package reporter

import (
	"bytes"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"log"
	"net"
	"net/http"
	"strings"
	"time"

	"kattila-agent/config"
	"kattila-agent/models"
	"kattila-agent/network"
	"kattila-agent/security"
)

var tickCounter int64 = 0

func StartLoop() {
	doReport() // run immediately
	ticker := time.NewTicker(30 * time.Second)
	go func() {
		for range ticker.C {
			doReport()
		}
	}()
}

func doReport() {
	data, err := network.GatherSystemData()
	if err != nil {
		log.Printf("reporter: gather error: %v", err)
		return
	}

	tickCounter++
	now := time.Now().Unix()

	report := models.Report{
		Version:      1,
		Tick:         tickCounter,
		Type:         "report",
		Nonce:        security.GenerateNonce(),
		Timestamp:    now,
		AgentID:      config.Cfg.AgentID,
		AgentVersion: 1,
		FleetID:      security.FleetID(),
		Data:         data,
	}

	report.HMAC = security.SignPayload(report.Data)

	err = pushToManager(report)
	if err != nil {
		log.Printf("reporter: direct push failed (%v). Attempting relay scan...", err)
		tryRelay(report, data)
	}
}

func pushToManager(report models.Report) error {
	body, _ := json.Marshal(report)
	url := strings.TrimRight(config.Cfg.ManagerURL, "/") + "/status/updates"
	req, err := http.NewRequest("POST", url, bytes.NewBuffer(body))
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", "application/json")

	client := &http.Client{Timeout: 5 * time.Second}
	resp, err := client.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		respBody, _ := io.ReadAll(resp.Body)
		return fmt.Errorf("bad status code %d: %s", resp.StatusCode, respBody)
	}
	log.Printf("reporter: Report successfully sent to Manager (tick %d)", report.Tick)
	return nil
}

func HandleRelay(body []byte) error {
	var envelope models.RelayEnvelope
	if err := json.Unmarshal(body, &envelope); err != nil {
		return err
	}

	for _, id := range envelope.RelayPath {
		if id == config.Cfg.AgentID {
			log.Println("reporter: Dropped relay request: routing loop detected")
			return errors.New("routing loop detected")
		}
	}

	envelope.RelayPath = append(envelope.RelayPath, config.Cfg.AgentID)
	if len(envelope.RelayPath) > 3 {
		return errors.New("relay hop limit exceeded")
	}

	envelopeBody, _ := json.Marshal(envelope)
	url := strings.TrimRight(config.Cfg.ManagerURL, "/") + "/status/updates"
	req, err := http.NewRequest("POST", url, bytes.NewBuffer(envelopeBody))
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", "application/json")

	client := &http.Client{Timeout: 5 * time.Second}
	resp, err := client.Do(req)
	if err != nil {
		log.Printf("reporter: Manager unreachable during relay forward, hopping further...")
		
		data, err := network.GatherSystemData()
		if err == nil {
			return tryRelayEnvelope(envelope, data)
		}
		return err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("bad status from manager: %d", resp.StatusCode)
	}

	log.Printf("reporter: Successfully relayed message for %s", envelope.Payload.AgentID)
	return nil
}

func tryRelay(report models.Report, localData models.SystemData) {
	env := models.RelayEnvelope{
		RelayPath: []string{config.Cfg.AgentID},
		Payload:   report,
	}
	err := tryRelayEnvelope(env, localData)
	if err != nil {
		log.Printf("reporter: Exhausted all relays, couldn't push report: %v", err)
	}
}

func tryRelayEnvelope(env models.RelayEnvelope, data models.SystemData) error {
	for _, wg := range data.WGPeers {
		for _, allowedRaw := range wg.AllowedIPs {
			ip, _, err := net.ParseCIDR(allowedRaw)
			if err != nil {
				ip = net.ParseIP(allowedRaw)
			}
			if ip != nil {
				ipTarget := ip.String()
				if pingPeer(ipTarget) {
					log.Printf("reporter: Found relay peer at %s, forwarding...", ipTarget)
					err := pushToRelay(ipTarget, env)
					if err == nil {
						return nil
					}
					log.Printf("reporter: Failed to push to relay %s: %v", ipTarget, err)
				}
			}
		}
	}
	return errors.New("no working relays found")
}

func pingPeer(ip string) bool {
	client := &http.Client{Timeout: 2 * time.Second}
	resp, err := client.Get(fmt.Sprintf("http://%s:%s/status/peer", ip, config.Cfg.AgentPort))
	if err == nil {
		defer resp.Body.Close()
		return resp.StatusCode == http.StatusOK
	}
	return false
}

func pushToRelay(ip string, env models.RelayEnvelope) error {
	body, _ := json.Marshal(env)
	client := &http.Client{Timeout: 5 * time.Second}
	resp, err := client.Post(fmt.Sprintf("http://%s:%s/status/relay", ip, config.Cfg.AgentPort), "application/json", bytes.NewBuffer(body))
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("relay rejected forwarding attempt with %d", resp.StatusCode)
	}
	return nil
}