/// @file
/// @brief Task3: program with command line options

/// @todo Include header from modules/iue-*, as needed
/// e.g. #include "iue-po/cpo.h"
/// e.g. #include "iue-io/ccsv.h"

/// @todo Include header of task2, if needed
// #include "task2.h"

/// @todo Include C standard library headers, as needed
/// e.g. #include <stdlib.h> // EXIT_FAILURE, EXIT_SUCCESS

/// @todo Implement an executable program which the following top-level description:
///       1. reads two matrices 'L', and 'R' from two separate .csv-files
///       2. calculates the matrix product LR (i.e. a matrix-matrix multiplication)
///       3. stores the resulting matrix in a third .csv-file
/// Detailed Requirements:
/// 1. All .csv-files which are involved need to be compatible with
///    the format supported by 'iueio_savetxt' and 'iueio_loadtxt' from the header 'iue-io/ccsv.h'
///    using ';' as delimiter and '#' as comment
/// 2. The program needs to support the following three mandatory command line arguments in arbitrary order:
///    --left     relative filepath to the 'L' matrix
///    --right    relative filepath to the 'R' matrix
///    --out      relative filepath for the produced result
/// 3. The program prints an error message to stderr, terminates, and returns EXIT_FAILURE if
///    a) If any of the mandatory arguments is missing
///    b) If any of the provided filepaths is not valid
///    c) If any of the provided files cannot be parsed successfully
///    d) If the dimension of the provided matrices are not compatible
/// 4. If the program finishes without any issue, it returns EXIT_SUCCESS
///
/// Implementation hints/valid assumtions for this exercise:
///    - you do not need to support empty .csv-files
///    - you can always assume that all rows in a .csv-file have the same length

/// @file
/// @brief Task3: program with command line options

#include "modules/iue-io/ccsv.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#define DELIM ';'
#define COMMENT '#'

// Function to multiply two matrices
double** multiply_matrices(double** L, size_t L_rows, size_t L_cols, double** R, size_t R_rows, size_t R_cols, size_t* out_rows, size_t* out_cols) {
  if (L_cols != R_rows) {
    return NULL; // Incompatible dimensions
  }

  *out_rows = L_rows;
  *out_cols = R_cols;

  double** result = malloc(L_rows * sizeof(double*));
  for (size_t i = 0; i < L_rows; ++i) {
    result[i] = malloc(R_cols * sizeof(double));
    for (size_t j = 0; j < R_cols; ++j) {
      result[i][j] = 0.0;
      for (size_t k = 0; k < L_cols; ++k) {
        result[i][j] += L[i][k] * R[k][j];
      }
    }
  }

  return result;
}

int main(int argc, char* argv[]) {
  char* left_filepath = NULL;
  char* right_filepath = NULL;
  char* out_filepath = NULL;
  bool left_set = false;
  bool right_set = false;
  bool out_set = false;

  // Parse command line arguments
  for (int i = 1; i < argc; i++) {
    if (strcmp(argv[i], "--left") == 0) {
      if (i + 1 >= argc) {
        fprintf(stderr, "Missing argument for --left\n");
        return EXIT_FAILURE;
      }
      left_filepath = argv[i + 1];
      left_set = true;
      i++;
    } else if (strcmp(argv[i], "--right") == 0) {
      if (i + 1 >= argc) {
        fprintf(stderr, "Missing argument for --right\n");
        return EXIT_FAILURE;
      }
      right_filepath = argv[i + 1];
      right_set = true;
      i++;
    } else if (strcmp(argv[i], "--out") == 0) {
      if (i + 1 >= argc) {
        fprintf(stderr, "Missing argument for --out\n");
        return EXIT_FAILURE;
      }
      out_filepath = argv[i + 1];
      out_set = true;
      i++;
    }
  }

  // Check for missing mandatory arguments
  if (!left_set || !right_set || !out_set) {
    fprintf(stderr,
            "Missing mandatory arguments. Usage: %s --left <left_file.csv> --right <right_file.csv> --out "
            "<output_file.csv>\n",
            argv[0]);
    return EXIT_FAILURE;
  }

    // Load matrices from files
    struct Table left_table = {NULL, 0};
    struct Table right_table = {NULL, 0};
    if (iueio_loadtxt(left_filepath, &left_table, DELIM, COMMENT) != 0) {
        fprintf(stderr, "Error loading file %s\n", left_filepath);
        return EXIT_FAILURE;
    }
    if (iueio_loadtxt(right_filepath, &right_table, DELIM, COMMENT) != 0) {
        fprintf(stderr, "Error loading file %s\n", right_filepath);
        return EXIT_FAILURE;
    }

    // Check if the matrices are compatible
    //if (left_table.n == 0 || right_table.n == 0 || left_table.rows[0].n != right_table.rows[0].n) {
    //    fprintf(stderr, "Incompatible dimensions\n");
    //    return EXIT_FAILURE;
    //}

    // Convert tables to matrices
    size_t L_rows = left_table.n;
    size_t L_cols = left_table.rows[0].n;
    double** L = malloc(L_rows * sizeof(double*));
    for (size_t i = 0; i < L_rows; ++i) {
        L[i] = malloc(L_cols * sizeof(double));
        for (size_t j = 0; j < L_cols; ++j) {
            L[i][j] = left_table.rows[i].values[j];
        }
    }

    size_t R_rows = right_table.n;
    size_t R_cols = right_table.rows[0].n;
    double** R = malloc(R_rows * sizeof(double*));
    for (size_t i = 0; i < R_rows; ++i) {
        R[i] = malloc(R_cols * sizeof(double));
        for (size_t j = 0; j < R_cols; ++j) {
            R[i][j] = right_table.rows[i].values[j];
        }
    }

    // Multiply matrices
    size_t out_rows, out_cols;
    double** result = multiply_matrices(L, L_rows, L_cols, R, R_rows, R_cols, &out_rows, &out_cols);
    if (result == NULL) {
        fprintf(stderr, "Incompatible dimensions\n");
        return EXIT_FAILURE;
    }

    // Convert result to table
    struct Table out_table = {NULL, 0};
    for (size_t i = 0; i < out_rows; ++i) {
        table_append_copy(&out_table, result[i], out_cols);
    }

    // Save result to file
    if (iueio_savetxt(out_filepath, &out_table, DELIM, "", COMMENT) != 0) {
        fprintf(stderr, "Error saving file %s\n", out_filepath);
        return EXIT_FAILURE;
    }

    // Free memory
    for (size_t i = 0; i < L_rows; ++i) {
        free(L[i]);
    }
    free(L);
    for (size_t i = 0; i < R_rows; ++i) {
        free(R[i]);
    }
    free(R);
    for (size_t i = 0; i < out_rows; ++i) {
        free(result[i]);
    }
    free(result);
    table_clear(&left_table);
    table_clear(&right_table);
    table_clear(&out_table);

    return EXIT_SUCCESS;
}