import { useRef, useState, useCallback } from 'react';
import type { RefObject } from 'react';
import type { BoardManager, SudokuBoard, SudokuCell, Difficulty } from './types';
import { SudokuGenerator } from './SudokuGenerator';
import { SudokuRenderer } from './SudokuRenderer';

export function useBoard(): BoardManager {
  const containerRef = useRef<HTMLDivElement | null>(null);
  const boardRef = useRef<SudokuBoard>([]);
  const initialBoardRef = useRef<string>('');
  const solutionRef = useRef<string | null>(null);

  const initializeBoard = useCallback((boardString: string): SudokuBoard => {
    const board: SudokuBoard = [];
    for (let row = 0; row < 9; row++) {
      const boardRow: SudokuCell[] = [];
      for (let col = 0; col < 9; col++) {
        const index = row * 9 + col;
        const value = boardString[index];
        boardRow.push({
          value: value === '.' ? '' : value,
          isGiven: value !== '.',
          hasConflict: false
        });
      }
      board.push(boardRow);
    }
    return board;
  }, []);

  const getCell = useCallback((row: number, col: number): SudokuCell | null => {
    const board = boardRef.current;
    if (row < 0 || row >= 9 || col < 0 || col >= 9) return null;
    return board[row]?.[col] || null;
  }, []);

  const canEditCell = useCallback((row: number, col: number): boolean => {
    const cell = getCell(row, col);
    return cell ? !cell.isGiven : false;
  }, [getCell]);

  const isValidPlacement = useCallback((boardString: string, row: number, col: number, digit: string): boolean => {
    if (digit === '.') return true;

    for (let c = 0; c < 9; c++) {
      const checkIdx = row * 9 + c;
      if (c !== col && boardString[checkIdx] === digit) {
        return false;
      }
    }

    for (let r = 0; r < 9; r++) {
      const checkIdx = r * 9 + col;
      if (r !== row && boardString[checkIdx] === digit) {
        return false;
      }
    }

    const boxRow = Math.floor(row / 3) * 3;
    const boxCol = Math.floor(col / 3) * 3;
    for (let r = boxRow; r < boxRow + 3; r++) {
      for (let c = boxCol; c < boxCol + 3; c++) {
        const checkIdx = r * 9 + c;
        if ((r !== row || c !== col) && boardString[checkIdx] === digit) {
          return false;
        }
      }
    }

    return true;
  }, []);

  const getConflicts = useCallback((boardString: string, row: number, col: number): number[] => {
    const conflicts: number[] = [];
    const digit = boardString[row * 9 + col];

    if (digit === '.') return conflicts;

    for (let c = 0; c < 9; c++) {
      if (c !== col && boardString[row * 9 + c] === digit) {
        conflicts.push(row * 9 + c);
      }
    }

    for (let r = 0; r < 9; r++) {
      if (r !== row && boardString[r * 9 + col] === digit) {
        conflicts.push(r * 9 + col);
      }
    }

    const boxRow = Math.floor(row / 3) * 3;
    const boxCol = Math.floor(col / 3) * 3;
    for (let r = boxRow; r < boxRow + 3; r++) {
      for (let c = boxCol; c < boxCol + 3; c++) {
        const idx = r * 9 + c;
        if ((r !== row || c !== col) && boardString[idx] === digit) {
          if (!conflicts.includes(idx)) {
            conflicts.push(idx);
          }
        }
      }
    }

    return conflicts;
  }, []);

  const isFullyValid = useCallback((boardString: string): boolean => {
    for (let r = 0; r < 9; r++) {
      let rowSum = 0;
      for (let c = 0; c < 9; c++) {
        const digit = boardString[r * 9 + c];
        if (digit === '.') return false;
        rowSum += parseInt(digit, 10);
      }
      if (rowSum !== 45) return false;
    }

    for (let c = 0; c < 9; c++) {
      let colSum = 0;
      for (let r = 0; r < 9; r++) {
        const digit = boardString[r * 9 + c];
        colSum += parseInt(digit, 10);
      }
      if (colSum !== 45) return false;
    }

    for (let boxRow = 0; boxRow < 3; boxRow++) {
      for (let boxCol = 0; boxCol < 3; boxCol++) {
        let boxSum = 0;
        for (let r = boxRow * 3; r < boxRow * 3 + 3; r++) {
          for (let c = boxCol * 3; c < boxCol * 3 + 3; c++) {
            const digit = boardString[r * 9 + c];
            boxSum += parseInt(digit, 10);
          }
        }
        if (boxSum !== 45) return false;
      }
    }

    return true;
  }, []);

  const isComplete = useCallback((boardString: string): boolean => {
    return !boardString.includes('.');
  }, []);

  const boardToString = useCallback((board: SudokuBoard): string => {
    return board.map(row => 
      row.map(cell => cell.value || '.').join('')
    ).join('');
  }, []);

  const setCell = useCallback((row: number, col: number, value: string): boolean => {
    if (!canEditCell(row, col)) return false;

    const board = boardRef.current;
    const boardString = boardToString(board);
    const newBoardString = boardString.substring(0, row * 9 + col) + value + boardString.substring(row * 9 + col + 1);

    if (!isValidPlacement(newBoardString, row, col, value)) {
      return false;
    }

    board[row][col] = {
      value: value === '.' ? '' : value,
      isGiven: board[row][col].isGiven,
      hasConflict: false
    };

    return true;
  }, [canEditCell, isValidPlacement, boardToString]);

  const generateBoard = useCallback((difficulty: Difficulty): void => {
    const newBoardString = SudokuGenerator.generate(difficulty);
    const solution = SudokuGenerator.solve(newBoardString);
    
    initialBoardRef.current = newBoardString;
    solutionRef.current = solution;
    boardRef.current = initializeBoard(newBoardString);
  }, [initializeBoard]);

  const solveBoard = useCallback((): boolean => {
    const solution = solutionRef.current;
    if (!solution) return false;

    boardRef.current = initializeBoard(solution);
    return true;
  }, [initializeBoard]);

  const resetBoard = useCallback((): void => {
    const initialBoard = initialBoardRef.current;
    if (initialBoard) {
      boardRef.current = initializeBoard(initialBoard);
    }
  }, [initializeBoard]);

  const renderBoard = useCallback((): void => {
    const container = containerRef.current;
    const board = boardRef.current;
    
    if (!container || board.length === 0) {
      if (container) {
        SudokuRenderer.renderEmptyBoard(container);
      }
      return;
    }

    SudokuRenderer.renderBoard(container, board);
  }, []);

  return {
    containerRef,
    boardRef,
    initialBoardRef,
    solutionRef,
    renderBoard,
    generateBoard,
    getCell,
    setCell,
    canEditCell,
    isValidPlacement: (row, col, digit) => {
      const boardString = boardToString(boardRef.current);
      return isValidPlacement(boardString, row, col, digit);
    },
    getConflicts: (row, col) => {
      const boardString = boardToString(boardRef.current);
      return getConflicts(boardString, row, col);
    },
    isComplete: () => {
      const boardString = boardToString(boardRef.current);
      return isComplete(boardString);
    },
    isFullyValid: () => {
      const boardString = boardToString(boardRef.current);
      return isFullyValid(boardString);
    },
    solveBoard,
    resetBoard
  };
}