#include <stdlib.h>
#include <stdio.h>
#include "memory.c"

// ================ ARENA ================  //
void test_arena_init(unsigned char *buffer, u32 buffer_size)
{
  struct Arena a = {0};
  arena_init(&a, buffer, buffer_size);
  assert((a.buffer == buffer) && "Arena does not start at the buffer");
  assert((a.curr_offset == 0) && (a.prev_offset == 0) && "Arena offsets not initialised properly");
  assert((a.capacity == buffer_size) && "Arena capacity does not match buffer size");
}

void test_arena_alloc(unsigned char *buffer, u32 buffer_size)
{
  struct Arena a = {0};
  arena_init(&a, buffer, buffer_size);
  void *qres = arena_alloc(&a, 8);
  assert((qres != NULL) && "Arena Allocation Test Failed: "
      "Reason: Failed to allocate memory");
}

void test_arena_alloc_low_memory(unsigned char *buffer, u32 buffer_size)
{
  struct Arena a = {0};
  arena_init(&a, buffer, buffer_size);
  void *qres = arena_alloc(&a, buffer_size + 20);
  assert((qres == NULL) && "Low Memory Arena Allocation Test Failed: "
      "Reason: Should have allocated the entire buffer since size is larger. \n");
  qres = arena_alloc(&a, 20);
}

void test_arena_alloc_negative_size(unsigned char *buffer, u32 buffer_size)
{
  struct Arena a = {0};
  arena_init(&a, buffer, buffer_size);
  void *qres = arena_alloc(&a, 16);
  u8* n1 = (u8*)qres;

  qres = arena_alloc(&a, -16);

  assert((qres == NULL) && "Low Memory Arena Allocation Test Failed: "
      "Reason: Should have allocated the remaining buffer. \n");
}

void test_arena_resize(unsigned char *buffer, u32 buffer_size)
{
  struct Arena a = {0};
  arena_init(&a, buffer, buffer_size);
  void *qres = arena_alloc(&a, 8);
  u8* n1 = (u8*)qres;
  *n1 = 23;

  qres = arena_alloc(&a, 8);
  u8* n2 = (u8*)qres;
  *n2 = 20;

  qres = arena_resize(&a, n1, 8, 16);
  assert((qres != NULL) && "Arena Resize Test Failed: "
  "Reason: Failed to resize previously allocated memory\n"
  "this should not have happened since we do not have anything causing availability issues\n");
  u8* n1_1 = (u8*)qres;

  assert((*n1 == *n1_1) && "Arena Resize Test Failed: "
  "Reason: Value of resized memory changed. This should not happen in any case!\n");
}

void test_arena_resize_tail(unsigned char *buffer, u32 buffer_size)
{
  struct Arena a = {0};
  arena_init(&a, buffer, buffer_size);
  void *qres = arena_alloc(&a, 16);
  u8* n1 = (u8*)qres;
  *n1 = 23;

  qres = arena_alloc(&a, 16);
  u8* n2 = (u8*)qres;
  *n2 = 20;

  qres = arena_resize(&a, n2, 16, 8);
  /*assert((qres.bytes_count == 8) && "Arena Resize Tail Test Failed: "
  "Reason: Failed to resize previously allocated memory at tail\n");*/
  u8* n2_1 = (u8*)qres;

  assert((*n2 == *n2_1) && "Arena Resize Test Failed: "
  "Reason: Value of resized memory changed. This should not happen in any case!\n");
}

void test_arena_resize_filled_completely(unsigned char *buffer, u32 buffer_size)
{
  struct Arena a = {0};
  arena_init(&a, buffer, buffer_size);
  void *qres = arena_alloc(&a, 8);
  u8* n1 = (u8*)qres;
  *n1 = 23;

  qres = arena_alloc(&a, 8);
  u8* n2 = (u8*)qres;
  *n2 = 20;
  
  qres = arena_resize(&a, n1, 8, buffer_size - 32);
  assert((qres != NULL) && "Arena Resize Filled Completely Failed: \n"
  "Reason: Failed to resize an element even though it perfectly fills the memory Arena");
}

void test_arena_resize_out_of_bounds(unsigned char *buffer, u32 buffer_size)
{
  struct Arena a = {0};
  arena_init(&a, buffer, buffer_size);
  void *qres = arena_alloc(&a, 8);
  u8* n1 = (u8*)qres;
  *n1 = 23;

  qres = arena_alloc(&a, 8);
  u8* n2 = (u8*)qres;
  *n2 = 20;
  
  qres = arena_resize(&a, n1, 8, buffer_size - 8);
  assert(qres == NULL && "Arena Resize OUT OF BOUNDS test Failed: \n"
  "Reason: Allocated a larger than capacity element within Arena capacity.\n");
}

void test_arena_resize_negative_size(unsigned char *buffer, u32 buffer_size)
{
  struct Arena a = {0};
  arena_init(&a, buffer, buffer_size);
  void *qres = arena_alloc(&a, 8);
  u8* n1 = (u8*)qres;
  *n1 = 23;

  qres = arena_alloc(&a, 8);
  u8* n2 = (u8*)qres;
  *n2 = 20;
  
  qres = arena_resize(&a, n1, 8, -35);
  assert(qres == NULL && "Arena Resize -ve size test Failed: \n"
  "Reason: Failed to handle allocating a -ve size (VERY LARGE IN UINT) space.\n");
}

void test_arena_resize_tail_negative_size(unsigned char *buffer, u32 buffer_size)
{
  struct Arena a = {0};
  arena_init(&a, buffer, buffer_size);
  void *qres = arena_alloc(&a, 8);
  u8* n1 = (u8*)qres;
  *n1 = 23;

  qres = arena_alloc(&a, 8);
  u8* n2 = (u8*)qres;
  *n2 = 20;
  
  qres = arena_resize(&a, n2, 8, -35);
  assert(qres == NULL && "Arena Resize OUT OF BOUNDS test Failed: \n"
  "Reason: Failed to fit a larger than capacity element within Arena capacity.\n");
}

void test_arena_clear(unsigned char *buffer, u32 buffer_size)
{
  struct Arena a = {0};
  arena_init(&a, buffer, buffer_size);
  void *qres = arena_alloc(&a, 8);
  arena_clear(&a);
  assert((a.prev_offset == 0) && (a.curr_offset == 0) && "Arena Clear Test Failed: \n"
  "Reason: Failed to clear offsets on an active Arena entity after it was cleared.\n");
}

void test_arena_realloc(unsigned char *buffer, u32 buffer_size)
{
  struct Arena a = {0};
  arena_init(&a, buffer, buffer_size);
  void *qres = arena_alloc(&a, 8);
  u8* n1 = (u8*)qres;
  *n1 = 12;
  u8 n1_value = *n1;

  // free Arena
  arena_clear(&a);

  qres = arena_alloc(&a, 16);
  u8* n1_realloc = (u8*)qres;

  assert((*n1_realloc != n1_value) && "Arena Realloc Test Failed: \n"
      "Reason: Failed to properly clear memory in a region where memory was already allocated.\n");
}

// ================ STACK ================  //

void test_stack_init(unsigned char *buffer, u32 buffer_size)
{
  struct stack s = {0};
  stack_init(&s, buffer, buffer_size);
  assert((s.buffer == buffer) && "stack does not start at the buffer");
  assert((s.curr_offset == 0) && (s.prev_offset == 0) && "stack offsets not initialised properly");
  assert((s.capacity == buffer_size) && "stack capacity does not match buffer size");
}

void test_stack_alloc_n1(unsigned char *buffer, u32 buffer_size)
{
  struct stack s = {0};
  stack_init(&s, buffer, buffer_size);

  u8 ele_sz = 16;
  struct ResVoid qres = stack_alloc(&s, ele_sz);
  assert((qres.status == MEM_OK) && "failed to allocate stack element");

  u8 *ele = (u8 *)qres.memory;
  struct stack_hdr *header = (struct stack_hdr*)((uintptr_t)ele - sizeof(struct stack_hdr));
  assert((header->prev_offset == 0) && "incorrect prev_offset for first stack element");

  size_t pad = header->padding;

  assert((s.curr_offset == pad + ele_sz ) && "incorrect curr offset memory");
}

void test_stack_alloc_n2(unsigned char *buffer, u32 buffer_size)
{
  struct stack s = {0};
  stack_init(&s, buffer, buffer_size);

  u8 ele_sz = 16;
  stack_alloc(&s, ele_sz);

  size_t last_ele_head = s.prev_offset;
  size_t last_ele_tail = s.curr_offset;
  struct ResVoid qres = stack_alloc(&s, ele_sz);
  assert((qres.status == MEM_OK) && "failed to allocate stack element");

  u8 *ele = (u8 *)qres.memory;
  struct stack_hdr *header = (struct stack_hdr*)((uintptr_t)ele - sizeof(struct stack_hdr));
  assert((header->prev_offset == last_ele_head) && "incorrect prev_offset for second stack element");

  size_t pad = header->padding;
  assert((s.curr_offset == last_ele_tail + pad + ele_sz ) && "incorrect curr offset memory");
}

void test_stack_free(unsigned char *buffer, u32 buffer_size)
{
  struct stack s = {0};
  stack_init(&s, buffer, buffer_size);

  u8 ele_sz = 16;
  stack_alloc(&s, ele_sz);

  enum MemStatus status = stack_free(&s);
  assert((status == MEM_OK) && "failed to free stack element");

  assert((s.buffer == buffer) && "failed to reset buffer pointer to start of memory");
  assert((s.prev_offset == 0) && (s.curr_offset == 0) && "failed to move offsets back correctly");
}

void test_stack_resize_n0(unsigned char *buffer, u32 buffer_size)
{
  struct stack s = {0};
  stack_init(&s, buffer, buffer_size);

  u8 static_mem[8] = {0,1,2,3,4,5,6,7};
  struct ResVoid qres = stack_resize(&s, static_mem, 8, 16);
  assert((qres.status == MEM_OUT_OF_BOUNDS) && "Stack Resize n0 Failed: \
        Reason: should not have resized an element not belonging to the stack\n");
}

void test_stack_resize_n1(unsigned char *buffer, u32 buffer_size)
{
  struct stack s = {0};
  stack_init(&s, buffer, buffer_size);

  u8 ele_sz = 16;
  struct ResVoid qres =  stack_alloc(&s, ele_sz);
  u8* n1 = (u8*)qres.memory;
  *n1 = 23;

  qres = stack_resize(&s, n1, ele_sz, ele_sz + 20);
  assert((qres.status == MEM_OK) && "Stack Resize n1 Failed: \
      Reason: failed to resize stack element\n");
  n1 = (u8*)qres.memory;

  struct stack_hdr* header = (struct stack_hdr*)(n1 - sizeof(struct stack_hdr));
  assert((s.curr_offset == 52) && "Stack Resize n1 Failed: \
      Reason: incorrectly resized stack element\n");
}

void test_stack_resize_n1_low_memory(unsigned char *buffer, u32 buffer_size)
{
  struct stack s = {0};
  stack_init(&s, buffer, buffer_size);

  u8 ele_sz = 16;
  struct ResVoid qres =  stack_alloc(&s, ele_sz);
  u8* n1 = (u8*)qres.memory;
  *n1 = 23;

  qres = stack_resize(&s, n1, ele_sz, ele_sz + 256);
  n1 = (u8*)qres.memory;

  assert((qres.status == MEM_FULL) && "Stack Resize n1 low memory Failed: \
      Reason: Should not be allowed to resize beyond the allocated stack capacity\n");
}

void test_stack_resize_n2(unsigned char *buffer, u32 buffer_size)
{
  struct stack s = {0};
  stack_init(&s, buffer, buffer_size);

  u8 ele_sz = 16;
  struct ResVoid qres =  stack_alloc(&s, ele_sz);
  u8* n1 = (u8*)qres.memory;
  *n1 = 1;

  qres = stack_alloc(&s, ele_sz);
  u8* n2 = (u8*)qres.memory;
  *n2 = 2;

  size_t last_ele_head = s.prev_offset;

  qres = stack_resize(&s, n1, ele_sz, 8);
  u8* n3 = (u8*)qres.memory;
  assert((qres.status == MEM_OK) && "Stack Resize n2 Failed: "
      "Reason: failed to resize first element in a two element array\n");

  assert((*n3 == *n1) && "Stack Resize n2 Failed: "
      "Reason: failed to move over data properly after resizing elements");

  struct stack_hdr* header = (struct stack_hdr*)(n3 - sizeof(struct stack_hdr));
  assert((header->prev_offset == last_ele_head) && "Stack Resize 2 Failed: "
      "Reason: failed to set the previous offset of the header element properly after resize");
}

void test_stack_resize_tail(unsigned char *buffer, u32 buffer_size)
{
  struct stack s = {0};
  stack_init(&s, buffer, buffer_size);

  u8 ele_sz = 16;
  struct ResVoid qres =  stack_alloc(&s, ele_sz);
  u8* n1 = (u8*)qres.memory;
  *n1 = 1;

  qres = stack_resize(&s, n1, ele_sz, 8);
  assert((qres.status == MEM_OK) && "Stack Resize tail Failed: "
      "Reason: failed to resize last element to be smaller\n");
}

void test_stack_alloc_free(unsigned char *buffer, u32 buffer_size)
{
  struct stack s = {0};
  stack_init(&s, buffer, buffer_size);

  u8 ele_sz = 16;
  struct ResVoid qres = stack_alloc(&s, ele_sz);
  u8* n1 = (u8*)qres.memory;
  *n1 = 1;
  size_t head_n1 = s.prev_offset;
  size_t tail_n1 = s.curr_offset;

  qres = stack_alloc(&s, ele_sz);
  u8* n2 = (u8*)qres.memory;
  *n2 = 2;
  size_t head_n2 = s.prev_offset;
  size_t tail_n2 = s.curr_offset;

  /* @note: elements are allocated, now we will be testing a few things
   *
   * 1. can we free all elements up till the stack UNTIL the point where, 
   * we can not free the stack since it is empty
   *
   * 2. when we free elements, does the offset reset to the point we expect it to
   * By which I mean,
   *
   *                . . . . . ele_1 . . . . . ele_2 . . . . .
   *                              |               |
   *                              |               |-> curr_offset is here at the end of ele2
   *                              |
   *                              |-> this is the end of ele1, once we free, we expect the curr_offset
   *                              to return to this point and we expect to start considering allocations from
   *                              this point on
   *
   *
   * */
  stack_free(&s);

  assert((s.prev_offset == head_n1) && "Stack alloc free error"
      "Reason: failed to move the prev_offset back to the correct position");
  assert((s.curr_offset == tail_n1) && "Stack alloc free error"
      "Reason: failed to move the curr_offset back to the correct position");

  /*
   * @note: we now want to test after allocating something, whether the memory was overwritten properly
   * and there was no garbage data present
   */

  qres = stack_alloc(&s, ele_sz);
  u8* n2_1 = (u8*)qres.memory;
  assert((*n2_1 == 0) && "Stack Alloc Free error"
      "Reason: failed to free up memory properly on allocating memory that was cleared");
}

void test_stack_alloc_free_resize(unsigned char *buffer, u32 buffer_size)
{
  struct stack s = {0};
  stack_init(&s, buffer, buffer_size);

  u8 ele_sz = 16;
  struct ResVoid qres = stack_alloc(&s, ele_sz);
  u8* n1 = (u8*)qres.memory;
  *n1 = 1;
  size_t head_n1 = s.prev_offset;
  size_t tail_n1 = s.curr_offset;

  qres = stack_alloc(&s, ele_sz);
  u8* n2 = (u8*)qres.memory;
  *n2 = 2;
  size_t head_n2 = s.prev_offset;
  size_t tail_n2 = s.curr_offset;

  qres = stack_alloc(&s, ele_sz);
  u8* n3 = (u8*)qres.memory;
  *n3 = 3;
  size_t head_n3 = s.prev_offset;
  size_t tail_n3 = s.curr_offset;

  stack_free(&s);

  qres = stack_resize(&s, n1, ele_sz, 32);
  u8* n1_1 = (u8*)qres.memory;
  assert((*n1_1 != 3) && "Stack Alloc Free Resize Test Failed: "
      "Reason: the newly resized memory was not setup properly.\n"
      "It had the memory contents of a previously allocated statement\n");
  assert((n1_1 == n3) && "Stack Alloc Free Resize Test Failed: "
      "Reason: the newly resized memory was not allocated to the correct next region\n"
      "It should have the same memory address as memory allocation #3\n");
}

void test_stack_resize_n2_low_space(unsigned char *buffer, u32 buffer_size)
{
  struct stack s = {0};
  stack_init(&s, buffer, buffer_size);

  u8 ele_sz = 16;
  struct ResVoid qres = stack_alloc(&s, ele_sz);
  u8* n1 = (u8*)qres.memory;
  *n1 = 1;
  size_t head_n1 = s.prev_offset;
  size_t tail_n1 = s.curr_offset;

  qres = stack_alloc(&s, s.capacity - 64);
  u8* n2 = (u8*)qres.memory;
  *n2 = 2;
  size_t head_n2 = s.prev_offset;
  size_t tail_n2 = s.curr_offset;

  qres = stack_resize(&s, n1, ele_sz, 30);
  
  assert((qres.status == MEM_FULL) && "Test Stack Resize Low Space with 2 elements Failed: "
      "Reason: Failed to catch resize with size larger than available space. \n");
}

void test_stack_alloc_negative_size(unsigned char *buffer, u32 buffer_size)
{
  struct stack s = {0};
  stack_init(&s, buffer, buffer_size);

  // @note: the way this works is that size_t is unsigned, which is what the function takes
  // so we get a really large number, that actually ends up looping around and becomes less than the array.
  // so we have a bounds check for that.
  stack_alloc(&s, 16);
  struct ResVoid qres = stack_alloc(&s, -16);
  assert((qres.status == MEM_FULL) && "Test Stack Alloc Negative Size Failed\n"
      "Reason: Failed to catch allocation with -ve size. \n"
      "That will translate to be a very large size since the size variable is a size_t (unsigned)\n");
}

void test_stack_resize_negative_size(unsigned char *buffer, u32 buffer_size)
{
  struct stack s = {0};
  stack_init(&s, buffer, buffer_size);

  struct ResVoid qres = stack_alloc(&s, 16);
  s8* n1 = (s8*)qres.memory;
  *n1 = -20;

  qres = stack_resize(&s, n1, 16, -16);
  assert((qres.status == MEM_FULL) && "Test Stack Alloc Negative Size Failed\n"
      "Reason: Failed to catch resize with -ve size. \n"
      "That will translate to be a very large size since the size variable is a size_t (unsigned)\n");
}

void test_stack_resize_tail_negative_size(unsigned char *buffer, u32 buffer_size)
{
  struct stack s = {0};
  stack_init(&s, buffer, buffer_size);

  u8 ele_sz = 16;
  struct ResVoid qres =  stack_alloc(&s, ele_sz);
  u8* n1 = (u8*)qres.memory;
  *n1 = 1;

  qres = stack_resize(&s, n1, ele_sz, -8);
  u8* n2 = (u8*)qres.memory;
  assert((qres.status == MEM_FULL) && "Stack Resize tail Negative Size Failed: "
      "Reason: Failed to catch resize with -ve size. \n"
      "That will translate to be a very large size since the size variable is a size_t (unsigned)\n");
}

int main(int argc, char** argv) {
  u32 sz = 256*sizeof(u8);
  u8 *buffer = (u8 *)malloc(sz);
  // --------- ARENA --------- //
  printf("\n===== Testing Arena Allocator =====\n");
  test_arena_init(buffer, sz);
  printf("- Arena initialization test passed\n");
  test_arena_alloc(buffer, sz);
  test_arena_alloc_low_memory(buffer, sz);
  test_arena_alloc_negative_size(buffer, sz);
  printf("- Arena allocation tests passed\n");
  test_arena_resize(buffer, sz);
  test_arena_resize_tail(buffer, sz);
  test_arena_resize_negative_size(buffer, sz);
  test_arena_resize_tail_negative_size(buffer, sz);
  test_arena_resize_filled_completely(buffer, sz);
  test_arena_resize_out_of_bounds(buffer, sz);
  printf("- Arena resize tests passed\n");
  test_arena_clear(buffer, sz);
  printf("- Arena clear tests passed\n");
  test_arena_realloc(buffer, sz);
  printf("- Arena reallocation tests passed\n");

  // --------- STACK --------- //
  printf("\n===== Testing Stack Allocator =====\n");

  test_stack_init(buffer, sz);
  printf("- stack initialization passed\n");

  test_stack_alloc_n1(buffer, sz);
  test_stack_alloc_n2(buffer, sz);
  printf("- Stack allocation tests passed\n");

  test_stack_free(buffer, sz);
  printf("- stack free passed\n");

  test_stack_resize_n0(buffer, sz);
  test_stack_resize_n1(buffer, sz);
  test_stack_resize_n1_low_memory(buffer, sz);
  test_stack_resize_n2(buffer, sz);
  test_stack_resize_tail(buffer, sz);
  printf("- stack resize passed\n");

  printf("- testing stack alloc free edge cases \n");
  printf("  - edge cases passed:\n");
  test_stack_alloc_free(buffer, sz);
  printf("    1. alloc then free\n");
  test_stack_alloc_free_resize(buffer, sz);
  printf("    2. alloc then free then resize\n");
  test_stack_resize_n2_low_space(buffer, sz);
  printf("    3. alloc two elements and then resize when there is low space\n");
  test_stack_alloc_negative_size(buffer, sz);
  printf("    4. allocating negative size detection\n");
  test_stack_resize_negative_size(buffer, sz);
  printf("    5. resizing negative size detection\n");
  test_stack_resize_tail_negative_size(buffer, sz);
  printf("    6. resizing tail to negative size detection\n");

  printf("\n===== Memory tests completed successfully =====\n");
  free(buffer);
  return 1;
}