/**
 * OAS pi runtime bridge — minimal glue.
 *
 * The kernel materializes every spawned instance's exact set in
 * .agents/skills; this bridge contributes it inside an instance, plus the
 * pre-workspace oas-getting-started bootstrap outside one, and drives the
 * memory session events. Ambient skills coexist with the OAS-composed set.
 */
import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";
import { appendLogEntry, PACKAGED_SKILLS_DIR } from "./core-loader.mjs";
import { existsSync, readFileSync } from "node:fs";
import { join } from "node:path";

export default function (pi: ExtensionAPI) {
  const agentHome = process.env.PI_AGENT_HOME;
  const isInstance = !!agentHome && existsSync(join(agentHome, "instance.json"));

  pi.on("resources_discover", async () => {
    if (isInstance) {
      const local = join(agentHome!, ".agents", "skills");
      return existsSync(local) ? { skillPaths: [local] } : undefined;
    }
    const gettingStarted = join(PACKAGED_SKILLS_DIR, "oas-getting-started");
    return existsSync(gettingStarted) ? { skillPaths: [gettingStarted] } : undefined;
  });

  if (isInstance) {
    pi.on("session_compact", async (event) => {
      if (!existsSync(join(agentHome!, "STATE.md"))) return;
      try {
        const summary = (event.compactionEntry?.summary ?? "").replace(/\s+/g, " ").trim();
        appendLogEntry(
          join(agentHome!, "log.md"),
          `**Compaction** (${event.reason}): ${summary.slice(0, 400)}${summary.length > 400 ? "…" : ""}`,
          "Instance Log",
        );
      } catch { /* memory automation must never break a session */ }
      pi.sendMessage({
        customType: "oas-memory",
        content: "Context was just compacted. Before continuing, update ./STATE.md (Plan/Progress/Next) so a fresh session could resume from files alone.",
        display: false,
      }, { deliverAs: "steer" });
    });

    pi.on("session_start", async (event) => {
      if (event.reason !== "startup" && event.reason !== "resume" && event.reason !== "new") return;
      const statePath = join(agentHome!, "STATE.md");
      if (!existsSync(statePath)) return;
      const state = readFileSync(statePath, "utf8");
      const touched = !/_No task assigned yet/.test(state) || !/_\(the single next action/.test(state);
      if (event.reason === "startup" && !touched) return;
      pi.sendMessage({
        customType: "oas-memory",
        content: `You are agent instance home ${agentHome}. Read ./STATE.md and the recent entries of ./log.md now, then continue from STATE.md's "Next" section. Keep STATE.md current as you work.`,
        display: false,
      }, { deliverAs: "steer", triggerTurn: false });
    });
  }
}