/**
 * goal-driven-loop extension for Pi.
 *
 * Wires together trigger detection, state injection, and timed
 * auto-defaults to eliminate unnecessary user interaction.
 */

import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";
import { join } from "node:path";
import { existsSync, unlinkSync } from "node:fs";
import { detectTrigger, isCoarseGrained } from "./trigger-detector.js";
import {
  readGoalState,
  buildInjectionText,
  buildContinuationPrompt,
} from "./state-injector.js";
import {
  promptStaleState,
  notifyCoarseGrainedDelegation,
  notifyStagnation,
  shouldNotifyStagnation,
  type UIContext,
} from "./ui-prompts.js";

const CONTEXT_TENSION_THRESHOLD = 0.8;
const ABANDON_KEYWORDS = ["abandon", "cancel", "不要了", "放弃", "停"];

export default function (pi: ExtensionAPI) {
  // ---- Trigger detection on user input ----
  pi.on("input", async (event, ctx) => {
    if (event.source === "extension") {
      return { action: "continue" };
    }

    // Check for explicit abandon first
    const lowerText = event.text.toLowerCase();
    const isAbandon = ABANDON_KEYWORDS.some((kw) =>
      lowerText.includes(kw.toLowerCase())
    );
    if (isAbandon) {
      const state = readGoalState(ctx.cwd);
      if (state) {
        handleAbandon(ctx);
        return { action: "continue" };
      }
    }

    // Try to detect a goal-setting trigger
    const match = detectTrigger(event.text);
    if (!match) {
      return { action: "continue" };
    }

    // Trigger detected — check stale state
    const existingState = readGoalState(ctx.cwd);
    if (existingState && existingState.status === "in-progress") {
      const ui = buildUIContext(ctx);
      const choice = await promptStaleState(ui);
      if (choice === "abandon") {
        handleAbandon(ctx);
        return { action: "continue" };
      }
      if (choice === "replace") {
        // Let the skill handle replacement on the next turn
        return { action: "continue" };
      }
      // "continue" or undefined → let the skill resume
    }

    // Granularity check
    if (isCoarseGrained(match.goalText)) {
      const ui = buildUIContext(ctx);
      notifyCoarseGrainedDelegation(ui, match.goalText);
      pi.sendUserMessage(`/skill:comet-open ${match.goalText}`, {
        deliverAs: "followUp",
      });
      return { action: "continue" };
    }

    // Fine-grained — let the skill handle it
    return { action: "continue" };
  });

  // ---- State injection on every agent start ----
  pi.on("before_agent_start", async (event, ctx) => {
    const state = readGoalState(ctx.cwd);
    if (!state) {
      return;
    }

    // Context tension check
    const usage = ctx.getContextUsage();
    if (
      usage &&
      usage.contextWindow > 0 &&
      usage.tokens / usage.contextWindow > CONTEXT_TENSION_THRESHOLD
    ) {
      const continuationMsg = buildContinuationPrompt(state);
      return {
        systemPrompt:
          event.systemPrompt +
          "\n\n" +
          continuationMsg +
          "\n\nContext is tight. Finalize .agents/goal/GOAL.md updates before completing this turn.",
      };
    }

    // Inject goal state
    const injection = buildInjectionText(state);
    return {
      systemPrompt: event.systemPrompt + "\n\n" + injection,
    };
  });
}

function buildUIContext(ctx: any): UIContext {
  return {
    hasUI: ctx.hasUI,
    select: ctx.ui.select.bind(ctx.ui),
    notify: ctx.ui.notify.bind(ctx.ui),
    confirm: ctx.ui.confirm.bind(ctx.ui),
  };
}

function handleAbandon(ctx: any): void {
  const goalPath = join(ctx.cwd, ".agents", "goal", "GOAL.md");
  try {
    if (existsSync(goalPath)) {
      unlinkSync(goalPath);
    }
  } catch {
    // best effort
  }
  if (ctx.hasUI) {
    ctx.ui.notify("目标已放弃", "info");
  }
}