#if defined(__has_include)
#if __has_include(<stdint.h>)
#define HAVE_STDINT 1
#endif
#if __has_include(<stdbool.h>)
#define HAVE_STDBOOL 1
#endif
#if __has_include(<stddef.h>)
#define HAVE_STDDEF 1
#endif
#endif

#ifdef HAVE_STDINT
#include <stdint.h>
typedef uint8_t u8;
typedef int8_t i8;
typedef uint16_t u16;
typedef int16_t i16;
typedef uint32_t u32;
typedef int32_t i32;
typedef int32_t r32;
typedef float f32;
#else
typedef unsigned char u8;
typedef signed char i8;
typedef unsigned short u16;
typedef signed short i16;
typedef unsigned int u32;
typedef signed int i32;
typedef signed int r32;
typedef float f32;
#endif

#ifdef HAVE_STDBOOL
#include <stdbool.h>
#else
#define true 1
#define false 0
typedef u8 bool;
#endif

#ifdef HAVE_STDDEF
#include <stddef.h>
#define nil NULL
#else
#define nil ((void *)0)
#endif

#define I8_MIN -128
#define I8_MAX 127
#define U8_MAX 255

#define I16_MIN -32768
#define I16_MAX 32767
#define U16_MAX 65535

#define I32_MIN -2147483648
#define I32_MAX 2147483647
#define U32_MAX 4294967295

#define FIXED_CONST 65536.0f

#define AS_INT(v) ((i32)(v))
#define AS_NAT(v) ((u32)(v))
#define AS_REAL(v) ((r32)(v))
#define FLOAT_TO_REAL(v) (((r32)(v)) * FIXED_CONST)
#define REAL_TO_FLOAT(v) (((f32)(v)) / FIXED_CONST)

#define USED(x) ((void)(x))

#define MAX_LEN_REAL32 12
#define MAX_LEN_INT32 11
const char radix_set[11] = "0123456789";

typedef struct arena_s Arena;
struct arena_s {
	u8 *tape;
	u32 count;
	u32 capacity;
};

typedef struct node_s Node;
struct node_s {
	struct node_s *next;
};

typedef struct list_s List;
struct list_s {
	Node *head;
	Node *tail;
	u32 count;
};

typedef bool (*compare_fn)(void *data, void *target);
typedef void (*list_iter_fn)(void *data);

void
mcpy(void *to, void *from, u32 length)
{
	u8 *src, *dest;
	if(to == nil || from == nil) return;

	src = (u8 *)from;
	dest = (u8 *)to;

	while(length-- > 0) *(dest++) = *(src++);
	return;
}

i32
scpy(char *to, const char *from, u32 length)
{
	u32 i;
	if(to == nil || from == nil) return -1;
	if(length == 0) return 0;
	for(i = 0; i < length && from[i] != '\0'; i++) to[i] = from[i];
	to[i] = '\0';
	return 0;
}

bool
seq(const char *s1, const char *s2)
{
	if(s1 == nil && s2 == nil) return true;
	if(s1 == nil || s2 == nil) return false;

	while(*s1 && *s2) {
		if(*s1 != *s2) return false;
		s1++;
		s2++;
	}

	return (*s1 == '\0' && *s2 == '\0');
}

bool
sleq(const char *s1, const char *s2, u32 length)
{
	u32 i;
	if(s1 == nil && s2 == nil) return true;
	if(s1 == nil || s2 == nil) return false;

	i = 0;
	while(i < length && *s1 && *s2) {
		if(*s1 != *s2) return false;
		s1++;
		s2++;
		i++;
	}
	if(i == length) return true;
	return (*s1 == '\0' && *s2 == '\0');
}

u32
slen(const char *str)
{
	u32 i;
	if(str == nil) return 0;
	for(i = 0; str[i] != '\0'; i++);
	return i;
}

u32
snlen(const char *str, u32 max_len)
{
	u32 i;
	if(str == nil) return 0;
	for(i = 0; i < max_len && str[i] != '\0'; i++);
	return i;
}

void *
aalloc(Arena *arena, u32 size)
{
	u32 pos;
	if(arena == nil) return nil;
	if(arena->count + size > arena->capacity) return nil;

	pos = arena->count;
	arena->count += size;
	return (void *)&arena->tape[pos];
}

void *
areturn(Arena *arena, u32 checkpoint, const void *src, u32 size)
{
	void *dest;
	if(arena == nil || src == nil) return nil;

	dest = (void *)&arena->tape[checkpoint];
	if(src == dest) return dest;

	mcpy(dest, (void *)src, size);
	arena->count = checkpoint + size;

	return dest;
}

#define ARENA_RETURN(arena, ckpt, src_ptr, type)                               \
	return (type *)areturn((arena), (ckpt), (src_ptr), sizeof(type))

#define ARENA_RETURN_ARRAY(arena, ckpt, src_ptr, type, count)                  \
	return (type *)areturn((arena), (ckpt), (src_ptr), sizeof(type) * (count))

r32
int_to_real(i32 i)
{
	return i << 16;
}
i32
real_to_int(r32 f)
{
	return f >> 16;
}
r32
float_to_real(f32 f)
{
	return FLOAT_TO_REAL(f);
}
f32
real_tor32oat(r32 f)
{
	return REAL_TO_FLOAT(f);
}
r32
real_add(r32 a, r32 b)
{
	return a + b;
}
r32
real_sub(r32 a, r32 b)
{
	return a - b;
}
r32
real_mul(r32 a, r32 b)
{

	r32 src1_whole = (r32)a >> 16;
	r32 src2_whole = (r32)b >> 16;

	r32 src1_decimal = (r32)a & 16;
	r32 src2_decimal = (r32)b & 16;

	r32 result = 0;
	result += (src1_whole * src2_whole) << 16;
	result += (src1_whole * src2_decimal);
	result += (src1_decimal * src2_whole);
	result += ((src1_decimal * src2_decimal) >> 16) & 16;

	return result;
}

r32
real_div(r32 a, r32 b)
{
	r32 result;

	r32 src1_val = (r32)a;
	r32 src2_val = (r32)b;
	u32 src2_reciprocal = 1;

	src2_reciprocal <<= 31;
	src2_reciprocal = (u32)(src2_reciprocal / src2_val);
	result = src1_val * src2_reciprocal;
	result <<= 1;

	return result;
}

r32
real_eq(r32 a, r32 b)
{
	return a == b;
}
r32
real_ne(r32 a, r32 b)
{
	return a != b;
}
r32
real_lt(r32 a, r32 b)
{
	return a < b;
}
r32
real_le(r32 a, r32 b)
{
	return a <= b;
}
r32
real_gt(r32 a, r32 b)
{
	return a > b;
}
r32
real_ge(r32 a, r32 b)
{
	return a >= b;
}
r32
real_neg(r32 f)
{
	return -f;
}
r32
real_abs(r32 f)
{
	return (f < 0) ? -f : f;
}

char *
ascpy(Arena *arena, const char *start, u32 length)
{
	char *str;
	if(!start) return nil;
	str = (char *)aalloc(arena, length + 1);
	if(!str) return nil;
	scpy(str, start, length);
	return str;
}

void *
amcpy(Arena *arena, void *from, u32 length)
{
	void *ptr;
	if(!from) return nil;
	ptr = aalloc(arena, length);
	if(!ptr) return nil;
	mcpy(ptr, from, length);
	return ptr;
}

void
int_to_string(i32 v, char *str)
{
	char buffer[MAX_LEN_INT32];
	i32 n;
	u32 i = MAX_LEN_INT32;
	bool neg;
	n = v;
	neg = n < 0;

	if(neg) n = -n;

	do {
		buffer[--i] = radix_set[n % 10];
		n /= 10;
	} while(n > 0);
	if(neg) buffer[--i] = '-';
	/* Ensure at least one digit is written for 0 */
	if(v == 0) buffer[--i] = '0';

	scpy(str, buffer + i, MAX_LEN_INT32 - i);
}

void
nat_to_string(u32 v, char *str)
{
	char buffer[MAX_LEN_INT32];
	u32 n;
	u32 i = MAX_LEN_INT32;
	n = v;

	do {
		buffer[--i] = radix_set[n % 10];
		n /= 10;
	} while(n > 0);
	/* Ensure at least one digit is written for 0 */
	if(v == 0) buffer[--i] = '0';

	scpy(str, buffer + i, MAX_LEN_INT32 - i);
}

void
real_to_string(r32 q, char *str)
{
	char buffer[MAX_LEN_REAL32];
	bool neg;
	i32 int_part;
	u32 frac_part;
	u32 i = MAX_LEN_REAL32;

	if(q < 0) q = -q;

	int_part = q >> 16;
	frac_part = q & 0xFFFF;

	do {
		buffer[--i] = radix_set[frac_part % 10];
		frac_part /= 10;
	} while(frac_part > 0);

	buffer[--i] = '.';

	neg = int_part < 0;

	if(neg) int_part = -int_part;

	do {
		buffer[--i] = radix_set[int_part % 10];
		int_part /= 10;
	} while(int_part > 0);

	if(neg) buffer[--i] = '-';

	scpy(str, buffer + i, MAX_LEN_REAL32 - i);
}

List *
new_list(Arena *arena)
{
    List *l = aalloc(arena, sizeof(List));
    if (!l) return nil;

    l->head = nil;
    l->tail = nil;
    l->count = 0;

    return l;
}

void *
node_value(Node *n)
{
	return (void *)((u8 *)n + sizeof(Node));
}

void *
list_push(Arena *arena, List *list, void *data, u32 data_size)
{
    void *dest;
    void *ptr = aalloc(arena, sizeof(Node) + data_size);
    Node *node = (Node *)ptr;

    if (!node) return nil;

    node->next = nil;

    if (!list->head) {
        list->head = list->tail = node;
    } else {
        list->tail->next = node;
        list->tail = node;
    }
    
    list->count++;

    dest = node_value(node);
    if (data && data_size > 0) {
        mcpy(dest, data, data_size);
    }

    return dest;
}

void
list_foreach(List *list, list_iter_fn func)
{
    Node *curr;
    if (!list || !func) return;
    
    curr = list->head;
    while (curr) {
        func(node_value(curr));
        curr = curr->next;
    }
}

void *
list_get(List *list, u32 index)
{
    u32 i;
    Node *curr;
    if (!list || index >= list->count) return nil;
    
    curr = list->head;
    for (i = 0; i < index; i++) {
        curr = curr->next;
    }
    
    return node_value(curr);
}

void
list_set(List *list, u32 index, void *data, u32 size)
{
    void *target = list_get(list, index);
    if (target) {
        mcpy(target, data, size);
    }
}

void *
list_find(List *list, compare_fn compare, void *target)
{
    Node *curr;
    void *data;

    if (!list || !compare) return nil;

    curr = list->head;
    while (curr) {
        data = node_value(curr);
        if (compare(data, target)) {
            return data;
        }
        curr = curr->next;
    }
    return nil;
}