package database

import (
	"fmt"

	"git.phc.dm.unipi.it/phc/website/libs/db"
	"git.phc.dm.unipi.it/phc/website/libs/sl"

	"git.phc.dm.unipi.it/phc/website/server/model"
)

var Slot = sl.NewSlot[Database]()

// Database is the main database service interface
type Database interface {
	// User

	CreateUser(user model.User) error
	ReadUser(id db.Ref[model.User]) (model.User, error)
	ReadUsers() ([]model.User, error)
	UpdateUser(user model.User) error
	DeleteUser(id db.Ref[model.User]) error

	// Accounts

	CreateAccount(account model.Account) (db.Ref[model.Account], error)
	ReadAccount(id db.Ref[model.Account]) (model.Account, error)
	UpdateAccount(user model.Account) error
	DeleteAccount(id db.Ref[model.Account]) error

	// Users & Accounts

	ReadUserAccounts(user db.Ref[model.User]) ([]model.Account, error)
}

// Memory is an in-memory implementation of [Database] that can be used for testing
type Memory struct {
	Database // TODO: Per ora almeno così facciamo compilare il codice

	Users []model.User
}

func (m *Memory) CreateUser(user model.User) error {
	m.Users = append(m.Users, user)
	return nil
}

func (m *Memory) ReadUser(id db.Ref[model.User]) (model.User, error) {
	for _, u := range m.Users {
		if u.Id == id {
			return u, nil
		}
	}

	return model.User{}, fmt.Errorf(`no user with id "%s"`, id)
}

func (m *Memory) ReadUsers() ([]model.User, error) {
	return m.Users, nil
}

func (m *Memory) UpdateUser(user model.User) error {
	for i, u := range m.Users {
		if u.Id == user.Id {
			m.Users[i] = user
			return nil
		}
	}

	return fmt.Errorf(`no user with id "%s"`, user.Id)
}

func (m *Memory) DeleteUser(id db.Ref[model.User]) error {
	for i, u := range m.Users {
		if u.Id == id {
			m.Users = append(m.Users[:i], m.Users[i+1:]...)
			return nil
		}
	}

	return fmt.Errorf(`no user with id "%s"`, id)
}