package logic

import (
	"context"
	"time"

	"spark-server/internal/module/energy/entity"
)

// Repository persists wallets, signs, and energy logs. Model implements it.
type Repository interface {
	GetWallet(ctx context.Context, userID int64) (*entity.Wallet, error)
	EnsureWallet(ctx context.Context, userID int64) (*entity.Wallet, error)
	AddEnergy(ctx context.Context, userID, delta int64, reason string, dayKey int, source string) (*entity.Wallet, *entity.EnergyLog, error)
	ListSignsInRange(ctx context.Context, userID int64, fromDay, toDay int) ([]*entity.SignRecord, error)
	GetSign(ctx context.Context, userID int64, dayKey int) (*entity.SignRecord, error)
	CreateSign(ctx context.Context, rec *entity.SignRecord) error
	ListEnergyLogs(ctx context.Context, userID, cursor int64, limit int) ([]*entity.EnergyLog, error)
	ListRecentSigns(ctx context.Context, userID int64, limit int) ([]*entity.SignRecord, error)
}

// Clock abstracts "now" for tests.
type Clock interface {
	Now() time.Time
}

type realClock struct{}

func (realClock) Now() time.Time { return time.Now() }

// Service is the sign + energy use-case layer.
type Service struct {
	repo  Repository
	clock Clock
	loc   *time.Location
}

func NewService(repo Repository) *Service {
	loc, err := time.LoadLocation("Asia/Shanghai")
	if err != nil {
		loc = time.FixedZone("CST", 8*3600)
	}
	return &Service{repo: repo, clock: realClock{}, loc: loc}
}

func (s *Service) withClock(c Clock) *Service {
	if c != nil {
		s.clock = c
	}
	return s
}

func (s *Service) ready() bool {
	return s != nil && s.repo != nil
}

func (s *Service) now() time.Time {
	if s.clock == nil {
		return time.Now().In(s.loc)
	}
	return s.clock.Now().In(s.loc)
}

func dayKeyOf(t time.Time) int {
	y, m, d := t.Date()
	return y*10000 + int(m)*100 + d
}

func parseDayKey(day int) (time.Time, bool) {
	if day < 19700101 || day > 21001231 {
		return time.Time{}, false
	}
	y, rem := day/10000, day%10000
	mo, d := rem/100, rem%100
	if mo < 1 || mo > 12 || d < 1 || d > 31 {
		return time.Time{}, false
	}
	return time.Date(y, time.Month(mo), d, 0, 0, 0, 0, time.UTC), true
}

func addDays(day int, n int) int {
	t, ok := parseDayKey(day)
	if !ok {
		return day
	}
	t = t.AddDate(0, 0, n)
	return dayKeyOf(t)
}