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

package asm

import (
	"testing"

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

func TestEmitDWARF(t *testing.T) {
	src := `#include "textflag.h"
TEXT ·add(SB), NOSPLIT, $0-24
	MOVQ a+0(FP), AX
	MOVQ b+8(FP), BX
	ADDQ BX, AX
	MOVQ AX, ret+16(FP)
	RET
`
	f, errs := parser.Parse("test_amd64.s", src)
	if len(errs) > 0 {
		t.Fatalf("parse: %v", errs)
	}
	img, err := AssembleFile(f)
	if err != nil {
		t.Fatalf("assemble: %v", err)
	}

	ds := emitDWARF(img, "test_amd64.s")

	// .debug_abbrev must not be empty and must start with abbrev code 1.
	if len(ds.debugAbbrev) == 0 {
		t.Fatal("empty .debug_abbrev")
	}
	if ds.debugAbbrev[0] != 1 {
		t.Fatalf(".debug_abbrev first byte = %d, want 1", ds.debugAbbrev[0])
	}

	// .debug_info must have a compile unit header (DWARF5 version 5).
	if len(ds.debugInfo) < 12 {
		t.Fatalf(".debug_info too short: %d bytes", len(ds.debugInfo))
	}
	// Version field at offset 4 (after unit_length).
	if ds.debugInfo[4] != 5 || ds.debugInfo[5] != 0 {
		t.Fatalf(".debug_info version = %d, want 5", uint16(ds.debugInfo[4])|uint16(ds.debugInfo[5])<<8)
	}

	// .debug_line must have a header.
	if len(ds.debugLine) < 20 {
		t.Fatalf(".debug_line too short: %d bytes", len(ds.debugLine))
	}
	// Version at offset 4.
	if ds.debugLine[4] != 5 || ds.debugLine[5] != 0 {
		t.Fatalf(".debug_line version = %d, want 5", uint16(ds.debugLine[4])|uint16(ds.debugLine[5])<<8)
	}

	// .debug_line_str must contain the source file name.
	if len(ds.debugLineStr) == 0 {
		t.Fatal("empty .debug_line_str")
	}

	// Relocations must reference the function.
	if len(ds.lineRelocs) == 0 {
		t.Fatal("no .debug_line relocations")
	}
	if len(ds.infoRelocs) == 0 {
		t.Fatal("no .debug_info relocations")
	}
}

func TestDwarfAbbrevTable(t *testing.T) {
	abbrev := dwarfAbbrevTable()
	if len(abbrev) == 0 {
		t.Fatal("empty abbrev table")
	}
	// Must end with a zero byte (end of table).
	if abbrev[len(abbrev)-1] != 0 {
		t.Fatalf("abbrev table last byte = %d, want 0", abbrev[len(abbrev)-1])
	}
}