#!/usr/bin/env node
import { createHash } from "node:crypto";
import { existsSync, lstatSync, readdirSync, readFileSync } from "node:fs";
import { join, relative, resolve } from "node:path";
import { execFileSync } from "node:child_process";
import { pathToFileURL } from "node:url";

const serviceId = "agentrun-mgr";
const envIdentityExcludedPaths = new Set([
  "scripts/ci-plan.mjs",
  "scripts/ci-plan.test.mjs",
  "scripts/ci/verify-reviewed-plan.mjs",
  "scripts/ci/verify-reviewed-plan.test.mjs",
]);

if (import.meta.url === pathToFileURL(process.argv[1]).href) {
  const options = parseArgs(process.argv.slice(2));
  const root = resolve(options.root);
  const sourceCommitId = git(root, ["rev-parse", options.targetRef]);
  const baseCommitId = git(root, ["rev-parse", options.baseRef]);
  const sourceChangedPaths = git(root, ["diff", "--name-only", baseCommitId, sourceCommitId]).split("\n").filter(Boolean);
  const materializationPaths = Array.isArray(options.materializationPaths) ? options.materializationPaths : [];
  const changedPaths = materializationPaths.length === 0
    ? sourceChangedPaths
    : sourceChangedPaths.filter((changedPath) => materializationPaths.some((inputPath) => changedPath === inputPath || changedPath.startsWith(`${inputPath}/`)));
  const envIdentity = calculateEnvIdentity({
    root,
    envIdentityFiles: JSON.parse(options.envIdentityFilesJson),
    buildArgs: JSON.parse(options.buildArgsJson),
    containerHttpProxy: options.containerHttpProxy,
    containerHttpsProxy: options.containerHttpsProxy,
    containerNoProxy: options.containerNoProxy,
  });
  const registryProbe = await probeRegistry({
    registryProbeBase: options.registryProbeBase,
    imageRepository: options.imageRepository,
    envIdentity,
  });
  process.stdout.write(`${JSON.stringify(createPlan({
    sourceCommitId,
    baseCommitId,
    target: options.target,
    consumer: options.consumer,
    lane: options.lane,
    changedPaths,
    envIdentity,
    imageRepository: options.imageRepository,
    registryProbe,
  }))}\n`);
}

export function calculateEnvIdentity(input) {
  const root = resolve(input.root);
  const hash = createHash("sha256");
  for (const item of input.buildArgs) {
    hash.update("build-arg\0");
    hash.update(item);
    hash.update("\0");
  }
  for (const item of [
    `HTTP_PROXY=${input.containerHttpProxy || ""}`,
    `HTTPS_PROXY=${input.containerHttpsProxy || ""}`,
    `NO_PROXY=${input.containerNoProxy || ""}`,
  ]) {
    hash.update("build-container-proxy\0");
    hash.update(item);
    hash.update("\0");
  }
  for (const inputPath of input.envIdentityFiles) {
    for (const entry of collectFiles(root, inputPath)) {
      hash.update(entry.path);
      hash.update("\0");
      if (!entry.missing) hash.update(readFileSync(join(root, entry.path)));
      hash.update("\0");
    }
  }
  return hash.digest("hex").slice(0, 24);
}

export function createPlan(input) {
  const affectedServices = input.changedPaths.length > 0 ? [serviceId] : [];
  const rolloutServices = [...affectedServices];
  const buildServices = affectedServices.length > 0 && input.registryProbe.status !== "present" ? [serviceId] : [];
  const registryProbe = {
    enabled: true,
    services: [{
      serviceId,
      imageRepository: input.imageRepository,
      envIdentity: input.envIdentity,
      status: input.registryProbe.status,
      digest: input.registryProbe.digest ?? null,
    }],
  };
  const identityInput = {
    version: "v1",
    inputs: {
      target: input.target,
      consumer: input.consumer,
      lane: input.lane,
      sourceCommitId: input.sourceCommitId,
      baseCommitId: input.baseCommitId,
      catalog: null,
      registryProbe,
    },
    scope: { buildServices, rolloutServices, affectedServices },
  };
  return {
    sourceCommitId: input.sourceCommitId,
    baseCommitId: input.baseCommitId,
    changedPaths: input.changedPaths,
    services: [{ serviceId, changedPaths: input.changedPaths }],
    envIdentity: input.envIdentity,
    imageRepository: input.imageRepository,
    registryProbe,
    envArtifactGroups: [{
      id: "agentrun-runtime-env",
      buildService: serviceId,
      imageRepository: input.imageRepository,
      buildRequired: buildServices.length > 0,
      services: [serviceId],
      buildServices,
      consumerServices: [serviceId],
    }],
    reusedServices: input.registryProbe.status === "present" ? [serviceId] : [],
    serviceReusedCount: input.registryProbe.status === "present" ? 1 : 0,
    imageBuildSkippedServices: input.registryProbe.status === "present" ? [serviceId] : [],
    buildServices,
    rolloutServices,
    affectedServices,
    planIdentity: {
      value: `sha256:${createHash("sha256").update(stable(identityInput)).digest("hex")}`,
      inputs: identityInput.inputs,
      scope: identityInput.scope,
    },
    valuesPrinted: false,
  };
}

async function probeRegistry({ registryProbeBase, imageRepository, envIdentity }) {
  const base = registryProbeBase.replace(/\/+$/u, "");
  const repositoryPath = imageRepository.replace(/^[^/]+\//u, "");
  let response;
  try {
    response = await fetch(`${base}/v2/${repositoryPath}/manifests/${envIdentity}`, {
      method: "HEAD",
      headers: { Accept: "application/vnd.oci.image.index.v1+json, application/vnd.oci.image.manifest.v1+json, application/vnd.docker.distribution.manifest.v2+json" },
      signal: AbortSignal.timeout(5000),
    });
  } catch (error) {
    throw new Error(`registry probe failed: ${error instanceof Error ? error.message : String(error)}`);
  }
  if (response.status === 404) return { status: "missing", digest: null };
  if (!response.ok) throw new Error(`registry probe failed with HTTP ${response.status}`);
  const digest = response.headers.get("docker-content-digest");
  if (!digest) throw new Error("registry probe succeeded without docker-content-digest");
  return { status: "present", digest };
}

function collectFiles(root, inputPath) {
  const absolute = join(root, inputPath);
  if (!existsSync(absolute)) return [{ path: inputPath, missing: true }];
  const stat = lstatSync(absolute);
  if (stat.isFile()) return [{ path: inputPath, missing: false }];
  if (!stat.isDirectory()) return [{ path: inputPath, missing: true }];
  const skip = new Set([".git", ".worktree", ".state", "node_modules", "coverage", "tmp", ".tmp"]);
  const files = [];
  const stack = [absolute];
  while (stack.length > 0) {
    const directory = stack.pop();
    for (const entry of readdirSync(directory, { withFileTypes: true }).sort((left, right) => left.name.localeCompare(right.name))) {
      if (entry.isDirectory() && skip.has(entry.name)) continue;
      const child = join(directory, entry.name);
      if (entry.isDirectory()) stack.push(child);
      else if (entry.isFile()) files.push({ path: relative(root, child), missing: false });
    }
  }
  return files
    .filter((entry) => !envIdentityExcludedPaths.has(entry.path))
    .sort((left, right) => left.path.localeCompare(right.path));
}

function stable(value) {
  if (Array.isArray(value)) return `[${value.map(stable).join(",")}]`;
  if (value && typeof value === "object") return `{${Object.keys(value).sort().map((key) => `${JSON.stringify(key)}:${stable(value[key])}`).join(",")}}`;
  return JSON.stringify(value);
}

function git(root, args) {
  return execFileSync("git", args, { cwd: root, encoding: "utf8" }).trim();
}

function parseArgs(argv) {
  const result = { root: "." };
  for (let index = 0; index < argv.length; index += 1) {
    const name = argv[index];
    if (!name.startsWith("--")) throw new Error(`unexpected argument ${name}`);
    const key = name.slice(2).replace(/-([a-z])/gu, (_match, letter) => letter.toUpperCase());
    const value = argv[++index];
    if (!value || value.startsWith("--")) throw new Error(`${name} requires a value`);
    result[key] = value;
  }
  if (typeof result.configFile === "string") {
    const configured = JSON.parse(readFileSync(result.configFile, "utf8"));
    for (const [key, value] of Object.entries(configured)) {
      if (result[key] === undefined) result[key] = value;
    }
  }
  for (const key of ["baseRef", "targetRef", "target", "consumer", "lane", "imageRepository", "registryProbeBase", "envIdentityFilesJson", "buildArgsJson", "containerHttpProxy", "containerHttpsProxy", "containerNoProxy"]) {
    if (typeof result[key] !== "string") throw new Error(`--${key.replace(/[A-Z]/gu, (letter) => `-${letter.toLowerCase()}`)} is required`);
  }
  return result;
}