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

package main

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

const clean = "#include \"textflag.h\"\n" +
	"TEXT ·f(SB), NOSPLIT, $0\n" +
	"\tMOVQ AX, BX\n" +
	"loop:\n" +
	"\tJMP loop\n" +
	"\tRET\n"

const buggy = "#include \"textflag.h\"\n" +
	"TEXT ·f(SB), NOSPLIT, $0\n" +
	"\tBOGUS AX, BX\n" +
	"\tJMP nowhere\n" +
	"\tRET\n"

func writeTemp(t *testing.T, name, content string) string {
	t.Helper()
	path := filepath.Join(t.TempDir(), name)
	if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
		t.Fatal(err)
	}
	return path
}

// capture runs fn with stdout and stderr redirected and returns both plus the
// exit code fn produced.
func capture(fn func() int) (stdout, stderr string, code int) {
	oldOut, oldErr := os.Stdout, os.Stderr
	rOut, wOut, _ := os.Pipe()
	rErr, wErr, _ := os.Pipe()
	os.Stdout, os.Stderr = wOut, wErr

	code = fn()

	wOut.Close()
	wErr.Close()
	os.Stdout, os.Stderr = oldOut, oldErr
	ob, _ := io.ReadAll(rOut)
	eb, _ := io.ReadAll(rErr)
	return string(ob), string(eb), code
}

func TestCmdTokens(t *testing.T) {
	path := writeTemp(t, "f_amd64.s", clean)
	out, _, code := capture(func() int { return cmdTokens([]string{path}) })
	if code != 0 {
		t.Fatalf("code = %d", code)
	}
	if !strings.Contains(out, "IDENT") || !strings.Contains(out, "TEXT") {
		t.Errorf("token dump missing expected tokens:\n%s", out)
	}
}

func TestCmdParseOK(t *testing.T) {
	path := writeTemp(t, "f_amd64.s", clean)
	out, _, code := capture(func() int { return cmdParse([]string{path}) })
	if code != 0 {
		t.Fatalf("code = %d", code)
	}
	if !strings.Contains(out, "OK") || !strings.Contains(out, "1 functions") {
		t.Errorf("parse output = %q", out)
	}
}

func TestCmdParseError(t *testing.T) {
	path := writeTemp(t, "bad_amd64.s", "TEXT ·f(SB), NOSPLIT, $0\n) (\n\tRET\n")
	_, errOut, code := capture(func() int { return cmdParse([]string{path}) })
	if code != 1 {
		t.Fatalf("code = %d, want 1", code)
	}
	if errOut == "" {
		t.Error("expected a parse error on stderr")
	}
}

func TestCmdParseMissingFile(t *testing.T) {
	_, _, code := capture(func() int { return cmdParse([]string{"/nonexistent/file.s"}) })
	if code != 1 {
		t.Fatalf("code = %d, want 1", code)
	}
}

func TestCmdLintClean(t *testing.T) {
	path := writeTemp(t, "f_amd64.s", clean)
	_, _, code := capture(func() int { return cmdLint([]string{path}) })
	if code != 0 {
		t.Fatalf("clean file should lint with code 0, got %d", code)
	}
}

func TestCmdLintErrors(t *testing.T) {
	path := writeTemp(t, "f_amd64.s", buggy)
	out, _, code := capture(func() int { return cmdLint([]string{path}) })
	if code != 1 {
		t.Fatalf("code = %d, want 1", code)
	}
	if !strings.Contains(out, "unknown-instruction") || !strings.Contains(out, "undefined-label") {
		t.Errorf("lint output missing expected codes:\n%s", out)
	}
}

func TestCmdLintDisable(t *testing.T) {
	path := writeTemp(t, "f_amd64.s", buggy)
	args := []string{"-disable", "unknown-instruction,undefined-label", path}
	_, _, code := capture(func() int { return cmdLint(args) })
	if code != 0 {
		t.Fatalf("disabling both rules should yield code 0, got %d", code)
	}
}

func TestCmdFmtStdout(t *testing.T) {
	path := writeTemp(t, "f_amd64.s", "TEXT ·f(SB),NOSPLIT,$0\nMOVQ AX,BX\nRET\n")
	out, _, code := capture(func() int { return cmdFmt([]string{path}) })
	if code != 0 {
		t.Fatalf("code = %d", code)
	}
	if !strings.Contains(out, "TEXT ·f(SB), NOSPLIT, $0") || !strings.Contains(out, "\tMOVQ AX, BX") {
		t.Errorf("formatted output unexpected:\n%s", out)
	}
}

func TestCmdFmtWrite(t *testing.T) {
	path := writeTemp(t, "f_amd64.s", "TEXT ·f(SB),NOSPLIT,$0\nMOVQ AX,BX\nRET\n")
	_, _, code := capture(func() int { return cmdFmt([]string{"-w", path}) })
	if code != 0 {
		t.Fatalf("code = %d", code)
	}
	b, _ := os.ReadFile(path)
	if !strings.Contains(string(b), "\tMOVQ AX, BX") {
		t.Errorf("file not rewritten:\n%s", b)
	}
	// Idempotent: a second -w pass leaves the file unchanged.
	_, _, _ = capture(func() int { return cmdFmt([]string{"-w", path}) })
	b2, _ := os.ReadFile(path)
	if string(b) != string(b2) {
		t.Error("fmt -w is not idempotent")
	}
}

func TestUsage(t *testing.T) {
	var b bytes.Buffer
	usage(&b)
	if !strings.Contains(b.String(), "gasm") {
		t.Errorf("usage text unexpected:\n%s", b.String())
	}
}

func TestCmdArgErrors(t *testing.T) {
	// Missing file arguments produce a usage error (code 2).
	if _, _, code := capture(func() int { return cmdFmt(nil) }); code != 2 {
		t.Errorf("cmdFmt() code = %d, want 2", code)
	}
	if _, _, code := capture(func() int { return cmdLint(nil) }); code != 2 {
		t.Errorf("cmdLint() code = %d, want 2", code)
	}
	if _, _, code := capture(func() int { return cmdTokens(nil) }); code != 2 {
		t.Errorf("cmdTokens() code = %d, want 2", code)
	}
	if _, _, code := capture(func() int { return cmdParse(nil) }); code != 2 {
		t.Errorf("cmdParse() code = %d, want 2", code)
	}
}