/**
 * VersionGuard — INV-16's editor face (spec §6.2/§6.4, PUC-4): a sidecar whose
 * schemaVersion major is newer than this extension understands is READ-ONLY.
 * Controllers render best-effort but skip every store.update path; the user is
 * warned ONCE per document. One shared instance (extension.ts) because the
 * sidecar is co-owned by three controllers — one warning, not three. The
 * store's update() throw is the backstop; this gate is the UX.
 */
import * as vscode from "vscode";
import { SCHEMA_VERSION, isNewerMajor } from "./model";
import type { SidecarStore } from "./sidecarStore";

export class VersionGuard {
  private readonly warned = new Set<string>();

  constructor(private readonly store: SidecarStore) {}

  /** True → skip the write path (and warn once per doc). */
  isReadOnly(docPath: string): boolean {
    const artifact = this.store.load(docPath);
    if (!artifact || !isNewerMajor(artifact)) return false;
    if (!this.warned.has(docPath)) {
      this.warned.add(docPath);
      void vscode.window.showWarningMessage(
        `Cowriting: ${docPath}'s coauthoring sidecar is schemaVersion ${artifact.schemaVersion} — newer than this extension understands (${SCHEMA_VERSION}). Showing what it can; writing nothing (INV-16). Upgrade the extension to edit the record.`,
      );
    }
    return true;
  }

  /** Test-facing: did the newer-major warning fire for this doc? */
  wasWarned(docPath: string): boolean {
    return this.warned.has(docPath);
  }
}