package readmemory

import (
	"strings"
	"syscall"
	"unsafe"

	windows "golang.org/x/sys/windows"
)

const TH32CS_SNAPPROCESS = 0x00000002

type WindowsProcess struct {
	ProcessID       int
	ParentProcessID int
	Exe             string
}

func processes() ([]WindowsProcess, error) {
	handle, err := windows.CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0)
	if err != nil {
		return nil, err
	}
	defer windows.CloseHandle(handle)

	var entry windows.ProcessEntry32
	entry.Size = uint32(unsafe.Sizeof(entry))
	err = windows.Process32First(handle, &entry)
	if err != nil {
		return nil, err
	}

	results := make([]WindowsProcess, 0, 50)
	for {
		results = append(results, newWindowsProcess(&entry))

		err = windows.Process32Next(handle, &entry)
		if err != nil {
			if err == syscall.ERROR_NO_MORE_FILES {
				return results, nil
			}
			return nil, err
		}
	}
}

func findProcessByName(processes []WindowsProcess, name string) *WindowsProcess {
	for _, p := range processes {
		if strings.ToLower(p.Exe) == strings.ToLower(name) {
			return &p
		}
	}
	return nil
}

func newWindowsProcess(e *windows.ProcessEntry32) WindowsProcess {
	end := 0
	for {
		if e.ExeFile[end] == 0 {
			break
		}
		end++
	}

	return WindowsProcess{
		ProcessID:       int(e.ProcessID),
		ParentProcessID: int(e.ParentProcessID),
		Exe:             syscall.UTF16ToString(e.ExeFile[:end]),
	}
}

func BindDefaultProcess(defaultName string) (uint32, bool) {
	procs, err := processes()
	if err != nil {
		return 0, false
	}

	explorer := findProcessByName(procs, defaultName)
	if explorer == nil {
		return 0, false
	}

	return uint32(explorer.ProcessID), true
}