package trantor

import (
	log "github.com/cihub/seelog"

	"net/http"
	"strings"
	"time"

	"github.com/gorilla/mux"
	"gitlab.com/trantor/trantor/lib/database"
	"gitlab.com/trantor/trantor/lib/instrument"
	"gitlab.com/trantor/trantor/lib/storage"
)

const (
	statsChanSize = 100
)

type handler struct {
	w        http.ResponseWriter
	r        *http.Request
	sess     *Session
	db       database.DB
	store    storage.Store
	template *Template
	hostname string
	ro       bool
}

func (h handler) load(tmpl string, data interface{}) {
	var err error
	fmt := h.r.FormValue("fmt")
	switch fmt {
	case "rss":
		err = h.template.rss.ExecuteTemplate(h.w, tmpl+".rss", data)
	case "opds":
		err = h.template.opds.ExecuteTemplate(h.w, tmpl+".opds", data)
	case "json":
		err = loadJson(h.w, tmpl, data)
	default:
		err = h.template.html.ExecuteTemplate(h.w, tmpl+".html", data)
	}
	if err != nil {
		h.template.html.ExecuteTemplate(h.w, "404.html", data)
		log.Warn("An error ocurred loading the template ", tmpl, ".", fmt, ": ", err)
	}
}

type StatsGatherer struct {
	db         database.DB
	store      storage.Store
	template   *Template
	instrument instrument.Instrument
	hostname   string
	channel    chan statsRequest
	ro         bool
}

func InitStats(database database.DB, store storage.Store, hostname string, template *Template, ro bool) *StatsGatherer {
	in := instrument.Init()

	sg := StatsGatherer{
		channel:    make(chan statsRequest, statsChanSize),
		db:         database,
		store:      store,
		instrument: in,
		template:   template,
		hostname:   hostname,
		ro:         ro,
	}

	go sg.worker()
	return &sg
}

func (sg StatsGatherer) Gather(function func(handler)) func(http.ResponseWriter, *http.Request) {
	return func(w http.ResponseWriter, r *http.Request) {
		log.Info("Query ", r.Method, " ", r.RequestURI)

		h := handler{
			store:    sg.store,
			db:       sg.db,
			template: sg.template,
			hostname: sg.hostname,
			w:        w,
			r:        r,
			sess:     GetSession(r, sg.db),
			ro:       sg.ro,
		}

		t0 := time.Now()
		function(h)
		t1 := time.Now()
		sg.channel <- statsRequest{r, t1.Sub(t0)}
	}
}

type statsRequest struct {
	r        *http.Request
	duration time.Duration
}

func (sg StatsGatherer) worker() {
	for req := range sg.channel {
		var err error
		id := mux.Vars(req.r)["id"]
		search := strings.Join(req.r.Form["q"], " ")
		fmt := req.r.FormValue("fmt")
		pattern := strings.Split(req.r.URL.Path, "/")

		section := "/"
		if len(pattern) > 1 && pattern[1] != "" {
			section = pattern[1]
		}

		sg.instrument.Visit(section, id, search, fmt)
		sg.instrument.Duration(section, req.duration*time.Microsecond)
		switch section {
		case "download":
			err = sg.db.IncDownloads(id)
		case "book":
			err = sg.db.IncViews(id)
		case "read":
			err = sg.db.IncViews(id)
		}

		if err != nil {
			log.Warn("Problem incrementing visits: ", err)
		}
	}
}