package processor

import (
	"context"
	"strings"
	"time"

	"github.com/google/uuid"

	"apskel-pos-be/internal/models"
	"apskel-pos-be/internal/repository"
)

const (
	// leaderboardLimit is how many ranks a leaderboard shows unless asked, and
	// leaderboardMaxLimit the most it shows.
	leaderboardLimit    = 10
	leaderboardMaxLimit = 100
)

// Leaderboard ranks the customers of the customer's organization by the EnakCoin they
// won from games in one week, Monday to Sunday in Asia/Jakarta: this week, or the one
// holding q.Date. A session counts in the week it started. Refunded, expired and
// flagged sessions count for nothing.
func (p *GameSessionProcessor) Leaderboard(ctx context.Context, customerID uuid.UUID, q models.EnakGameLeaderboardQuery) (*models.EnakGameLeaderboard, error) {
	day := walletDay(p.now())
	if s := strings.TrimSpace(q.Date); s != "" {
		d, err := time.ParseInLocation("2006-01-02", s, walletDisplayLocation)
		if err != nil {
			return nil, gameSessionRejected("date must be YYYY-MM-DD")
		}
		day = d
	}
	weekStart := leaderboardWeekStart(day)
	filter := repository.LeaderboardFilter{
		CustomerID: customerID, From: weekStart, To: weekStart.AddDate(0, 0, 7), Limit: q.Limit,
	}
	if filter.Limit < 1 || filter.Limit > leaderboardMaxLimit {
		filter.Limit = leaderboardLimit
	}
	if s := strings.TrimSpace(q.GameID); s != "" {
		id, err := uuid.Parse(s)
		if err != nil {
			return nil, gameSessionRejected("game_id must be a UUID")
		}
		filter.GameID = &id
	}
	customer, err := p.customers.GetCustomer(ctx, customerID)
	if err != nil {
		return nil, err
	}
	filter.OrganizationID = customer.OrganizationID
	rows, err := p.sessions.Leaderboard(ctx, filter)
	if err != nil {
		return nil, err
	}
	board := &models.EnakGameLeaderboard{
		WeekStart: weekStart.Format("2006-01-02"), WeekEnd: weekStart.AddDate(0, 0, 6).Format("2006-01-02"),
		GameID: filter.GameID, Entries: []models.EnakGameLeaderboardEntry{},
	}
	for _, row := range rows {
		entry := models.EnakGameLeaderboardEntry{
			Rank: row.Rank, Name: maskCustomerName(row.Name), Coins: row.Coins, IsMe: row.CustomerID == customerID,
		}
		if row.Rank <= filter.Limit {
			board.Entries = append(board.Entries, entry)
		}
		if entry.IsMe {
			me := entry
			board.Me = &me
		}
	}
	return board, nil
}

// leaderboardWeekStart is the Monday, at midnight in Asia/Jakarta, of the week of day.
func leaderboardWeekStart(day time.Time) time.Time {
	day = walletDay(day)
	return day.AddDate(0, 0, -((int(day.Weekday()) + 6) % 7))
}

// maskCustomerName keeps the first word of a name and the first letter of every other
// word: "Budi Santoso" is shown as "Budi S******". A word with a digit, as when a phone
// number was used for the name, keeps only its first character, the first word too.
func maskCustomerName(name string) string {
	words := strings.Fields(name)
	if len(words) == 0 {
		return "Pemain"
	}
	for i, w := range words {
		if i == 0 && !strings.ContainsAny(w, "0123456789") {
			continue
		}
		r := []rune(w)
		words[i] = string(r[0]) + strings.Repeat("*", len(r)-1)
	}
	return strings.Join(words, " ")
}