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

package verify

import (
	"bytes"
	"os"
	"testing"

	"sourcedock.dev/petrbalvin/gasm-devkit/asm"
	"sourcedock.dev/petrbalvin/gasm-devkit/parser"
)

// TestGroundTruthRISCV assembles the riscv64 test kernels with gasm and
// compares them byte-for-byte against `go tool asm` (GOARCH=riscv64).  The
// relocation fields of static-symbol references are masked before the
// comparison, since the toolchain leaves them zero for the linker.
func TestGroundTruthRISCV(t *testing.T) {
	for _, path := range []string{
		"../testdata/verify/basic_riscv64.s",
		"../testdata/verify/rvc_riscv64.s",
		"../testdata/verify/loadstore_riscv64.s",
		"../testdata/verify/largeimm_riscv64.s",
		"../testdata/verify/movimm_riscv64.s",
		"../testdata/verify/branch_riscv64.s",
		"../testdata/verify/call_riscv64.s",
		"../testdata/verify/bigframe_riscv64.s",
		"../testdata/verify/guard_riscv64.s",
		"../testdata/verify/indirect_riscv64.s",
		"../testdata/verify/misc_riscv64.s",
		"../testdata/verify/rvcstore_riscv64.s",
		"../testdata/verify/atomics_riscv64.s",
		"../testdata/verify/vector_riscv64.s",
		"../testdata/verify/bitmanip_riscv64.s",
		"trampoline_riscv64.s",
	} {
		t.Run(path, func(t *testing.T) {
			testGroundTruthRISCVFile(t, path)
		})
	}
}

func testGroundTruthRISCVFile(t *testing.T, path string) {
	src, err := os.ReadFile(path)
	if err != nil {
		t.Fatalf("read: %v", err)
	}
	f, errs := parser.Parse(path, string(src))
	if len(errs) > 0 {
		t.Fatalf("parse: %v", errs)
	}
	img, err := asm.AssembleFileRISCV(f)
	if err != nil {
		t.Fatalf("AssembleFileRISCV: %v", err)
	}
	gt, err := GroundTruthRISCV(path)
	if err != nil {
		t.Fatalf("GroundTruthRISCV: %v", err)
	}

	matched := 0
	for _, fn := range img.Funcs {
		gasmCode := maskRelocs(append([]byte(nil), img.Code[fn.Offset:fn.Offset+fn.Size]...), fn.Relocs)
		goCode, ok := gt[fn.Name]
		if !ok {
			t.Errorf("%s: not in ground truth (%d functions)", fn.Name, len(gt))
			continue
		}
		goCode = maskRelocs(goCode, fn.Relocs)
		if !bytes.Equal(gasmCode, goCode) {
			t.Errorf("%s: MISMATCH gasm=%d go=%d bytes\n%s", fn.Name, len(gasmCode), len(goCode), diffHex(gasmCode, goCode))
			continue
		}
		matched++
		t.Logf("%s: MATCH (%d bytes)", fn.Name, fn.Size)
	}
	if matched == 0 {
		t.Fatal("no functions matched")
	}
}