// non-pub versions of array functions
// that allocale new memory using `GC_MALLOC_ATOMIC()`
// when `-gc boehm_*_opt` is used. These memory areas are not
// scanned for pointers.

module builtin

fn __new_array_noscan(mylen int, cap int, elm_size int) array {
    cap_ := if cap < mylen { mylen } else { cap }
    arr := array{
        element_size: elm_size
        data: vcalloc_noscan(u64(cap_) * u64(elm_size))
        len: mylen
        cap: cap_
    }
    return arr
}

fn __new_array_with_default_noscan(mylen int, cap int, elm_size int, val voidptr) array {
    cap_ := if cap < mylen { mylen } else { cap }
    mut arr := array{
        element_size: elm_size
        data: vcalloc_noscan(u64(cap_) * u64(elm_size))
        len: mylen
        cap: cap_
    }
    if val != 0 && arr.data != unsafe { nil } {
        if elm_size == 1 {
            byte_value := *(&u8(val))
            dptr := &u8(arr.data)
            for i in 0 .. arr.len {
                unsafe {
                    dptr[i] = byte_value
                }
            }
        } else {
            for i in 0 .. arr.len {
                unsafe { arr.set_unsafe(i, val) }
            }
        }
    }
    return arr
}

fn __new_array_with_multi_default_noscan(mylen int, cap int, elm_size int, val voidptr) array {
    cap_ := if cap < mylen { mylen } else { cap }
    mut arr := array{
        element_size: elm_size
        data: vcalloc_noscan(u64(cap_) * u64(elm_size))
        len: mylen
        cap: cap_
    }
    if val != 0 && arr.data != unsafe { nil } {
        for i in 0 .. arr.len {
            unsafe { arr.set_unsafe(i, charptr(val) + i * elm_size) }
        }
    }
    return arr
}

fn __new_array_with_array_default_noscan(mylen int, cap int, elm_size int, val array) array {
    cap_ := if cap < mylen { mylen } else { cap }
    mut arr := array{
        element_size: elm_size
        data: vcalloc_noscan(u64(cap_) * u64(elm_size))
        len: mylen
        cap: cap_
    }
    for i in 0 .. arr.len {
        val_clone := val.clone()
        unsafe { arr.set_unsafe(i, &val_clone) }
    }
    return arr
}

// Private function, used by V (`nums := [1, 2, 3]`)
fn new_array_from_c_array_noscan(len int, cap int, elm_size int, c_array voidptr) array {
    cap_ := if cap < len { len } else { cap }
    arr := array{
        element_size: elm_size
        data: vcalloc_noscan(u64(cap_) * u64(elm_size))
        len: len
        cap: cap_
    }
    // TODO Write all memory functions (like memcpy) in V
    unsafe { vmemcpy(arr.data, c_array, u64(len) * u64(elm_size)) }
    return arr
}

// Private function. Doubles array capacity if needed.
fn (mut a array) ensure_cap_noscan(required int) {
    if required <= a.cap {
        return
    }
    if a.flags.has(.nogrow) {
        panic('array.ensure_cap_noscan: array with the flag `.nogrow` cannot grow in size, array required new size: ${required}')
    }
    mut cap := if a.cap > 0 { a.cap } else { 2 }
    for required > cap {
        cap *= 2
    }
    new_size := u64(cap) * u64(a.element_size)
    new_data := vcalloc_noscan(new_size)
    if a.data != unsafe { nil } {
        unsafe { vmemcpy(new_data, a.data, u64(a.len) * u64(a.element_size)) }
        // TODO: the old data may be leaked when no GC is used (ref-counting?)
    }
    a.data = new_data
    a.offset = 0
    a.cap = cap
}

// repeat returns a new array with the given array elements repeated given times.
// `cgen` will replace this with an apropriate call to `repeat_to_depth()`

// version of `repeat()` that handles multi dimensional arrays
// `unsafe` to call directly because `depth` is not checked
[unsafe]
fn (a array) repeat_to_depth_noscan(count int, depth int) array {
    if count < 0 {
        panic('array.repeat: count is negative: ${count}')
    }
    mut size := u64(count) * u64(a.len) * u64(a.element_size)
    if size == 0 {
        size = u64(a.element_size)
    }
    arr := array{
        element_size: a.element_size
        data: if depth > 0 { vcalloc(size) } else { vcalloc_noscan(size) }
        len: count * a.len
        cap: count * a.len
    }
    if a.len > 0 {
        a_total_size := u64(a.len) * u64(a.element_size)
        arr_step_size := u64(a.len) * u64(arr.element_size)
        mut eptr := &u8(arr.data)
        unsafe {
            for _ in 0 .. count {
                if depth > 0 {
                    ary_clone := a.clone_to_depth_noscan(depth)
                    vmemcpy(eptr, &u8(ary_clone.data), a_total_size)
                } else {
                    vmemcpy(eptr, &u8(a.data), a_total_size)
                }
                eptr += arr_step_size
            }
        }
    }
    return arr
}

// insert inserts a value in the array at index `i`
fn (mut a array) insert_noscan(i int, val voidptr) {
    $if !no_bounds_checking {
        if i < 0 || i > a.len {
            panic('array.insert: index out of range (i == ${i}, a.len == ${a.len})')
        }
    }
    a.ensure_cap_noscan(a.len + 1)
    unsafe {
        vmemmove(a.get_unsafe(i + 1), a.get_unsafe(i), u64(a.len - i) * u64(a.element_size))
        a.set_unsafe(i, val)
    }
    a.len++
}

// insert_many inserts many values into the array from index `i`.
[unsafe]
fn (mut a array) insert_many_noscan(i int, val voidptr, size int) {
    $if !no_bounds_checking {
        if i < 0 || i > a.len {
            panic('array.insert_many: index out of range (i == ${i}, a.len == ${a.len})')
        }
    }
    a.ensure_cap_noscan(a.len + size)
    elem_size := a.element_size
    unsafe {
        iptr := a.get_unsafe(i)
        vmemmove(a.get_unsafe(i + size), iptr, u64(a.len - i) * u64(elem_size))
        vmemcpy(iptr, val, u64(size) * u64(elem_size))
    }
    a.len += size
}

// prepend prepends one value to the array.
fn (mut a array) prepend_noscan(val voidptr) {
    a.insert_noscan(0, val)
}

// prepend_many prepends another array to this array.
[unsafe]
fn (mut a array) prepend_many_noscan(val voidptr, size int) {
    unsafe { a.insert_many_noscan(0, val, size) }
}

// pop returns the last element of the array, and removes it.
fn (mut a array) pop_noscan() voidptr {
    // in a sense, this is the opposite of `a << x`
    $if !no_bounds_checking {
        if a.len == 0 {
            panic('array.pop: array is empty')
        }
    }
    new_len := a.len - 1
    last_elem := unsafe { &u8(a.data) + u64(new_len) * u64(a.element_size) }
    a.len = new_len
    // Note: a.cap is not changed here *on purpose*, so that
    // further << ops on that array will be more efficient.
    return unsafe { memdup_noscan(last_elem, a.element_size) }
}

// `clone_static_to_depth_noscan()` returns an independent copy of a given array.
// Unlike `clone_to_depth_noscan()` it has a value receiver and is used internally
// for slice-clone expressions like `a[2..4].clone()` and in -autofree generated code.
fn (a array) clone_static_to_depth_noscan(depth int) array {
    return unsafe { a.clone_to_depth_noscan(depth) }
}

// recursively clone given array - `unsafe` when called directly because depth is not checked
[unsafe]
fn (a &array) clone_to_depth_noscan(depth int) array {
    mut size := u64(a.cap) * u64(a.element_size)
    if size == 0 {
        size++
    }
    mut arr := array{
        element_size: a.element_size
        data: if depth == 0 { vcalloc_noscan(size) } else { vcalloc(size) }
        len: a.len
        cap: a.cap
    }
    // Recursively clone-generated elements if array element is array type
    if depth > 0 {
        for i in 0 .. a.len {
            ar := array{}
            unsafe { vmemcpy(&ar, a.get_unsafe(i), int(sizeof(array))) }
            ar_clone := unsafe { ar.clone_to_depth_noscan(depth - 1) }
            unsafe { arr.set_unsafe(i, &ar_clone) }
        }
        return arr
    } else {
        if a.data != 0 {
            unsafe { vmemcpy(&u8(arr.data), a.data, u64(a.cap) * u64(a.element_size)) }
        }
        return arr
    }
}

fn (mut a array) push_noscan(val voidptr) {
    a.ensure_cap_noscan(a.len + 1)
    unsafe { vmemcpy(&u8(a.data) + u64(a.element_size) * u64(a.len), val, a.element_size) }
    a.len++
}

// push_many implements the functionality for pushing another array.
// `val` is array.data and user facing usage is `a << [1,2,3]`
[unsafe]
fn (mut a3 array) push_many_noscan(val voidptr, size int) {
    if size <= 0 || val == unsafe { nil } {
        return
    }
    if a3.data == val && a3.data != 0 {
        // handle `arr << arr`
        copy := a3.clone()
        a3.ensure_cap_noscan(a3.len + size)
        unsafe {
            vmemcpy(a3.get_unsafe(a3.len), copy.data, u64(a3.element_size) * u64(size))
        }
    } else {
        a3.ensure_cap_noscan(a3.len + size)
        if a3.data != 0 && val != 0 {
            unsafe { vmemcpy(a3.get_unsafe(a3.len), val, u64(a3.element_size) * u64(size)) }
        }
    }
    a3.len += size
}

// reverse returns a new array with the elements of the original array in reverse order.
fn (a array) reverse_noscan() array {
    if a.len < 2 {
        return a
    }
    mut arr := array{
        element_size: a.element_size
        data: vcalloc_noscan(u64(a.cap) * u64(a.element_size))
        len: a.len
        cap: a.cap
    }
    for i in 0 .. a.len {
        unsafe { arr.set_unsafe(i, a.get_unsafe(a.len - 1 - i)) }
    }
    return arr
}

// grow_cap grows the array's capacity by `amount` elements.
fn (mut a array) grow_cap_noscan(amount int) {
    a.ensure_cap_noscan(a.cap + amount)
}

// grow_len ensures that an array has a.len + amount of length
[unsafe]
fn (mut a array) grow_len_noscan(amount int) {
    a.ensure_cap_noscan(a.len + amount)
    a.len += amount
}