import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";
import { getCompactionService } from "../pi-compaction/src/service.js";

function formatNumber(value: number): string {
  return new Intl.NumberFormat("en-US").format(Math.round(value));
}

export default function contextView(pi: ExtensionAPI): void {
  pi.registerCommand("context", {
    description: "Show the effective pi-compaction context projection",
    handler: async (_args, ctx) => {
      const sessionId = ctx.sessionManager.getSessionId();
      const metrics = getCompactionService()?.getMetrics(sessionId);
      const text = metrics
        ? [
            `Effective: ${formatNumber(metrics.effectiveTokens)} / ${formatNumber(metrics.contextWindow)} (${metrics.percent.toFixed(1)}%, ${metrics.confidence})`,
            `Raw: ${formatNumber(metrics.rawTokens)} / ${formatNumber(metrics.contextWindow)}`,
            `Reclaimed: ${formatNumber(metrics.reclaimedTokens)}`,
            `Segments: ${formatNumber(metrics.segmentCount)}`,
            `Masked tool results: ${formatNumber(metrics.maskedResults)}`,
            `Generation: ${formatNumber(metrics.generation)}`,
          ].join("\n")
        : "No pi-compaction projection is available yet. Send one message to build the first snapshot.";
      if (ctx.hasUI) ctx.ui.notify(text, "info");
      else process.stderr.write(`${text}\n`);
    },
  });
}