import fs from "node:fs/promises";
import path from "node:path";
import os from "node:os";
import { execFile as execFileCallback } from "node:child_process";
import { promisify } from "node:util";
import { createHash } from "node:crypto";
import { compileWorkspaceRepository, compileCapabilityResourceRepository } from "./assembly.js";
import { createGitCapabilityResolver } from "./git-resolver.js";
import { contentDigest, planEvolution, type EvolutionReview, type WorkspaceRevision } from "../capability-model/index.js";
import { bindingSchema } from "../bindings/index.js";
import {snapshotCommit, checkoutCommit, buildCheckedPackage} from "./checked-build.js";
const execFile = promisify(execFileCallback);
const bytesDigest = (value: Uint8Array) => `sha256:${createHash("sha256").update(value).digest("hex")}`;

export const localResourceSnapshots = async (root: string, filename?: string): Promise<{resources: {kind: string; repository: string; commit: string; directory: string}[]}> => {
  if (filename) {
    const document = JSON.parse(await fs.readFile(filename, "utf8"));
    return {resources: document.resources.map((entry: {directory: string}) => ({...entry, directory: path.resolve(path.dirname(filename), entry.directory)}))};
  }
  let directory = await fs.realpath(root);
  for (;;) {
    let graphText: string | undefined;
    try {graphText = await fs.readFile(path.join(directory, ".quixos/resource-graph.json"), "utf8");}
    catch (error) {if ((error as NodeJS.ErrnoException).code !== "ENOENT") throw error;}
    if (graphText !== undefined) {
      const graph = JSON.parse(graphText);
      const resources = [];
      for (const entry of graph.resources) {
        const location = await fs.realpath(path.resolve(directory, entry.directory));
        if (!location.startsWith(`${directory}/resources/`)) throw new Error("Workbench resource escapes managed directory");
        resources.push({kind: entry.kind, ...entry.source, directory: location});
      }
      return {resources};
    }
    const parent = path.dirname(directory);
    if (parent === directory) return {resources: []};
    directory = parent;
  }
};

/** Copy actual authoring files without snapshotting jj or creating a Git commit. */
export const snapshotRepository = async (source: string, destination: string) => {
  const root = await fs.realpath(source);
  const files = async () => (await execFile("git", ["-C", root, "ls-files", "--cached", "--others", "--exclude-standard", "-z"], { maxBuffer: 16 * 1024 * 1024 })).stdout.split("\0").filter(Boolean).sort();
  const names = [...new Set(await files())];
  if (names.length > 50_000) throw new Error("Candidate source exceeds 50000 files");
  const contents: {name: string; digest: string; mode: number}[] = [];
  let bytes = 0;
  await fs.mkdir(destination, { recursive: true, mode: 0o700 });
  for (const name of names) {
    if (path.isAbsolute(name) || name.split(/[\\/]/).some((part) => part === ".." || part === ".git" || part === ".jj")) throw new Error("Invalid candidate source path");
    const file = path.join(root, name);
    let metadata;
    try { metadata = await fs.lstat(file); } catch (error) { if ((error as NodeJS.ErrnoException).code === "ENOENT") continue; throw error; }
    if (!metadata.isFile() || metadata.isSymbolicLink() || !(await fs.realpath(file)).startsWith(`${root}${path.sep}`)) throw new Error(`Candidate source must be a regular file: ${name}`);
    const data = await fs.readFile(file);
    bytes += data.length;
    if (bytes > 128 * 1024 * 1024) throw new Error("Candidate source exceeds 128 MiB");
    contents.push({ name, digest: bytesDigest(data), mode: metadata.mode & 0o777 });
    await fs.mkdir(path.dirname(path.join(destination, name)), { recursive: true });
    await fs.writeFile(path.join(destination, name), data, { flag: "wx", mode: metadata.mode & 0o777 });
  }
  if (JSON.stringify([...new Set(await files())]) !== JSON.stringify(names)) throw new Error("Source files changed during candidate snapshot");
  for (const entry of contents) if (bytesDigest(await fs.readFile(path.join(root, entry.name))) !== entry.digest) throw new Error(`Source changed during candidate snapshot: ${entry.name}`);
  return { source: root, directory: destination, treeDigest: contentDigest(contents), files: contents };
};

// Local mirrors accelerate resolution, but only their committed locked trees
// may stand in for published dependencies. Never relabel dirty files as a pin.
async function committedResolver(root: string, temporary: string, filename?: string, publishedOnly = false) {
  const map = publishedOnly ? {resources: []} : await localResourceSnapshots(root, filename);
  const resources = [];
  for (const [index, entry] of map.resources.entries()) {
    const directory = path.join(temporary, `dependency-${index}`);
    await checkoutCommit(entry.directory, entry.commit, directory);
    resources.push({...entry, directory});
  }
  const snapshotMap = path.join(temporary, "snapshots.json");
  await fs.writeFile(snapshotMap, JSON.stringify({resources}));
  return createGitCapabilityResolver({checkoutRoot: path.join(temporary, "resolved"), snapshotMap});
}

export const checkResourceCandidate = async (options: {root: string; output: string; kind: "package" | "interface"; source: {repository: string; commit: string}; snapshotMap?: string; publishedOnly?: boolean}) => {
  await fs.mkdir(options.output, {mode: 0o700});
  const temporary = await fs.mkdtemp(path.join(os.tmpdir(), "qx-resource-check-"));
  const blockers: string[] = [];
  let treeDigest: string | undefined, commit: string | undefined, artifactPath: string | undefined;
  try {
    commit = await snapshotCommit(options.root);
    treeDigest = (await snapshotRepository(options.root, path.join(temporary, "observed"))).treeDigest;
    const root = path.join(temporary, "source");
    await checkoutCommit(options.root, commit, root);
    const resolveResource = await committedResolver(options.root, temporary, options.snapshotMap, options.publishedOnly);
    const compiled = await compileCapabilityResourceRepository({rootDirectory: root, kind: options.kind, source: {resolver: "git", repository: options.source.repository, commit}, resolveResource});
    if (compiled.resource.kind === "package") {
      const schema = path.join(temporary, "bindings.json");
      await fs.writeFile(schema, JSON.stringify(bindingSchema(compiled)));
      artifactPath = await buildCheckedPackage(root, schema, compiled.resource.revision.revisionId);
    }
    if (await snapshotCommit(options.root) !== commit) throw new Error("Source changed during verification; run the check again");
    await fs.writeFile(path.join(options.output, "candidate.json"), JSON.stringify(compiled.resource, null, 2));
  } catch (error) {
    blockers.push(error instanceof Error ? error.message : String(error));
  } finally {await fs.rm(temporary, {recursive: true, force: true});}
  const result = {candidateOnly: true, activationEvidence: false, commit, treeDigest, artifactPath, blockers,
    note: "Checked immutable candidate; cutover independently checks current migration/review requirements. No publication or activation performed."};
  await fs.writeFile(path.join(options.output, "report.json"), JSON.stringify(result, null, 2));
  return result;
};

export const checkWorkspaceCandidate = async (options: {root: string; output: string; snapshotMap?: string; baseline?: string; reviews?: string}) => {
  await fs.mkdir(options.output, {mode: 0o700});
  const temporary = await fs.mkdtemp(path.join(os.tmpdir(), "qx-workspace-check-"));
  const blockers: string[] = [], checks: {packageRevisionId: string; artifactPath: string}[] = [];
  let commit: string | undefined;
  try {
    commit = await snapshotCommit(options.root);
    for (const entry of (await localResourceSnapshots(options.root, options.snapshotMap)).resources) {
      const current = await snapshotCommit(entry.directory);
      const tree = async (revision: string) => (await execFile("git", ["rev-parse", `${revision}^{tree}`], {cwd: entry.directory})).stdout.trim();
      if (await tree(current) !== await tree(entry.commit)) throw new Error(`Edited resource is not in the root's locked candidate: ${entry.directory}. Check that resource, then run qx-workspace resource upgrade --publish to propagate its revision.`);
    }
    const root = path.join(temporary, "source");
    await checkoutCommit(options.root, commit, root);
    const resolveResource = await committedResolver(options.root, temporary, options.snapshotMap);
    const compiled = await compileWorkspaceRepository({rootDirectory: root, sourceRootCommit: commit, resolveResource});
    const baseline = options.baseline ? JSON.parse(await fs.readFile(options.baseline, "utf8")) as WorkspaceRevision : null;
    const reviews = options.reviews ? JSON.parse(await fs.readFile(options.reviews, "utf8")) as EvolutionReview[] : [];
    const evolution = planEvolution(baseline, compiled.workspace, {reviews});
    blockers.push(...evolution.blockers);
    for (const resource of compiled.resources.filter(entry => entry.kind === "package")) {
      // Per-package recursive schema, identical to host activation, not unrelated
      // workspace declarations that would unnecessarily invalidate build caches.
      const candidate = await compileCapabilityResourceRepository({rootDirectory: resource.directory, kind: "package", source: resource.source, resolveResource});
      const schema = path.join(temporary, "bindings.json");
      await fs.writeFile(schema, JSON.stringify(bindingSchema(candidate)));
      const artifactPath = await buildCheckedPackage(resource.directory, schema, candidate.resource.revision.revisionId);
      checks.push({packageRevisionId: candidate.resource.revision.revisionId, artifactPath});
    }
    if (await snapshotCommit(options.root) !== commit) throw new Error("Source changed during verification; run the check again");
    const result = {schemaVersion: 1, candidateOnly: true, activationEvidence: false, commit, evolution, checks, blockers,
      note: "Checks the committed root and its exact locked dependencies. Resource edits must be verified and repinned before they enter this candidate. No publication or activation performed."};
    await fs.writeFile(path.join(options.output, "candidate.json"), JSON.stringify(compiled.workspace, null, 2));
    await fs.writeFile(path.join(options.output, "report.json"), JSON.stringify(result, null, 2));
    return result;
  } catch (error) {
    const result = {schemaVersion: 1, candidateOnly: true, activationEvidence: false, commit, checks, blockers: [...blockers, error instanceof Error ? error.message : String(error)]};
    await fs.writeFile(path.join(options.output, "report.json"), JSON.stringify(result, null, 2));
    return result;
  } finally {await fs.rm(temporary, {recursive: true, force: true});}
};