package fileops

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

func TestReadRegularFileEnforcesLimitAndRegularFileIdentity(t *testing.T) {
	root := t.TempDir()
	path := filepath.Join(root, "result.json")
	if err := os.WriteFile(path, []byte("1234"), 0o600); err != nil {
		t.Fatalf("WriteFile() error = %v", err)
	}
	data, err := ReadRegularFile(path, 4)
	if err != nil {
		t.Fatalf("ReadRegularFile(exact limit) error = %v", err)
	}
	if string(data) != "1234" {
		t.Fatalf("data = %q, want exact file content", data)
	}
	if _, err := ReadRegularFile(path, 3); err == nil || !strings.Contains(err.Error(), "3-byte limit") {
		t.Fatalf("ReadRegularFile(limit plus one) error = %v, want limit failure", err)
	}
	if err := os.Remove(path); err != nil {
		t.Fatalf("Remove(file) error = %v", err)
	}
	if err := os.Mkdir(path, 0o700); err != nil {
		t.Fatalf("Mkdir(non-regular file) error = %v", err)
	}
	if _, err := ReadRegularFile(path, 4); err == nil || !strings.Contains(err.Error(), "not a regular file") {
		t.Fatalf("ReadRegularFile(directory) error = %v, want regular-file failure", err)
	}
}

func TestReadRegularFileRejectsSymlinkedPaths(t *testing.T) {
	if runtime.GOOS == "windows" {
		t.Skip("symlink behavior differs on windows")
	}
	root := t.TempDir()
	outside := t.TempDir()
	outsideFile := filepath.Join(outside, "result.json")
	if err := os.WriteFile(outsideFile, []byte("outside"), 0o600); err != nil {
		t.Fatalf("WriteFile(outside) error = %v", err)
	}
	leaf := filepath.Join(root, "result.json")
	if err := os.Symlink(outsideFile, leaf); err != nil {
		t.Fatalf("Symlink(leaf) error = %v", err)
	}
	if _, err := ReadRegularFile(leaf, 64); err == nil {
		t.Fatal("ReadRegularFile(leaf symlink) error = nil, want rejection")
	}
	if err := os.Remove(leaf); err != nil {
		t.Fatalf("Remove(leaf symlink) error = %v", err)
	}
	linkedParent := filepath.Join(root, "linked")
	if err := os.Symlink(outside, linkedParent); err != nil {
		t.Fatalf("Symlink(parent) error = %v", err)
	}
	if _, err := ReadRegularFile(filepath.Join(linkedParent, "result.json"), 64); err == nil {
		t.Fatal("ReadRegularFile(symlinked parent) error = nil, want rejection")
	}
}