package storage

import (
	"errors"
	"fmt"

	"github.com/glebarez/sqlite"
	"gorm.io/driver/postgres"
	"gorm.io/gorm"
)

// Storage is responsible for all database, cache and media related actions
// and serves as the lowest layer of the cake
type Storage struct {
	db *gorm.DB
}

var ErrAccountNotFound = errors.New("account not found")

// Build a new storage using sqlite as database backend
func NewStorageSqlite(filePath string) (*Storage, error) {
	db, err := gorm.Open(sqlite.Open(filePath))
	if err != nil {
		return nil, err
	}
	return storageFromEmptyDb(db)
}

func NewStoragePostgres(dbUrl string) (*Storage, error) {
	db, err := gorm.Open(postgres.Open(dbUrl))
	if err != nil {
		return nil, err
	}
	return storageFromEmptyDb(db)
}

func storageFromEmptyDb(db *gorm.DB) (*Storage, error) {
	// AutoMigrate ensures the db is in a state where all the structs given here
	// have their own tables and relations setup. It also updates tables if necessary
	if err := db.AutoMigrate(
		placeholderMediaFile,
		placeholderUser,
		placeholderNote,
		placeholderServer,
	); err != nil {
		return nil, fmt.Errorf("problem while auto migrating: %w", err)
	}
	// Afterwards add the placeholder entries for each table.
	// FirstOrCreate either creates a new entry or retrieves the first matching one
	// We only care about the creation if there is none yet, so no need to carry the result over
	if res := db.FirstOrCreate(placeholderMediaFile); res.Error != nil {
		return nil, fmt.Errorf("failed to add placeholder media file: %w", res.Error)
	}
	if res := db.FirstOrCreate(placeholderUser()); res.Error != nil {
		return nil, fmt.Errorf("failed to add placeholder media file: %w", res.Error)
	}
	if res := db.FirstOrCreate(placeholderNote); res.Error != nil {
		return nil, fmt.Errorf("failed to add placeholder media file: %w", res.Error)
	}
	if res := db.FirstOrCreate(placeholderServer); res.Error != nil {
		return nil, fmt.Errorf("failed to add placeholder media file: %w", res.Error)
	}

	// And finally, build the actual storage struct
	return &Storage{
		db: db,
	}, nil
}

func (s *Storage) FindLocalAccount(handle string) (*User, error) {
	acc := User{}
	res := s.db.Where("handle = ?", handle).First(&acc)
	if res.Error != nil {
		return nil, fmt.Errorf("failed to query db: %w", res.Error)
	}
	if res.RowsAffected == 0 {
		return nil, ErrAccountNotFound
	}
	return nil, errors.New("unimplemented")
}