package front

import (
	"context"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"time"

	hm "gitlab.codemonkeysoftware.net/b/hatmill"
	a "gitlab.codemonkeysoftware.net/b/hatmill/attribute"
	e "gitlab.codemonkeysoftware.net/b/hatmill/element"
	"gitlab.codemonkeysoftware.net/b/henwen/back"
)

const (
	pathRoot     = "/"
	pathCreate   = "/create"
	pathDoCreate = "/create/do"
	pathAdmin    = "/admin"
	pathVote     = "/vote"
	pathDoVote   = "/vote/do"
)

type handler struct {
	mux     *http.ServeMux
	store   *back.Store
	title   string
	baseURL string
}

type HandlerParams struct {
	Title   string
	Store   *back.Store
	BaseURL string
}

func NewHandler(params HandlerParams) http.Handler {
	h := &handler{
		store:   params.Store,
		title:   params.Title,
		baseURL: params.BaseURL,
		mux:     http.NewServeMux(),
	}
	h.mux.HandleFunc(pathRoot, h.handleRoot)
	h.mux.HandleFunc(pathCreate, h.handleCreate)
	h.mux.HandleFunc(pathDoCreate, h.handleDoCreate)
	h.mux.HandleFunc(pathAdmin, h.handleAdmin)
	h.mux.HandleFunc(pathVote, h.handleVote)
	h.mux.HandleFunc(pathDoVote, h.handleDoVote)
	return h
}

func (h *handler) handleRoot(w http.ResponseWriter, r *http.Request) {
	body := hm.Terms{
		e.H2()(hm.Text("Welcome!")),
		e.A(a.Href(pathCreate))(
			hm.Text("Create event"),
		),
	}
	_ = h.writePage(w, body)
}

var timeLabels = []string{
	"12 AM", "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11",
	"12 PM", "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11",
}

func disableIf(cond bool, input hm.Term) hm.Term {
	if !cond {
		return input
	}
	switch e := input.(type) {
	case hm.ParentElement:
		e.Attribs = append(e.Attribs, a.Disabled())
		return e
	case hm.VoidElement:
		e.Attribs = append(e.Attribs, a.Disabled())
		return e
	default:
		return e
	}
}

type voteState struct {
	name                     string
	earliestDate, latestDate time.Time
}

func voteForm(disabled bool, st voteState) hm.Term {
	var dates []time.Time
	for curr := st.earliestDate; curr.Before(st.latestDate.Add(time.Hour)); curr = curr.AddDate(0, 0, 1) {
		dates = append(dates, curr)
	}

	var ths = hm.Terms{e.Th()()}
	for _, date := range dates {
		ths = append(ths, e.Th()(hm.Text(date.Format("Jan 2"))))
	}

	var rows = hm.Terms{e.Thead()(ths)}
	for hour := 0; hour < 24; hour++ {
		var row = hm.Terms{
			e.Td()(hm.Text(timeLabels[hour])),
		}
		for day := 0; day < len(dates); day++ {
			row = append(row, e.Td()(disableIf(disabled, e.Input(a.Type("checkbox")))))
		}
		rows = append(rows, e.Tr()(row))
	}
	return e.Form(a.Method(http.MethodPost), a.Action(pathDoVote))(
		e.Label()(hm.Text("What's your name?")),
		e.Br(),
		disableIf(disabled, e.Input(a.Size(40), a.Value(st.name))),
		e.Fieldset()(
			e.Legend()(hm.Text("When are you available?")),
			e.Table()(rows),
		),
		e.Input(a.Type("submit"), a.Value("Submit")),
	)
}

func (h *handler) handleVote(w http.ResponseWriter, r *http.Request) {
	// TODO use actual data
	state := voteState{
		name:         "Suzie Q",
		earliestDate: time.Date(2006, time.May, 3, 0, 0, 0, 0, time.UTC),
		latestDate:   time.Date(2006, time.May, 8, 0, 0, 0, 0, time.UTC),
	}
	body := hm.Terms{
		e.H2()(hm.Text("Billy's birthday party")),
		e.P()(hm.Text("At Billy's house. Bring presents. Eat cake.")),
		voteForm(false, state),
	}
	_ = h.writePage(w, body)
}

func (h *handler) handleDoVote(w http.ResponseWriter, r *http.Request) {
	// TODO use actual data
	state := voteState{
		name:         "Suzie Q",
		earliestDate: time.Date(2006, time.May, 3, 0, 0, 0, 0, time.UTC),
		latestDate:   time.Date(2006, time.May, 8, 0, 0, 0, 0, time.UTC),
	}
	body := hm.Terms{
		e.H2()(hm.Text("Billy's birthday party")),
		e.P()(hm.Text("At Billy's house. Bring presents. Eat cake.")),
		e.H3()(hm.Text("Thanks for voting!")),
		e.P()(
			hm.Text("You can edit your response anytime at "),
			e.A(a.Href("#"))(hm.Text("this link")),
			hm.Text("."),
		),
		voteForm(true, state),
	}
	_ = h.writePage(w, body)
}

func (h *handler) handleCreate(w http.ResponseWriter, r *http.Request) {
	body := hm.Terms{
		e.H2()(hm.Text("Create an event")),
		e.Form(a.Action(pathDoCreate), a.Method(http.MethodPost))(
			e.Label(a.For(fieldNameEventName))(hm.Text("Event name")),
			e.Input(a.Name(fieldNameEventName)),

			e.Label(a.For(fieldNameDescription))(hm.Text("Description")),
			e.Textarea(a.Name(fieldNameDescription), a.Placeholder("What's going on?"))(),

			e.Label(a.For(fieldNameEarliest))(hm.Text("Earliest date")),
			e.Input(a.Name(fieldNameEarliest), a.Type("date")),

			e.Label(a.For(fieldNameLatest))(hm.Text("Latest date")),
			e.Input(a.Name(fieldNameLatest), a.Type("date")),

			e.Input(a.Type("submit")),
		),
	}
	_ = h.writePage(w, body)
}

func (h *handler) handleDoCreate(w http.ResponseWriter, r *http.Request) {
	earliest, err := time.Parse(formDateLayout, r.FormValue(fieldNameEarliest))
	if err != nil {
		fmt.Fprint(w, "bad earliest date")
		return
	}
	latest, err := time.Parse(formDateLayout, r.FormValue(fieldNameLatest))
	if err != nil {
		fmt.Fprint(w, "bad latest date")
		return
	}
	eventName := r.FormValue(fieldNameEventName)
	if eventName == "" {
		fmt.Fprint(w, "event name is required")
		return
	}
	description := r.FormValue(fieldNameDescription)

	event, err := h.store.CreateEvent(context.Background(), back.CreateEventCommand{
		Name:         eventName,
		Description:  description,
		EarliestDate: earliest,
		LatestDate:   latest,
	})
	if err != nil {
		fmt.Fprint(w, err)
		return
	}
	var adminQuery = make(url.Values)
	adminQuery.Add(keyEventID, event.AlphaID)
	adminQuery.Add(keyAdminCode, event.AdminCode)
	adminURL := h.baseURL + pathAdmin + "?" + adminQuery.Encode()

	const dateDisplayFmt = "Monday, January 2, 2006"

	body := hm.Terms{
		e.H2()(hm.Text("Created event!")),
		e.P()(
			hm.Text("You can find it again at "),
			e.A(a.Href(adminURL))(hm.Text(adminURL)),
			hm.Text("."),
		),

		e.H3()(hm.Text("Name")),
		hm.Text(eventName),

		e.H3()(hm.Text("Description")),
		hm.Text(description),

		e.H3()(hm.Text("Earliest date")),
		hm.Text(earliest.Format(dateDisplayFmt)),

		e.H3()(hm.Text("Latest date")),
		hm.Text(latest.Format(dateDisplayFmt)),
	}
	_ = h.writePage(w, body)
}

func (h *handler) handleAdmin(w http.ResponseWriter, r *http.Request) {
	query := r.URL.Query()
	event, err := h.store.GetEvent(context.Background(), back.GetEventQuery{
		AlphaID:   query.Get(keyEventID),
		AdminCode: query.Get(keyAdminCode),
	})
	if err != nil {
		fmt.Fprint(w, err)
		return
	}

	body := hm.Terms{
		e.H2()(hm.Text("Edit your event")),
		e.Form()(
			e.Label(a.For(fieldNameEventName))(hm.Text("Event name")),
			e.Input(
				a.Name(fieldNameEventName),
				a.Value(event.Name),
			),
			e.Br(),

			e.Label(a.For(fieldNameDescription))(hm.Text("Description")),
			e.Textarea(a.Name(fieldNameDescription))(hm.Text(event.Description)),
			e.Br(),

			e.Label(a.For(fieldNameEarliest))(hm.Text("Earliest date")),
			e.Input(
				a.Name(fieldNameEarliest),
				a.Type("date"),
				a.Value(event.EarliestDate.Format(formDateLayout)),
			),
			e.Br(),

			e.Label(a.For(fieldNameLatest))(hm.Text("Latest date")),
			e.Input(
				a.Name(fieldNameLatest),
				a.Type("date"),
				a.Value(event.LatestDate.Format(formDateLayout)),
			),
			e.Br(),

			e.Input(a.Type("submit")),
		),
	}
	_ = h.writePage(w, body)
}

func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	h.mux.ServeHTTP(w, r)
}

func (h *handler) writePage(w io.Writer, contents hm.Term) error {
	page := e.Html()(
		e.Head()(
			e.Title()(hm.Text(h.title)),
		),
		e.Body()(
			e.H1()(hm.Text(h.title)),
			e.Div()(contents),
		),
	)
	_, err := hm.WriteDocument(w, page)
	return err
}

const (
	fieldNameEarliest    = "earliestDate"
	fieldNameLatest      = "latestDate"
	fieldNameEventName   = "eventName"
	fieldNameDescription = "eventDescription"
)

const keyEventID = "event_id"
const keyAdminCode = "admin_code"

const formDateLayout = "2006-01-02"