package seasonsview

import (
	"encoding/json"

	"git.haelnorr.com/h/oslstats/internal/db"
)

// seriesByNumber returns a map of series_number -> *PlayoffSeries for quick lookup
func seriesByNumber(series []*db.PlayoffSeries) map[int]*db.PlayoffSeries {
	m := make(map[int]*db.PlayoffSeries, len(series))
	for _, s := range series {
		m[s.SeriesNumber] = s
	}
	return m
}

// formatLabel returns a human-readable format description
func formatLabel(format db.PlayoffFormat) string {
	switch format {
	case db.PlayoffFormat5to6:
		return "Top 5 qualify"
	case db.PlayoffFormat7to9:
		return "Top 6 qualify"
	case db.PlayoffFormat10to15:
		return "Top 8 qualify"
	default:
		return string(format)
	}
}

// bracketConnection represents a line to draw between two series cards
type bracketConnection struct {
	From   int    `json:"from"`
	To     int    `json:"to"`
	Type   string `json:"type"`             // "winner" or "loser"
	ToSide string `json:"toSide,omitempty"` // "left" or "right" — enters side of dest card
}

// connectionsJSON returns a JSON string of connections for the bracket overlay JS.
// Connections are derived from the series advancement links stored in the DB.
// For the 10-15 format, QF winner lines enter PF cards from the side.
func connectionsJSON(series []*db.PlayoffSeries) string {
	// Build a lookup of series ID → series for resolving advancement targets
	byID := make(map[int]*db.PlayoffSeries, len(series))
	for _, s := range series {
		byID[s.ID] = s
	}

	var conns []bracketConnection
	for _, s := range series {
		if s.WinnerNextID != nil {
			if target, ok := byID[*s.WinnerNextID]; ok {
				conn := bracketConnection{
					From: s.SeriesNumber,
					To:   target.SeriesNumber,
					Type: "winner",
				}
				// QF winners enter PF cards from the side in the 10-15 format
				if s.Round == "qualifying_final" && target.Round == "preliminary_final" {
					if s.SeriesNumber == 1 {
						conn.ToSide = "left"
					} else if s.SeriesNumber == 2 {
						conn.ToSide = "right"
					}
				}
				conns = append(conns, conn)
			}
		}
		if s.LoserNextID != nil {
			if target, ok := byID[*s.LoserNextID]; ok {
				conns = append(conns, bracketConnection{
					From: s.SeriesNumber,
					To:   target.SeriesNumber,
					Type: "loser",
				})
			}
		}
	}

	b, err := json.Marshal(conns)
	if err != nil {
		return "[]"
	}
	return string(b)
}