package handlers

import (
	"context"
	"net/http"

	"git.haelnorr.com/h/golib/hws"
	"git.haelnorr.com/h/oslstats/internal/db"
	"git.haelnorr.com/h/oslstats/internal/throw"
	homeview "git.haelnorr.com/h/oslstats/internal/view/homeview"
	"github.com/pkg/errors"
	"github.com/uptrace/bun"
)

// Index handles responses to the / path. Also serves a 404 Page for paths that
// don't have explicit handlers
func Index(s *hws.Server, conn *db.DB) http.Handler {
	return http.HandlerFunc(
		func(w http.ResponseWriter, r *http.Request) {
			if r.URL.Path != "/" {
				throw.NotFound(s, w, r, r.URL.Path)
				return
			}

			var season *db.Season
			var standings []homeview.LeagueStandings

			if ok := conn.WithReadTx(s, w, r, func(ctx context.Context, tx bun.Tx) (bool, error) {
				// Get the most recent season
				seasons, err := db.ListSeasons(ctx, tx, &db.PageOpts{
					Page:    1,
					PerPage: 1,
					Order:   bun.OrderDesc,
					OrderBy: "start_date",
				})
				if err != nil {
					return false, errors.Wrap(err, "db.ListSeasons")
				}

				if seasons.Total == 0 || len(seasons.Items) == 0 {
					return true, nil
				}

				season = seasons.Items[0]

				// Build leaderboards for each league in this season
				standings = make([]homeview.LeagueStandings, 0, len(season.Leagues))
				for _, league := range season.Leagues {
					_, l, teams, err := db.GetSeasonLeagueWithTeams(ctx, tx, season.ShortName, league.ShortName)
					if err != nil {
						return false, errors.Wrap(err, "db.GetSeasonLeagueWithTeams")
					}

					fixtures, err := db.GetAllocatedFixtures(ctx, tx, season.ID, l.ID)
					if err != nil {
						return false, errors.Wrap(err, "db.GetAllocatedFixtures")
					}

					fixtureIDs := make([]int, len(fixtures))
					for i, f := range fixtures {
						fixtureIDs[i] = f.ID
					}

					resultMap, err := db.GetFinalizedResultsForFixtures(ctx, tx, fixtureIDs)
					if err != nil {
						return false, errors.Wrap(err, "db.GetFinalizedResultsForFixtures")
					}

					leaderboard := db.ComputeLeaderboard(teams, fixtures, resultMap)

					standings = append(standings, homeview.LeagueStandings{
						League:      l,
						Leaderboard: leaderboard,
					})
				}

				return true, nil
			}); !ok {
				return
			}

			renderSafely(homeview.IndexPage(season, standings), s, r, w)
		},
	)
}