import { defineTool } from "@earendil-works/pi-coding-agent";
import { Type } from "@sinclair/typebox";
import { steerAgent } from "../agent-runner.js";
import { logger } from "../logger.js";
import { formatLifetimeTokens, textResult } from "../tool-result-helpers.js";
import { getSessionContextPercent } from "../usage.js";
import type { ToolContext } from "./context.js";

export function createSteerTool(ctx: ToolContext) {
  return defineTool({
    name: "steer_subagent",
    label: "Steer Agent",
    description:
      "Send a steering message to a running agent. The message will interrupt the agent after its current tool execution " +
      "and be injected into its conversation, allowing you to redirect its work mid-run. Only works on running agents.",
    parameters: Type.Object({
      agent_id: Type.String({
        description: "The agent ID to steer (must be currently running).",
      }),
      message: Type.String({
        description: "The steering message to send. This will appear as a user message in the agent's conversation.",
      }),
    }),
    execute: async (_toolCallId, params, _signal, _onUpdate, _ctx) => {
      const record = ctx.manager.getRecord(params.agent_id);
      if (!record) {
        return textResult(`Agent not found: "${params.agent_id}". It may have been cleaned up.`);
      }
      if (record.status !== "running") {
        return textResult(`Agent "${params.agent_id}" is not running (status: ${record.status}). Cannot steer a non-running agent.`);
      }
      if (!record.session) {
        if (!record.pendingSteers) record.pendingSteers = [];
        record.pendingSteers.push(params.message);
        ctx.pi.events.emit("subagents:steered", { id: record.id, message: params.message });
        return textResult(`Steering message queued for agent ${record.id}. It will be delivered once the session initializes.`);
      }

      try {
        await steerAgent(record.session, params.message);
        ctx.hookRegistry
          .dispatch("subagent:steer", record.id, { message: params.message })
          .catch((err) => { logger.debug(`Hook dispatch error: ${err instanceof Error ? err.message : String(err)}`); });
        ctx.pi.events.emit("subagents:steered", { id: record.id, message: params.message });
        const tokens = formatLifetimeTokens(record);
        const contextPercent = getSessionContextPercent(record.session);
        const stateParts: string[] = [];
        if (tokens) stateParts.push(tokens);
        stateParts.push(`${record.toolUses} tool ${record.toolUses === 1 ? "use" : "uses"}`);
        if (contextPercent !== null) stateParts.push(`context ${Math.round(contextPercent)}% full`);
        if (record.compactionCount) stateParts.push(`${record.compactionCount} compaction${record.compactionCount === 1 ? "" : "s"}`);
        return textResult(
          `Steering message sent to agent ${record.id}. The agent will process it after its current tool execution.\n` +
          `Current state: ${stateParts.join(" · ")}`,
        );
      } catch (err) {
        return textResult(`Failed to steer agent: ${err instanceof Error ? err.message : String(err)}`);
      }
    },
  });
}