import { useCallback, useRef, useState } from "react";
import type { RuntimeModelFile } from "../features/runtime/types";
import { resolveAlias } from "../lib/modelAlias";
import { useToast } from "../components/Toast";

interface Options {
  preferredModel: string;
  onSwitchToCooper: (cooperPath: string) => void;
  localModels: RuntimeModelFile[];
}

interface SessionModelController {
  effectiveModel: string;
  overrideSource: 'auto' | 'user';
  setUserOverride: (modelPath: string) => void;
  clearOverride: () => void;
  onDegradationDetected: () => void;
  degradationPromptShown: boolean;
}

export function useSessionModelController({
  preferredModel,
  onSwitchToCooper,
  localModels,
}: Options): SessionModelController {
  const { showToast } = useToast();
  const [effectiveModel, setEffectiveModel] = useState<string>(preferredModel);
  const [overrideSource, setOverrideSource] = useState<'auto' | 'user'>('auto');
  const [degradationPromptShown, setDegradationPromptShown] = useState(false);

  // Keep effectiveModel in sync when preferredModel changes externally (e.g. startup auto-select)
  // but only if the user hasn't manually overridden
  const prevPreferredRef = useRef(preferredModel);
  if (preferredModel !== prevPreferredRef.current) {
    prevPreferredRef.current = preferredModel;
    if (overrideSource === 'auto') {
      setEffectiveModel(preferredModel);
    }
  }

  const setUserOverride = useCallback((modelPath: string) => {
    setEffectiveModel(modelPath);
    setOverrideSource('user');
  }, []);

  const clearOverride = useCallback(() => {
    setEffectiveModel(preferredModel);
    setOverrideSource('auto');
  }, [preferredModel]);

  const onDegradationDetected = useCallback(() => {
    // Don't show if user already chose manually or already shown
    if (overrideSource === 'user' || degradationPromptShown) return;

    // Find Copper's path from localModels
    const copperModel = localModels.find((m) => resolveAlias(m.path) === 'Copper');
    if (!copperModel) return; // Copper not available, can't suggest

    setDegradationPromptShown(true);

    showToast({
      id: 'tps-degradation',
      variant: 'warning',
      message: 'Performance degraded',
      detail: 'TPS dropped below 30 for 5s. Switch to Copper (0.8B) for faster responses?',
      action: {
        label: 'Switch to Copper',
        onClick: () => {
          setUserOverride(copperModel.path);
          onSwitchToCooper(copperModel.path);
        },
      },
      duration: 0, // persistent until dismissed
    });
  }, [overrideSource, degradationPromptShown, localModels, showToast, setUserOverride, onSwitchToCooper]);

  return {
    effectiveModel,
    overrideSource,
    setUserOverride,
    clearOverride,
    onDegradationDetected,
    degradationPromptShown,
  };
}