#include <iostream>
#include <fstream>
#include <sstream>
#include <vector>

using namespace std;

// Function prototypes
vector<vector<int>> inputMatrix(const string& name);
vector<vector<int>> readMatrixFromFile(const string& fileName);
vector<vector<int>> multiplyMatrices(const vector<vector<int>>& matrixA, const vector<vector<int>>& matrixB);
void displayMatrix(const vector<vector<int>>& matrix);
void saveMatrixToFile(const vector<vector<int>>& matrix, const string& filename);

int main() {
    cout << "Choose an option:" << endl;
    cout << "1. Input matrices manually" << endl;
    cout << "2. Read matrices from a text file" << endl;

    int option;
    cin >> option;

    vector<vector<int>> matrixA, matrixB;

    if (option == 1) {
        matrixA = inputMatrix("first");
        matrixB = inputMatrix("second");
    } else if (option == 2) {
        cout << "Enter the file name for matrix A: ";
        string fileNameA;
        cin >> fileNameA;
        matrixA = readMatrixFromFile(fileNameA);

        cout << "Enter the file name for matrix B: ";
        string fileNameB;
        cin >> fileNameB;
        matrixB = readMatrixFromFile(fileNameB);
    } else {
        cout << "Invalid option. Exiting program." << endl;
        return 1;
    }

    if (matrixA.empty() || matrixB.empty()) {
        cout << "Error in reading matrices. Exiting program." << endl;
        return 1;
    }

    // Perform matrix multiplication
    vector<vector<int>> resultMatrix = multiplyMatrices(matrixA, matrixB);

    // Display the result
    cout << "Result of matrix multiplication:" << endl;
    displayMatrix(resultMatrix);

    // Save the result to a text file
    saveMatrixToFile(resultMatrix, "resultMatrix.txt");
    cout << "Result matrix saved to resultMatrix.txt" << endl;

    return 0;
}

// Function to input matrix from the user
vector<vector<int>> inputMatrix(const string& name) {
    cout << "Enter the number of rows for the " << name << " matrix: ";
    int rows, cols;
    cin >> rows;

    cout << "Enter the number of columns for the " << name << " matrix: ";
    cin >> cols;

    if (rows <= 0 || cols <= 0) {
        cout << "Error: Matrix dimensions must be positive." << endl;
        return {};
    }

    vector<vector<int>> matrix(rows, vector<int>(cols, 0));

    cout << "Enter the elements for the " << name << " matrix:" << endl;
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            cout << "Element at position (" << (i + 1) << ", " << (j + 1) << "): ";
            cin >> matrix[i][j];
        }
    }

    return matrix;
}

// Function to read matrix from a text file
vector<vector<int>> readMatrixFromFile(const string& fileName) {
    ifstream file(fileName);

    if (!file.is_open()) {
        cout << "Error: File not found or cannot be read." << endl;
        return {};
    }

    // Initialize a stringstream to parse each line
    stringstream ss;
    string line;
    int rows = 0;
    int cols = 0;

    // Count the number of rows and columns
    while (getline(file, line)) {
        ss.clear();
        ss.str(line);

        int value;
        while (ss >> value) {
            cols++;
        }

        rows++;
    }

    // Reset file to the beginning
    file.clear();
    file.seekg(0);

    // Initialize the matrix
    vector<vector<int>> matrix(rows, vector<int>(cols / rows, 0));

    // Read matrix elements
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols / rows; j++) {
            if (!(file >> matrix[i][j])) {
                cout << "Error: Insufficient data in the file." << endl;
                return {};
            }
        }
    }

    file.close();
    return matrix;
}

// Function to multiply two matrices
vector<vector<int>> multiplyMatrices(const vector<vector<int>>& matrixA, const vector<vector<int>>& matrixB) {
    int rowsA = matrixA.size();
    int colsA = matrixA[0].size();
    int colsB = matrixB[0].size();

    vector<vector<int>> resultMatrix(rowsA, vector<int>(colsB, 0));

    for (int i = 0; i < rowsA; i++) {
        for (int j = 0; j < colsB; j++) {
            for (int k = 0; k < colsA; k++) {
                resultMatrix[i][j] += matrixA[i][k] * matrixB[k][j];
            }
        }
    }

    return resultMatrix;
}

// Function to display a matrix
void displayMatrix(const vector<vector<int>>& matrix) {
    for (const auto& row : matrix) {
        for (int value : row) {
            cout << value << " ";
        }
        cout << endl;
    }
}

// Function to save a matrix to a text file
void saveMatrixToFile(const vector<vector<int>>& matrix, const string& filename) {
    ofstream writer(filename);

    if (!writer.is_open()) {
        cout << "Error: Unable to save result matrix to file." << endl;
        return;
    }

////    writer << matrix.size() << " " << matrix[0].size() << endl;

    for (const auto& row : matrix) {
        for (int value : row) {
            writer << value << " ";
        }
        writer << endl;
    }

    writer.close();
}