package miner

import (
	"context"
	"os/exec"
	"runtime"
	"strings"
	"time"
)

// WSLRuntimeInfo describes a detected WSL2 installation on Windows.
type WSLRuntimeInfo struct {
	Available bool
	CLI       string   // path to wsl.exe
	Distros   []string // registered distro names (first is default launch target)
}

// WSLDetector probes WSL availability. Tests inject a mock via SetWSLDetector.
var WSLDetector = DetectWSL

// SetWSLDetector restores the default detector when fn is nil.
func SetWSLDetector(fn func() WSLRuntimeInfo) {
	if fn == nil {
		WSLDetector = DetectWSL
		return
	}
	WSLDetector = fn
}

// DetectWSL checks for wsl.exe and at least one registered distro.
func DetectWSL() WSLRuntimeInfo {
	if runtime.GOOS != "windows" {
		return WSLRuntimeInfo{}
	}
	path, err := exec.LookPath("wsl.exe")
	if err != nil {
		return WSLRuntimeInfo{}
	}
	out, err := func() ([]byte, error) {
		ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
		defer cancel()
		return exec.CommandContext(ctx, path, "-l", "-q").CombinedOutput()
	}()
	if err != nil {
		// WSL may be installed but no distros — still not usable for mining.
		return WSLRuntimeInfo{CLI: path}
	}
	var distros []string
	for _, line := range strings.Split(string(out), "\n") {
		name := strings.TrimSpace(line)
		if name != "" {
			distros = append(distros, name)
		}
	}
	if len(distros) == 0 {
		return WSLRuntimeInfo{CLI: path}
	}
	return WSLRuntimeInfo{Available: true, CLI: path, Distros: distros}
}