/**
 * Patch: filter out self-sent Create activities in the AP inbox.
 *
 * When the local AP actor sends a post that mentions itself (e.g. cross-posting
 * loops, self-tagging, or loopback delivery), handleCreate receives a Create
 * activity whose actor URL matches ourActorUrl. Without a self-exclusion guard
 * these are stored as inbound notifications (type "mention" or "reply") and
 * displayed as "Anonymous" because the own actor is unreachable via hairpin NAT.
 *
 * Fix: insert a self-exclusion gate immediately after ourActorUrl is derived.
 * Defense-in-depth: also add `actorUrl !== ourActorUrl` to the mention tag check
 * so the mention branch is safe even if the gate is ever moved or regressed.
 */

import { access, readFile, writeFile } from "node:fs/promises";

const candidates = [
  "node_modules/@rmdes/indiekit-endpoint-activitypub/lib/inbox-handlers.js",
  "node_modules/@indiekit/indiekit/node_modules/@rmdes/indiekit-endpoint-activitypub/lib/inbox-handlers.js",
];

const patchSpecs = [
  {
    name: "ap-inbox-self-create-gate",
    marker: "// [patch] ap-inbox-self-create-gate",
    oldSnippet: `  const ourActorUrl = ctx.getActorUri(handle).href;
  const followersUrl = ctx.getFollowersUri(handle)?.href || "";

  if (computeVisibility(object, { ourActorUrl, followersUrl }) === "direct") {`,
    newSnippet: `  const ourActorUrl = ctx.getActorUri(handle).href;
  const followersUrl = ctx.getFollowersUri(handle)?.href || "";

  // [patch] ap-inbox-self-create-gate
  // Never process activities sent by our own actor as inbound — they produce
  // spurious "Anonymous" notifications due to hairpin NAT blocking self-fetch.
  if (actorUrl && actorUrl === ourActorUrl) return;

  if (computeVisibility(object, { ourActorUrl, followersUrl }) === "direct") {`,
  },
  {
    name: "ap-inbox-mention-self-guard",
    marker: "// [patch] ap-inbox-mention-self-guard",
    // Upstream fork (>= 32ea375) reads mention tags via getTags() and matches on
    // tag.constructor.name instead of tag.type. Anchor on the new line shape.
    oldSnippet: `      if (tag.constructor?.name === "Mention" && tag.href?.href === ourActorUrl) {`,
    newSnippet: `      if (tag.constructor?.name === "Mention" && tag.href?.href === ourActorUrl && actorUrl !== ourActorUrl) { // [patch] ap-inbox-mention-self-guard`,
  },
];

async function exists(filePath) {
  try {
    await access(filePath);
    return true;
  } catch {
    return false;
  }
}

const checkedFiles = new Set();
const patchedFiles = new Set();

for (const spec of patchSpecs) {
  let foundAnyTarget = false;

  for (const filePath of candidates) {
    if (!(await exists(filePath))) continue;

    foundAnyTarget = true;
    checkedFiles.add(filePath);

    const source = await readFile(filePath, "utf8");

    if (source.includes(spec.marker)) {
      continue;
    }

    if (!source.includes(spec.oldSnippet)) {
      console.warn(`[postinstall] ${spec.name}: oldSnippet not found in ${filePath} — upstream may have changed`);
      continue;
    }

    const updated = source.replace(spec.oldSnippet, spec.newSnippet);
    if (updated === source) continue;

    await writeFile(filePath, updated, "utf8");
    patchedFiles.add(filePath);
  }

  if (!foundAnyTarget) {
    console.log(`[postinstall] ${spec.name}: no target files found`);
  }
}

if (checkedFiles.size === 0) {
  console.log("[postinstall] ap-inbox-self-mention-filter: no target files found");
} else if (patchedFiles.size === 0) {
  console.log("[postinstall] ap-inbox-self-mention-filter: patches already applied");
} else {
  console.log(
    `[postinstall] Patched ap-inbox-self-mention-filter in ${patchedFiles.size}/${checkedFiles.size} file(s)`,
  );
}