package xx

import (
	"runtime"
	"strings"
	"unsafe"

	"git.brut.systems/judah/xx/mem"
)

// Copy copies src number of bytes into dst.
// Returns dst.
//
// Copy panics if src is smaller than dst.
func Copy[TDst any, TSrc any](dst *TDst, src *TSrc) *TDst {
	if mem.Sizeof[TSrc]() < mem.Sizeof[TDst]() {
		panic("copy: size of src must be >= dst")
	}
	mem.Copy(unsafe.Pointer(dst), unsafe.Pointer(src), mem.Sizeof[TDst]())
	return dst
}

// Clone returns a newly allocated shallow copy of the given value.
func Clone[T any](value *T) *T {
	return Copy(new(T), value)
}

// BoolUint converts a boolean to an integer.
func BoolUint(b bool) uint {
	return uint(*(*uint8)(unsafe.Pointer(&b)))
}

// CallerLocation returns the source location of the function CallerLocation is called in.
func CallerLocation() (file string, line int) {
	_, file, line, _ = runtime.Caller(2)

	// @todo: I'm sure there's a better way to do this
	// Special-case when CallerLocation is called from main
	if strings.Contains(file, "runtime") && strings.Contains(file, "proc.go") {
		_, file, line, _ = runtime.Caller(1)
	}

	return
}

// HashLocation returns a hash of file and line, most likely returned from [CallerLocation].
func HashLocation(file string, line int) uint64 {
	const (
		FNV64_PRIME uint64 = 0x100000001B3
		FNV64_BIAS  uint64 = 0xCBF29CE484222325
	)

	h := FNV64_BIAS
	for _, c := range file {
		h = (h ^ uint64(c)) * FNV64_PRIME
	}

	h = (h ^ uint64(line)) * FNV64_PRIME
	return h
}