// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: BSD-3-Clause

package verify

import (
	"os"
	"os/exec"
	"testing"
)

// goobjVectorMainSrc is the Go side of the vector regression.  The kernel
// computes a signed byte checksum through the RVV load/store and arithmetic
// families; main derives the same value in Go and panics on any divergence
// before printing the deterministic line the baseline and the gasm-linked
// binaries must agree on.
const goobjVectorMainSrc = `package main

func checksum(buf []byte, seed int64) int64

func main() {
	buf := []byte("gasm link parity vector kernel!")
	total := int64(0)
	for _, b := range buf {
		total += int64(int8(b))
	}
	want := total*0x0101010101010101 ^ 0x5eed
	if got := checksum(buf, 0x5eed); got != want {
		panic("checksum")
	}
	println("ok", checksum(buf, 0x5eed))
}
`

// TestGOOBJLinkRVVKernel proves the riscv64 vector families merged into the
// encoder corpus are proven end to end: the kernel assembles by gasm into a
// GOOBJ object, substitutes byte-wise into a real go build archive, relinks
// with cmd/link and the linked binary computes the same checksum as the
// toolchain-built one under qemu-user.  The reduction reads the live vl, so
// the checksum holds for any hardware VLEN.
func TestGOOBJLinkRVVKernel(t *testing.T) {
	if testing.Short() {
		t.Skip("builds the gasm binary and links Go programs")
	}
	if os.Getenv("GASM_LINK_PARITY") == "" {
		t.Skip("deliberate verification: set GASM_LINK_PARITY=1 (just link-parity)")
	}
	goBin, err := exec.LookPath("go")
	if err != nil {
		t.Skip("no Go toolchain available")
	}
	gasmBin := buildLinkParityGasm(t, goBin)
	t.Run("riscv64", func(t *testing.T) {
		goobjLinkKernel(t, goBin, gasmBin, "riscv64", "linkvec_riscv64.s", goobjVectorMainSrc)
	})
}