'use client';

import React, { createContext, useContext, useReducer, useEffect, useMemo, ReactNode } from 'react';
import { ModelInfo, AutoSelectionState } from '@/lib/api';
import { AutoModelSelector } from '@/lib/services/auto-model-selector';

// Types for the context
interface ModelSelectionState {
  selectedCheckpoint: string | null;
  selectedModels: Record<string, string | undefined>; // modelType -> modelHash
  autoSelectedModels: Record<string, string>; // modelType -> modelHash
  userOverrides: Record<string, string>; // modelType -> modelHash (user manual selections)
  autoSelectionState: AutoSelectionState | null;
  availableModels: ModelInfo[];
  isLoading: boolean;
  error: string | null;
  warnings: string[];
  isAutoSelecting: boolean;
}

type ModelSelectionAction =
  | { type: 'SET_MODELS'; payload: ModelInfo[] }
  | { type: 'SET_SELECTED_CHECKPOINT'; payload: string | null }
  | { type: 'SET_SELECTED_MODEL'; payload: { type: string; hash: string | undefined } }
  | { type: 'SET_USER_OVERRIDE'; payload: { type: string; hash: string } }
  | { type: 'CLEAR_USER_OVERRIDE'; payload: string }
  | { type: 'SET_AUTO_SELECTION_STATE'; payload: AutoSelectionState }
  | { type: 'SET_LOADING'; payload: boolean }
  | { type: 'SET_ERROR'; payload: string | null }
  | { type: 'ADD_WARNING'; payload: string }
  | { type: 'CLEAR_WARNINGS' }
  | { type: 'SET_AUTO_SELECTING'; payload: boolean }
  | { type: 'RESET_SELECTION' };

// Initial state
const initialState: ModelSelectionState = {
  selectedCheckpoint: null,
  selectedModels: {},
  autoSelectedModels: {},
  userOverrides: {},
  autoSelectionState: null,
  availableModels: [],
  isLoading: false,
  error: null,
  warnings: [],
  isAutoSelecting: false,
};

// Reducer function
function modelSelectionReducer(
  state: ModelSelectionState,
  action: ModelSelectionAction
): ModelSelectionState {
  switch (action.type) {
    case 'SET_MODELS':
      return {
        ...state,
        availableModels: action.payload,
        error: null,
      };

    case 'SET_SELECTED_CHECKPOINT':
      return {
        ...state,
        selectedCheckpoint: action.payload,
        // Clear auto-selection when checkpoint changes
        autoSelectedModels: {},
        autoSelectionState: null,
        warnings: [],
      };

    case 'SET_SELECTED_MODEL':
      return {
        ...state,
        selectedModels: {
          ...state.selectedModels,
          [action.payload.type]: action.payload.hash,
        },
      };

    case 'SET_USER_OVERRIDE':
      return {
        ...state,
        userOverrides: {
          ...state.userOverrides,
          [action.payload.type]: action.payload.hash,
        },
        selectedModels: {
          ...state.selectedModels,
          [action.payload.type]: action.payload.hash,
        },
      };

    case 'CLEAR_USER_OVERRIDE':
      const newUserOverrides = { ...state.userOverrides };
      delete newUserOverrides[action.payload];
      
      // If we had an auto-selected model for this type, restore it
      const restoredModel = state.autoSelectedModels[action.payload];
      const newSelectedModels = { ...state.selectedModels };
      if (restoredModel) {
        newSelectedModels[action.payload] = restoredModel;
      } else {
        delete newSelectedModels[action.payload];
      }

      return {
        ...state,
        userOverrides: newUserOverrides,
        selectedModels: newSelectedModels,
      };

    case 'SET_AUTO_SELECTION_STATE':
      return {
        ...state,
        autoSelectionState: action.payload,
        // Merge auto-selected models with current selections, but don't override user selections
        selectedModels: {
          ...action.payload.autoSelectedModels,
          ...state.userOverrides, // User overrides take precedence
        },
        autoSelectedModels: action.payload.autoSelectedModels,
        warnings: [...state.warnings, ...action.payload.warnings],
        error: action.payload.errors.length > 0 ? action.payload.errors[0] : state.error,
      };

    case 'SET_LOADING':
      return {
        ...state,
        isLoading: action.payload,
      };

    case 'SET_ERROR':
      return {
        ...state,
        error: action.payload,
      };

    case 'ADD_WARNING':
      return {
        ...state,
        warnings: [...state.warnings, action.payload],
      };

    case 'CLEAR_WARNINGS':
      return {
        ...state,
        warnings: [],
      };

    case 'SET_AUTO_SELECTING':
      return {
        ...state,
        isAutoSelecting: action.payload,
      };

    case 'RESET_SELECTION':
      return {
        ...initialState,
        availableModels: state.availableModels,
      };

    default:
      return state;
  }
}

// Context type
interface ModelSelectionContextType {
  state: ModelSelectionState;
  actions: {
    setModels: (models: ModelInfo[]) => void;
    setSelectedCheckpoint: (checkpointHash: string | null) => void;
    setSelectedModel: (type: string, hash: string | undefined) => void;
    setUserOverride: (type: string, hash: string) => void;
    clearUserOverride: (type: string) => void;
    performAutoSelection: (checkpointModel: ModelInfo) => Promise<void>;
    clearWarnings: () => void;
    resetSelection: () => void;
    validateSelection: (checkpointModel: ModelInfo) => {
      isValid: boolean;
      missingRequired: string[];
      warnings: string[];
    };
  };
}

// Create context
const ModelSelectionContext = createContext<ModelSelectionContextType | null>(null);

// Provider component
interface ModelSelectionProviderProps {
  children: ReactNode;
}

export function ModelSelectionProvider({ children }: ModelSelectionProviderProps) {
  const [state, dispatch] = useReducer(modelSelectionReducer, initialState);
  const autoSelectorRef = React.useRef<AutoModelSelector>(new AutoModelSelector());

  // Update auto selector when models change
  useEffect(() => {
    autoSelectorRef.current.updateModels(state.availableModels);
  }, [state.availableModels]);

  // Actions
  const actions = useMemo(() => ({
    setModels: (models: ModelInfo[]) => {
      dispatch({ type: 'SET_MODELS', payload: models });
    },

    setSelectedCheckpoint: (checkpointHash: string | null) => {
      dispatch({ type: 'SET_SELECTED_CHECKPOINT', payload: checkpointHash });
    },

    setSelectedModel: (type: string, hash: string | undefined) => {
      dispatch({ type: 'SET_SELECTED_MODEL', payload: { type, hash } });
    },

    setUserOverride: (type: string, hash: string) => {
      dispatch({ type: 'SET_USER_OVERRIDE', payload: { type, hash } });
    },

    clearUserOverride: (type: string) => {
      dispatch({ type: 'CLEAR_USER_OVERRIDE', payload: type });
    },

    performAutoSelection: async (checkpointModel: ModelInfo) => {
      try {
        dispatch({ type: 'SET_AUTO_SELECTING', payload: true });
        dispatch({ type: 'SET_LOADING', payload: true });
        dispatch({ type: 'SET_ERROR', payload: null });

        const autoSelectionState = await autoSelectorRef.current.selectModels(checkpointModel);
        
        dispatch({ type: 'SET_AUTO_SELECTION_STATE', payload: autoSelectionState });
      } catch (error) {
        const errorMessage = error instanceof Error ? error.message : 'Auto-selection failed';
        dispatch({ type: 'SET_ERROR', payload: errorMessage });
      } finally {
        dispatch({ type: 'SET_AUTO_SELECTING', payload: false });
        dispatch({ type: 'SET_LOADING', payload: false });
      }
    },

    clearWarnings: () => {
      dispatch({ type: 'CLEAR_WARNINGS' });
    },

    resetSelection: () => {
      dispatch({ type: 'RESET_SELECTION' });
    },

    validateSelection: (checkpointModel: ModelInfo) => {
      return autoSelectorRef.current.validateSelection(checkpointModel, state.selectedModels);
    },
  }), [state.selectedModels]);

  // Auto-select when checkpoint changes
  useEffect(() => {
    if (state.selectedCheckpoint && state.availableModels.length > 0) {
      const checkpointModel = state.availableModels.find(
        model => (model.sha256_short === state.selectedCheckpoint || model.sha256 === state.selectedCheckpoint || model.id === state.selectedCheckpoint) &&
        (model.type === 'checkpoint' || model.type === 'stable-diffusion')
      );

      if (checkpointModel) {
        actions.performAutoSelection(checkpointModel);
      }
    }
  }, [state.selectedCheckpoint, state.availableModels, actions]);

  const value = {
    state,
    actions,
  };

  return (
    <ModelSelectionContext.Provider value={value}>
      {children}
    </ModelSelectionContext.Provider>
  );
}

// Hook to use the context
export function useModelSelection() {
  const context = useContext(ModelSelectionContext);
  if (!context) {
    throw new Error('useModelSelection must be used within a ModelSelectionProvider');
  }
  return context;
}

// Helper hook for checkpoint selection
export function useCheckpointSelection() {
  const { state, actions } = useModelSelection();
  
  const checkpointModels = state.availableModels.filter(model => 
    model.type === 'checkpoint' || model.type === 'stable-diffusion'
  );

  const selectedCheckpointModel = state.selectedCheckpoint
    ? state.availableModels.find(model =>
        model.sha256_short === state.selectedCheckpoint ||
        model.sha256 === state.selectedCheckpoint ||
        model.id === state.selectedCheckpoint ||
        model.name === state.selectedCheckpoint
      )
    : null;

  return {
    checkpointModels,
    selectedCheckpointModel,
    selectedCheckpoint: state.selectedCheckpoint,
    setSelectedCheckpoint: actions.setSelectedCheckpoint,
    autoSelectedModels: state.autoSelectedModels,
    userOverrides: state.userOverrides,
    isAutoSelecting: state.isAutoSelecting,
    warnings: state.warnings,
    error: state.error,
  };
}

// Helper hook for model type selection
export function useModelTypeSelection(modelType: string) {
  const { state, actions } = useModelSelection();
  
  const availableModels = state.availableModels.filter(model => 
    model.type.toLowerCase() === modelType.toLowerCase()
  );

  const selectedModel = state.selectedModels[modelType];
  const isUserOverride = !!state.userOverrides[modelType];
  const isAutoSelected = !!state.autoSelectedModels[modelType] && !isUserOverride;

  return {
    availableModels,
    selectedModel,
    isUserOverride,
    isAutoSelected,
    setSelectedModel: (hash: string | undefined) => actions.setSelectedModel(modelType, hash),
    setUserOverride: (hash: string) => actions.setUserOverride(modelType, hash),
    clearUserOverride: () => actions.clearUserOverride(modelType),
  };
}