package database

import (
	"context"
	"database/sql"
	"fmt"
	"log"
	"strings"
	"time"

	"github.com/go-shiori/shiori/internal/model"
	"github.com/jmoiron/sqlx"
	"github.com/pkg/errors"
	"golang.org/x/crypto/bcrypt"

	_ "modernc.org/sqlite"
)

var sqliteMigrations = []migration{
	newFileMigration("0.0.0", "0.1.0", "sqlite/0000_system"),
	newFileMigration("0.1.0", "0.2.0", "sqlite/0001_initial"),
	newFuncMigration("0.2.0", "0.3.0", func(db *sql.DB) error {
		// Ensure that bookmark table has `has_content` column and account table has `config` column
		// for users upgrading from <1.5.4 directly into this version.
		tx, err := db.Begin()
		if err != nil {
			return fmt.Errorf("failed to start transaction: %w", err)
		}
		defer tx.Rollback()

		_, err = tx.Exec(`ALTER TABLE bookmark ADD COLUMN has_content BOOLEAN DEFAULT FALSE NOT NULL`)
		if err != nil && strings.Contains(err.Error(), `duplicate column name`) {
			tx.Rollback()
		} else if err != nil {
			return fmt.Errorf("failed to add has_content column to bookmark table: %w", err)
		} else if err == nil {
			if errCommit := tx.Commit(); errCommit != nil {
				return fmt.Errorf("failed to commit transaction: %w", errCommit)
			}
		}

		tx, err = db.Begin()
		if err != nil {
			return fmt.Errorf("failed to start transaction: %w", err)
		}
		defer tx.Rollback()

		_, err = tx.Exec(`ALTER TABLE account ADD COLUMN config JSON NOT NULL DEFAULT '{}'`)
		if err != nil && strings.Contains(err.Error(), `duplicate column name`) {
			tx.Rollback()
		} else if err != nil {
			return fmt.Errorf("failed to add config column to account table: %w", err)
		} else if err == nil {
			if errCommit := tx.Commit(); errCommit != nil {
				return fmt.Errorf("failed to commit transaction: %w", errCommit)
			}
		}

		return nil
	}),
	newFileMigration("0.3.0", "0.4.0", "sqlite/0002_denormalize_content"),
	newFileMigration("0.4.0", "0.5.0", "sqlite/0003_uniq_id"),
	newFileMigration("0.5.0", "0.6.0", "sqlite/0004_created_time"),
}

// SQLiteDatabase is implementation of Database interface
// for connecting to SQLite3 database.
type SQLiteDatabase struct {
	dbbase
}

type bookmarkContent struct {
	ID      int    `db:"docid"`
	Content string `db:"content"`
	HTML    string `db:"html"`
}

type tagContent struct {
	ID int `db:"bookmark_id"`
	model.Tag
}

// DBX returns the underlying sqlx.DB object
func (db *SQLiteDatabase) DBx() *sqlx.DB {
	return db.DB
}

// Migrate runs migrations for this database engine
func (db *SQLiteDatabase) Migrate(ctx context.Context) error {
	if err := runMigrations(ctx, db, sqliteMigrations); err != nil {
		return errors.WithStack(err)
	}

	return nil
}

// GetDatabaseSchemaVersion fetches the current migrations version of the database
func (db *SQLiteDatabase) GetDatabaseSchemaVersion(ctx context.Context) (string, error) {
	var version string

	err := db.GetContext(ctx, &version, "SELECT database_schema_version FROM shiori_system")
	if err != nil {
		return "", errors.WithStack(err)
	}

	return version, nil
}

// SetDatabaseSchemaVersion sets the current migrations version of the database
func (db *SQLiteDatabase) SetDatabaseSchemaVersion(ctx context.Context, version string) error {
	tx := db.MustBegin()
	defer tx.Rollback()

	_, err := tx.Exec("UPDATE shiori_system SET database_schema_version = ?", version)
	if err != nil {
		return errors.WithStack(err)
	}

	return tx.Commit()
}

// SaveBookmarks saves new or updated bookmarks to database.
// Returns the saved ID and error message if any happened.
func (db *SQLiteDatabase) SaveBookmarks(ctx context.Context, create bool, bookmarks ...model.BookmarkDTO) ([]model.BookmarkDTO, error) {
	var result []model.BookmarkDTO

	if err := db.withTx(ctx, func(tx *sqlx.Tx) error {
		// Prepare statement

		stmtInsertBook, err := tx.PreparexContext(ctx, `INSERT INTO bookmark
			(url, title, excerpt, author, public, modified_at, has_content, created_at)
			VALUES(?, ?, ?, ?, ?, ?, ?, ?) RETURNING id`)
		if err != nil {
			return errors.WithStack(err)
		}

		stmtUpdateBook, err := tx.PreparexContext(ctx, `UPDATE bookmark SET
			url = ?, title = ?,	excerpt = ?, author = ?,
			public = ?, modified_at = ?, has_content = ?
			WHERE id = ?`)
		if err != nil {
			return errors.WithStack(err)
		}

		stmtInsertBookContent, err := tx.PreparexContext(ctx, `INSERT OR REPLACE INTO bookmark_content
			(docid, title, content, html)
			VALUES (?, ?, ?, ?)`)
		if err != nil {
			return errors.WithStack(err)
		}

		stmtUpdateBookContent, err := tx.PreparexContext(ctx, `UPDATE bookmark_content SET
			title = ?, content = ?, html = ?
			WHERE docid = ?`)
		if err != nil {
			return errors.WithStack(err)
		}

		stmtGetTag, err := tx.PreparexContext(ctx, `SELECT id FROM tag WHERE name = ?`)
		if err != nil {
			return errors.WithStack(err)
		}

		stmtInsertTag, err := tx.PreparexContext(ctx, `INSERT INTO tag (name) VALUES (?)`)
		if err != nil {
			return errors.WithStack(err)
		}

		stmtInsertBookTag, err := tx.PreparexContext(ctx, `INSERT OR IGNORE INTO bookmark_tag
			(tag_id, bookmark_id) VALUES (?, ?)`)
		if err != nil {
			return errors.WithStack(err)
		}

		stmtDeleteBookTag, err := tx.PreparexContext(ctx, `DELETE FROM bookmark_tag
			WHERE bookmark_id = ? AND tag_id = ?`)
		if err != nil {
			return errors.WithStack(err)
		}

		// Prepare modified time
		modifiedTime := time.Now().UTC().Format(model.DatabaseDateFormat)

		// Execute statements

		for _, book := range bookmarks {
			// Check URL and title
			if book.URL == "" {
				return errors.New("URL must not be empty")
			}

			if book.Title == "" {
				return errors.New("title must not be empty")
			}

			// Set modified time
			if book.ModifiedAt == "" {
				book.ModifiedAt = modifiedTime
			}

			hasContent := book.Content != ""

			// Create or update bookmark
			var err error
			if create {
				book.CreatedAt = modifiedTime
				err = stmtInsertBook.QueryRowContext(ctx,
					book.URL, book.Title, book.Excerpt, book.Author, book.Public, book.ModifiedAt, hasContent, book.CreatedAt).Scan(&book.ID)
			} else {
				_, err = stmtUpdateBook.ExecContext(ctx,
					book.URL, book.Title, book.Excerpt, book.Author, book.Public, book.ModifiedAt, hasContent, book.ID)
			}
			if err != nil {
				return errors.WithStack(err)
			}

			// Try to update it first to check for existence, we can't do an UPSERT here because
			// bookmant_content is a virtual table
			res, err := stmtUpdateBookContent.ExecContext(ctx, book.Title, book.Content, book.HTML, book.ID)
			if err != nil {
				return errors.WithStack(err)
			}

			rows, err := res.RowsAffected()
			if err != nil {
				return errors.WithStack(err)
			}

			if rows == 0 {
				_, err = stmtInsertBookContent.ExecContext(ctx, book.ID, book.Title, book.Content, book.HTML)
				if err != nil {
					return errors.WithStack(err)
				}
			}

			// Save book tags
			newTags := []model.Tag{}
			for _, tag := range book.Tags {
				// If it's deleted tag, delete and continue
				if tag.Deleted {
					_, err = stmtDeleteBookTag.ExecContext(ctx, book.ID, tag.ID)
					if err != nil {
						return errors.WithStack(err)
					}
					continue
				}

				// Normalize tag name
				tagName := strings.ToLower(tag.Name)
				tagName = strings.Join(strings.Fields(tagName), " ")

				// If tag doesn't have any ID, fetch it from database
				if tag.ID == 0 {
					if err := stmtGetTag.GetContext(ctx, &tag.ID, tagName); err != nil && err != sql.ErrNoRows {
						return errors.WithStack(err)
					}

					// If tag doesn't exist in database, save it
					if tag.ID == 0 {
						res, err := stmtInsertTag.ExecContext(ctx, tagName)
						if err != nil {
							return errors.WithStack(err)
						}

						tagID64, err := res.LastInsertId()
						if err != nil && err != sql.ErrNoRows {
							return errors.WithStack(err)
						}

						tag.ID = int(tagID64)
					}

					if _, err := stmtInsertBookTag.ExecContext(ctx, tag.ID, book.ID); err != nil {
						return errors.WithStack(err)
					}
				}

				newTags = append(newTags, tag)
			}

			book.Tags = newTags
			result = append(result, book)
		}

		return nil
	}); err != nil {
		return nil, errors.WithStack(err)
	}

	return result, nil
}

// GetBookmarks fetch list of bookmarks based on submitted options.
func (db *SQLiteDatabase) GetBookmarks(ctx context.Context, opts GetBookmarksOptions) ([]model.BookmarkDTO, error) {
	// Create initial query
	query := `SELECT
		b.id,
		b.url,
		b.title,
		b.excerpt,
		b.author,
		b.public,
		b.created_at,
		b.modified_at,
		b.has_content
		FROM bookmark b
		WHERE 1`

	// Add where clause
	args := []interface{}{}

	// Add where clause for IDs
	if len(opts.IDs) > 0 {
		query += ` AND b.id IN (?)`
		args = append(args, opts.IDs)
	}

	// Add where clause for search keyword
	if opts.Keyword != "" {
		query += ` AND (b.url LIKE '%' || ? || '%' OR b.excerpt LIKE '%' || ? || '%' OR b.id IN (
			SELECT docid id
			FROM bookmark_content
			WHERE title MATCH ? OR content MATCH ?))`

		args = append(args, opts.Keyword, opts.Keyword)

		// Replace dash with spaces since FTS5 uses `-name` as column identifier and double quote
		// since FTS5 uses double quote as string identifier
		// Reference: https://sqlite.org/fts5.html#fts5_strings
		ftsKeyword := strings.ReplaceAll(opts.Keyword, "-", " ")

		// Properly set double quotes for string literals in sqlite's fts
		ftsKeyword = strings.ReplaceAll(ftsKeyword, "\"", "\"\"")

		args = append(args, "\""+ftsKeyword+"\"", "\""+ftsKeyword+"\"")
	}

	// Add where clause for tags.
	// First we check for * in excluded and included tags,
	// which means all tags will be excluded and included, respectively.
	excludeAllTags := false
	for _, excludedTag := range opts.ExcludedTags {
		if excludedTag == "*" {
			excludeAllTags = true
			opts.ExcludedTags = []string{}
			break
		}
	}

	includeAllTags := false
	for _, includedTag := range opts.Tags {
		if includedTag == "*" {
			includeAllTags = true
			opts.Tags = []string{}
			break
		}
	}

	// If all tags excluded, we will only show bookmark without tags.
	// In other hand, if all tags included, we will only show bookmark with tags.
	if excludeAllTags {
		query += ` AND b.id NOT IN (SELECT DISTINCT bookmark_id FROM bookmark_tag)`
	} else if includeAllTags {
		query += ` AND b.id IN (SELECT DISTINCT bookmark_id FROM bookmark_tag)`
	}

	// Now we only need to find the normal tags
	if len(opts.Tags) > 0 {
		query += ` AND b.id IN (
			SELECT bt.bookmark_id
			FROM bookmark_tag bt
			LEFT JOIN tag t ON bt.tag_id = t.id
			WHERE t.name IN(?)
			GROUP BY bt.bookmark_id
			HAVING COUNT(bt.bookmark_id) = ?)`

		args = append(args, opts.Tags, len(opts.Tags))
	}

	if len(opts.ExcludedTags) > 0 {
		query += ` AND b.id NOT IN (
			SELECT DISTINCT bt.bookmark_id
			FROM bookmark_tag bt
			LEFT JOIN tag t ON bt.tag_id = t.id
			WHERE t.name IN(?))`

		args = append(args, opts.ExcludedTags)
	}

	// Add order clause
	switch opts.OrderMethod {
	case ByLastAdded:
		query += ` ORDER BY b.id DESC`
	case ByLastModified:
		query += ` ORDER BY b.modified_at DESC`
	default:
		query += ` ORDER BY b.id`
	}

	if opts.Limit > 0 && opts.Offset >= 0 {
		query += ` LIMIT ? OFFSET ?`
		args = append(args, opts.Limit, opts.Offset)
	}

	// Expand query, because some of the args might be an array
	query, args, err := sqlx.In(query, args...)
	if err != nil {
		return nil, errors.WithStack(err)
	}

	// Fetch bookmarks
	bookmarks := []model.BookmarkDTO{}
	err = db.SelectContext(ctx, &bookmarks, query, args...)
	if err != nil && err != sql.ErrNoRows {
		return nil, errors.WithStack(err)
	}

	// store bookmark IDs for further enrichment
	var bookmarkIds = make([]int, 0, len(bookmarks))
	for _, book := range bookmarks {
		bookmarkIds = append(bookmarkIds, book.ID)
	}

	if len(bookmarkIds) == 0 {
		return bookmarks, nil
	}

	// If content needed, fetch it separately
	// It's faster than join with virtual table
	if opts.WithContent {
		contents := make([]bookmarkContent, 0, len(bookmarks))
		contentMap := make(map[int]bookmarkContent, len(bookmarks))

		contentQuery, args, err := sqlx.In(`SELECT docid, content, html FROM bookmark_content WHERE docid IN (?)`, bookmarkIds)
		contentQuery = db.Rebind(contentQuery)
		if err != nil {
			return nil, errors.WithStack(err)
		}

		err = db.Select(&contents, contentQuery, args...)
		if err != nil && err != sql.ErrNoRows {
			return nil, errors.WithStack(err)
		}
		for _, content := range contents {
			contentMap[content.ID] = content
		}
		for i := range bookmarks[:] {
			book := &bookmarks[i]
			if bookmarkContent, found := contentMap[book.ID]; found {
				book.Content = bookmarkContent.Content
				book.HTML = bookmarkContent.HTML
			} else {
				log.Printf("not found content for bookmark %d, but it should be; check DB consistency", book.ID)
			}
		}

	}

	// Fetch tags for each bookmark
	tags := make([]tagContent, 0, len(bookmarks))
	tagsMap := make(map[int][]model.Tag, len(bookmarks))

	tagsQuery, tagArgs, err := sqlx.In(`SELECT bt.bookmark_id, t.id, t.name
		FROM bookmark_tag bt
		LEFT JOIN tag t ON bt.tag_id = t.id
		WHERE bt.bookmark_id IN (?)
		ORDER BY t.name`, bookmarkIds)
	tagsQuery = db.Rebind(tagsQuery)
	if err != nil {
		return nil, errors.WithStack(err)
	}

	err = db.Select(&tags, tagsQuery, tagArgs...)
	if err != nil && err != sql.ErrNoRows {
		return nil, errors.WithStack(err)
	}
	for _, fetchedTag := range tags {
		if tags, found := tagsMap[fetchedTag.ID]; found {
			tagsMap[fetchedTag.ID] = append(tags, fetchedTag.Tag)
		} else {
			tagsMap[fetchedTag.ID] = []model.Tag{fetchedTag.Tag}
		}
	}
	for i := range bookmarks[:] {
		book := &bookmarks[i]
		if tags, found := tagsMap[book.ID]; found {
			book.Tags = tags
		} else {
			book.Tags = []model.Tag{}
		}
	}

	return bookmarks, nil
}

// GetBookmarksCount fetch count of bookmarks based on submitted options.
func (db *SQLiteDatabase) GetBookmarksCount(ctx context.Context, opts GetBookmarksOptions) (int, error) {
	// Create initial query
	query := `SELECT COUNT(b.id)
		FROM bookmark b
		WHERE 1`

	// Add where clause
	args := []interface{}{}

	// Add where clause for IDs
	if len(opts.IDs) > 0 {
		query += ` AND b.id IN (?)`
		args = append(args, opts.IDs)
	}

	// Add where clause for search keyword
	if opts.Keyword != "" {
		query += ` AND (b.url LIKE '%' || ? || '%' OR b.excerpt LIKE '%' || ? || '%' OR b.id IN (
			SELECT docid id
			FROM bookmark_content
			WHERE title MATCH ? OR content MATCH ?))`

		args = append(args, opts.Keyword, opts.Keyword)

		// Replace dash with spaces since FTS5 uses `-name` as column identifier and double quote
		// since FTS5 uses double quote as string identifier
		// Reference: https://sqlite.org/fts5.html#fts5_strings
		ftsKeyword := strings.ReplaceAll(opts.Keyword, "-", " ")

		// Properly set double quotes for string literals in sqlite's fts
		ftsKeyword = strings.ReplaceAll(ftsKeyword, "\"", "\"\"")

		args = append(args, "\""+ftsKeyword+"\"", "\""+ftsKeyword+"\"")
	}

	// Add where clause for tags.
	// First we check for * in excluded and included tags,
	// which means all tags will be excluded and included, respectively.
	excludeAllTags := false
	for _, excludedTag := range opts.ExcludedTags {
		if excludedTag == "*" {
			excludeAllTags = true
			opts.ExcludedTags = []string{}
			break
		}
	}

	includeAllTags := false
	for _, includedTag := range opts.Tags {
		if includedTag == "*" {
			includeAllTags = true
			opts.Tags = []string{}
			break
		}
	}

	// If all tags excluded, we will only show bookmark without tags.
	// In other hand, if all tags included, we will only show bookmark with tags.
	if excludeAllTags {
		query += ` AND b.id NOT IN (SELECT DISTINCT bookmark_id FROM bookmark_tag)`
	} else if includeAllTags {
		query += ` AND b.id IN (SELECT DISTINCT bookmark_id FROM bookmark_tag)`
	}

	// Now we only need to find the normal tags
	if len(opts.Tags) > 0 {
		query += ` AND b.id IN (
			SELECT bt.bookmark_id
			FROM bookmark_tag bt
			LEFT JOIN tag t ON bt.tag_id = t.id
			WHERE t.name IN(?)
			GROUP BY bt.bookmark_id
			HAVING COUNT(bt.bookmark_id) = ?)`

		args = append(args, opts.Tags, len(opts.Tags))
	}

	if len(opts.ExcludedTags) > 0 {
		query += ` AND b.id NOT IN (
			SELECT DISTINCT bt.bookmark_id
			FROM bookmark_tag bt
			LEFT JOIN tag t ON bt.tag_id = t.id
			WHERE t.name IN(?))`

		args = append(args, opts.ExcludedTags)
	}

	// Expand query, because some of the args might be an array
	query, args, err := sqlx.In(query, args...)
	if err != nil {
		return 0, errors.WithStack(err)
	}

	// Fetch count
	var nBookmarks int
	err = db.GetContext(ctx, &nBookmarks, query, args...)
	if err != nil && err != sql.ErrNoRows {
		return 0, errors.WithStack(err)
	}

	return nBookmarks, nil
}

// DeleteBookmarks removes all record with matching ids from database.
func (db *SQLiteDatabase) DeleteBookmarks(ctx context.Context, ids ...int) error {
	if err := db.withTx(ctx, func(tx *sqlx.Tx) error {
		// Prepare queries
		delBookmark := `DELETE FROM bookmark`
		delBookmarkTag := `DELETE FROM bookmark_tag`
		delBookmarkContent := `DELETE FROM bookmark_content`

		// Delete bookmark(s)
		if len(ids) == 0 {
			_, err := tx.ExecContext(ctx, delBookmarkContent)
			if err != nil {
				return errors.WithStack(err)
			}

			_, err = tx.ExecContext(ctx, delBookmarkTag)
			if err != nil {
				return errors.WithStack(err)
			}

			_, err = tx.ExecContext(ctx, delBookmark)
			if err != nil {
				return errors.WithStack(err)
			}
		} else {
			delBookmark += ` WHERE id = ?`
			delBookmarkTag += ` WHERE bookmark_id = ?`
			delBookmarkContent += ` WHERE docid = ?`

			stmtDelBookmark, err := tx.Preparex(delBookmark)
			if err != nil {
				return errors.WithStack(err)
			}

			stmtDelBookmarkTag, err := tx.Preparex(delBookmarkTag)
			if err != nil {
				return errors.WithStack(err)
			}

			stmtDelBookmarkContent, err := tx.Preparex(delBookmarkContent)
			if err != nil {
				return errors.WithStack(err)
			}

			for _, id := range ids {
				_, err = stmtDelBookmarkContent.ExecContext(ctx, id)
				if err != nil {
					return errors.WithStack(err)
				}

				_, err = stmtDelBookmarkTag.ExecContext(ctx, id)
				if err != nil {
					return errors.WithStack(err)
				}

				_, err = stmtDelBookmark.ExecContext(ctx, id)
				if err != nil {
					return errors.WithStack(err)
				}
			}
		}

		return nil
	}); err != nil {
		return errors.WithStack(err)
	}

	return nil
}

// GetBookmark fetches bookmark based on its ID or URL.
// Returns the bookmark and boolean whether it's exist or not.
func (db *SQLiteDatabase) GetBookmark(ctx context.Context, id int, url string) (model.BookmarkDTO, bool, error) {
	args := []interface{}{id}
	query := `SELECT
		b.id, b.url, b.title, b.excerpt, b.author, b.public, b.modified_at,
		bc.content, bc.html, b.has_content, b.created_at
		FROM bookmark b
		LEFT JOIN bookmark_content bc ON bc.docid = b.id
		WHERE b.id = ?`

	if url != "" {
		query += ` OR b.url = ?`
		args = append(args, url)
	}

	book := model.BookmarkDTO{}
	if err := db.GetContext(ctx, &book, query, args...); err != nil && err != sql.ErrNoRows {
		return book, false, errors.WithStack(err)
	}

	return book, book.ID != 0, nil
}

// SaveAccount saves new account to database. Returns error if any happened.
func (db *SQLiteDatabase) SaveAccount(ctx context.Context, account model.Account) error {
	if err := db.withTx(ctx, func(tx *sqlx.Tx) error {
		// Hash password with bcrypt
		hashedPassword, err := bcrypt.GenerateFromPassword([]byte(account.Password), 10)
		if err != nil {
			return err
		}

		// Insert account to database
		_, err = tx.Exec(`INSERT INTO account
		(username, password, owner, config) VALUES (?, ?, ?, ?)
		ON CONFLICT(username) DO UPDATE SET
		password = ?, owner = ?`,
			account.Username, hashedPassword, account.Owner, account.Config,
			hashedPassword, account.Owner, account.Config)
		return errors.WithStack(err)
	}); err != nil {
		return errors.WithStack(err)
	}

	return nil
}

// SaveAccountSettings update settings for specific account  in database. Returns error if any happened.
func (db *SQLiteDatabase) SaveAccountSettings(ctx context.Context, account model.Account) error {
	if err := db.withTx(ctx, func(tx *sqlx.Tx) error {
		// Update account config in database for specific user
		_, err := tx.Exec(`UPDATE account
	   SET config = ?
	   WHERE username = ?`,
			account.Config, account.Username)
		return errors.WithStack(err)
	}); err != nil {
		return errors.WithStack(err)
	}

	return nil
}

// GetAccounts fetch list of account (without its password) based on submitted options.
func (db *SQLiteDatabase) GetAccounts(ctx context.Context, opts GetAccountsOptions) ([]model.Account, error) {
	// Create query
	args := []interface{}{}
	query := `SELECT id, username, owner, config FROM account WHERE 1`

	if opts.Keyword != "" {
		query += " AND username LIKE ?"
		args = append(args, "%"+opts.Keyword+"%")
	}

	if opts.Owner {
		query += " AND owner = 1"
	}

	query += ` ORDER BY username`

	// Fetch list account
	accounts := []model.Account{}
	err := db.SelectContext(ctx, &accounts, query, args...)
	if err != nil && err != sql.ErrNoRows {
		return nil, errors.WithStack(err)
	}

	return accounts, nil
}

// GetAccount fetch account with matching username.
// Returns the account and boolean whether it's exist or not.
func (db *SQLiteDatabase) GetAccount(ctx context.Context, username string) (model.Account, bool, error) {
	account := model.Account{}
	if err := db.GetContext(ctx, &account, `SELECT
		id, username, password, owner, config FROM account WHERE username = ?`,
		username,
	); err != nil {
		return account, false, errors.WithStack(err)
	}

	return account, account.ID != 0, nil
}

// DeleteAccounts removes all record with matching usernames.
func (db *SQLiteDatabase) DeleteAccounts(ctx context.Context, usernames ...string) error {
	if err := db.withTx(ctx, func(tx *sqlx.Tx) error {
		// Delete account
		stmtDelete, err := tx.Preparex(`DELETE FROM account WHERE username = ?`)
		if err != nil {
			return errors.WithStack(err)
		}

		for _, username := range usernames {
			_, err := stmtDelete.ExecContext(ctx, username)
			if err != nil {
				return errors.WithStack(err)
			}
		}

		return nil
	}); err != nil {
		return errors.WithStack(err)
	}

	return nil
}

// CreateTags creates new tags from submitted objects.
func (db *SQLiteDatabase) CreateTags(ctx context.Context, tags ...model.Tag) error {
	query := `INSERT INTO tag (name) VALUES `
	values := []interface{}{}

	for _, t := range tags {
		query += "(?),"
		values = append(values, t.Name)
	}
	query = query[0 : len(query)-1]

	if err := db.withTx(ctx, func(tx *sqlx.Tx) error {
		stmt, err := tx.Preparex(query)
		if err != nil {
			return errors.Wrap(errors.WithStack(err), "error preparing query")
		}

		_, err = stmt.ExecContext(ctx, values...)
		if err != nil {
			return errors.Wrap(errors.WithStack(err), "error executing query")
		}

		return nil
	}); err != nil {
		return errors.Wrap(errors.WithStack(err), "error running transaction")
	}

	return nil
}

// GetTags fetch list of tags and their frequency.
func (db *SQLiteDatabase) GetTags(ctx context.Context) ([]model.Tag, error) {
	tags := []model.Tag{}
	query := `SELECT bt.tag_id id, t.name, COUNT(bt.tag_id) n_bookmarks
		FROM bookmark_tag bt
		LEFT JOIN tag t ON bt.tag_id = t.id
		GROUP BY bt.tag_id ORDER BY t.name`

	err := db.SelectContext(ctx, &tags, query)
	if err != nil && err != sql.ErrNoRows {
		return nil, errors.WithStack(err)
	}

	return tags, nil
}

// RenameTag change the name of a tag.
func (db *SQLiteDatabase) RenameTag(ctx context.Context, id int, newName string) error {
	if err := db.withTx(ctx, func(tx *sqlx.Tx) error {
		_, err := tx.ExecContext(ctx, `UPDATE tag SET name = ? WHERE id = ?`, newName, id)
		return err
	}); err != nil {
		return errors.WithStack(err)
	}

	return nil
}