import { execFileSync, spawnSync } from "node:child_process";
import { mkdtempSync, rmSync, writeFileSync } from "node:fs";
import { tmpdir } from "node:os";
import { join } from "node:path";
import { MEMORY_CONSTRAINTS_VALIDATOR_SCRIPT } from "./memory-constraints";

export interface MemoryConstraintsValidationResult {
  valid: boolean;
  output: string;
}

/** Validate the committed MemFS tree without changing its index or working tree. */
export function validateMemoryConstraintsHead(
  memoryDir: string,
): MemoryConstraintsValidationResult {
  const tempDir = mkdtempSync(join(tmpdir(), "letta-memory-audit-"));
  const indexPath = join(tempDir, "index");
  const validatorPath = join(tempDir, "validator.cjs");
  const env = { ...process.env, GIT_INDEX_FILE: indexPath };

  try {
    execFileSync("git", ["read-tree", "HEAD"], {
      cwd: memoryDir,
      env,
      stdio: ["ignore", "pipe", "pipe"],
    });
    const hasRootMarker =
      spawnSync("git", ["cat-file", "-e", "HEAD:MEMORY.md"], {
        cwd: memoryDir,
        stdio: "ignore",
      }).status === 0;
    writeFileSync(validatorPath, MEMORY_CONSTRAINTS_VALIDATOR_SCRIPT, "utf8");
    const result = spawnSync(
      "node",
      [
        validatorPath,
        "--layout",
        hasRootMarker ? "root-marker" : "legacy-only",
        "--audit",
      ],
      {
        cwd: memoryDir,
        encoding: "utf8",
        env,
      },
    );
    return {
      valid: result.status === 0,
      output: `${result.stdout ?? ""}${result.stderr ?? ""}`.trim(),
    };
  } catch (error) {
    return {
      valid: false,
      output: error instanceof Error ? error.message : String(error),
    };
  } finally {
    rmSync(tempDir, { recursive: true, force: true });
  }
}