// The AEAD must produce the RFC 8439 §2.8.2 ciphertext when it is a dependency
// of an application build, not only when its own package is the build root.
package main

import (
	"fmt"

	"golang.org/x/crypto/chacha20poly1305"
)

func unhex(s string) (b []byte) {
	b = []byte{:len(s) / 2}
	digit := func(c byte) (v byte, ok bool) {
		switch {
		case c >= '0' && c <= '9':
			return c - '0', true
		case c >= 'a' && c <= 'f':
			return c - 'a' + 10, true
		}
		return 0, false
	}
	for i := int32(0); i < int32(len(b)); i++ {
		hi, ok1 := digit(s[2*i])
		lo, ok2 := digit(s[2*i+1])
		if !ok1 || !ok2 {
			return nil
		}
		b[i] = hi<<4 | lo
	}
	return
}

func main() {
	key := unhex("808182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9f")
	nonce := unhex("070000004041424344454647")
	aad := unhex("50515253c0c1c2c3c4c5c6c7")
	plaintext := []byte("Ladies and Gentlemen of the class of '99: If I could offer you only one tip for the future, sunscreen would be it.")
	// Text joins with |, not +: '+' on text is a compile error in Moxie.
	wantHex := "d31a8d34648e60db7b86afbc53ef7ec2" |
		"a4aded51296e08fea9e2b5a736ee62d6" |
		"3dbea45e8ca9671282fafb69da92728b" |
		"1a71de0a9e060b2905d6a5b67ecd3b36" |
		"92ddbd7f2d778b8c9803aee328091b58" |
		"fab324e4fad675945585808b4831d7bc" |
		"3ff4def08e4b7a9de576d26586cec64b" |
		"6116" |
		"1ae10b594f09e26a7e902ecbd0600691"
	want := unhex(wantHex)
	aead, err := chacha20poly1305.New(key)
	if err != nil {
		fmt.Printf("New failed: %s\n", err.Error())
		return
	}
	ct := aead.Seal(nil, nonce, plaintext, aad)
	if len(ct) != len(want) {
		fmt.Printf("bad length: got %d want %d\n", int32(len(ct)), int32(len(want)))
		return
	}
	for i := int32(0); i < int32(len(want)); i++ {
		if ct[i] != want[i] {
			fmt.Printf("MISMATCH at %d: got %02x want %02x (first=%02x)\n", i, int32(ct[i]), int32(want[i]), int32(ct[0]))
			return
		}
	}
	fmt.Printf("ok %02x %02x\n", int32(ct[0]), int32(ct[len(ct)-1]))
}