#include "chunk_array.h"
#include "stdbool.h"

#define MAX_CHUNK_SIZE 2048*2048

int min(int value1, int value2) {
    if (value1 < value2) return value1;
    return value2;
}

void chunk_array_free(chunk_array_t* chunk_array) {
  	fclose(chunk_array->fp);
    free(chunk_array->data);
	free(chunk_array);  
}

void chunk_array_flush(chunk_array_t* chunk_array) {
    size_t mod;
    if (chunk_array->total_size - chunk_array->init_pos > chunk_array->chunk_size ) {
        mod = chunk_array->chunk_size;
    } else {
        mod = chunk_array->total_size - chunk_array->init_pos;
    }
    fseek(chunk_array->fp, chunk_array->init_pos * sizeof(double), SEEK_SET);
    fwrite(chunk_array->data, sizeof(double), mod, chunk_array->fp);
}

bool chunk_array_update(chunk_array_t* chunk_array, size_t pos) {
    chunk_array_flush(chunk_array);

    int new_init = pos/chunk_array->chunk_size;
    chunk_array->init_pos = new_init * chunk_array->chunk_size;

    fseek(chunk_array->fp, chunk_array->init_pos * sizeof(double), SEEK_SET);
    fread(chunk_array->data, sizeof(double), chunk_array->chunk_size, chunk_array->fp);
}

chunk_array_t* chunk_array_create(char* filename, size_t total_size) {
    chunk_array_t* chunk_array = (chunk_array_t*)malloc(sizeof(chunk_array_t));

    chunk_array->fp = fopen(filename, "r+");

    if (chunk_array == NULL || chunk_array->fp == NULL) {
        chunk_array->fp = fopen(filename, "w+");

        if (chunk_array->fp == NULL) {
            return NULL;
        }
    }

    chunk_array->chunk_size = min(MAX_CHUNK_SIZE, total_size);

    chunk_array->data = malloc(chunk_array->chunk_size * sizeof(double));

    if (MAX_CHUNK_SIZE > 0 && chunk_array->data == NULL) {
        free(chunk_array);
        return NULL;
    }

    fread(chunk_array->data, sizeof(double), MAX_CHUNK_SIZE, chunk_array->fp);

    chunk_array->filename = filename;
    chunk_array->init_pos = 0;
    chunk_array->total_size = total_size;
    return chunk_array;
}

bool chunk_array_get(chunk_array_t* chunk_array, size_t pos, double *valor) {

    if (pos<chunk_array->init_pos || pos>chunk_array->init_pos + chunk_array->chunk_size-1) {
        chunk_array_update(chunk_array, pos);
	}
    size_t mod;
    if (chunk_array->total_size - chunk_array->init_pos > chunk_array->chunk_size ) {
        mod = chunk_array->chunk_size;
    } else {
        mod = chunk_array->total_size - chunk_array->init_pos;
    }
    int real_pos = pos%mod;
    *valor=chunk_array->data[real_pos];
    return true;
}


bool chunk_array_save(chunk_array_t* chunk_array, size_t pos, double valor) {
	if (pos<chunk_array->init_pos || pos>chunk_array->init_pos + chunk_array->chunk_size-1) {
        chunk_array_update(chunk_array,pos);
	}
    size_t mod;
    if (chunk_array->total_size - chunk_array->init_pos > chunk_array->chunk_size ) {
        mod = chunk_array->chunk_size;
    } else {
        mod = chunk_array->total_size - chunk_array->init_pos;
    }
	chunk_array->data[pos%mod]=valor;

	return true;
}