package lists

import (
	"database/sql"
	"encoding/json"
	"errors"
	"fagott.pw/charakterin"
	"fagott.pw/grilist/frontend"
	"fagott.pw/grilist/grilist"
	"fagott.pw/grilist/cache"
	"fagott.pw/grilist/modules/grils"
	"fmt"
	"github.com/julienschmidt/httprouter"
	"github.com/lib/pq"
	"io/ioutil"
	"log"
	"net/http"
	"net/url"
	"sort"
	"strconv"
)

// Module und so.
type Module struct {
	g     *grilist.Grilist
    c *cache.Cache
	grils *grils.GrilsModule
}

// List ist eine Liste an DINGEN.
type List struct {
	ID          int
	Name        string
	Description string
	Owner       *charakterin.User
	ForkOf      sql.NullInt64
	UpdatedAt   pq.NullTime
	Grils       []*ListGril
}

// ListGril ist ein geranktes Gril
type ListGril struct {
	Gril  *grils.Gril
	Order int
}

// ListGrils ist die Sort-Interface Implementation für Grils einer Liste.
type ListGrils []*ListGril

func (l ListGrils) Len() int           { return len(l) }
func (l ListGrils) Swap(i, j int)      { l[i], l[j] = l[j], l[i] }
func (l ListGrils) Less(i, j int) bool { return l[i].Order < l[j].Order }

// Name gibt den Namen des Moduls zurück
func (m *Module) Name() string {
	return "Lists"
}

// Init initialisiert das Modul
func (m *Module) Init(g *grilist.Grilist) {
	m.g = g

	gm, ok := g.Modules["Grils"]
	if !ok {
		log.Fatal("lists: grils module not found")
	}

	grilsModule, ok := gm.(*grils.GrilsModule)
	if !ok {
		log.Fatal("lists: error with grils module")
	}
	m.grils = grilsModule
	m.g.Router.GET("/list/:id", m.viewList)
	m.g.Router.POST("/list/:id/order", m.updateGrilOrder)
	m.g.Router.POST("/list/:id", m.addGrilToList)
	m.g.Router.DELETE("/list/:id/order", m.removeGrilFromList)
	m.g.Router.GET("/new/list", m.displayCreateList)
	m.g.Router.POST("/new/list", m.createList)

	m.g.Router.GET("/api/lists/user", m.APIgetUserLists)
    
    m.c = cache.New()
}

func (m *Module) getListGrils(list *List) error {
	rows, err := m.g.DB.Query(`SELECT gril_id, "order" FROM grilist.lists_grils WHERE list_id = $1 ORDER BY "order" ASC`, list.ID)
	if err != nil {
		return err
	}

	defer rows.Close()
    list.Grils = list.Grils[:0]
	for rows.Next() {
		var grilID int
		lg := &ListGril{}

		if err := rows.Scan(&grilID, &lg.Order); err != nil {
			log.Println("error scanning row in getListGrils:", err)
			continue
		}

		gril, err := m.grils.FromID(grilID)
		if err != nil {
			log.Println("error getting listGril:", err)
			continue
		}
		lg.Gril = gril

		list.Grils = append(list.Grils, lg)
	}
	sort.Sort(ListGrils(list.Grils))
	return nil
}

func (m *Module) getLists(whereClause string, params ...interface{}) ([]*List, error) {
	var lists []*List

	rows, err := m.g.DB.Query(fmt.Sprintf(`SELECT id, name, description, fork_of, updated_at, user_id FROM grilist.lists WHERE %s`, whereClause), params...)
	if err != nil {
		return nil, err
	}

	defer rows.Close()
	for rows.Next() {
		list := &List{}
		var ownerID int
		if err := rows.Scan(&list.ID, &list.Name, &list.Description, &list.ForkOf, &list.UpdatedAt, &ownerID); err != nil {
			log.Println("error scanning row in getLists:", err)
			continue
		}
        
        if clist, ok := m.c.Get(list.ID); ok {
            // weiteres parsen abbrechen
            lists = append(lists, clist.(*List))
            continue
        }

		// Owner kriegn
		owner, err := m.g.Charakterin.GetUserByID(ownerID)
		if err != nil {
			log.Println("error retreiving owner of list", err)
			continue
		}
		list.Owner = owner
        
        m.c.Insert(list.ID, list)
		lists = append(lists, list)
	}

	return lists, nil
}

// GetUserLists gibt die Listen eines Benutzers zurück.
func (m *Module) GetUserLists(u *charakterin.User, withGrils bool) []*List {
	lists, err := m.getLists(`user_id = $1`, u.ID)
	if err != nil {
		log.Println(err)
	}

	if withGrils {
		for _, list := range lists {
			if err := m.getListGrils(list); err != nil {
				log.Println(err)
			}
		}
	}
	return lists
}

// FromID sucht nach der Liste mit der gegebenen ID und gibt sie, falls sie existiert, zurück.
func (m *Module) FromID(id int, withGrils bool) (*List, error) {
    if lst, ok := m.c.Get(id); ok {
        l := lst.(*List)
        // Potenzieller Optimierungsbedarf: neue query, wenn die Liste leer ist. updateGrilOrder nutzt derzeit aber genau dieses verhalten.
        if withGrils && len(l.Grils) == 0 {
            if err := m.getListGrils(l); err != nil {
				return nil, err
			}
        }
        return l, nil
    }

	lists, err := m.getLists(`id = $1`, id)
	if err != nil {
		return nil, err
	}

	if withGrils {
		for _, list := range lists {
			if err := m.getListGrils(list); err != nil {
				return nil, err
			}
		}
	}

	if len(lists) == 0 {
		return nil, errors.New("no list found")
	}
	return lists[0], nil
}

func ListsToCards(lists []*List) []frontend.Card {
	var cards []frontend.Card

	for _, list := range lists {
		cards = append(cards, frontend.Card{
			Title:       list.Name,
			Description: list.Description,
			Size:        "medium",
			Actions: []frontend.Action{
				frontend.Action{
					Name: "anguckieren",
					Link: fmt.Sprintf("/list/%d", list.ID),
				},
				frontend.Action{
					Name:     fmt.Sprintf(`<span class="chip">von <a class="purple-text text-lighten-2" style="margin-right: 0px" href="/user/%d/%s">%s</a></span>`, list.Owner.ID, list.Owner.GetName(), list.Owner.GetName()),
					Link:     "#",
					Disabled: true,
				},
			},
		})
	}
	return cards
}

// ProvideDashboardData gibt Daten für das Dashboard bezogen auf den Benutzer zurück
func (m *Module) ProvideDashboardData(user *charakterin.User) []grilist.DashboardCategory {
	var categories []grilist.DashboardCategory

	// Neue Listen
	lists, err := m.getLists(`1=1 ORDER BY id DESC LIMIT 5`)
	if err != nil {
		log.Println(err)
		return categories
	}
    
	for _, list := range lists {
        if err := m.getListGrils(list); err != nil {
            log.Println(err)
        }
	}

	categories = append(categories, grilist.DashboardCategory{
		Title: "Neueste Listen",
		Cards: ListsToCards(lists),
	})

	if user == nil {
		return categories
	}

	// Listen des Benutzers
	lists = m.GetUserLists(user, false)

	categories = append(categories, grilist.DashboardCategory{
		Title: "Meine Listen",
		Cards: ListsToCards(lists),
	})

	return categories
}

func (m *Module) viewList(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
	user, _ := m.g.Charakterin.GetUserFromRequest(r)
	sid := p.ByName("id")

	id, err := strconv.Atoi(sid)
	if err != nil {
        log.Println("redir")
		http.Redirect(w, r, "/", 302)
		return
	}

	list, err := m.FromID(id, true)
	if err != nil {
        log.Println("redir")
		http.Redirect(w, r, "/", 302)
		return
	}

	data := m.g.Renderer.DefaultData()
	data["user"] = user
	data["list"] = list

	m.g.Renderer.RenderPage("list", w, data)
}

func (m *Module) addGrilToList(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
	slistID := p.ByName("id")

	user, err := m.g.Charakterin.GetUserFromRequest(r)
	if err != nil {
		http.Error(w, "403", http.StatusForbidden)
		return
	}

	listID, err := strconv.Atoi(slistID)
	if err != nil {
		log.Println("invalid list id")
		return
	}

	values, err := readBody(r)
	if err != nil {
		log.Println("invalid POST data")
		return
	}

	grilID, err := strconv.Atoi(values.Get("id"))
	if err != nil {
		log.Println("invalid gril id")
		return
	}

	list, err := m.FromID(listID, true)
	if err != nil {
		http.Error(w, "invalid list", 404)
		return
	}

	if list.Owner.ID != user.ID {
		http.Error(w, "403", http.StatusForbidden)
		return
	}

	rank := 0
	if len(list.Grils) > 0 {
		rank = list.Grils[len(list.Grils)-1].Order + 1
	}

	// rein in die DB damit
	_, err = m.g.DB.Query(`INSERT INTO grilist.lists_grils(list_id, gril_id, "order") VALUES($1, $2, $3)`, listID, grilID, rank)
	if err != nil {
		log.Println("error inserting gril into list:", err)
		http.Error(w, "could not insert gril", 500)
		return
	}

	gril, err := m.grils.FromID(grilID)
	if err != nil {
		log.Println("inserted gril into list but couldnt get gril afterwards:", err)
		http.Error(w, "error after insert", 500)
		return
	}

	data := m.g.Renderer.DefaultData()
	data["Index"] = len(list.Grils)
	value := make(map[string]interface{})
	value["IsListOwner"] = true
	value["Gril"] = ListGril{gril, rank}
	data["Value"] = value
	m.g.Renderer.RenderPage("list_gril", w, data)
	return
}

func (m *Module) displayCreateList(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
	user, err := m.g.Charakterin.GetUserFromRequest(r)
	if err != nil {
		http.Redirect(w, r, "/", 302)
		return
	}

	data := m.g.Renderer.DefaultData()
	data["user"] = user

	m.g.Renderer.RenderPage("create_list", w, data)
}

func (m *Module) createList(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
	user, err := m.g.Charakterin.GetUserFromRequest(r)
	if err != nil {
		log.Println(err)
		http.Error(w, "500", http.StatusInternalServerError)
		return
	}

	values, err := readBody(r)
	if err != nil {
		log.Println(err)
		http.Error(w, "500", http.StatusInternalServerError)
		return
	}

	var id int
	err = m.g.DB.QueryRow(`INSERT INTO grilist.lists(user_id, name, description) VALUES($1, $2, $3) RETURNING id`, user.ID, values.Get("name"), values.Get("description")).Scan(&id)
	if err != nil {
		log.Println(err)
		http.Error(w, "500", http.StatusInternalServerError)
		return
	}

	http.Redirect(w, r, fmt.Sprintf("/list/%d", id), 302)
}

func (m *Module) updateGrilOrder(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
	slistID := p.ByName("id")

	user, err := m.g.Charakterin.GetUserFromRequest(r)
	if err != nil {
		http.Error(w, "403", http.StatusForbidden)
		return
	}

	listID, err := strconv.Atoi(slistID)
	if err != nil {
		http.Error(w, "invalid list ID (type mismatch)", 400)
		return
	}

	values, err := readBody(r)
	if err != nil {
		http.Error(w, "invalid POST data", 400)
		return
	}

	grilID, err := strconv.Atoi(values.Get("gril"))
	if err != nil {
		http.Error(w, "invalid gril ID", 404)
		return
	}

	pos, err := strconv.Atoi(values.Get("pos"))
	if err != nil {
		http.Error(w, "invalid position", 400)
		return
	}

	// rein in die DB damit
	_, err = m.g.DB.Exec(`SELECT grilist.set_gril_order($1, $2, $3, $4)`, user.ID, listID, grilID, pos)
	if err != nil {
		log.Println("error reordering gril:", err)
		http.Error(w, "could not update gril order", 500)
		return
	}
    
    // wenn die liste im cache ist, die Grils clearen, damit beim naechsten aufruf die Gril-Liste neu geholt wird.
    if l, ok := m.c.Get(listID); ok {
        ls := l.(*List)
        ls.Grils = ls.Grils[:0]
    }

	w.WriteHeader(200)
	w.Write([]byte("ok"))
	return
}

func (m *Module) removeGrilFromList(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
	slistID := p.ByName("id")

	listID, err := strconv.Atoi(slistID)
	if err != nil {
		http.Error(w, "invalid list ID (type mismatch)", 400)
		return
	}

	values, err := readBody(r)
	if err != nil {
		http.Error(w, "invalid POST data", 400)
		return
	}

	grilID, err := strconv.Atoi(values.Get("gril"))
	if err != nil {
		http.Error(w, "invalid gril ID", 404)
		return
	}

	res, err := m.g.DB.Exec(`DELETE FROM grilist.lists_grils WHERE list_id=$1 AND gril_id=$2`, listID, grilID)
	if err != nil {
		log.Println("error removing gril:", err)
		http.Error(w, "could not remove gril", 500)
		return
	}

	if r, err := res.RowsAffected(); err != nil || r == 0 {
		log.Println("invalid rows affected in removing gril")
		http.Error(w, "gril not in list / other error", 500)
		return
	}

	w.WriteHeader(200)
	w.Write([]byte("ok"))
	return
}

func (m *Module) APIgetUserLists(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
	user, err := m.g.Charakterin.GetUserFromRequest(r)
	if err != nil {
		http.Error(w, "403", http.StatusForbidden)
		return
	}

	lists := m.GetUserLists(user, false)

	for _, list := range lists {
		// owner wegen SICHERHEIT rausfiltern (nodumppassword2k16)
		list.Owner = nil
	}

	data, err := json.Marshal(&lists)
	if err != nil {
		log.Println(err)
		http.Error(w, "500", http.StatusInternalServerError)
		return
	}
	w.WriteHeader(200)
	w.Write(data)
}

// New erstellt eine neue Instanz des Modules
func New() *Module {
	return &Module{}
}

func readBody(r *http.Request) (url.Values, error) {
	defer r.Body.Close()
	data, err := ioutil.ReadAll(r.Body)
	if err != nil {
		return nil, err
	}

	values, err := url.ParseQuery(string(data))
	if err != nil {
		return nil, err
	}

	return values, nil
}