import { auth } from "@/app/(auth)/auth";
import { getSystemSetting } from "@/lib/db/queries";
import {
  DEFAULT_BFL_BASE_URL,
  RealtimeCanvasConfig,
  resolveRealtimeProviders,
} from "@/lib/realtime/config";

const defaultConfig = {
  session: {
    idleTimeoutMs: 120000,
  },
  transport: {
    throttleInterval: 100,
    maxBuffering: 2,
  },
  image: {
    maxInputResolution: 1024,
    jpegQuality: 0.55,
  },
  model: {
    id: "flux-2-klein-4b",
    defaults: {
      steps: 3,
      cfgScale: 7,
      strength: 0.32,
      imageSize: "square" as const,
    },
    limits: {
      steps: { min: 1, max: 6 },
      cfgScale: { min: 1, max: 14 },
      strength: { min: 0.05, max: 1.0 },
    },
  },
  features: {
    history: true,
    abCompare: false,
  },
};

function clamp(value: number, min: number, max: number) {
  return Math.min(max, Math.max(min, value));
}

export async function GET() {
  const session = await auth();
  if (!session?.user?.id) {
    return Response.json({ code: "UNAUTHORIZED", message: "请先登录" }, { status: 401 });
  }

  const setting = await getSystemSetting({ key: "realtime_canvas_config" }).catch(() => null);
  const config = (setting?.value || {}) as RealtimeCanvasConfig;

  if (config.enabled === false) {
    return Response.json(
      { code: "FEATURE_DISABLED", message: "实时画布功能未开启" },
      { status: 403 }
    );
  }

  const providers = resolveRealtimeProviders(config);
  const activeProvider = providers[0];

  if (!activeProvider) {
    return Response.json(
      {
        code: "BFL_KEY_MISSING",
        message: "未配置可用的实时画布服务（请在服务器环境变量或设置中配置）",
      },
      { status: 500 }
    );
  }

  const throttleInterval = clamp(
    Number(config.throttleInterval || defaultConfig.transport.throttleInterval),
    60,
    260
  );
  const maxBuffering = clamp(
    Number(config.maxBuffering || defaultConfig.transport.maxBuffering),
    1,
    6
  );
  const maxInputResolution = clamp(
    Number(config.maxInputResolution || defaultConfig.image.maxInputResolution),
    512,
    1536
  );
  const jpegQuality = clamp(
    Number(config.jpegQuality || defaultConfig.image.jpegQuality),
    0.35,
    0.82
  );
  const steps = clamp(
    Number(config.defaults?.steps || defaultConfig.model.defaults.steps),
    defaultConfig.model.limits.steps.min,
    defaultConfig.model.limits.steps.max
  );
  const legacyScheduleMu = Number(config.defaults?.scheduleMu);
  const cfgScaleBase = Number(
    config.defaults?.cfgScale ??
      (Number.isFinite(legacyScheduleMu) ? legacyScheduleMu * 2.5 : defaultConfig.model.defaults.cfgScale)
  );
  const cfgScale = clamp(
    cfgScaleBase,
    defaultConfig.model.limits.cfgScale.min,
    defaultConfig.model.limits.cfgScale.max
  );
  const strength = clamp(
    Number(config.defaults?.strength ?? defaultConfig.model.defaults.strength),
    defaultConfig.model.limits.strength.min,
    defaultConfig.model.limits.strength.max
  );
  const imageSize = config.defaults?.imageSize === "square_hd" ? "square_hd" : "square";
  const modelId = activeProvider.model;

  return Response.json({
    ...defaultConfig,
    provider: {
      type: activeProvider.type,
      baseUrl: activeProvider.baseUrl || DEFAULT_BFL_BASE_URL,
    },
    failover: {
      enabled: providers.length > 1,
      fallbackProvider:
        providers.length > 1
          ? {
              type: providers[1].type,
              baseUrl: providers[1].baseUrl,
              model: providers[1].model,
            }
          : null,
    },
    transport: {
      throttleInterval,
      maxBuffering,
    },
    image: {
      maxInputResolution,
      jpegQuality,
    },
    model: {
      ...defaultConfig.model,
      id: modelId || defaultConfig.model.id,
      defaults: {
        steps,
        cfgScale,
        strength,
        imageSize,
      },
    },
    behavior: {
      strictSketch: config.strictSketch !== false,
      renderMode:
        config.renderMode === "strict-structure" || config.renderMode === "stylize"
          ? config.renderMode
          : "balanced",
    },
  });
}