#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

char *read_text();

char *read_pattern();

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

void apply_shift(int, int *, int);

int sum_array(int *, int);

int main() {
    int rank, size, private_text_len, text_len, pattern_len;
    char *pattern, *text;

    MPI_Init(NULL, NULL);

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

    if (rank == MASTER) {
        text = read_text();
        pattern = read_pattern();
        printf("text: %s\n", text);
        printf("pattern: %s\n", pattern);
        text_len = strlen(text);
        pattern_len = strlen(pattern);
        private_text_len = text_len / size; // TODO: size non divisibile
    }

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

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

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

    printf("%d -> input: %s\n", rank, 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);
    }

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

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

    if (rank == MASTER) {
        int match_numbers[size];
        match_numbers[MASTER] = match_number;

        for (int i = 0; i < size; ++i) {
            if (i == MASTER) continue;

            MPI_Recv(match_numbers + i, 1, MPI_INT, i, DEFAULT_TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
        }

        match_number = sum_array(match_numbers, size);
        matches = (int *) realloc(matches, sizeof(int) * match_number);

        int offset = 0;
        for (int i = 0; i < size; ++i) {
            if (i == MASTER) {
                offset += match_numbers[i];
                continue;
            }

            MPI_Recv(matches + offset, match_numbers[i], MPI_INT, i, DEFAULT_TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
            offset += match_numbers[i];
        }
    } else {
        MPI_Send(&match_number, 1, MPI_INT, MASTER, DEFAULT_TAG, MPI_COMM_WORLD);
        MPI_Send(matches, match_number, MPI_INT, MASTER, DEFAULT_TAG, MPI_COMM_WORLD);
    }

    MPI_Finalize();

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

char *read_text() {
    // TODO
    return "abc";
}

char *read_pattern() {
    // TODO
    return "mamma";
}

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);

    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 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;
}