package bcap

import (
	"sync"
	"time"

	"github.com/gopacket/gopacket"
)

type Analyzer struct {
	decoder *Decoder
	tracker *Tracker

	mu            sync.Mutex
	firstPacketTS time.Time
}

func NewAnalyzer() *Analyzer {
	return NewAnalyzerWithConfig(nil)
}

func NewAnalyzerWithConfig(config *PacketsConfig) *Analyzer {
	return &Analyzer{
		decoder: NewDecoder(),
		tracker: NewTrackerWithConfig(config),
	}
}

func (a *Analyzer) Stop() {
	if a.tracker != nil {
		a.tracker.Stop()
	}
}

func (a *Analyzer) Decoder() *Decoder {
	return a.decoder
}

func (a *Analyzer) Tracker() *Tracker {
	return a.tracker
}

func (a *Analyzer) ObservePacket(packet gopacket.Packet) (Observation, error) {
	return a.ObservePacketWithOptions(packet, DecodeOptions{})
}

func (a *Analyzer) ObservePacketWithOptions(packet gopacket.Packet, opts DecodeOptions) (Observation, error) {
	if opts.BaseTime.IsZero() {
		opts.BaseTime = a.ensureBaseTime(packet)
	}
	decoded, err := a.decoder.DecodeWithOptions(packet, opts)
	if err != nil {
		return Observation{}, err
	}
	return a.tracker.Observe(decoded)
}

func (a *Analyzer) ensureBaseTime(packet gopacket.Packet) time.Time {
	a.mu.Lock()
	defer a.mu.Unlock()

	if packet == nil {
		return time.Time{}
	}
	metadata := packet.Metadata()
	if metadata == nil || metadata.Timestamp.IsZero() {
		return time.Time{}
	}
	if a.firstPacketTS.IsZero() {
		a.firstPacketTS = metadata.Timestamp
	}
	return a.firstPacketTS
}