/*
 * SPDX-FileCopyrightText: 2023 jordi fita mas <jfita@peritasoft.com>
 * SPDX-License-Identifier: AGPL-3.0-only
 */

package season

import (
	"context"
	"fmt"
	"net/http"
	"net/url"
	"strconv"
	"strings"
	"time"

	"github.com/jackc/pgtype"
	"github.com/jackc/pgx/v4"

	"dev.tandem.ws/tandem/camper/pkg/auth"
	"dev.tandem.ws/tandem/camper/pkg/database"
	"dev.tandem.ws/tandem/camper/pkg/form"
	httplib "dev.tandem.ws/tandem/camper/pkg/http"
	"dev.tandem.ws/tandem/camper/pkg/locale"
	"dev.tandem.ws/tandem/camper/pkg/template"
	"dev.tandem.ws/tandem/camper/pkg/uuid"
)

const unsetColor = 13750495

type AdminHandler struct {
	locales locale.Locales
}

func NewAdminHandler(locales locale.Locales) *AdminHandler {
	return &AdminHandler{
		locales: locales,
	}
}

func (h *AdminHandler) Handler(user *auth.User, company *auth.Company, conn *database.Conn) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		var head string
		head, r.URL.Path = httplib.ShiftPath(r.URL.Path)

		switch head {
		case "":
			switch r.Method {
			case http.MethodGet:
				serveSeasonIndex(w, r, user, company, conn)
			case http.MethodPost:
				addSeason(w, r, user, company, conn)
			default:
				httplib.MethodNotAllowed(w, r, http.MethodGet, http.MethodPost)
			}
		case "new":
			switch r.Method {
			case http.MethodGet:
				f := newSeasonForm()
				f.MustRender(w, r, user, company)
			default:
				httplib.MethodNotAllowed(w, r, http.MethodGet)
			}
		case "range":
			switch r.Method {
			case http.MethodGet:
				serveSeasonCalendar(w, r, user, company, conn)
			case http.MethodPut:
				updateSeasonCalendar(w, r, user, company, conn)
			default:
				httplib.MethodNotAllowed(w, r, http.MethodGet, http.MethodPut)
			}
		default:
			if !uuid.Valid(head) {
				http.NotFound(w, r)
				return
			}
			f := newSeasonForm()
			if err := f.FillFromDatabase(r.Context(), conn, head); err != nil {
				if database.ErrorIsNotFound(err) {
					http.NotFound(w, r)
					return
				}
				panic(err)
			}
			var langTag string
			langTag, r.URL.Path = httplib.ShiftPath(r.URL.Path)

			switch langTag {
			case "":
				switch r.Method {
				case http.MethodGet:
					f.MustRender(w, r, user, company)
				case http.MethodPut:
					editSeason(w, r, user, company, conn, f)
				default:
					httplib.MethodNotAllowed(w, r, http.MethodGet, http.MethodPut)
				}
			default:
				loc, ok := h.locales.Get(langTag)
				if !ok {
					http.NotFound(w, r)
					return
				}
				l10n := newSeasonL10nForm(f, loc)
				if err := l10n.FillFromDatabase(r.Context(), conn); err != nil {
					panic(err)
				}
				switch r.Method {
				case http.MethodGet:
					l10n.MustRender(w, r, user, company)
				case http.MethodPut:
					editSeasonL10n(w, r, user, company, conn, l10n)
				default:
					httplib.MethodNotAllowed(w, r, http.MethodGet, http.MethodPut)
				}
			}
		}
	}
}

func serveSeasonIndex(w http.ResponseWriter, r *http.Request, user *auth.User, company *auth.Company, conn *database.Conn) {
	seasons, err := collectSeasonEntries(r.Context(), company, conn)
	if err != nil {
		panic(err)
	}
	calendar, err := collectSeasonCalendar(r.Context(), company, conn, getCalendarYear(r.URL.Query()))
	if err != nil {
		panic(err)
	}
	calendar.Form = newCalendarForm(r.Context(), company, conn)
	page := &seasonIndex{
		Seasons:  seasons,
		Calendar: calendar,
	}
	page.MustRender(w, r, user, company)
}

func getCalendarYear(query url.Values) int {
	yearStr := strings.TrimSpace(query.Get("year"))
	if yearStr != "" {
		if year, err := strconv.Atoi(yearStr); err == nil {
			return year
		}
	}
	return time.Now().Year()
}

func collectSeasonEntries(ctx context.Context, company *auth.Company, conn *database.Conn) ([]*seasonEntry, error) {
	rows, err := conn.Query(ctx, `
		select '/admin/seasons/' || season.slug
		     , season.name
		     , to_color(color)::text
		     , active
		     , array_agg((lang_tag, endonym, not exists (select 1 from season_i18n as i18n where i18n.season_id = season.season_id and i18n.lang_tag = language.lang_tag)) order by endonym)
		from season
		    join company using (company_id)
		   , language
		where lang_tag <> default_lang_tag
		  and language.selectable
		  and season.company_id = $1
		group by season.slug
		       , season.name
		       , to_color(color)::text
		       , active
		order by name`, pgx.QueryResultFormats{pgx.BinaryFormatCode}, company.ID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var seasons []*seasonEntry
	for rows.Next() {
		entry := &seasonEntry{}
		var translations database.RecordArray
		if err = rows.Scan(&entry.URL, &entry.Name, &entry.Color, &entry.Active, &translations); err != nil {
			return nil, err
		}
		for _, el := range translations.Elements {
			entry.Translations = append(entry.Translations, &locale.Translation{
				URL:     entry.URL + "/" + el.Fields[0].Get().(string),
				Endonym: el.Fields[1].Get().(string),
				Missing: el.Fields[2].Get().(bool),
			})
		}
		seasons = append(seasons, entry)
	}

	return seasons, nil
}

type seasonEntry struct {
	ID           int
	URL          string
	Name         string
	Color        string
	Active       bool
	Translations []*locale.Translation
}

var longMonthNames = []string{
	locale.PgettextNoop("January", "month"),
	locale.PgettextNoop("February", "month"),
	locale.PgettextNoop("March", "month"),
	locale.PgettextNoop("April", "month"),
	locale.PgettextNoop("May", "month"),
	locale.PgettextNoop("June", "month"),
	locale.PgettextNoop("July", "month"),
	locale.PgettextNoop("August", "month"),
	locale.PgettextNoop("September", "month"),
	locale.PgettextNoop("October", "month"),
	locale.PgettextNoop("November", "month"),
	locale.PgettextNoop("December", "month"),
}

func collectSeasonCalendar(ctx context.Context, company *auth.Company, conn *database.Conn, year int) (*seasonCalendar, error) {
	firstDay := time.Date(year, time.January, 1, 0, 0, 0, 0, time.UTC)
	lastDay := time.Date(year, time.December, 31, 23, 59, 59, 0, time.UTC)
	rows, err := conn.Query(ctx, `
		select t.day::date
		     , to_color(coalesce(color, $1)) as color
		from generate_series($2, $3, interval '1 day') as t(day)
		    left join season_calendar on season_range @> t.day::date
		    left join season on season.season_id = season_calendar.season_id and company_id = $4
	`, unsetColor, firstDay, lastDay, company.ID)
	if err != nil {
		return nil, err
	}

	var month *seasonMonth
	var week seasonWeek
	calendar := &seasonCalendar{
		Year: year,
	}
	weekday := int(time.Monday)
	for rows.Next() {
		day := &seasonDay{}
		if err = rows.Scan(&day.Date, &day.Color); err != nil {
			return nil, err
		}
		dayMonth := day.Date.Month()
		if month == nil || month.Month != dayMonth {
			if month != nil {
				for ; weekday != int(time.Sunday); weekday = (weekday + 1) % 7 {
					week = append(week, &seasonDay{})
				}
				month.Weeks = append(month.Weeks, week)
				calendar.Months = append(calendar.Months, month)
			}
			month = &seasonMonth{
				Month: dayMonth,
				Name:  longMonthNames[dayMonth-1],
			}
			week = seasonWeek{}
			weekday = int(time.Monday)
			dayWeekday := int(day.Date.Weekday())
			for ; weekday != dayWeekday; weekday = (weekday + 1) % 7 {
				week = append(week, &seasonDay{})
			}
		}
		week = append(week, day)
		weekday = (weekday + 1) % 7
		if weekday == int(time.Monday) {
			month.Weeks = append(month.Weeks, week)
			week = seasonWeek{}
		}
	}
	if month != nil {
		for ; weekday != int(time.Sunday); weekday = (weekday + 1) % 7 {
			week = append(week, &seasonDay{})
		}
		month.Weeks = append(month.Weeks, week)
		calendar.Months = append(calendar.Months, month)
	}

	return calendar, nil
}

type seasonCalendar struct {
	Year   int
	Months []*seasonMonth
	Form   *calendarForm
}

type seasonMonth struct {
	Month time.Month
	Name  string
	Weeks []seasonWeek
}

type seasonWeek []*seasonDay

type seasonDay struct {
	Date  time.Time
	Color string
}

type seasonIndex struct {
	Seasons  []*seasonEntry
	Calendar *seasonCalendar
}

func (page *seasonIndex) MustRender(w http.ResponseWriter, r *http.Request, user *auth.User, company *auth.Company) {
	template.MustRenderAdminFiles(w, r, user, company, page, "season/index.gohtml", "season/calendar.gohtml")
}

func processSeasonForm(w http.ResponseWriter, r *http.Request, user *auth.User, company *auth.Company, conn *database.Conn, f *seasonForm, act func()) {
	if err := f.Parse(r); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}
	if err := user.VerifyCSRFToken(r); err != nil {
		http.Error(w, err.Error(), http.StatusForbidden)
		return
	}
	if ok, err := f.Valid(r.Context(), conn, user.Locale); err != nil {
		panic(err)
	} else if !ok {
		if !httplib.IsHTMxRequest(r) {
			w.WriteHeader(http.StatusUnprocessableEntity)
		}
		f.MustRender(w, r, user, company)
		return
	}
	act()
	httplib.Redirect(w, r, "/admin/seasons", http.StatusSeeOther)
}

func addSeason(w http.ResponseWriter, r *http.Request, user *auth.User, company *auth.Company, conn *database.Conn) {
	f := newSeasonForm()
	processSeasonForm(w, r, user, company, conn, f, func() {
		conn.MustExec(r.Context(), "select add_season($1, $2, $3)", company.ID, f.Name, f.Color)
	})
}

func editSeason(w http.ResponseWriter, r *http.Request, user *auth.User, company *auth.Company, conn *database.Conn, f *seasonForm) {
	processSeasonForm(w, r, user, company, conn, f, func() {
		conn.MustExec(r.Context(), "select edit_season($1, $2, $3, $4)", f.Slug, f.Name, f.Color, f.Active)
	})
}

type seasonForm struct {
	Slug   string
	Active *form.Checkbox
	Name   *form.Input
	Color  *form.Input
}

func newSeasonForm() *seasonForm {
	return &seasonForm{
		Active: &form.Checkbox{
			Name:    "active",
			Checked: true,
		},
		Name: &form.Input{
			Name: "label",
		},
		Color: &form.Input{
			Name: "season",
		},
	}
}

func (f *seasonForm) FillFromDatabase(ctx context.Context, conn *database.Conn, slug string) error {
	f.Slug = slug
	row := conn.QueryRow(ctx, "select name, to_color(color)::text, active from season where slug = $1", slug)
	return row.Scan(&f.Name.Val, &f.Color.Val, &f.Active.Checked)
}

func (f *seasonForm) Parse(r *http.Request) error {
	if err := r.ParseForm(); err != nil {
		return err
	}
	f.Active.FillValue(r)
	f.Name.FillValue(r)
	f.Color.FillValue(r)
	return nil
}

func (f *seasonForm) Valid(ctx context.Context, conn *database.Conn, l *locale.Locale) (bool, error) {
	v := form.NewValidator(l)
	v.CheckRequired(f.Name, l.GettextNoop("Name can not be empty."))
	if v.CheckRequired(f.Color, l.GettextNoop("Color can not be empty.")) {
		if _, err := v.CheckValidColor(ctx, conn, f.Color, l.Gettext("This color is not valid. It must be like #123abc.")); err != nil {
			return false, err
		}
	}
	return v.AllOK, nil
}

func (f *seasonForm) MustRender(w http.ResponseWriter, r *http.Request, user *auth.User, company *auth.Company) {
	template.MustRenderAdmin(w, r, user, company, "season/form.gohtml", f)
}

func serveSeasonCalendar(w http.ResponseWriter, r *http.Request, user *auth.User, company *auth.Company, conn *database.Conn) {
	f := newCalendarForm(r.Context(), company, conn)
	f.MustRender(w, r, user, company, conn, getCalendarYear(r.URL.Query()))
}

func updateSeasonCalendar(w http.ResponseWriter, r *http.Request, user *auth.User, company *auth.Company, conn *database.Conn) {
	f := newCalendarForm(r.Context(), company, conn)
	if ok, err := form.Handle(f, w, r, user); err != nil {
		return
	} else if ok {
		var seasonRange pgtype.Daterange
		if err = seasonRange.Set(fmt.Sprintf("[%s,%s]", f.StartDate.Val, f.EndDate.Val)); err != nil {
			panic(err)
		}
		if f.SeasonID.Val == "" {
			// Nothing to do
		} else if f.SeasonID.Val == "0" {
			conn.MustExec(r.Context(), "select unset_season_range($1)", seasonRange)
		} else {
			conn.MustExec(r.Context(), "select set_season_range($1, $2)", f.SeasonID, seasonRange)
		}
		f.StartDate.Val = ""
		f.EndDate.Val = ""
	}
	f.MustRender(w, r, user, company, conn, getCalendarYear(r.Form))
}

type calendarForm struct {
	Seasons   []*seasonEntry
	StartDate *form.Input
	EndDate   *form.Input
	SeasonID  *form.Input
}

func newCalendarForm(ctx context.Context, company *auth.Company, conn *database.Conn) *calendarForm {
	return &calendarForm{
		Seasons: mustCollectCalendarSeasons(ctx, company, conn),
		StartDate: &form.Input{
			Name: "start_date",
		},
		EndDate: &form.Input{
			Name: "end_date",
		},
		SeasonID: &form.Input{
			Name: "season_id",
		},
	}
}

func mustCollectCalendarSeasons(ctx context.Context, company *auth.Company, conn *database.Conn) []*seasonEntry {
	rows, err := conn.Query(ctx, `
		select 0 as season_id
		     , $1 as name
		     , to_color($2)::text
		     , true
		     , 0 as sort
		union all
		select season_id
		     , name
		     , to_color(color)::text
		     , active
		     , 1 as sort
		from season
		where company_id = $3
		  and active
		order by sort, name`, locale.PgettextNoop("Unset", "action"), unsetColor, company.ID)
	if err != nil {
		panic(err)
	}
	defer rows.Close()

	var seasons []*seasonEntry
	for rows.Next() {
		entry := &seasonEntry{}
		var sort int
		if err = rows.Scan(&entry.ID, &entry.Name, &entry.Color, &entry.Active, &sort); err != nil {
			panic(err)
		}
		seasons = append(seasons, entry)
	}

	return seasons
}

func (f *calendarForm) Parse(r *http.Request) error {
	if err := r.ParseForm(); err != nil {
		return err
	}
	f.StartDate.FillValue(r)
	f.EndDate.FillValue(r)
	f.SeasonID.FillValue(r)
	return nil
}

func (f *calendarForm) Valid(l *locale.Locale) bool {
	v := form.NewValidator(l)
	if v.CheckRequired(f.StartDate, l.GettextNoop("Start date can not be empty.")) {
		v.CheckValidDate(f.StartDate, l.GettextNoop("Start date must be a valid date."))
	}
	if v.CheckRequired(f.EndDate, l.GettextNoop("End date can not be empty.")) {
		v.CheckValidDate(f.EndDate, l.GettextNoop("End date must be a valid date."))
	}
	return v.AllOK
}

func (f *calendarForm) MustRender(w http.ResponseWriter, r *http.Request, user *auth.User, company *auth.Company, conn *database.Conn, year int) {
	calendar, err := collectSeasonCalendar(r.Context(), company, conn, year)
	if err != nil {
		panic(err)
	}
	calendar.Form = f
	template.MustRenderNoLayout(w, r, user, company, "season/calendar.gohtml", calendar)
}