/**
 * `initBrain` — the idempotent runtime scaffold for the second brain (SB-S0 D1/D5).
 *
 * Creates the `brain/` + `ingest/` tree under the per-user data dir (via the
 * `dataRoot` resolver, so `LINKEDIN_STUDIO_DATA` relocates it for tests + real
 * installs). Idempotent + migration-safe: a directory that exists is left alone,
 * a file that exists is NEVER rewritten (compare-then-skip, never blind-write) —
 * so a second run is a no-op and a user-edited file is preserved.
 *
 * NO session-start wiring (SB-S2 owns that) — this only ships the invokable init.
 */

import { existsSync, mkdirSync, readFileSync, writeFileSync } from "node:fs";
import { dirname, join } from "node:path";
import { fileURLToPath } from "node:url";

import { dataRoot } from "./dataRoot.js";
import { foldUserProfile, serializeProfile } from "./profile.js";

const HERE = dirname(fileURLToPath(import.meta.url));
/** The shipped template that defines the canonical profile field-set. */
const TEMPLATE_PATH = join(HERE, "..", "..", "..", "config", "user-profile.template.md");
/** The runtime instance (if the user copied + filled the template). */
const INSTANCE_SUB = join("profile", "user-profile.md");

const SCAFFOLD_DIRS = ["brain/journal", "ingest/inbox", "ingest/published"];

function today(): string {
  return new Date().toISOString().slice(0, 10);
}

function indexSeed(): string {
  return `# Brain — Index (MOC)

> Map of Content — one screen pointing at every tributary, with a freshness flag.
> Generated by \`brain init\`; safe to hand-edit (a re-run never clobbers it).

| Tributary | What it holds | Freshness |
|-----------|---------------|-----------|
| voice-samples | writing style | — |
| specifics-bank | lived raw material | — |
| trends | external signal | — |
| analytics | performance | — |
| ingest | inbox + published (the gold signal) | — |

- [profile.md](profile.md) — semantic, two-layer (static + dynamic) profile
- [operations.md](operations.md) — plans · ideas · the "who I am now" anchor
- journal/ — episodic, append-only session log (the consolidation loop's source)
`;
}

function operationsSeed(): string {
  return `# Operations

> The operations centre — where you're headed now, what you're working on, what you might
> do next. User-authored: the brain motor never writes here (a re-run of init never
> re-touches an existing file, so your edits are safe).

## Who I am now (anchor)

<!-- Frozen-past-self guard: a DATED, user-authored "where I'm headed now" statement.
     It deprecates older inferences — when a profile.md fact predates or contradicts this
     anchor, the anchor wins. Re-date it when your direction shifts. -->

_As of YYYY-MM-DD:_ <one or two sentences on your current direction — replace this line>

## Plans

<!-- Active commitments — what you're working toward now. One per line. -->

## Ideas

<!-- Parking lot — possible content/strategy ideas, not yet commitments. One per line. -->
`;
}

function profileSeed(): string {
  const templateText = readFileSync(TEMPLATE_PATH, "utf8");
  const instancePath = dataRoot(INSTANCE_SUB);
  const instanceText = existsSync(instancePath) ? readFileSync(instancePath, "utf8") : undefined;
  return serializeProfile(foldUserProfile({ templateText, instanceText, today: today() }));
}

export interface InitResult {
  /** Data-relative paths created this run. */
  created: string[];
  /** Data-relative paths that already existed and were left untouched. */
  skipped: string[];
}

/**
 * Create the brain scaffold idempotently. Returns the created/skipped split.
 * File content seeds are computed lazily, so an already-present file costs no
 * template read or fold.
 */
export function initBrain(): InitResult {
  const created: string[] = [];
  const skipped: string[] = [];

  for (const sub of SCAFFOLD_DIRS) {
    const abs = dataRoot(sub);
    if (existsSync(abs)) {
      skipped.push(sub);
    } else {
      mkdirSync(abs, { recursive: true });
      created.push(sub);
    }
  }

  const files: Array<{ sub: string; seed: () => string }> = [
    { sub: "brain/profile.md", seed: profileSeed },
    { sub: "brain/index.md", seed: indexSeed },
    { sub: "brain/operations.md", seed: operationsSeed },
  ];

  for (const { sub, seed } of files) {
    const abs = dataRoot(sub);
    if (existsSync(abs)) {
      skipped.push(sub);
      continue;
    }
    mkdirSync(dirname(abs), { recursive: true });
    writeFileSync(abs, seed(), "utf8");
    created.push(sub);
  }

  return { created, skipped };
}