#include <stdio.h>
#include <string.h>
#include "kmp.h"
#include "util.h"
#include <mpi.h>
#include <malloc.h>

#define MASTER 0
#define DEFAULT_TAG 17

void find_end(int, char *, char *, int **, int *);

void apply_shift(int, int *, int);

int sum_array(int *, int);

void initialize();

int rank, size;
int text_len;       // length of all text
int private_text_len;   // length of private text
int pattern_len;    //length of the pattern
char *text;
char *pattern;
int remain = 0;
int *text_piece;
int *displacements;

int main() {
    int *match_numbers;
    int *total_matches;
    int total_match_number;

    MPI_Init(NULL, NULL);

    MPI_Comm_size(MPI_COMM_WORLD, &size);
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);

    if (rank == MASTER)
        initialize();

    MPI_Scatter(text_piece, 1, MPI_INT, &private_text_len, 1, MPI_INT, MASTER, MPI_COMM_WORLD);

    char *private_text = (char *) malloc(sizeof(char) * (private_text_len + 1));

    MPI_Scatterv(text, text_piece, displacements, MPI_CHAR, private_text, private_text_len, MPI_CHAR, MASTER,
                 MPI_COMM_WORLD);
    private_text[private_text_len] = '\0';

    if (rank == MASTER)
        MPI_Send(&remain, 1, MPI_INT, size - 1, DEFAULT_TAG, MPI_COMM_WORLD);
    else if (rank == size -1)
        MPI_Recv(&remain, 1, MPI_INT, MASTER, DEFAULT_TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE);

    printf("%d -> input: %s\n", rank, private_text);
    printf("%d -> text len: %d\n", rank, private_text_len);
    printf("%d -> text len_: %d\n", rank, strlen(private_text));

    MPI_Bcast(&pattern_len, 1, MPI_INT, MASTER, MPI_COMM_WORLD);

    if (rank != MASTER) {
        pattern = (char *) malloc(sizeof(char) * (pattern_len + 1));
    }

    MPI_Bcast(pattern, pattern_len + 1, MPI_CHAR, MASTER, MPI_COMM_WORLD);

    int lps[pattern_len];

    create_lps(pattern, pattern_len, lps);

    int match_number = 0, residue;
    int *matches = search_pattern(private_text, pattern, lps, &match_number, &residue);


    if (rank + 1 != size) {
        MPI_Send(&residue, 1, MPI_INT, rank + 1, DEFAULT_TAG, MPI_COMM_WORLD);
    }

    if (rank != 0) {
        MPI_Recv(&residue, 1, MPI_INT, rank - 1, DEFAULT_TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
        if (residue != 0)
            find_end(residue, pattern, private_text, &matches, &match_number);
    }

    //print_array(matches, match_number);

    int shift = rank * (private_text_len - remain);
    apply_shift(shift, matches, match_number);

    printf("%d -> result number: %d\n", rank, match_number);

    if (rank == MASTER) {
        match_numbers = (int *) malloc(sizeof(int) * size);
    }

    MPI_Gather(&match_number, 1, MPI_INT, match_numbers, 1, MPI_INT, MASTER, MPI_COMM_WORLD);

    if (rank == MASTER) {
        total_match_number = sum_array(match_numbers, size);

        total_matches = (int *) malloc(sizeof(int) * total_match_number);
        displacements[0] = 0;
        for (int i = 0; i < size - 1; ++i) {
            displacements[i + 1] = displacements[i] + match_numbers[i];
        }
    }

    MPI_Gatherv(matches, match_number, MPI_INT, total_matches, match_numbers, displacements, MPI_INT, MASTER,
                MPI_COMM_WORLD);

    MPI_Finalize();

    if (rank == MASTER) {
        printf("total matches: %d\n", total_match_number);
        printf("matches index: ");
        print_array(total_matches, total_match_number);
    }
}

void find_end(int residue, char *pattern, char *text, int **matches, int *match_number) {
    int pattern_index = residue;
    int text_index = 0;
    int text_len = strlen(text);
    int pattern_len = strlen(pattern);

    // TODO: match splitted on 3+ node
    if (pattern_len - residue > text_len) return;

    while (pattern_index < pattern_len && pattern[pattern_index] == text[text_index]) {
        pattern_index++;
        text_index++;
    }

    if (pattern_index != pattern_len) return;

    *match_number = *match_number + 1;
    *matches = (int *) realloc(*matches, *match_number * sizeof(int));
    (*matches)[*match_number - 1] = -residue;
}

void initialize() {
    text = "questo è un test di esempio. Qui c'è la prima occorenza mamma e qui la seconda mamma";//read_file("data/text.txt", &text_len);
    pattern = "mamma";//read_file("data/pattern.txt", &pattern_len);

    text_len = strlen(text);
    pattern_len = strlen(pattern);

    printf("text: %s\n", text);
    printf("pattern: %s\n", pattern);

    private_text_len = text_len / size;
    remain = text_len % size;

    if (pattern_len > private_text_len)
        MPI_Abort(MPI_COMM_WORLD, 1);

    text_piece = (int *) malloc(sizeof(int) * size);
    displacements = (int *) malloc(sizeof(int) * size);

    displacements[0] = 0;
    for (int i = 0; i < size - 1; ++i) {
        text_piece[i] = private_text_len;
        displacements[i + 1] = displacements[i] + private_text_len;
    }

    text_piece[size - 1] = private_text_len + remain;
}

void apply_shift(int shift, int *array, int size) {
    for (int i = 0; i < size; ++i) {
        array[i] += shift;
    }
}

int sum_array(int *array, int size) {
    int sum = 0;
    for (int i = 0; i < size; ++i) {
        sum += array[i];
    }

    return sum;
}