package database

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

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

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

// OpenSQLiteDatabase creates and open connection to new SQLite3 database.
func OpenSQLiteDatabase(databasePath string) (*SQLiteDatabase, error) {
	// Open database and start transaction
	var err error
	db := sqlx.MustConnect("sqlite3", databasePath)

	tx, err := db.Beginx()
	if err != nil {
		return nil, err
	}

	// Make sure to rollback if panic ever happened
	defer func() {
		if r := recover(); r != nil {
			panicErr, _ := r.(error)
			tx.Rollback()

			db = nil
			err = panicErr
		}
	}()

	// Create tables
	tx.MustExec(`CREATE TABLE IF NOT EXISTS account(
		id INTEGER NOT NULL,
		username TEXT NOT NULL,
		password TEXT NOT NULL,
		CONSTRAINT account_PK PRIMARY KEY(id),
		CONSTRAINT account_username_UNIQUE UNIQUE(username))`)

	tx.MustExec(`CREATE TABLE IF NOT EXISTS bookmark(
		id INTEGER NOT NULL,
		url TEXT NOT NULL,
		title TEXT NOT NULL,
		excerpt TEXT NOT NULL DEFAULT "",
		author TEXT NOT NULL DEFAULT "",
		modified TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP,
		CONSTRAINT bookmark_PK PRIMARY KEY(id),
		CONSTRAINT bookmark_url_UNIQUE UNIQUE(url))`)

	tx.MustExec(`CREATE TABLE IF NOT EXISTS tag(
		id INTEGER NOT NULL,
		name TEXT NOT NULL,
		CONSTRAINT tag_PK PRIMARY KEY(id),
		CONSTRAINT tag_name_UNIQUE UNIQUE(name))`)

	tx.MustExec(`CREATE TABLE IF NOT EXISTS bookmark_tag(
		bookmark_id INTEGER NOT NULL,
		tag_id INTEGER NOT NULL,
		CONSTRAINT bookmark_tag_PK PRIMARY KEY(bookmark_id, tag_id),
		CONSTRAINT bookmark_id_FK FOREIGN KEY(bookmark_id) REFERENCES bookmark(id),
		CONSTRAINT tag_id_FK FOREIGN KEY(tag_id) REFERENCES tag(id))`)

	tx.MustExec(`CREATE VIRTUAL TABLE IF NOT EXISTS bookmark_content USING fts4(title, content, html)`)

	err = tx.Commit()
	checkError(err)

	return &SQLiteDatabase{*db}, err
}

// SaveBookmarks saves new or updated bookmarks to database.
// Returns the saved ID and error message if any happened.
func (db *SQLiteDatabase) SaveBookmarks(bookmarks ...model.Bookmark) (result []model.Bookmark, err error) {
	// Prepare transaction
	tx, err := db.Beginx()
	if err != nil {
		return []model.Bookmark{}, err
	}

	// Make sure to rollback if panic ever happened
	defer func() {
		if r := recover(); r != nil {
			panicErr, _ := r.(error)
			tx.Rollback()

			result = []model.Bookmark{}
			err = panicErr
		}
	}()

	// Prepare statement
	stmtInsertBook, _ := tx.Preparex(`INSERT INTO bookmark
		(id, url, title, excerpt, author, modified)
		VALUES(?, ?, ?, ?, ?, ?)
		ON CONFLICT(id) DO UPDATE SET
		url = ?, title = ?,	excerpt = ?, author = ?, modified = ?`)

	stmtInsertBookContent, _ := tx.Preparex(`INSERT OR IGNORE INTO bookmark_content
		(docid, title, content, html) 
		VALUES (?, ?, ?, ?)`)

	stmtUpdateBookContent, _ := tx.Preparex(`UPDATE bookmark_content SET
		title = ?, content = ?, html = ? 
		WHERE docid = ?`)

	stmtGetTag, _ := tx.Preparex(`SELECT id FROM tag WHERE name = ?`)

	stmtInsertTag, _ := tx.Preparex(`INSERT INTO tag (name) VALUES (?)`)

	stmtInsertBookTag, _ := tx.Preparex(`INSERT OR IGNORE INTO bookmark_tag
		(tag_id, bookmark_id) VALUES (?, ?)`)

	stmtDeleteBookTag, _ := tx.Preparex(`DELETE FROM bookmark_tag
		WHERE bookmark_id = ? AND tag_id = ?`)

	// Prepare modified time
	modifiedTime := time.Now().UTC().Format("2006-01-02 15:04:05")

	// Execute statements
	result = []model.Bookmark{}
	for _, book := range bookmarks {
		// Check ID, URL and title
		if book.ID == 0 {
			panic(fmt.Errorf("ID must not be empty"))
		}

		if book.URL == "" {
			panic(fmt.Errorf("URL must not be empty"))
		}

		if book.Title == "" {
			panic(fmt.Errorf("title must not be empty"))
		}

		// Set modified time
		book.Modified = modifiedTime

		// Save bookmark
		stmtInsertBook.MustExec(book.ID,
			book.URL, book.Title, book.Excerpt, book.Author, book.Modified,
			book.URL, book.Title, book.Excerpt, book.Author, book.Modified)

		stmtUpdateBookContent.MustExec(book.Title, book.Content, book.HTML, book.ID)
		stmtInsertBookContent.MustExec(book.ID, book.Title, book.Content, book.HTML)

		// Save book tags
		newTags := []model.Tag{}
		for _, tag := range book.Tags {
			// If it's deleted tag, delete and continue
			if tag.Deleted {
				stmtDeleteBookTag.MustExec(book.ID, tag.ID)
				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 {
				err = stmtGetTag.Get(&tag.ID, tagName)
				checkError(err)

				// If tag doesn't exist in database, save it
				if tag.ID == 0 {
					res := stmtInsertTag.MustExec(tagName)
					tagID64, err := res.LastInsertId()
					checkError(err)

					tag.ID = int(tagID64)
				}

				stmtInsertBookTag.Exec(tag.ID, book.ID)
			}

			newTags = append(newTags, tag)
		}

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

	// Commit transaction
	err = tx.Commit()
	checkError(err)

	return result, err
}

// GetBookmarks fetch list of bookmarks based on submitted options.
func (db *SQLiteDatabase) GetBookmarks(opts GetBookmarksOptions) ([]model.Bookmark, error) {
	// Create initial query
	columns := []string{
		`b.id`,
		`b.url`,
		`b.title`,
		`b.excerpt`,
		`b.author`,
		`b.modified`,
		`bc.content <> "" has_content`}

	if opts.WithContent {
		columns = append(columns, `bc.content`, `bc.html`)
	}

	query := `SELECT ` + strings.Join(columns, ",") + `
		FROM bookmark b
		LEFT JOIN bookmark_content bc ON bc.docid = b.id
		WHERE 1`

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

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

	if opts.Keyword != "" {
		query += ` AND (b.url LIKE ? OR b.id IN (
			SELECT docid id 
			FROM bookmark_content 
			WHERE title MATCH ? OR content MATCH ?))`

		args = append(args,
			"%"+opts.Keyword+"%",
			opts.Keyword,
			opts.Keyword)
	}

	if len(opts.Tags) > 0 {
		query += ` AND b.id IN (
			SELECT bookmark_id FROM bookmark_tag 
			WHERE tag_id IN (SELECT id FROM tag WHERE name IN (?)))`

		args = append(args, opts.Tags)
	}

	// Add order clause
	switch opts.OrderMethod {
	case ByLastAdded:
		query += ` ORDER BY b.id DESC`
	case ByLastModified:
		query += ` ORDER BY b.modified 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, fmt.Errorf("failed to expand query: %v", err)
	}

	// Fetch bookmarks
	bookmarks := []model.Bookmark{}
	err = db.Select(&bookmarks, query, args...)
	if err != nil && err != sql.ErrNoRows {
		return nil, fmt.Errorf("failed to fetch data: %v", err)
	}

	// Fetch tags for each bookmarks
	stmtGetTags, err := db.Preparex(`SELECT t.id, t.name 
		FROM bookmark_tag bt 
		LEFT JOIN tag t ON bt.tag_id = t.id
		WHERE bt.bookmark_id = ? 
		ORDER BY t.name`)
	if err != nil {
		return nil, fmt.Errorf("failed to prepare tag query: %v", err)
	}
	defer stmtGetTags.Close()

	for i, book := range bookmarks {
		book.Tags = []model.Tag{}
		err = stmtGetTags.Select(&book.Tags, book.ID)
		if err != nil && err != sql.ErrNoRows {
			return nil, fmt.Errorf("failed to fetch tags: %v", err)
		}

		bookmarks[i] = book
	}

	return bookmarks, nil
}

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

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

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

	if opts.Keyword != "" {
		query += ` AND (b.url LIKE ? OR b.id IN (
			SELECT docid id 
			FROM bookmark_content 
			WHERE title MATCH ? OR content MATCH ?))`

		args = append(args,
			"%"+opts.Keyword+"%",
			opts.Keyword,
			opts.Keyword)
	}

	if len(opts.Tags) > 0 {
		query += ` AND b.id IN (
			SELECT bookmark_id FROM bookmark_tag 
			WHERE tag_id IN (SELECT id FROM tag WHERE name IN (?)))`

		args = append(args, opts.Tags)
	}

	// Expand query, because some of the args might be an array
	query, args, err := sqlx.In(query, args...)
	if err != nil {
		return 0, fmt.Errorf("failed to expand query: %v", err)
	}

	// Fetch count
	var nBookmarks int
	err = db.Get(&nBookmarks, query, args...)
	if err != nil && err != sql.ErrNoRows {
		return 0, fmt.Errorf("failed to fetch count: %v", err)
	}

	return nBookmarks, nil
}

// DeleteBookmarks removes all record with matching ids from database.
func (db *SQLiteDatabase) DeleteBookmarks(ids ...int) (err error) {
	// Begin transaction
	tx, err := db.Beginx()
	if err != nil {
		return err
	}

	// Make sure to rollback if panic ever happened
	defer func() {
		if r := recover(); r != nil {
			panicErr, _ := r.(error)
			tx.Rollback()

			err = panicErr
		}
	}()

	// Prepare queries
	delBookmark := `DELETE FROM bookmark`
	delBookmarkTag := `DELETE FROM bookmark_tag`
	delBookmarkContent := `DELETE FROM bookmark_content`

	// Delete bookmark(s)
	if len(ids) == 0 {
		tx.MustExec(delBookmarkContent)
		tx.MustExec(delBookmarkTag)
		tx.MustExec(delBookmark)
	} else {
		delBookmark += ` WHERE id = ?`
		delBookmarkTag += ` WHERE bookmark_id = ?`
		delBookmarkContent += ` WHERE docid = ?`

		stmtDelBookmark, _ := tx.Preparex(delBookmark)
		stmtDelBookmarkTag, _ := tx.Preparex(delBookmarkTag)
		stmtDelBookmarkContent, _ := tx.Preparex(delBookmarkContent)

		for _, id := range ids {
			stmtDelBookmarkContent.MustExec(id)
			stmtDelBookmarkTag.MustExec(id)
			stmtDelBookmark.MustExec(id)
		}
	}

	// Commit transaction
	err = tx.Commit()
	checkError(err)

	return err
}

// GetBookmark fetchs bookmark based on its ID or URL.
// Returns the bookmark and boolean whether it's exist or not.
func (db *SQLiteDatabase) GetBookmark(id int, url string) (model.Bookmark, bool) {
	args := []interface{}{id}
	query := `SELECT
		b.id, b.url, b.title, b.excerpt, b.author, b.modified,
		bc.content, bc.html, bc.content <> "" has_content
		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.Bookmark{}
	db.Get(&book, query, args...)

	return book, book.ID != 0
}

// SaveAccount saves new account to database. Returns error if any happened.
func (db *SQLiteDatabase) SaveAccount(username, password string) (err error) {
	// Hash password with bcrypt
	hashedPassword, err := bcrypt.GenerateFromPassword([]byte(password), 10)
	if err != nil {
		return err
	}

	// Insert account to database
	_, err = db.Exec(`INSERT INTO account
		(username, password) VALUES (?, ?)
		ON CONFLICT(username) DO UPDATE SET
		password = ?`,
		username, hashedPassword, hashedPassword)

	return err
}

// GetAccounts fetch list of account (without its password) with matching keyword.
func (db *SQLiteDatabase) GetAccounts(keyword string) ([]model.Account, error) {
	// Create query
	args := []interface{}{}
	query := `SELECT id, username FROM account WHERE 1`

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

	query += ` ORDER BY username`

	// Fetch list account
	accounts := []model.Account{}
	err := db.Select(&accounts, query, args...)
	if err != nil && err != sql.ErrNoRows {
		return nil, fmt.Errorf("failed to fetch accounts: %v", 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(username string) (model.Account, bool) {
	account := model.Account{}
	db.Get(&account, `SELECT 
		id, username, password FROM account WHERE username = ?`,
		username)

	return account, account.ID != 0
}

// DeleteAccounts removes all record with matching usernames.
func (db *SQLiteDatabase) DeleteAccounts(usernames ...string) (err error) {
	// Begin transaction
	tx, err := db.Beginx()
	if err != nil {
		return err
	}

	// Make sure to rollback if panic ever happened
	defer func() {
		if r := recover(); r != nil {
			panicErr, _ := r.(error)
			tx.Rollback()

			err = panicErr
		}
	}()

	// Delete account
	stmtDelete, _ := tx.Preparex(`DELETE FROM account WHERE username = ?`)
	for _, username := range usernames {
		stmtDelete.MustExec(username)
	}

	// Commit transaction
	err = tx.Commit()
	checkError(err)

	return err
}

// GetTags fetch list of tags and their frequency.
func (db *SQLiteDatabase) GetTags() ([]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.Select(&tags, query)
	if err != nil && err != sql.ErrNoRows {
		return nil, fmt.Errorf("failed to fetch tags: %v", err)
	}

	return tags, nil
}

// CreateNewID creates new ID for specified table
func (db *SQLiteDatabase) CreateNewID(table string) (int, error) {
	var tableID int
	query := fmt.Sprintf(`SELECT IFNULL(MAX(id) + 1, 1) FROM %s`, table)

	err := db.Get(&tableID, query)
	if err != nil && err != sql.ErrNoRows {
		return -1, err
	}

	return tableID, nil
}