fable-agent/src/fable5/forgejo-writeback.ts

import * as fs from "node:fs";
import * as path from "node:path";
import { findPromptInjection, type PromptInjectionFinding } from "../core/prompt-injection-safety.js";
import { emitChannelEvent } from "./channel.js";
import { parseForgejoRef } from "./forgejo-intake.js";

export type ForgejoWritebackAction = "comment" | "label";

type ForgejoWritebackFetch = (input: string, init?: { method?: string; headers?: Record<string, string>; body?: string }) => Promise<{ ok: boolean; status: number; json(): Promise<unknown> }>;

export interface ForgejoWritebackOptions {
  ref: string;
  action: ForgejoWritebackAction;
  body?: string;
  labels?: string[];
  repo?: string;
  baseUrl?: string;
  token?: string;
  outDir?: string;
  dryRun?: boolean;
  runId?: string;
  channelRoot?: string;
  now?: Date;
  fetcher?: ForgejoWritebackFetch;
}

export interface ForgejoWritebackReceipt {
  schema: "fable.forgejo.writeback.v1";
  createdAt: string;
  source: {
    ref: string;
    repo: string;
    id: string;
    kind: "issue" | "pull" | "wiki";
  };
  action: ForgejoWritebackAction;
  request: {
    body?: string;
    labels?: string[];
  };
  result: {
    status: "dry-run" | "posted" | "blocked";
    url?: string;
    httpStatus?: number;
  };
  receipts: {
    unicode_scan: "passed" | "failed";
    injection_scan: "passed" | "failed";
    deploy_attempted: false;
    quarantine: boolean;
    findings: PromptInjectionFinding[];
  };
}

export async function writebackForgejo(opts: ForgejoWritebackOptions): Promise<{ receipt: ForgejoWritebackReceipt; path?: string }> {
  const parsed = parseForgejoRef(opts.ref, opts.repo);
  if (parsed.kind === "wiki") throw new Error("Forgejo writeback supports issues and PRs only");
  const body = opts.body;
  const labels = opts.labels?.filter(Boolean);
  if (opts.action === "comment" && !body?.trim()) throw new Error("comment body is required");
  if (opts.action === "label" && (!labels || labels.length === 0)) throw new Error("at least one label is required");

  const findings = findPromptInjection(`${body ?? ""}\n${labels?.join("\n") ?? ""}`);
  const quarantine = findings.length > 0;
  const receipt = createReceipt(opts, parsed, findings, quarantine);

  if (!quarantine && !opts.dryRun) {
    const baseUrl = configuredBaseUrl(opts.baseUrl, parsed.baseUrl);
    const token = baseUrl.fromConfig ? opts.token : undefined;
    const res = await postWriteback({ ...opts, baseUrl: baseUrl.url, token, labels }, parsed, opts.fetcher ?? fetch);
    receipt.result.status = "posted";
    receipt.result.httpStatus = res.status;
    receipt.result.url = res.url;
  }

  if (quarantine) receipt.result.status = "blocked";
  if (opts.runId) emitChannelEvent(opts.runId, { source: "intake", type: "receipt", data: receipt }, opts.channelRoot, opts.now);
  if (opts.dryRun) return { receipt };

  const outDir = opts.outDir ?? ".fable/tasks";
  fs.mkdirSync(outDir, { recursive: true });
  const file = path.join(outDir, `forgejo-writeback-${opts.action}-${safeFilePart(parsed.id)}.json`);
  fs.writeFileSync(file, `${JSON.stringify(receipt, null, 2)}\n`);
  return { receipt, path: file };
}

function createReceipt(opts: ForgejoWritebackOptions, parsed: ReturnType<typeof parseForgejoRef>, findings: PromptInjectionFinding[], quarantine: boolean): ForgejoWritebackReceipt {
  return {
    schema: "fable.forgejo.writeback.v1",
    createdAt: (opts.now ?? new Date()).toISOString(),
    source: { ref: opts.ref, repo: parsed.repo, id: parsed.id, kind: parsed.kind },
    action: opts.action,
    request: { body: opts.body, labels: opts.labels },
    result: { status: opts.dryRun ? "dry-run" : quarantine ? "blocked" : "dry-run" },
    receipts: {
      unicode_scan: findings.some((f) => f.kind === "hidden-unicode") ? "failed" : "passed",
      injection_scan: findings.some((f) => f.kind !== "hidden-unicode") ? "failed" : "passed",
      deploy_attempted: false,
      quarantine,
      findings,
    },
  };
}

async function postWriteback(opts: ForgejoWritebackOptions & { baseUrl: string; labels?: string[] }, parsed: ReturnType<typeof parseForgejoRef>, fetcher: ForgejoWritebackFetch): Promise<{ status: number; url?: string }> {
  const base = opts.baseUrl.replace(/\/$/, "");
  const kindPath = parsed.kind === "pull" ? "pulls" : "issues";
  const endpoint = opts.action === "comment"
    ? `${base}/api/v1/repos/${parsed.repo}/${kindPath}/${encodeURIComponent(parsed.id)}/comments`
    : `${base}/api/v1/repos/${parsed.repo}/issues/${encodeURIComponent(parsed.id)}/labels`;
  const res = await fetcher(endpoint, {
    method: "POST",
    headers: {
      "content-type": "application/json",
      ...(opts.token ? { Authorization: `token ${opts.token}` } : {}),
    },
    body: JSON.stringify(opts.action === "comment" ? { body: opts.body } : { labels: opts.labels }),
  });
  if (!res.ok) throw new Error(`Forgejo API returned HTTP ${res.status}`);
  const json = await res.json() as { html_url?: string; url?: string };
  return { status: res.status, url: json.html_url ?? json.url };
}

function configuredBaseUrl(baseUrl: string | undefined, parsedBaseUrl: string | undefined): { url: string; fromConfig: boolean } {
  const configured = baseUrl?.replace(/\/$/, "");
  if (!configured && !parsedBaseUrl) throw new Error("FORGEJO_URL is required unless ref is a full Forgejo URL");
  if (configured && parsedBaseUrl && normalizedOrigin(configured) !== normalizedOrigin(parsedBaseUrl)) throw new Error("Forgejo reference host does not match configured FORGEJO_URL");
  return { url: configured ?? parsedBaseUrl!, fromConfig: Boolean(configured) };
}

function normalizedOrigin(value: string): string {
  return new URL(value).origin.replace(/\/$/, "").toLowerCase();
}

function safeFilePart(value: string): string {
  return value.replace(/[^A-Za-z0-9_.-]+/g, "-").replace(/(^-+)|(-+$)/g, "") || "item";
}