package service

import (
	"context"
	"errors"
	"slices"
	"time"

	"gitrepo.ru/neonxp/nquest/pkg/models"
	"gorm.io/gorm"
	"gorm.io/gorm/clause"
)

var (
	ErrTeamNotFound = errors.New("team not found")
)

type Team struct {
	DB   *gorm.DB
	User *User
}

// NewTeam returns new Team.
func NewTeam(db *gorm.DB, user *User) *Team {
	return &Team{
		DB:   db,
		User: user,
	}
}

func (ts *Team) GetByID(ctx context.Context, id uint) (*models.Team, error) {
	t := new(models.Team)

	err := ts.DB.
		WithContext(ctx).
		Preload("Members").
		Preload("Members.User").
		Preload("Requests").
		Preload("Requests.User").
		First(t, id).
		Error
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrTeamNotFound
		}

		return nil, err
	}

	return t, nil
}

func (ts *Team) List(ctx context.Context) ([]*models.Team, error) {
	teams := []*models.Team{}

	return teams, ts.DB.WithContext(ctx).Preload("Members").Find(&teams).Error
}

func (ts *Team) Create(ctx context.Context, name string, user *models.User) (*models.Team, error) {
	t := &models.Team{
		Name: name,
		Members: []*models.TeamMember{{
			User: user,
			Role: models.Captain,
		}},
	}

	db := ts.DB.WithContext(ctx)

	if err := db.Delete(&models.TeamRequest{}, `user_id = ?`, user.ID).Error; err != nil {
		return t, err
	}

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

func (ts *Team) Delete(ctx context.Context, id uint) error {
	if err := ts.DB.WithContext(ctx).Delete(&models.Team{}, id).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return ErrTeamNotFound
		}

		return err
	}

	return nil
}

func (ts *Team) Request(ctx context.Context, teamID uint, user *models.User) error {
	team, err := ts.GetByID(ctx, teamID)
	if err != nil {
		return err
	}

	return ts.DB.
		WithContext(ctx).
		Clauses(clause.OnConflict{DoNothing: true}).
		Create(&models.TeamRequest{
			Team: team,
			User: user,
		}).
		Error
}

func (ts *Team) UpdateMembers(
	ctx context.Context,
	teamID uint,
	newMembers []int,
) error {
	team, err := ts.GetByID(ctx, teamID)
	if err != nil {
		return err
	}

	newMembersList := make([]*models.TeamMember, 0, len(newMembers))

	for _, tm := range team.Members {
		idx, ok := slices.BinarySearch(newMembers, int(tm.UserID))
		if ok {
			newMembers = slices.Delete(newMembers, idx, idx)
			newMembersList = append(newMembersList, tm)
			continue
		}
		if err := ts.DB.WithContext(ctx).Delete(tm).Error; err != nil {
			return err
		}
	}

	for _, userID := range newMembers {
		_, found := slices.BinarySearchFunc(team.Members, userID, func(tm *models.TeamMember, i int) int {
			return int(tm.UserID) - i
		})
		if found {
			continue
		}
		user, err := ts.User.GetUserByID(ctx, uint(userID))
		if err != nil {
			return err
		}
		newMembersList = append(newMembersList, &models.TeamMember{
			TeamID:    teamID,
			Team:      team,
			UserID:    user.ID,
			User:      user,
			Role:      models.Member,
			CreatedAt: time.Now(),
		})
	}

	team.Members = newMembersList

	return ts.DB.
		WithContext(ctx).
		Session(&gorm.Session{FullSaveAssociations: true}).
		Updates(team).
		Error
}

func (ts *Team) ApproveRequest(ctx context.Context, teamID int, userID uint, approve bool) error {
	team, err := ts.GetByID(ctx, uint(teamID))
	if err != nil {
		return err
	}

	idx, found := slices.BinarySearchFunc(team.Requests, userID, func(tr *models.TeamRequest, i uint) int {
		return int(tr.UserID - i)
	})
	if !found {
		return nil
	}
	request := team.Requests[idx]
	team.Requests = slices.DeleteFunc(team.Requests, func(tr *models.TeamRequest) bool {
		return tr.UserID == uint(userID)
	})
	if err := ts.DB.WithContext(ctx).Delete(request).Error; err != nil {
		return err
	}

	if approve {
		team.Members = append(team.Members, &models.TeamMember{
			Team:      team,
			TeamID:    uint(teamID),
			UserID:    uint(userID),
			Role:      models.Member,
			CreatedAt: time.Now(),
		})

		return ts.DB.WithContext(ctx).Save(team).Error
	}

	return nil
}

func (ts *Team) DeleteMember(ctx context.Context, teamID int, userID uint) error {
	team, err := ts.GetByID(ctx, uint(teamID))
	if err != nil {
		return err
	}

	idx, found := slices.BinarySearchFunc(team.Members, userID, func(tm *models.TeamMember, u uint) int {
		return int(tm.UserID - u)
	})
	if !found {
		return nil
	}
	member := team.Members[idx]

	return ts.DB.WithContext(ctx).Delete(member).Error
}