package main

import (
	"bytes"
	"encoding/json"
	"flag"
	"fmt"
	"io"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"time"
)

type report struct {
	NodeID   string         `json:"nodeId"`
	Kind     string         `json:"kind"`
	Address  string         `json:"address,omitempty"`
	Version  string         `json:"version"`
	Status   string         `json:"status"`
	Metadata map[string]any `json:"metadata"`
}

func main() {
	listen := flag.String("listen", ":8091", "HTTP listen address")
	source := flag.String("source", ".", "directory permitted for replication")
	flag.Parse()
	root, err := filepath.Abs(*source)
	if err != nil {
		panic(err)
	}
	go heartbeat(root)

	http.HandleFunc("/healthz", func(w http.ResponseWriter, _ *http.Request) { w.WriteHeader(http.StatusNoContent) })
	http.HandleFunc("/replicate", func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			http.Error(w, "POST required", http.StatusMethodNotAllowed)
			return
		}
		var request struct {
			Host        string `json:"host"`
			Destination string `json:"destination"`
		}
		if json.NewDecoder(r.Body).Decode(&request) != nil || request.Host == "" || request.Destination == "" || filepath.IsAbs(request.Destination) || filepath.Clean(request.Destination) == ".." {
			http.Error(w, "host and relative destination required", http.StatusBadRequest)
			return
		}
		output, err := exec.Command("scp", "-r", root+"/.", request.Host+":"+request.Destination).CombinedOutput()
		if err != nil {
			http.Error(w, string(output), http.StatusBadGateway)
			return
		}
		w.WriteHeader(http.StatusAccepted)
	})
	fmt.Println(http.ListenAndServe(*listen, nil))
}

func heartbeat(root string) {
	central := os.Getenv("CENTRAL_URL")
	if central == "" {
		return
	}
	host, _ := os.Hostname()
	for {
		body, _ := json.Marshal(report{NodeID: host, Kind: "replica", Address: os.Getenv("PEER_PUBLIC_URL"), Version: "0.1.0", Status: "online", Metadata: map[string]any{"source": root}})
		request, _ := http.NewRequest(http.MethodPost, central+"/api/peers/heartbeat", bytes.NewReader(body))
		request.Header.Set("Content-Type", "application/json")
		if token := os.Getenv("PEER_API_TOKEN"); token != "" {
			request.Header.Set("Authorization", "Bearer "+token)
		}
		response, err := http.DefaultClient.Do(request)
		if err == nil {
			_, _ = io.Copy(io.Discard, response.Body)
			_ = response.Body.Close()
		}
		time.Sleep(time.Minute)
	}
}