fedilogue/poll/engine.go

package main

import (
	"github.com/microcosm-cc/bluemonday"
	"github.com/jackc/pgx/pgxpool"
	"encoding/json"
	"crypto/sha1"
	"io/ioutil"
	"net/http"
	"context"
	"strings"
	"time"
	"fmt"
	"net"
	"log"
	"io"
	"os"
)

type PollMessage struct {
	from			string
	status			int
	min_id			string
	numposts		int
}

// Parsing Unmarshal JSON type
type ReportPost struct {

	// Retrieved values
	Id			string `json:"id"`
	Url			string `json:"url"`
	Account			AccountType
	Content			string `json:"content"`

	// Derived values
	StrippedContent			string
	Posthash			[]byte
}

type AccountType struct {
	Acct			string	`json:"acct"`
	Avatar			string	`json:"avatar"`
	Bot			bool	`json:"bot"`
	Created_at		string	`json:"created_at"`
	Display_name		string	`json:"display_name"`
	Url			string	`json:"url"`
}


// Used to report a new instance to main
type ReportInstance struct {
	from				string
	endpoint			string
}

type RunningInstance struct {
	endpoint			string
	min_id				string
}

func handleClient(commandClient net.Conn) {
	rawCommand := make([]byte, 20)

	for {
		_, err := io.ReadFull(commandClient, rawCommand)
		if err != nil {
			fmt.Println(err)
			commandClient.Close()
		}
		fmt.Println(rawCommand)
	}
}

/*
 * This code can be refactored per
 * https://golang.org/pkg/encoding/binary/
 * But for now, this should be sufficient
 */
/*
func parseCommand(c net.Conn) {
	rawCommand := make([]byte, 1)
}
*/

func StartInstancePoll(endpoint string, min_id string, reportPostChan chan ReportPost, pollMessageChan chan PollMessage) {
	p := bluemonday.NewPolicy()
	newposts := make([]ReportPost, 0)

	api_timeline := "https://" + endpoint + "/api/v1/timelines/public?min_id=" + min_id
	resp, err := http.Get(api_timeline)
	if err != nil {
		log.Fatal(err)
		pollMessageChan <- PollMessage{endpoint, resp.StatusCode, "" , 0}
	}

	body, err := ioutil.ReadAll(resp.Body)
	err = json.Unmarshal(body, &newposts)
	if err != nil {
		log.Fatal(err)
		panic(err)
		pollMessageChan <- PollMessage{endpoint, resp.StatusCode, "", 0}
	}

	numposts := 0
	for _, newpost := range newposts {
		posthash := sha1.New()

		if strings.Contains(newpost.Account.Acct, "@") == false {
			newpost.Account.Acct += "@" + endpoint
		}
		// Calculate the post hash
		fmt.Fprint(posthash, newpost.Url)
		fmt.Fprint(posthash, newpost.Content)
		fmt.Fprint(posthash, newpost.Account.Acct)
		fmt.Fprint(posthash, newpost.Account.Created_at)
		fmt.Fprint(posthash, newpost.Account.Display_name)
		fmt.Fprint(posthash, newpost.Account.Url)
		newpost.Posthash = posthash.Sum(nil)

		newpost.StrippedContent = p.Sanitize(newpost.Content)

		reportPostChan <- newpost

		// Check min_id
		if newpost.Id > min_id {
			min_id = newpost.Id
		}
		numposts = numposts + 1
	}

	pollMessageChan <- PollMessage{endpoint, resp.StatusCode, min_id, numposts}
}

func StartGetPeers(endpoint string, reportInstanceChan chan ReportInstance) {
	var newpeers	[]string

	api_peers := "https://" + endpoint + "/api/v1/instance/peers"
	resp, err := http.Get(api_peers)
	if err != nil {
		fmt.Println("Peer instance failure")
		os.Exit(1)
	}

	body, err := ioutil.ReadAll(resp.Body)

	err = json.Unmarshal([]byte(body), &newpeers)
	if err != nil {
		fmt.Println("Unmarshal error")
		log.Fatal(err)
		panic(err)
	}

	for _, newpeer := range newpeers {
		var q ReportInstance
		q.from = endpoint
		q.endpoint = newpeer
		reportInstanceChan <- q
	}
}

func DeferRun(pollmessage PollMessage, runninginstances *[]RunningInstance, reportInstanceChan chan ReportInstance, reportPostChan chan ReportPost, pollMessageChan chan PollMessage) {
	var min_id string

	for _, runninginstance := range *runninginstances {
		if runninginstance.endpoint == pollmessage.from {
			min_id = runninginstance.min_id
			break
		}
	}

	delay := 2
	if pollmessage.status == 200 && pollmessage.numposts <= 10 {
		delay = 2
	} else if pollmessage.status == 200 && pollmessage.numposts > 10 {
		delay = 5
	} else if pollmessage.status == 429 {
		delay = 30
	} else {
		fmt.Println("error, status code is: ", pollmessage.status)
		os.Exit(1)
	}
	time.Sleep(time.Second * time.Duration(delay))

	go StartInstancePoll(pollmessage.from, min_id, reportPostChan, pollMessageChan)
}

func NewInstance(endpoint string, runninginstances *[]RunningInstance, reportInstanceChan chan ReportInstance, reportPostChan chan ReportPost, pollMessageChan chan PollMessage) {
	for _, runninginstance := range *runninginstances {
		if runninginstance.endpoint == endpoint {
			return
		}
	}
	newinstance := RunningInstance{endpoint, ""}
	*runninginstances = append(*runninginstances, newinstance)

	go StartInstancePoll(endpoint, "", reportPostChan, pollMessageChan)
	fmt.Println("Temporarily disabled Peer Hunting")
//	go StartGetPeers(endpoint, reportInstanceChan)
}

func writePost(pool *pgxpool.Pool, reportpost ReportPost) {
	fmt.Println("Writing post", reportpost)
//	sqlWritePost := `INSERT INTO post (url, content, strippedcontent, posthash) VALUES ($1, $2, $3, $4, $5) ON CONFLICT (posthash) DO NOTHING`

	conn, err := pool.Acquire(context.Background())
	if err != nil {
		fmt.Println("Error acquiring connection:", err)
		os.Exit(1)
	}
	defer conn.Release()

	_, err = conn.Exec(context.Background(), "INSERT INTO posts (url, content, strippedcontent, posthash) VALUES ($1, $2, $3, $4) ON CONFLICT (posthash) DO NOTHING", reportpost.Url, reportpost.Content, reportpost.StrippedContent, reportpost.Posthash)
	if err != nil {
		fmt.Println("Error on channel???")
		fmt.Println(err)
		os.Exit(1)
	}
}

func main() {

	// Current instances
	runninginstances := make([]RunningInstance, 0)

	// Initial Setup
	reportPostChan := make(chan ReportPost, 100)
	reportInstanceChan := make(chan ReportInstance, 100)
	pollMessageChan := make (chan PollMessage, 100)

	// Setup Database
	pool, err := pgxpool.Connect(context.Background(), "postgres://postgres@127.0.0.1/tutorial")
	if err != nil {
		fmt.Fprintln(os.Stderr, "Unable to connect to database:", err)
		os.Exit(1)
	}

	l, err := net.Listen("tcp", "127.0.0.1:5555")
	if err != nil {
		fmt.Println(err)
		return
	}
	defer l.Close()

	var q ReportInstance
	q.from = ""
	q.endpoint = "mastodon.social"
	reportInstanceChan <- q

	for {
		commandClient := make(chan net.Conn)

		go func(l net.Listener) {
			for {
				c, err := l.Accept()
				if err != nil {
					commandClient <- nil
					return
				}
				commandClient <- c
			}
		}(l)

		for {
			select {
			case c := <-commandClient:		// New client connection
				go handleClient(c)
			case p := <-pollMessageChan:		// A poller ended
				for i, runninginstance := range runninginstances {
					if runninginstance.endpoint == p.from {
						runninginstances[i].min_id = p.min_id
					}
				}
				go DeferRun(p, &runninginstances, reportInstanceChan, reportPostChan, pollMessageChan)
			case v := <-reportPostChan:		// New Post
				go writePost(pool, v)
			case w := <-reportInstanceChan:		// Start a new instance
				NewInstance(w.endpoint, &runninginstances, reportInstanceChan, reportPostChan, pollMessageChan)
			}
		}
	}
}