import { Router, type Request, type Response } from "express";
import { pricingService } from "../lib/pricing.js";
import { agentService } from "../lib/agent.js";
import { getBtcPriceUsd, usdToSats } from "../lib/btc-oracle.js";
import { freeTierService } from "../lib/free-tier.js";
import { trustService } from "../lib/trust.js";

const router = Router();

/**
 * GET /api/estimate?request=<text>[&nostr_token=<token>]
 *
 * Returns a pre-flight cost estimate for a request, including free-tier
 * status for the authenticated identity (if a valid nostr_token is supplied).
 *
 * No payment required. Does not create a job.
 */
router.get("/estimate", async (req: Request, res: Response) => {
  const requestText =
    typeof req.query.request === "string" ? req.query.request.trim() : "";

  if (!requestText) {
    res.status(400).json({ error: "Query param 'request' is required" });
    return;
  }

  try {
    const { estimatedInputTokens: inputTokens, estimatedOutputTokens: outputTokens, estimatedCostUsd: costUsd } =
      pricingService.estimateRequestCost(requestText, agentService.workModel);
    const btcPriceUsd  = await getBtcPriceUsd();
    const estimatedSats = usdToSats(costUsd, btcPriceUsd);

    // Optionally resolve Nostr identity from query param or header for free-tier preview
    const rawToken =
      (req.headers["x-nostr-token"] as string | undefined) ??
      (typeof req.query.nostr_token === "string" ? req.query.nostr_token : undefined);

    let pubkey: string | null = null;
    let trustTier = "anonymous";
    let freeTierDecision: { serve: string; absorbSats: number; chargeSats: number } | null = null;

    if (rawToken) {
      const parsed = trustService.verifyToken(rawToken.trim());
      if (parsed) {
        pubkey = parsed.pubkey;
        trustTier = await trustService.getTier(pubkey);
        const decision = await freeTierService.decideDryRun(pubkey, estimatedSats);
        freeTierDecision = {
          serve:       decision.serve,
          absorbSats:  decision.absorbSats,
          chargeSats:  decision.chargeSats,
        };
      }
    }

    const poolStatus = await freeTierService.poolStatus();

    res.json({
      estimatedSats,
      estimatedCostUsd: costUsd,
      btcPriceUsd,
      tokenEstimate: {
        inputTokens,
        outputTokens,
        model: agentService.workModel,
      },
      identity: {
        trust_tier:  trustTier,
        ...(pubkey ? { pubkey } : {}),
        ...(freeTierDecision ? { free_tier: freeTierDecision } : {}),
      },
      pool: {
        balanceSats:  poolStatus.balanceSats,
        dailyBudgets: poolStatus.budgets,
      },
    });
  } catch (err) {
    res.status(500).json({ error: err instanceof Error ? err.message : "Estimate failed" });
  }
});

export default router;