }
      }
    }
  }

  await walk(baseDir);
  return results;
}

// --- Main ---

async function main() {
  const args = process.argv.slice(2);

  let files: { path: string; type: FileType }[];
  let baseDir: string;

  if (args.length > 0 && args.every((a) => a.endsWith(".md"))) {
    baseDir = process.cwd();
    files = [];
    for (const arg of args) {
      const fullPath = resolve(arg);
      const type = detectFileType(fullPath);
      if (type) {
        files.push({ path: fullPath, type });
      }
    }
  } else {
    baseDir = args[0] || process.cwd();
    files = await findMdFiles(baseDir);
  }

  let totalErrors = 0;
  let totalWarnings = 0;

  console.log(`Validating ${files.length} frontmatter files...\n`);

  for (const { path: filePath, type } of files) {
    const rel = relative(baseDir, filePath);
    const content = await readFile(filePath, "utf-8");
    const result = parseFrontmatter(content);

    const issues: ValidationIssue[] = [];

    if (result.error) {
      issues.push({ level: "error", message: result.error });
    }

    if (!result.error) {
      switch (type) {
        case "agent":
          issues.push(...validateAgent(result.frontmatter));
          break;
        case "skill":
          issues.push(...validateSkill(result.frontmatter));
          break;
        case "command":
          issues.push(...validateCommand(result.frontmatter));
          break;
      }
    }

    if (issues.length > 0) {
      console.log(`${rel} (${type})`);
      for (const issue of issues) {
        const prefix = issue.level === "error" ? "  ERROR" : "  WARN ";
        console.log(`${prefix}: ${issue.message}`);
        if (issue.level === "error") totalErrors++;
        else totalWarnings++;
      }
      console.log();
    }
  }

  console.log("---");
  console.log(
    `Validated ${files.length} files: ${totalErrors} errors, ${totalWarnings} warnings`
  );

  if (totalErrors > 0) {
    process.exit(1);
  }
}

main().catch((err) => {
  console.error("Fatal error:", err);
  process.exit(2);
});