package api

import (
	"net/http"
	"net/url"
	"strconv"
	"strings"
	"time"
	"velvettear/worklog/internal/config"
	"velvettear/worklog/internal/database"
	"velvettear/worklog/internal/log"
	"velvettear/worklog/internal/workday"
)

// exported function(s)
func Run() {
	serverAddress := config.ServerListen() + ":" + strconv.Itoa(config.ServerPort())
	http.HandleFunc("/", handleRequests)
	log.Info("starting server '" + serverAddress + "'...")
	err := http.ListenAndServe(serverAddress, nil)
	if err != nil {
		log.Fatal("encountered an error starting the server", err.Error())
	}
}

// unexported function(s)
func handleRequests(writer http.ResponseWriter, request *http.Request) {
	requestPath := request.URL.Path
	requestMethod := strings.ToLower(request.Method)
	user, authorized := isAuthorized(request)
	if !authorized {
		log.Debug("denying unauthorized '" + requestMethod + "' request for path '" + requestPath + "'")
		writer.WriteHeader(404)
		writer.Write([]byte("error: basic authorization failed\n"))
		return
	}
	handled := false
	switch requestMethod {
	case "get":
		log.Debug("handling '" + requestMethod + "' request for path '" + requestPath + "'...")
		handled = handleGet(user, writer, request)
	case "post":
		log.Debug("handling '" + requestMethod + "' request for path '" + requestPath + "'...")
		handled = handlePost(user, writer, request)
	}
	if handled {
		return
	}
	log.Debug("ignoring '" + requestMethod + "' request for path '" + requestPath + "'\n")
	writer.WriteHeader(501)
	writer.Write([]byte("error: endpoint '" + requestPath + "' not implemented\n"))
}

func isAuthorized(request *http.Request) (string, bool) {
	username, password, ok := request.BasicAuth()
	if !ok {
		return username, false
	}
	return username, password == config.GetString("users."+username+".password")
}

func handleGet(user string, writer http.ResponseWriter, request *http.Request) bool {
	handled := true
	switch request.URL.Path {
	case "/today":
		workday, error := workday.GetToday(user)
		if error != nil {
			writer.WriteHeader(404)
			break
		}
		json, error := workday.ToJSON(user)
		if error != nil {
			msg := "encountered an error generating json output"
			log.Error(msg, error.Error())
			writer.WriteHeader(500)
			writer.Write([]byte(msg + "\n"))
			break
		}
		writer.WriteHeader(200)
		writer.Write([]byte(json + "\n"))
	case "/json":
		from, to := getTimespan(request.URL.Query())
		json, error := workday.ToJSON(from, to, user)
		if error != nil {
			msg := "encountered an error generating json output"
			log.Error(msg, error.Error())
			writer.WriteHeader(500)
			writer.Write([]byte(msg + "\n"))
			break
		}
		writer.WriteHeader(200)
		writer.Write([]byte(json + "\n"))
	case "/csv":
		from, to := getTimespan(request.URL.Query())
		result := workday.ToCSV(from, to, user)
		writer.WriteHeader(200)
		writer.Write([]byte(result + "\n"))
	default:
		handled = false
	}
	return handled
}

func handlePost(user string, writer http.ResponseWriter, request *http.Request) bool {
	handled := true
	switch request.URL.Path {
	case "/start":
		success, workday := database.StartTimestamp(user)
		if !success {
			if workday.ID > 0 {
				writer.WriteHeader(400)
				writer.Write([]byte("workday for today has already been started at " + strconv.Itoa(workday.Start.Hour()) + ":" + strconv.Itoa(workday.Start.Minute()) + ":" + strconv.Itoa(workday.Start.Second()) + "\n"))
			} else {
				writer.WriteHeader(500)
				writer.Write([]byte("encountered an error starting a new workday\n"))
			}
			break
		}
		writer.WriteHeader(200)
		writer.Write([]byte("started new workday for user '" + workday.User + "' at " + strconv.Itoa(workday.Start.Hour()) + ":" + strconv.Itoa(workday.Start.Minute()) + ":" + strconv.Itoa(workday.Start.Second()) + "\n"))
	case "/stop":
		success, workday := database.StopTimestamp()
		if !success {
			if workday.ID > 0 {
				writer.WriteHeader(500)
				writer.Write([]byte("encountered an error stopping workday for user '" + workday.User + "'\n"))
			} else {
				writer.WriteHeader(400)
				writer.Write([]byte("there is no open workday to stop\n"))
			}
			break
		}
		writer.WriteHeader(200)
		writer.Write([]byte("stopped workday for user '" + workday.User + "' started at " + strconv.Itoa(workday.Start.Hour()) + ":" + strconv.Itoa(workday.Start.Minute()) + ":" + strconv.Itoa(workday.Start.Second()) + "\n"))
	default:
		handled = false
	}
	return handled
}

func getTimespan(values url.Values) (time.Time, time.Time) {
	from := time.Date(1, 1, 1, 0, 0, 0, 0, time.UTC)
	to := time.Now()
	layout := "02.01.2006"
	if values.Has("from") {
		tmp, error := time.Parse(layout, values.Get("from"))
		if error != nil {
			log.Error("error parsing date '"+values.Get("from"), error.Error())
		}
		from = tmp
	}
	if values.Has("to") {
		tmp, error := time.Parse(layout, values.Get("to"))
		if error != nil {
			log.Error("error parsing date '"+values.Get("from"), error.Error())
		}
		to = tmp
		to = to.Add(time.Hour * 23).Add(time.Minute * 59).Add(time.Second * 59)
	}
	return from, to
}