import { realpath } from "node:fs/promises";
import type { EventStore } from "../events/event-store.js";
import type { IndexedSkill, SkillIndex } from "./skill-catalog.js";

export type SkillEventInferenceOptions = {
  sessionId: string;
  runId: string;
  eventStore: EventStore;
  skillIndex: SkillIndex;
};

export class SkillEventInference {
  readonly #sessionId: string;
  readonly #runId: string;
  readonly #eventStore: EventStore;
  readonly #skillIndex: SkillIndex;
  readonly #pending = new Map<string, IndexedSkill>();

  public constructor(options: SkillEventInferenceOptions) {
    this.#sessionId = options.sessionId;
    this.#runId = options.runId;
    this.#eventStore = options.eventStore;
    this.#skillIndex = options.skillIndex;
  }

  public async onReadRequested(input: { toolCallId: string; path: string }): Promise<void> {
    let canonicalFilePath: string;
    try {
      canonicalFilePath = await realpath(input.path);
    } catch {
      return;
    }
    const skill = this.#skillIndex.find(canonicalFilePath);
    if (skill === undefined) return;

    this.#pending.set(input.toolCallId, skill);
    this.#eventStore.append(this.#sessionId, {
      type: "skill.requested",
      runId: this.#runId,
      payload: { name: skill.name, source: skill.source },
    });
  }

  public onReadCompleted(input: { toolCallId: string; success: boolean }): void {
    const skill = this.#pending.get(input.toolCallId);
    this.#pending.delete(input.toolCallId);
    if (skill === undefined || !input.success) return;

    this.#eventStore.append(this.#sessionId, {
      type: "skill.loaded",
      runId: this.#runId,
      payload: { name: skill.name, source: skill.source },
    });
  }
}