/*
 * c99-vector.c
 * - Description: Simple std::vector-like container implemented in C99, without error handling and thread-safety
 * - Author: Shao-Chung Chen
 * - License: CC0
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct _c_vector {
    size_t capacity;
    size_t length;
    size_t element_size;
    void *buffer;
} c_vector;

c_vector*
c_vector_init(c_vector *c_vector_p, size_t element_size) {
    if (!c_vector_p) return NULL;
    c_vector_p->capacity = 16;
    c_vector_p->length = 0;
    c_vector_p->element_size = element_size;
    c_vector_p->buffer = malloc(c_vector_p->capacity * element_size);
    return c_vector_p;
}

void
c_vector_destroy(c_vector *c_vector_p) {
    if (!c_vector_p) return;
    free(c_vector_p->buffer);
    c_vector_p->capacity = 0;
    c_vector_p->length = 0;
    c_vector_p->element_size = 0;
    c_vector_p->buffer = NULL;
}

size_t
c_vector_capacity(c_vector *c_vector_p) {
    if (!c_vector_p) return 0;
    return c_vector_p->capacity;
}

size_t
c_vector_length(c_vector *c_vector_p) {
    if (!c_vector_p) return 0;
    return c_vector_p->length;
}

void
c_vector_clear(c_vector *c_vector_p) {
    if (!c_vector_p) return;
    c_vector_p->length = 0;
}

void*
c_vector_at(c_vector *c_vector_p, size_t index) {
    if (!c_vector_p || index >= c_vector_p->length) return NULL;
    return (void*)((char*)c_vector_p->buffer + (index * c_vector_p->element_size));
}

void
c_vector_resize(c_vector *c_vector_p, size_t new_capacity) {
    if (!c_vector_p || new_capacity < c_vector_p->length) return;
    c_vector_p->capacity = new_capacity;
    c_vector_p->buffer = realloc(c_vector_p->buffer, c_vector_p->capacity * c_vector_p->element_size);
}

void*
c_vector_push_back(c_vector *c_vector_p, void* value_p) {
    if (!c_vector_p || !value_p) return NULL;
    if (c_vector_p->length+1 >= c_vector_p->capacity) {
        /* out of capacity, re-allocate with buffer size doubled */
        c_vector_resize(c_vector_p, c_vector_p->capacity * 2);
    }
    ++c_vector_p->length;
    void *dest_p = c_vector_at(c_vector_p, c_vector_p->length-1);
    memcpy(dest_p, value_p, c_vector_p->element_size);
    return dest_p;
}

void
c_vector_pop_back(c_vector *c_vector_p) {
    if (!c_vector_p || !c_vector_p->length) return;
    --c_vector_p->length;
}

void*
c_vector_insert(c_vector *c_vector_p, size_t index, void* value_p) {
    if (!c_vector_p || !value_p || index >= c_vector_p->length) return NULL;
    if (c_vector_p->length+1 >= c_vector_p->capacity) {
        /* out of capacity, re-allocate with buffer size doubled */
        c_vector_resize(c_vector_p, c_vector_p->capacity * 2);
    }
    void *dest_p = c_vector_at(c_vector_p, index);
    memmove((void*)((char*)dest_p+c_vector_p->element_size), dest_p, c_vector_p->element_size * (c_vector_p->length - index));
    ++c_vector_p->length;
    memcpy(dest_p, value_p, c_vector_p->element_size);
    return dest_p;
}

void
c_vector_erase(c_vector *c_vector_p, size_t index) {
    if (!c_vector_p || index >= c_vector_p->length) return;
    void *dest_p = c_vector_at(c_vector_p, index);
    --c_vector_p->length;
    memmove(dest_p, (void*)((char*)dest_p+c_vector_p->element_size), c_vector_p->element_size * (c_vector_p->length - index));
}

typedef struct _c_vector_iterator {
    c_vector *c_vector_p;
    size_t current_index;
} c_vector_iterator;

c_vector_iterator*
c_vector_iterator_init(c_vector_iterator *iterator_p, c_vector *c_vector_p) {
    if (!iterator_p || !c_vector_p) return NULL;
    iterator_p->c_vector_p = c_vector_p;
    iterator_p->current_index = 0;
    return iterator_p;
}

void
c_vector_iterator_destroy(c_vector_iterator *iterator_p) {
    /*do nothing*/
}

void*
c_vector_iterator_next(c_vector_iterator *iterator_p) {
    c_vector *c_vector_p = iterator_p->c_vector_p;
    if (iterator_p->current_index >= c_vector_p->length) return NULL;
    void *ret = (void*)((char*)c_vector_p->buffer + (c_vector_p->element_size * iterator_p->current_index));
    ++iterator_p->current_index;
    return ret;
}


int main() {
    c_vector v;

    c_vector_init(&v, sizeof(int));
    printf("v.capacity() = %zu\n", c_vector_capacity(&v));
    printf("v.length() = %zu\n", c_vector_length(&v));

    for (int i = 0; i < 42; i++) {
        c_vector_push_back(&v, (void*)&i);
    }
    printf("v.length() = %zu\n", c_vector_length(&v));

    c_vector_iterator it;
    c_vector_iterator_init(&it, &v);
    int *num_p = NULL;
    while ((num_p = (int*) c_vector_iterator_next(&it))) {
        printf("v.next() = %d\n", *num_p);
    }
    c_vector_iterator_destroy(&it);

    c_vector_pop_back(&v);
    c_vector_pop_back(&v);
    printf("v.capacity() = %zu\n", c_vector_capacity(&v));
    printf("v.length() = %zu\n", c_vector_length(&v));

    c_vector_resize(&v, 40);
    printf("v.capacity() = %zu\n", c_vector_capacity(&v));
    printf("v.length() = %zu\n", c_vector_length(&v));

    for (int i = 10; i < 16; i++) {
        c_vector_insert(&v, c_vector_length(&v)-1, &i);
    }
    printf("v.capacity() = %zu\n", c_vector_capacity(&v));
    printf("v.length() = %zu\n", c_vector_length(&v));

    for (size_t i = 0; i < c_vector_length(&v); ++i) {
        int *num_p = (int*)c_vector_at(&v, i);
        printf("v.at(%zu) = %d\n", i, *num_p);
    }

    c_vector_erase(&v, 0);
    c_vector_erase(&v, 0);
    c_vector_erase(&v, 0);
    c_vector_erase(&v, 0);
    printf("v.capacity() = %zu\n", c_vector_capacity(&v));
    printf("v.length() = %zu\n", c_vector_length(&v));
    for (size_t i = 0; i < c_vector_length(&v); ++i) {
        int *num_p = (int*)c_vector_at(&v, i);
        printf("v.at(%zu) = %d\n", i, *num_p);
    }

    c_vector_clear(&v);
    printf("v.capacity() = %zu\n", c_vector_capacity(&v));
    printf("v.length() = %zu\n", c_vector_length(&v));

    c_vector_destroy(&v);
    return 0;
}