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

package asm

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

// TestReadRuntimeSymbols verifies the GOOBJ reader can extract and find
// symbols from the runtime package's compiled archive.
func TestReadRuntimeSymbols(t *testing.T) {
	exp, err := exportPath("runtime")
	if err != nil {
		t.Skipf("cannot find runtime export: %v (need Go toolchain)", err)
	}
	data, err := os.ReadFile(exp)
	if err != nil {
		t.Skipf("cannot read runtime export: %v", err)
	}
	gobj, err := extractGOOBJ(data)
	if err != nil {
		t.Fatalf("extractGOOBJ: %v", err)
	}

	t.Logf("runtime: %d symbols", len(gobj.symbols()))

	// Verify we can find well-known runtime symbols.
	for _, tc := range []struct{ pkg, name string }{
		{"runtime", "g0"},
		{"runtime", "morestack"},
		{"runtime", "newstack"},
	} {
		idx := gobj.findSymbol(tc.pkg, tc.name)
		if idx < 0 {
			t.Errorf("findSymbol(%q, %q) = -1", tc.pkg, tc.name)
		} else {
			t.Logf("findSymbol(%q, %q) = %d", tc.pkg, tc.name, idx)
		}
	}
}

// TestResolveExternalSymbols verifies end-to-end resolution of external
// symbol references.
func TestResolveExternalSymbols(t *testing.T) {
	if _, err := exec.LookPath("go"); err != nil {
		t.Skip("go toolchain not available")
	}

	refs := map[string][]string{
		"runtime": {"g0"},
	}
	pkgIdx, symIdx, err := resolveExternalGOOBJ(refs)
	if err != nil {
		t.Fatalf("resolveExternalGOOBJ: %v", err)
	}
	if len(pkgIdx) != 1 || pkgIdx["runtime"] != 1 {
		// Index 0 is the dummy invalid package in the blkPkgIdx table;
		// the loader's reader loop starts at 1 (cmd/link/internal/
		// loader/loader.go: "PkgIdx 0 is a dummy invalid package"), so
		// the first real package must carry index 1.
		t.Errorf("pkgIdx = %v, want runtime→1", pkgIdx)
	}
	if _, ok := symIdx["runtime·g0"]; !ok {
		t.Errorf("symIdx missing runtime·g0, got %v", symIdx)
	}
	t.Logf("runtime·g0 → SymIdx=%d", symIdx["runtime·g0"])
}