import { NextRequest, NextResponse } from "next/server";
import { getBoothConfig, getBoothStyles } from "@/lib/config";
import { checkRateLimit, incrementRateLimit } from "@/lib/rate-limit";
import { orchestrateGeneration } from "@/lib/ai/orchestrator";
import { isContentSafetyError } from "@/lib/ai/safety";
import { logGenerationEvent } from "@/lib/storage";
import { validateAndSanitizeImage, getClientIp } from "@/lib/security";

export async function POST(req: NextRequest) {
  const requestStartTime = Date.now();
  let clientId = "127.0.0.1";
  let selectedStyle: any = null;
  let requestedStyleId = "";

  try {
    const body = await req.json().catch(() => null);
    if (!body || typeof body !== "object") {
      return NextResponse.json(
        { error: "Invalid JSON request body" },
        { status: 400 }
      );
    }

    const { imageBase64, styleId, clientId: clientProvidedId, mimeType } = body;
    requestedStyleId = typeof styleId === "string" ? styleId.slice(0, 64) : "";

    const config = getBoothConfig();

    // 1. Image binary validation & magic bytes verification (rejects executables, scripts, etc.)
    const maxUploadBytes = (config.camera.maxUploadSizeMb || 10) * 1024 * 1024;
    const validation = validateAndSanitizeImage(imageBase64, maxUploadBytes);

    if (!validation.valid) {
      console.warn(`[Security Alert] Rejected image upload: ${validation.error}`);
      return NextResponse.json(
        { error: validation.error || "Invalid or disallowed image file" },
        { status: 400 }
      );
    }

    const styles = getBoothStyles();

    // Find requested style
    selectedStyle = styles.find((s) => s.id === styleId) || styles[0];
    if (!selectedStyle) {
      return NextResponse.json(
        { error: "No styles available in configuration" },
        { status: 400 }
      );
    }

    // Determine client identifier for rate-limiting (bind strictly to verified IP)
    const ip = getClientIp(req);
    // Sanitize optional device token if provided, but always prefix with verified IP so clients cannot evade IP quotas
    const safeClientTag = typeof clientProvidedId === "string" 
      ? clientProvidedId.replace(/[^a-zA-Z0-9_-]/g, "").slice(0, 32) 
      : "";
    clientId = safeClientTag ? `${ip}#${safeClientTag}` : ip;

    // Check device rate limit
    const limitCheck = checkRateLimit(
      clientId,
      config.limits.maxGenerationsPerDevice,
      config.limits.cooldownMinutes
    );

    if (!limitCheck.allowed) {
      // Record rate limit refusal
      await logGenerationEvent({
        styleId: selectedStyle.id,
        styleName: selectedStyle.name,
        provider: "unknown",
        model: "rate_limiter",
        durationMs: Date.now() - requestStartTime,
        status: "refused",
        errorType: "rate_limit",
        errorMessage: "Device reached maximum generation quota within cooldown window.",
        refusalReason: `Rate limit hit. Wait ${limitCheck.resetMinutes} min.`,
        clientId,
      });

      return NextResponse.json(
        {
          error: "Rate limit reached for this device.",
          remaining: 0,
          resetMinutes: limitCheck.resetMinutes,
        },
        { status: 429 }
      );
    }

    // Execute generation pipeline with sanitized image and verified MIME type
    const result = await orchestrateGeneration({
      config,
      style: selectedStyle,
      imageBase64: validation.sanitizedBase64!,
      mimeType: validation.mimeType,
    });

    // Save successful generation & image file to persistent storage
    const record = await logGenerationEvent({
      styleId: selectedStyle.id,
      styleName: selectedStyle.name,
      provider: result.providerUsed,
      model: result.modelUsed,
      durationMs: result.durationMs,
      status: "success",
      rawImageUrl: result.imageUrl,
      clientId,
    });

    // Increment usage for this device
    incrementRateLimit(clientId);

    const updatedLimit = checkRateLimit(
      clientId,
      config.limits.maxGenerationsPerDevice,
      config.limits.cooldownMinutes
    );

    const servedImageUrl = record.imageUrl || result.imageUrl;

    return NextResponse.json({
      success: true,
      imageUrl: servedImageUrl,
      providerUsed: result.providerUsed,
      modelUsed: result.modelUsed,
      durationMs: result.durationMs,
      fallbackTriggered: result.fallbackTriggered,
      remainingQuota: updatedLimit.remaining,
      warnings: result.warnings,
    });
  } catch (error: any) {
    console.error("[API Generate] Exception:", error);
    const isSafety = isContentSafetyError(error);

    // Record error or content safety refusal in admin logs
    try {
      await logGenerationEvent({
        styleId: selectedStyle?.id || requestedStyleId || "unknown",
        styleName: selectedStyle?.name || "Unknown Disguise",
        provider: error.provider || "unknown",
        model: error.model || "ai-pipeline",
        durationMs: Date.now() - requestStartTime,
        status: isSafety ? "refused" : "error",
        errorType: isSafety ? "safety_refusal" : "server_error",
        errorMessage: error.message || "An unexpected error occurred during generation.",
        refusalReason: isSafety
          ? (error.message || "Content safety filter blocked output")
          : undefined,
        clientId,
      });
    } catch (logErr) {
      console.error("[API Generate] Failed to log error event:", logErr);
    }

    return NextResponse.json(
      {
        success: false,
        isSafetyRejection: isSafety,
        error: isSafety
          ? "This photo was rejected by the content safety filter. Please snap or select a different photo."
          : (error.message || "An unexpected error occurred during generation."),
      },
      { status: isSafety ? 422 : 500 }
    );
  }
}