include "std/num.zr"
include "std/mem.zr"

func u8.is_whitespace[x: u8] : bool
    return x == ' ' || x == '\n' || x == '\t' || x == '\r'

func u8.is_digit[x: u8] : bool
    return x >= '0' && x <= '9'

func u8.is_hex_digit[x: u8] : bool
    return (x >= '0' && x <= '9') || (x >= 'a' && x <= 'f') || (x >= 'A' && x <= 'F')

func u8.is_lowercase[x: u8] : bool
    return x >= 'a' && x <= 'z'

func u8.is_uppercase[x: u8] : bool
    return x >= 'A' && x <= 'Z'

func u8.is_letter[x: u8] : bool
    return x->is_uppercase() || x->is_lowercase()

func u8.is_alphanumeric[x: u8] : bool
    return x->is_letter() || x->is_digit()

func u8.to_str[c: u8] : str
    s := mem.alloc(2) as str
    s[0] = c
    s[1] = 0
    return s

func str.free[s: str] : void
    mem.free(s)

func str.len[s: str] : i64
    i := 0
    while s[i]
        i += 1
    return i

func str.make_copy[s: str] : str
    size := s->len() + 1
    dup := mem.alloc(size) as str
    mem.copy(s as ptr, dup as ptr, size)
    return dup

func str.equal[a: str, b: str] : bool
    i := 0
    while a[i] != 0 && b[i] != 0
        if a[i] != b[i]
            return false
        i += 1
    return a[i] == b[i]

func str.equal_n[a: str, b: str, n: i64] : bool
    i := 0
    while i < n
        if a[i] == 0 || b[i] == 0
            return false
        if a[i] != b[i]
            return false
        i += 1
    return true

func str.format_into[..] : i64
    buf := _var_arg(0) as ptr
    size := _var_arg(1) as i64
    if size <= 0
        return 0
    s := _var_arg(2) as ptr
    i := 3
    n := 0

    tmp := _stackalloc(64) as str

    while s[0]
        if s[0] == '%'
            s += 1

            if s[0] == 'd'
                (_var_arg(i) as i64)->to_str_buf(tmp as ptr)
                tmp_len := tmp->len()
                remaining := size - n - 1
                mem.copy(tmp as ptr, buf + n, math.min(tmp_len, remaining))
                n += tmp_len
                i += 1
            else if s[0] == 'x'
                (_var_arg(i) as i64)->to_hex_str_buf(tmp as ptr)
                tmp_len := tmp->len()
                remaining := size - n - 1
                mem.copy(tmp as ptr, buf + n, math.min(tmp_len, remaining))
                n += tmp_len
                i += 1
            else if s[0] == 's'
                tmp_str := _var_arg(i) as str
                tmp_len := tmp_str->len()
                remaining := size - n - 1
                mem.copy(tmp_str as ptr, buf + n, math.min(tmp_len, remaining))
                n += tmp_len
                i += 1
            else if s[0] == 'c'
                if n < size - 1
                    buf[n] = _var_arg(i) as u8
                n += 1
                i += 1
            else if s[0] == 'f'
                // TODO: fix when we implement f64 params
                f64.to_str_buf(_var_arg(i), tmp as ptr)
                tmp_len := tmp->len()
                remaining := size - n - 1
                mem.copy(tmp as ptr, buf + n, math.min(tmp_len, remaining))
                n += tmp_len
                i += 1
            else if s[0] == '%'
                if n < size - 1
                    buf[n] = '%'
                n += 1
            else if s[0] == 0
                break
            else
                panic("str.format_into: unrecognized format")
        else
            if n < size - 1
                buf[n] = s[0]
            n += 1
        s += 1

    if n < size
        buf[n] = 0
    else if size > 0
        buf[size - 1] = 0
    return n

func str.concat[a: str, b: str] : str
    a_len := a->len()
    b_len := b->len()
    out := mem.alloc(a_len + b_len + 1) as str
    mem.copy(a as ptr, out as ptr, a_len)
    mem.copy(b as ptr, out as ptr + a_len, b_len)
    out[a_len + b_len] = 0
    return out

func str.contains[haystack: str, needle: str] : bool
    return haystack->find(needle) != -1

func str.find[haystack: str, needle: str] : i64
    haystack_len := haystack->len()
    needle_len := needle->len()

    if needle_len == 0
        return 0
    
    if needle_len > haystack_len
        return -1

    for i in 0..(haystack_len - needle_len + 1)
        if haystack[i] != needle[0]
            continue
        if needle_len == 1
            return i
        match := true
        for j in 1..needle_len
            if haystack[i + j] != needle[j]
                match = false
                break
        if match
            return i
    return -1

func str.substr[s: str, start: i64, length: i64] : str
    out := mem.alloc(length + 1) as str
    mem.copy(s as ptr + start, out as ptr, length)
    out[length] = 0
    return out

func str.trim[s: str] : str
    len := s->len()
    if len == 0
        out := mem.alloc(1) as str
        out[0] = 0
        return out

    start := 0
    end := len - 1

    while start <= end && s[start]->is_whitespace()
        start += 1

    while end >= start && s[end]->is_whitespace()
        end -= 1

    return s->substr(start, end - start + 1)

func str.reverse[s: str] : str
    len := s->len()
    out := mem.alloc(len + 1) as str

    for i in 0..len
        out[i] = s[len - i - 1]
    out[len] = 0
    return out


func str.parse_i64[s: str] : i64
    len := s->len()
    i := 0

    sign := 1
    if i < len && s[i] == '-'
        sign = -1
        i += 1

    num := 0
    while i < len
        d := s[i]
        if !d->is_digit()
            break
        num = num * 10 + (d - '0')
        i += 1
    return num * sign

func str.hex_encode[s: str, s_len: i64] : str
    hex_chars := "0123456789abcdef"
    out := mem.alloc(s_len * 2 + 1) as str

    for i in 0..s_len
        b := s[i]
        out[i * 2]     = hex_chars[(b >> 4) & 15]
        out[i * 2 + 1] = hex_chars[b & 15]

    out[s_len * 2] = 0
    return out

func str._hex_digit_to_int[d: u8] : u8
    if d->is_digit()
        return d - '0'
    lower : u8 = d | 32 
    if lower >= 'a' && lower <= 'f'
        return lower - 'a' + 10
    panic("invalid hex digit passed to str._hex_digit_to_int")

func str.hex_decode[s: str] : str
    s_len := s->len()
    if s_len % 2 != 0
        panic("invalid hex string passed to str.hex_decode")

    out_len := s_len / 2
    out := mem.alloc(out_len + 1) as str

    for i in 0..out_len
        high := str._hex_digit_to_int(s[i * 2])
        low := str._hex_digit_to_int(s[i * 2 + 1])
        out[i] = (high << 4) | low

    out[out_len] = 0
    return out

struct str.Builder
    data: ptr
    size: i64
    capacity: i64

func str.Builder._grow[b: str.Builder, needed: i64] : void
    if b->size + needed > b->capacity
        new_capacity := 64
        if b->capacity != 0
            new_capacity = b->capacity * 2
        while new_capacity < b->size + needed
            new_capacity = new_capacity * 2
        b->data = b->data->realloc(new_capacity)
        b->capacity = new_capacity

func str.Builder.append_char[b: str.Builder, c: u8] : void
    b->_grow(1)
    b->data[b->size] = c
    b->size += 1

func str.Builder.append[b: str.Builder, s: str] : void
    len := s->len()
    b->_grow(len)
    mem.copy(s as ptr, b->data + b->size, len)
    b->size += len

func str.Builder.build[b: str.Builder] : str
    s := mem.alloc(b->size + 1) as str
    mem.copy(b->data, s as ptr, b->size)
    s[b->size] = 0
    return s

func str.Builder.destroy[b: str.Builder] : void
    if b->data != 0
        b->data->free()
    b->size = 0
    b->capacity = 0

// here to prevent num depending on mem
func i64.to_str[n: i64] : str
    out := mem.alloc(21)
    n->to_str_buf(out)
    return out as str

func i64.to_hex_str[n: i64] : str
    out := mem.alloc(17)
    n->to_hex_str_buf(out)
    return out as str