package cgi

import (
	"context"
	"fmt"
	"io/ioutil"
	"net"
	"net/http"
	"net/http/cgi"
	"os"
	"sync"
	"time"

	"git.capotej.com/capotej/communique/config"
	"github.com/dgraph-io/badger/v3"
	"go.uber.org/zap"
)

type Servers struct {
	log *zap.SugaredLogger
	db  *badger.DB
}

func NewServers(log *zap.SugaredLogger, db *badger.DB) *Servers {
	return &Servers{log: log, db: db}
}

// Start iterates over all Handlers and starts an internal CGI server for each one
// along with ticker for the configured handler interval then blocks indefinitely
func (s *Servers) Start(cfg config.Config) {
	var wg sync.WaitGroup

	for _, handler := range cfg.Handlers {
		wg.Add(2)
		go func(aHandler config.Handler) {
			defer wg.Done()
			startCGIServer(aHandler)
		}(handler)
		go func(aHandler config.Handler) {
			defer wg.Done()
			startTicker(aHandler, s.db, s.log)
		}(handler)
	}
	wg.Wait()
}

func startCGIServer(h config.Handler) {
	cgiHandler := cgi.Handler{Path: h.Exec}

	server := http.Server{
		Handler: &cgiHandler,
	}

	sock := fmt.Sprintf("%s.sock", h.Name)
	os.Remove(sock)
	unixListener, err := net.Listen("unix", sock)
	if err != nil {
		panic(err)
	}
	server.Serve(unixListener)
}

func startTicker(h config.Handler, db *badger.DB, log *zap.SugaredLogger) {
	ticker := time.NewTicker(h.Interval)
	done := make(chan bool)
	func() {
		for {
			select {
			case <-done:
				return
			case t := <-ticker.C:
				output := tick(h)
				keyName := fmt.Sprintf("outbox:%s:%d", h.Name, t.Unix())
				err := db.Update(func(txn *badger.Txn) error {
					e := badger.NewEntry([]byte(keyName), output)
					log.With("name", "ticker").Infof("writing '%s' to %s", output, keyName)
					return txn.SetEntry(e)
				})
				if err != nil {
					log.Error(err)
				}
			}
		}
	}()
}

func tick(h config.Handler) []byte {
	sock := fmt.Sprintf("%s.sock", h.Name)
	httpc := http.Client{
		Transport: &http.Transport{
			DialContext: func(_ context.Context, _, _ string) (net.Conn, error) {
				return net.Dial("unix", sock)
			},
		},
	}
	var response *http.Response
	var err error
	response, err = httpc.Get("http://unix/" + sock)
	if err != nil {
		panic(err)
	}

	body, err := ioutil.ReadAll(response.Body)
	response.Body.Close()
	return body
}