package service

import (
	"context"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"git.sundynix.cn/Blizzard/Veyra/internal/apperror"
	"git.sundynix.cn/Blizzard/Veyra/internal/model"
	"github.com/google/uuid"
	"regexp"
	"strings"
	"time"
	"unicode/utf8"
)

type TradeFillRepository interface {
	Record(context.Context, string, model.TradeFill, string) (model.TradeFill, error)
	List(context.Context, string, string) ([]model.TradeFill, error)
	Reverse(context.Context, string, string, string, string) (model.TradeReversal, error)
	Portfolio(context.Context, string, string) (model.PortfolioSummary, error)
}
type TradeFillService struct {
	repo        TradeFillRepository
	development bool
}

func NewTradeFillService(repo TradeFillRepository, development bool) *TradeFillService {
	return &TradeFillService{repo, development}
}
func (s *TradeFillService) authorize(actor model.User) error {
	if actor.Role != "USER" || actor.Status != "ACTIVE" {
		return apperror.ErrForbidden
	}
	if s == nil || s.repo == nil || !s.development {
		return apperror.ErrUnavailable
	}
	return nil
}

type FillInput struct {
	AccountID      string     `json:"account_id"`
	PlanID         *string    `json:"plan_id"`
	IdempotencyKey string     `json:"idempotency_key"`
	Side           string     `json:"side"`
	Symbol         string     `json:"symbol"`
	Exchange       string     `json:"exchange"`
	Name           string     `json:"name"`
	Quantity       string     `json:"quantity"`
	Price          string     `json:"price"`
	Fee            string     `json:"fee"`
	OccurredAt     time.Time  `json:"occurred_at"`
	SellableAt     *time.Time `json:"sellable_at"`
	Note           string     `json:"note"`
}

var fillSymbolPattern = regexp.MustCompile(`^[0-9]{6}$`)

func (s *TradeFillService) Record(ctx context.Context, actor model.User, input FillInput, requestID string) (model.TradeFill, error) {
	if err := s.authorize(actor); err != nil {
		return model.TradeFill{}, err
	}
	for _, id := range []string{input.AccountID, input.IdempotencyKey, requestID} {
		if _, err := uuid.Parse(id); err != nil {
			return model.TradeFill{}, apperror.ErrInvalidInput
		}
	}
	if input.PlanID != nil {
		if _, err := uuid.Parse(*input.PlanID); err != nil {
			return model.TradeFill{}, apperror.ErrInvalidInput
		}
	}
	qty, err := ParseQuantity(input.Quantity)
	if err != nil {
		return model.TradeFill{}, err
	}
	price, err := model.ParseMoney(input.Price)
	if err != nil || price == 0 {
		return model.TradeFill{}, apperror.ErrInvalidInput
	}
	fee, err := model.ParseMoney(input.Fee)
	if err != nil {
		return model.TradeFill{}, err
	}
	gross := price * qty
	if gross > 100000000000 || gross+fee > 100000000000 {
		return model.TradeFill{}, apperror.ErrInvalidInput
	}
	if !fillSymbolPattern.MatchString(input.Symbol) || (input.Exchange != "SSE" && input.Exchange != "SZSE") || strings.TrimSpace(input.Name) == "" || utf8.RuneCountInString(input.Name) > 80 || utf8.RuneCountInString(input.Note) > 1000 || input.OccurredAt.IsZero() || input.OccurredAt.After(time.Now().Add(time.Minute)) {
		return model.TradeFill{}, apperror.ErrInvalidInput
	}
	delta := gross - fee
	switch input.Side {
	case "BUY":
		if qty%100 != 0 || input.SellableAt == nil || input.SellableAt.Before(input.OccurredAt) {
			return model.TradeFill{}, apperror.ErrInvalidInput
		}
		delta = -gross - fee
	case "SELL":
		if input.SellableAt != nil || fee > gross || input.PlanID != nil {
			return model.TradeFill{}, apperror.ErrInvalidInput
		}
	default:
		return model.TradeFill{}, apperror.ErrInvalidInput
	}
	input.Price = model.FormatMoney(price)
	input.Fee = model.FormatMoney(fee)
	input.Name = strings.TrimSpace(input.Name)
	input.Note = strings.TrimSpace(input.Note)
	input.OccurredAt = input.OccurredAt.UTC()
	if input.SellableAt != nil {
		t := input.SellableAt.UTC()
		input.SellableAt = &t
	}
	encoded, err := json.Marshal(input)
	if err != nil {
		return model.TradeFill{}, apperror.ErrInvalidInput
	}
	digest := sha256.Sum256(encoded)
	fill := model.TradeFill{ID: uuid.NewString(), AccountID: input.AccountID, PlanID: input.PlanID, IdempotencyKey: input.IdempotencyKey, InputHash: hex.EncodeToString(digest[:]), Side: input.Side, Symbol: input.Symbol, Exchange: input.Exchange, Name: input.Name, Quantity: qty, PriceMinor: price, FeeMinor: fee, CashDeltaMinor: delta, OccurredAt: input.OccurredAt, SellableAt: input.SellableAt, Note: input.Note}
	return s.repo.Record(ctx, actor.ID, fill, requestID)
}
func (s *TradeFillService) List(ctx context.Context, actor model.User, account string) ([]model.TradeFill, error) {
	if err := s.authorize(actor); err != nil {
		return nil, err
	}
	if _, err := uuid.Parse(account); err != nil {
		return nil, apperror.ErrInvalidInput
	}
	return s.repo.List(ctx, actor.ID, account)
}
func (s *TradeFillService) Reverse(ctx context.Context, actor model.User, id, reason, requestID string) (model.TradeReversal, error) {
	if err := s.authorize(actor); err != nil {
		return model.TradeReversal{}, err
	}
	if _, err := uuid.Parse(id); err != nil {
		return model.TradeReversal{}, apperror.ErrInvalidInput
	}
	if err := model.ValidateReason(reason); err != nil {
		return model.TradeReversal{}, err
	}
	return s.repo.Reverse(ctx, actor.ID, id, reason, requestID)
}
func (s *TradeFillService) Portfolio(ctx context.Context, actor model.User, account string) (model.PortfolioSummary, error) {
	if err := s.authorize(actor); err != nil {
		return model.PortfolioSummary{}, err
	}
	if _, err := uuid.Parse(account); err != nil {
		return model.PortfolioSummary{}, apperror.ErrInvalidInput
	}
	return s.repo.Portfolio(ctx, actor.ID, account)
}