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

package main

import (
	"os"
	"path/filepath"
	"strings"
	"testing"
)

// writeTree writes a directory of files and returns its root.
func writeTree(t *testing.T, files map[string]string) string {
	t.Helper()
	dir := t.TempDir()
	for name, content := range files {
		path := filepath.Join(dir, name)
		if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
			t.Fatal(err)
		}
		if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
			t.Fatal(err)
		}
	}
	return dir
}

// TestAsmMacroAndIncludeEndToEnd drives `gasm asm` over a source with an
// in-file parameterised macro and an include resolved through -I, and checks
// the assembled bytes came from the expansion (the loop body counts six
// increments, two per expanded iteration).
func TestAsmMacroAndIncludeEndToEnd(t *testing.T) {
	if testing.Short() {
		t.Skip("runs the assembler end to end")
	}
	dir := writeTree(t, map[string]string{
		"inc/consts.h": "#define NITER 3\n",
		"main_amd64.s": "#include \"textflag.h\"\n" +
			"#include \"consts.h\"\n" +
			"#define STEP(r) ADDQ $1, r; ADDQ $1, r\n" +
			"TEXT ·f(SB), NOSPLIT, $0-8\n" +
			"\tXORQ AX, AX\n" +
			"\tMOVQ $NITER, CX\n" +
			"loop:\n" +
			"\tSTEP(AX)\n" +
			"\tDECQ CX\n" +
			"\tJNZ loop\n" +
			"\tMOVQ AX, ret+0(FP)\n" +
			"\tRET\n",
	})
	stdout, stderr, code := capture(func() int {
		return cmdAsm([]string{"-I", filepath.Join(dir, "inc"), "-GOARCH", "amd64", filepath.Join(dir, "main_amd64.s")})
	})
	if code != 0 {
		t.Fatalf("gasm asm exited %d: %s%s", code, stdout, stderr)
	}
	// The macro expanded to two ADDQ $1 encodings in the static body; the
	// iteration count lives in the runtime loop.
	if n := strings.Count(stdout, "83 c0 01"); n != 2 {
		t.Errorf("found %d ADDQ $1 encodings in the image, want 2:\n%s", n, stdout)
	}
}

// TestAsmIncludeResolutionOrder pins the -I search order end to end: the
// including file's directory wins over the -I directories.
func TestAsmIncludeResolutionOrder(t *testing.T) {
	if testing.Short() {
		t.Skip("runs the assembler end to end")
	}
	dir := writeTree(t, map[string]string{
		"src/main_amd64.s": "#include \"textflag.h\"\n" +
			"#include \"vals.h\"\n" +
			"TEXT ·f(SB), NOSPLIT, $0\n" +
			"\tMOVQ $VAL, AX\n" +
			"\tRET\n",
		"src/vals.h":   "#define VAL 1\n",
		"late/vals.h":  "#define VAL 2\n",
		"early/vals.h": "#define VAL 3\n",
	})
	stdout, stderr, code := capture(func() int {
		return cmdAsm([]string{"-I", filepath.Join(dir, "early"), "-I", filepath.Join(dir, "late"),
			"-GOARCH", "amd64", filepath.Join(dir, "src", "main_amd64.s")})
	})
	if code != 0 {
		t.Fatalf("gasm asm exited %d: %s%s", code, stdout, stderr)
	}
	// VAL came from src/vals.h, not from either -I directory: the image
	// loads the immediate 1.
	if !strings.Contains(stdout, "b8 01 00 00 00") {
		t.Errorf("expected the source-directory VAL (immediate 1) in:\n%s", stdout)
	}
}

// TestAsmMissingIncludeIsAnError pins the diagnostic for an include that
// resolves nowhere on the assembly path.
func TestAsmMissingIncludeIsAnError(t *testing.T) {
	if testing.Short() {
		t.Skip("runs the assembler end to end")
	}
	path := writeTemp(t, "main_amd64.s", "#include \"textflag.h\"\n#include \"nothere.h\"\nTEXT ·f(SB), NOSPLIT, $0\n\tRET\n")
	_, stderr, code := capture(func() int { return cmdAsm([]string{"-GOARCH", "amd64", path}) })
	if code == 0 {
		t.Fatal("gasm asm accepted a file whose include resolves nowhere")
	}
	if !strings.Contains(stderr, `#include "nothere.h"`) {
		t.Errorf("stderr does not name the failing include: %s", stderr)
	}
}