package win32api

import (
	"bytes"
	"syscall"
	"unsafe"
)

func (entry PROCESSENTRY32) ExeFile() string {
	n := bytes.IndexByte(entry.SzExeFile[:], 0)
	if n < 0 {
		n = len(entry.SzExeFile)
	}
	return string(entry.SzExeFile[:n])
}

func (entry MODULEENTRY32W) ModuleName() string {
	return syscall.UTF16ToString(entry.SzModule[:])
}

func (entry MODULEENTRY32W) ExePath() string {
	return syscall.UTF16ToString(entry.SzExePath[:])
}

func (info DebugEventInfo) String() string {
	return info.CodeName
}

func EnumerateProcesses() ([]PROCESSENTRY32, error) {
	snapshot, err := CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0)
	if err != nil {
		return nil, err
	}
	defer func() {
		_ = CloseHandle(snapshot)
	}()

	var entry PROCESSENTRY32
	entry.DwSize = Ulong(unsafe.Sizeof(entry))
	if err := Process32First(snapshot, &entry); err != nil {
		return nil, err
	}

	processes := make([]PROCESSENTRY32, 0, 64)
	for {
		processes = append(processes, entry)
		entry.DwSize = Ulong(unsafe.Sizeof(entry))
		err = Process32Next(snapshot, &entry)
		if err != nil {
			if errno, ok := err.(syscall.Errno); ok && errno == ERROR_NO_MORE_FILES {
				break
			}
			if err == syscall.EINVAL {
				break
			}
			return nil, err
		}
	}
	return processes, nil
}

func EnumerateThreads(ownerProcessID DWORD) ([]THREADENTRY32, error) {
	snapshot, err := CreateToolhelp32Snapshot(TH32CS_SNAPTHREAD, 0)
	if err != nil {
		return nil, err
	}
	defer func() {
		_ = CloseHandle(snapshot)
	}()

	var entry THREADENTRY32
	entry.DwSize = DWORD(unsafe.Sizeof(entry))
	if err := Thread32First(snapshot, &entry); err != nil {
		return nil, err
	}

	threads := make([]THREADENTRY32, 0, 64)
	for {
		if ownerProcessID == 0 || entry.Th32OwnerProcessID == ownerProcessID {
			threads = append(threads, entry)
		}
		entry.DwSize = DWORD(unsafe.Sizeof(entry))
		err = Thread32Next(snapshot, &entry)
		if err != nil {
			if errno, ok := err.(syscall.Errno); ok && errno == ERROR_NO_MORE_FILES {
				break
			}
			if err == syscall.EINVAL {
				break
			}
			return nil, err
		}
	}
	return threads, nil
}

func EnumerateModules(processID DWORD) ([]MODULEENTRY32W, error) {
	snapshot, err := CreateToolhelp32Snapshot(TH32CS_SNAPMODULE|TH32CS_SNAPMODULE32, processID)
	if err != nil {
		return nil, err
	}
	defer func() {
		_ = CloseHandle(snapshot)
	}()

	var entry MODULEENTRY32W
	entry.DwSize = DWORD(unsafe.Sizeof(entry))
	if err := Module32First(snapshot, &entry); err != nil {
		return nil, err
	}

	modules := make([]MODULEENTRY32W, 0, 32)
	for {
		modules = append(modules, entry)
		entry.DwSize = DWORD(unsafe.Sizeof(entry))
		err = Module32Next(snapshot, &entry)
		if err != nil {
			if errno, ok := err.(syscall.Errno); ok && errno == ERROR_NO_MORE_FILES {
				break
			}
			if err == syscall.EINVAL {
				break
			}
			return nil, err
		}
	}
	return modules, nil
}