package service

import (
	"context"
	"encoding/json"
	"git.sundynix.cn/Blizzard/Veyra/internal/apperror"
	"git.sundynix.cn/Blizzard/Veyra/internal/model"
	"github.com/google/uuid"
	"go.uber.org/zap"
	"strings"
	"time"
	"unicode/utf8"
)

type BacktestRepository interface {
	Create(context.Context, model.BacktestInput, string, string) (model.BacktestRun, error)
	List(context.Context) ([]model.BacktestRun, error)
	Detail(context.Context, string) (model.BacktestRun, error)
	Claim(context.Context) (model.BacktestRun, error)
	Finish(context.Context, model.BacktestRun, json.RawMessage, string) error
}
type ResearchEngine interface {
	Execute(context.Context, json.RawMessage) (json.RawMessage, error)
}
type BacktestService struct {
	repo        BacktestRepository
	engine      ResearchEngine
	development bool
	market      *MarketService
}

func NewBacktestService(repo BacktestRepository, engine ResearchEngine, development bool, markets ...*MarketService) *BacktestService {
	s := &BacktestService{repo: repo, engine: engine, development: development}
	if len(markets) > 0 {
		s.market = markets[0]
	}
	return s
}
func (s *BacktestService) authorize(u model.User) error {
	if u.Role != "ADMIN" || u.Status != "ACTIVE" {
		return apperror.ErrForbidden
	}
	if s == nil || s.repo == nil || !s.development {
		return apperror.ErrUnavailable
	}
	return nil
}
func (s *BacktestService) List(ctx context.Context, u model.User) ([]model.BacktestRun, error) {
	if e := s.authorize(u); e != nil {
		return nil, e
	}
	return s.repo.List(ctx)
}
func (s *BacktestService) Detail(ctx context.Context, u model.User, id string) (model.BacktestRun, error) {
	if e := s.authorize(u); e != nil {
		return model.BacktestRun{}, e
	}
	if _, e := uuid.Parse(id); e != nil {
		return model.BacktestRun{}, apperror.ErrInvalidInput
	}
	return s.repo.Detail(ctx, id)
}
func (s *BacktestService) Create(ctx context.Context, u model.User, in model.BacktestInput, requestID string) (model.BacktestRun, error) {
	in.DataOrigin = "manual"
	in.SourceVersion = 0
	in.DataReceivedAt = nil
	return s.createValidated(ctx, u, in, requestID)
}

func (s *BacktestService) createValidated(ctx context.Context, u model.User, in model.BacktestInput, requestID string) (model.BacktestRun, error) {
	if e := s.authorize(u); e != nil {
		return model.BacktestRun{}, e
	}
	if _, e := uuid.Parse(in.StrategyVersionID); e != nil {
		return model.BacktestRun{}, apperror.ErrInvalidInput
	}
	in.DatasetName = strings.TrimSpace(in.DatasetName)
	cash, e := model.ParseMoney(in.InitialCash)
	if e != nil || cash < 10000 || cash > 100000000000 || in.DatasetName == "" || utf8.RuneCountInString(in.DatasetName) > 120 || len(in.Symbol) != 6 || len(in.Bars) < 4 || len(in.Bars) > 1000 {
		return model.BacktestRun{}, apperror.ErrInvalidInput
	}
	for _, r := range in.Symbol {
		if r < '0' || r > '9' {
			return model.BacktestRun{}, apperror.ErrInvalidInput
		}
	}
	last := ""
	for _, b := range in.Bars {
		date, e := time.Parse("2006-01-02", b.Date)
		if e != nil || b.Date <= last || date.After(time.Now()) {
			return model.BacktestRun{}, apperror.ErrInvalidInput
		}
		last = b.Date
		o, e1 := model.ParseMoney(b.Open)
		h, e2 := model.ParseMoney(b.High)
		l, e3 := model.ParseMoney(b.Low)
		c, e4 := model.ParseMoney(b.Close)
		if e1 != nil || e2 != nil || e3 != nil || e4 != nil || l <= 0 || h > 100000000 || l > o || l > c || h < o || h < c {
			return model.BacktestRun{}, apperror.ErrInvalidInput
		}
	}
	in.InitialCash = model.FormatMoney(cash)
	return s.repo.Create(ctx, in, u.ID, requestID)
}
func (s *BacktestService) ProcessNext(ctx context.Context) (bool, error) {
	job, e := s.repo.Claim(ctx)
	if e == apperror.ErrNotFound {
		return false, nil
	}
	if e != nil {
		return false, e
	}
	result, e := s.engine.Execute(ctx, job.Input)
	if ctx.Err() != nil {
		return true, ctx.Err()
	} // The lease recovers interrupted work after restart.
	failure := ""
	if e != nil {
		failure = "Python 执行失败，请检查解释器安装和输入；本任务未生成研究结果。"
		result = nil
	}
	return true, s.repo.Finish(ctx, job, result, failure)
}
func (s *BacktestService) Run(ctx context.Context, logger *zap.Logger) {
	if s == nil || s.repo == nil || s.engine == nil || !s.development {
		return
	}
	timer := time.NewTicker(2 * time.Second)
	defer timer.Stop()
	for {
		select {
		case <-ctx.Done():
			return
		case <-timer.C:
			if _, e := s.ProcessNext(ctx); e != nil && ctx.Err() == nil {
				logger.Error("backtest worker failed", zap.Error(e))
			}
		}
	}
}

func (s *BacktestService) CreateMarket(ctx context.Context, u model.User, version, symbol, exchange, start, end, cash, requestID string) (model.BacktestRun, error) {
	if e := s.authorize(u); e != nil {
		return model.BacktestRun{}, e
	}
	if s.market == nil {
		return model.BacktestRun{}, apperror.ErrUnavailable
	}
	history, e := s.market.History(ctx, u, symbol, exchange, start, end)
	if e != nil {
		return model.BacktestRun{}, e
	}
	input := model.BacktestInput{StrategyVersionID: version, Symbol: symbol, InitialCash: cash, Bars: history.Bars, DatasetName: history.Source + " 日线 · 不复权 · " + start + " 至 " + end, DataOrigin: history.Source, SourceVersion: history.SourceVersion, DataReceivedAt: &history.ReceivedAt}
	return s.createValidated(ctx, u, input, requestID)
}