// Package recon provides the OSINT/recon framework: per-source rate limiting,
// stealth controls, robots.txt compliance, and parallel sweep orchestration.
package recon

import (
	"context"
	"math/rand"
	"sync"
	"time"

	"golang.org/x/time/rate"
)

// LimiterRegistry holds one *rate.Limiter per source name.
//
// RECON-INFRA-05: each source owns its own limiter — no centralization.
// Lookups are idempotent: the same name always returns the same *rate.Limiter
// pointer, guaranteeing that token state persists across calls for a source.
type LimiterRegistry struct {
	mu       sync.Mutex
	limiters map[string]*rate.Limiter
}

// NewLimiterRegistry constructs an empty registry.
func NewLimiterRegistry() *LimiterRegistry {
	return &LimiterRegistry{limiters: make(map[string]*rate.Limiter)}
}

// For returns the limiter for name, creating it with (r, burst) on first call.
// Repeat calls with the same name return the same *rate.Limiter pointer,
// regardless of subsequent (r, burst) arguments — the first registration wins.
func (lr *LimiterRegistry) For(name string, r rate.Limit, burst int) *rate.Limiter {
	lr.mu.Lock()
	defer lr.mu.Unlock()
	if l, ok := lr.limiters[name]; ok {
		return l
	}
	l := rate.NewLimiter(r, burst)
	lr.limiters[name] = l
	return l
}

// Wait blocks until the source's token is available. If stealth is true,
// an additional random jitter between 100ms and 1s is applied after the token
// acquisition to evade fingerprint-based detection (RECON-INFRA-06 partial —
// fully wired with the stealth package in 09-03).
//
// Context cancellation is honored both during the underlying limiter.Wait and
// during the jitter sleep; ctx.Err() is returned promptly in either case.
func (lr *LimiterRegistry) Wait(ctx context.Context, name string, r rate.Limit, burst int, stealth bool) error {
	l := lr.For(name, r, burst)
	if err := l.Wait(ctx); err != nil {
		return err
	}
	if stealth {
		jitter := time.Duration(100+rand.Intn(900)) * time.Millisecond
		select {
		case <-time.After(jitter):
		case <-ctx.Done():
			return ctx.Err()
		}
	}
	return nil
}