/**
 * manifest.js — Minimal manifest parsing and export lookup.
 *
 * The manifest is a JSON object with fields:
 *   schema, bundleType, tree, runtime, closure, roots, exports,
 *   imports, sections, metadata
 *
 * We parse only what we need for runtime entrypoint selection.
 */

/**
 * Validate the manifest against the runtime profile requirements.
 * Throws on violation.
 */
export function validateManifest(manifest) {
  if (manifest.schema !== "arboricx.bundle.manifest.v1") {
    throw new Error(
      `unsupported manifest schema: ${manifest.schema}`
    );
  }
  if (manifest.bundleType !== "tree-calculus-executable-object") {
    throw new Error(
      `unsupported bundle type: ${manifest.bundleType}`
    );
  }

  const tree = manifest.tree;
  if (tree.calculus !== "tree-calculus.v1") {
    throw new Error(`unsupported calculus: ${tree.calculus}`);
  }
  if (tree.nodeHash.algorithm !== "sha256") {
    throw new Error(
      `unsupported node hash algorithm: ${tree.nodeHash.algorithm}`
    );
  }
  if (tree.nodeHash.domain !== "arboricx.merkle.node.v1") {
    throw new Error(
      `unsupported node hash domain: ${tree.nodeHash.domain}`
    );
  }
  if (tree.nodePayload !== "arboricx.merkle.payload.v1") {
    throw new Error(`unsupported node payload: ${tree.nodePayload}`);
  }

  const runtime = manifest.runtime;
  if (runtime.semantics !== "tree-calculus.v1") {
    throw new Error(`unsupported runtime semantics: ${runtime.semantics}`);
  }
  if (runtime.abi !== "arboricx.abi.tree.v1") {
    throw new Error(`unsupported runtime ABI: ${runtime.abi}`);
  }
  if (runtime.capabilities && runtime.capabilities.length > 0) {
    throw new Error(
      `host/runtime capabilities not supported: ${runtime.capabilities.join(", ")}`
    );
  }

  if (manifest.closure !== "complete") {
    throw new Error("bundle v1 requires closure = complete");
  }
  if (manifest.imports && manifest.imports.length > 0) {
    throw new Error("bundle v1 requires an empty imports list");
  }
  if (!manifest.roots || manifest.roots.length === 0) {
    throw new Error("manifest has no roots");
  }
  if (!manifest.exports || manifest.exports.length === 0) {
    throw new Error("manifest has no exports");
  }

  for (const exp of manifest.exports) {
    if (!exp.name) {
      throw new Error("manifest export has empty name");
    }
    if (!exp.root) {
      throw new Error("manifest export has empty root");
    }
  }
}

/**
 * Select an export hash given a requested name.
 *
 * Selection strategy:
 *   1. Explicit export name
 *   2. Export named "main"
 *   3. Single export (auto-select)
 *   4. Error if multiple exports and no "main"
 */
export function selectExport(manifest, requestedName) {
  const exports = manifest.exports || [];

  // Strategy 1: explicit name
  if (requestedName) {
    const found = exports.find((e) => e.name === requestedName);
    if (found) {
      return found;
    }
    throw new Error(
      `requested export "${requestedName}" not found. Available: ${exports.map((e) => e.name).join(", ")}`
    );
  }

  // Strategy 2: prefer "main"
  const mainExport = exports.find((e) => e.name === "main");
  if (mainExport) {
    return mainExport;
  }

  // Strategy 3: single export
  if (exports.length === 1) {
    return exports[0];
  }

  // Strategy 4: multiple exports, require explicit
  throw new Error(
    `multiple exports available but none named "main": ${exports.map((e) => e.name).join(", ")}. Specify an export name.`
  );
}

/**
 * Get all root hashes from the manifest.
 */
export function getRootHashes(manifest) {
  return (manifest.roots || []).map((r) => r.hash);
}

/**
 * Get all export names.
 */
export function getExportNames(manifest) {
  return (manifest.exports || []).map((e) => e.name);
}

/**
 * Print manifest summary info.
 */
export function printManifestInfo(manifest, indent = "") {
  const tree = manifest.tree;
  const runtime = manifest.runtime;

  console.log(`${indent}Schema:          ${manifest.schema}`);
  console.log(`${indent}Bundle type:     ${manifest.bundleType}`);
  console.log(`${indent}Closure:         ${manifest.closure}`);
  console.log(`${indent}Tree calculus:   ${tree.calculus}`);
  console.log(`${indent}Hash algo:       ${tree.nodeHash.algorithm}`);
  console.log(`${indent}Hash domain:     ${tree.nodeHash.domain}`);
  console.log(`${indent}Runtime:         ${runtime.semantics}`);
  console.log(`${indent}ABI:             ${runtime.abi}`);
  console.log(`${indent}Evaluation:      ${runtime.evaluation || "N/A"}`);
  console.log("");
  console.log(`${indent}Roots (${getRootHashes(manifest).length}):`);
  for (const root of getRootHashes(manifest)) {
    console.log(`${indent}  ${root.substring(0, 16)}...`);
  }
  console.log("");
  console.log(`${indent}Exports (${getExportNames(manifest).length}):`);
  for (const name of getExportNames(manifest)) {
    console.log(`${indent}  ${name}`);
  }

  const meta = manifest.metadata;
  if (meta && meta.createdBy) {
    console.log("");
    console.log(`${indent}Created by:      ${meta.createdBy}`);
  }
}