package main

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"log"
	"net/http"
	"sort"
	"time"

	"golang.org/x/oauth2"
	"golang.org/x/oauth2/google"

	calendar "google.golang.org/api/calendar/v3"
)

type Account struct {
	CC              *CalClient
	Service         *calendar.Service
	CalendarList    []Calendar
	CalListUseBy    time.Time
	EventList       []Event // Today's Events
	EventListUseBy  time.Time
	ActiveCalendars []string
	QuickAddCal     string
	Colors          *calendar.Colors
}

func GetAccount(secret, token []byte) (*Account, error) {
	var err error
	a := new(Account)

	// Create the CalClient
	a.CC = CreateClient(secret, token)
	a.CC.TokenToRaw()

	// Create the Calendar Service
	a.Service, err = calendar.New(a.CC.client)
	if err != nil {
		return nil, errors.New("Unable to retrieve calendar Client: " + err.Error())
	}

	a.Colors, err = calendar.NewColorsService(a.Service).Get().Do()
	return a, err
}

// Get Todays Events gets events for today from all calendars
func (a *Account) GetTodaysEvents() []Event {
	if time.Now().Before(a.EventListUseBy) {
		return a.EventList
	}
	var ret []Event
	list := a.GetCalendarList()
	for i := range list {
		if list[i].Deleted {
			continue
		}
		ret = append(ret, list[i].GetTodaysEvents()...)
	}
	sort.Sort(ByStartTime(ret))
	a.EventList = ret
	a.EventListUseBy = time.Now().Add(time.Hour * 6)
	return ret
}

func (a *Account) GetTodaysActiveEvents() []Event {
	allEvents := a.GetTodaysEvents()
	var ret []Event
	var startIdx int
	for i := range allEvents {
		for _, calId := range a.ActiveCalendars {
			if allEvents[i].CalendarId == calId {
				if time.Until(allEvents[i].GetStartTime()) <= 0 {
					startIdx--
				}
				ret = append(ret, allEvents[i])
				break
			}
		}
	}
	sort.Sort(ByStartTime(ret))
	for i := range ret {
		ret[i].InstanceId = startIdx
		startIdx++
	}
	return ret
}

func (a *Account) GetDefaultCalendar() *Calendar {
	c, _ := a.Service.CalendarList.Get("primary").Do()
	return GoogleCalendarToLocal(c)
}

func (a *Account) GetCalendarList() []Calendar {
	if time.Now().Before(a.CalListUseBy) {
		return a.CalendarList
	}
	var ret []Calendar
	calList, err := a.Service.CalendarList.List().Do()
	if err != nil {
		return ret
	}
	for _, c := range calList.Items {
		ret = append(ret, *GoogleCalendarToLocal(c))
	}
	a.CalendarList = ret
	a.CalListUseBy = time.Now().Add(time.Hour * 24 * 7)
	return ret
}

func (a *Account) GetCalendarById(id string) (*Calendar, error) {
	calList := a.GetCalendarList()
	for _, c := range calList {
		if c.Id == id {
			return &c, nil
		}
	}
	return nil, errors.New("Couldn't find calendar")
}

func (a *Account) GetCalendarColor(id string) (*calendar.ColorDefinition, error) {
	var cal *Calendar
	var err error
	if cal, err = a.GetCalendarById(id); err != nil {
		return nil, err
	}
	if c, ok := a.Colors.Calendar[cal.ColorId]; ok {
		return &c, nil
	}
	return nil, errors.New("Error Finding Calendar Color")
}

type CalClient struct {
	rawClientSecret []byte
	rawToken        []byte
	ctx             context.Context
	cfg             *oauth2.Config
	tkn             *oauth2.Token
	client          *http.Client
}

func CreateClient(secret, tkn []byte) *CalClient {
	var err error
	c := CalClient{
		rawClientSecret: []byte(secret),
		rawToken:        []byte(tkn),
	}

	c.ctx = context.Background()
	c.cfg, err = google.ConfigFromJSON(c.rawClientSecret, calendar.CalendarScope)

	if err != nil {
		log.Fatalf("unable to parse client secret file to config: %v", err)
	}

	// Try to create the client with the passed token
	c.client, err = c.GetClient()
	if err != nil {
		log.Fatalf("unable to create client: %v", err)
	}
	return &c
}

func (c *CalClient) GetClient() (*http.Client, error) {
	err := c.tokenFromRaw()
	if err != nil {
		err = c.tokenFromWeb()
		if err != nil {
			return nil, err
		}
	}
	return c.cfg.Client(c.ctx, c.tkn), nil
}

func (c *CalClient) tokenFromRaw() error {
	c.tkn = &oauth2.Token{}
	tmpToken := bytes.NewBuffer(c.rawToken)
	err := json.NewDecoder(tmpToken).Decode(c.tkn)
	return err
}

func (c *CalClient) tokenFromWeb() error {
	var err error
	authURL := c.cfg.AuthCodeURL("state-token", oauth2.AccessTypeOffline)
	fmt.Printf("Go to the following link in your browser then type the authorization code:\n%v\n", authURL)
	var code string
	if _, err := fmt.Scan(&code); err != nil {
		log.Fatalf("Unable to read authorization code %v", err)
	}

	if c.tkn, err = c.cfg.Exchange(oauth2.NoContext, code); err == nil {
		c.TokenToRaw()
	}
	return err
}

func (c *CalClient) TokenToRaw() {
	var tmpToken bytes.Buffer
	t := c.tkn
	json.NewEncoder(&tmpToken).Encode(t)
	c.rawToken = tmpToken.Bytes()
}

func (c *CalClient) GetRawToken() []byte {
	return c.rawToken
}