package service

import (
	"context"
	"errors"
	"strings"

	"github.com/jackc/pgx/v5/pgconn"
	"gitrepo.ru/neonxp/nquest/pkg/models"
	"gorm.io/gorm"
)

var (
	ErrGameNotStarted = errors.New("game not started")
	ErrInvalidCode    = errors.New("invalid code")
	ErrOldCode        = errors.New("old code")
	ErrGameFinished   = errors.New("game finished")
)

type Engine struct {
	DB *gorm.DB
}

func NewEngine(db *gorm.DB) *Engine {
	return &Engine{
		DB: db,
	}
}

func (e *Engine) GetState(ctx context.Context, game *models.Game, user *models.User) (*models.GameCursor, error) {
	db := e.DB.WithContext(ctx)

	// Пытаемся получить GamePassing
	cursor := &models.GameCursor{
		User:   user,
		Game:   game,
		Task:   game.Tasks[0],
		Status: models.TaskStarted,
		Codes:  []*models.Code{},
	}
	err := db.
		Where(`user_id = ? and game_id = ? and status = ?`, user.ID, game.ID, models.TaskStarted).
		Preload("Task").
		Preload("Task.Codes").
		Preload("Task.Next").
		Preload("Task.Next.Codes").
		Preload("Codes").
		FirstOrCreate(cursor).
		Error
	if err != nil {
		if err, ok := err.(*pgconn.PgError); ok {
			if err.Code == "23505" {
				return nil, ErrGameNotStarted
			}
		}

		return nil, err
	}

	return cursor, nil
}

func (e *Engine) EnterCode(ctx context.Context, game *models.Game, user *models.User, code string) (*models.GameCursor, error) {
	db := e.DB.WithContext(ctx)
	st, err := e.GetState(ctx, game, user)
	if err != nil {
		return nil, err
	}
	code = strings.Trim(code, " \n\t")
	code = strings.ToLower(code)
	var currentCode *models.Code
	for _, c := range st.Task.Codes {
		if c.Code == code {
			currentCode = c
			break
		}
	}
	if currentCode == nil {
		return nil, ErrInvalidCode
	}
	for _, c := range st.Codes {
		if c.ID == currentCode.ID {
			return nil, ErrOldCode
		}
	}

	st.Codes = append(st.Codes, currentCode)

	if err := db.Save(st).Error; err != nil {
		return nil, err
	}

	if len(st.Codes) != len(st.Task.Codes) {
		return st, nil
	}

	// Уровень пройден. Выдаем следующий

	st.Status = models.TaskFinished
	if err := db.Save(st).Error; err != nil {
		return nil, err
	}

	if st.Task.Next == nil {

		user.Experience += st.Game.Points
		if err := db.Save(user).Error; err != nil {
			return nil, err
		}

		return nil, ErrGameFinished
	}

	newState := &models.GameCursor{
		User:   user,
		Game:   game,
		Task:   st.Task.Next,
		Status: models.TaskStarted,
		Codes:  []*models.Code{},
	}

	return newState, db.Create(newState).Error
}