package cgi

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

	"git.capotej.com/capotej/communique/config"
	"git.capotej.com/capotej/communique/models"
	"github.com/mmcdole/gofeed"
	"go.uber.org/zap"
)

type Servers struct {
	log       *zap.SugaredLogger
	persister *models.Persister
}

func NewServers(log *zap.SugaredLogger, persister *models.Persister) *Servers {
	return &Servers{log: log, persister: persister}
}

// 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
	logger := s.log.With("type", "cgi")

	for _, handler := range cfg.Handlers {
		handlerLogger := logger.With("handler", handler.Name)
		wg.Add(3)
		// Internal CGI server
		go func(aHandler config.Handler) {
			defer wg.Done()
			startCGIServer(aHandler, handlerLogger)
		}(handler)
		// Ticker
		go func(aHandler config.Handler) {
			defer wg.Done()
			startTicker(aHandler, s.persister, handlerLogger)
		}(handler)
		// Execute a handler tick on start since Go's ticker waits until $interval to trigger first tick
		go func(aHandler config.Handler) {
			defer wg.Done()
			time.Sleep(1 * time.Second)
			output := tick(aHandler, handlerLogger)
			err := processTick(aHandler, output, s.persister, handlerLogger)
			if err != nil {
				s.log.Error(err)
			}
		}(handler)

	}
	wg.Wait()
}

func startCGIServer(h config.Handler, log *zap.SugaredLogger) {
	cgiHandler := cgi.Handler{Path: h.Exec}

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

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

func startTicker(h config.Handler, persister *models.Persister, log *zap.SugaredLogger) {
	ticker := time.NewTicker(h.Interval) // TODO add some random jitter here so handlers dont run at the same exact intervals
	done := make(chan bool)
	func() {
		for {
			select {
			case <-done:
				return
			case _ = <-ticker.C:
				output := tick(h, log)
				err := processTick(h, output, persister, log)
				if err != nil {
					log.Error(err)
				}
			}
		}
	}()
}

func processTick(h config.Handler, output []byte, persister *models.Persister, log *zap.SugaredLogger) error {
	fp := gofeed.NewParser()
	fp.ParseString(string(output))
	feed, err := fp.ParseString(string(output))
	if err != nil {
		return err
	}

	for _, v := range feed.Items {
		var extractedContent string
		// if there is no content, use descrption
		if len(v.Content) != 0 {
			extractedContent = v.Content
		} else if len(v.Description) != 0 {
			extractedContent = v.Description
		}
		if len(extractedContent) != 0 {
			log.Debugf("extracted content '%s'", extractedContent)
			outboxItem := models.CreateOutboxItem(h, []byte(extractedContent))
			err = persister.StoreWithCallback(outboxItem, func() {
				log.With("handler", h.Name).Debug("callback for save")
			})
			if err != nil {
				return err
			}
		}
	}
	return nil
}

func tick(h config.Handler, log *zap.SugaredLogger) []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
	log.Debugf("executing cgi handler at %s", sock)
	response, err = httpc.Get("http://unix/" + sock)
	if err != nil {
		log.Errorf("received error from cgi handler %s", err)
	}

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