package processing

import (
	"sync"
	"time"

	"github.com/google/uuid"
)

// StartLimiter lightly rate-limits processing job starts per company.
// In-process only — not shared across API replicas (effective RPM ≈ N × replicas).
// RATE_LIMIT_REPLICAS does not divide this limiter; multi-replica hard caps need edge/WAF.
// Counts StartJob/RetryJob API calls once each — not per auto-split sibling job,
// and not per product in a bulk StartJob payload (capped by MaxStartProducts).
type StartLimiter struct {
	mu     sync.Mutex
	window time.Duration
	max    int
	events map[uuid.UUID][]time.Time
}

// NewStartLimiter allows maxStarts per window (e.g. 20/min).
func NewStartLimiter(maxStarts int, window time.Duration) *StartLimiter {
	if maxStarts <= 0 {
		maxStarts = 20
	}
	if window <= 0 {
		window = time.Minute
	}
	return &StartLimiter{
		window: window,
		max:    maxStarts,
		events: make(map[uuid.UUID][]time.Time),
	}
}

// Allow reports whether a new job start is permitted for companyID.
func (l *StartLimiter) Allow(companyID uuid.UUID) bool {
	if l == nil {
		return true
	}
	now := time.Now()
	l.mu.Lock()
	defer l.mu.Unlock()
	cut := now.Add(-l.window)
	ev := l.events[companyID]
	kept := ev[:0]
	for _, t := range ev {
		if t.After(cut) {
			kept = append(kept, t)
		}
	}
	if len(kept) >= l.max {
		l.events[companyID] = kept
		return false
	}
	kept = append(kept, now)
	l.events[companyID] = kept
	return true
}