package justguestbook

import (
	"database/sql"
	_ "embed"
	"fmt"
	"time"

	_ "github.com/mattn/go-sqlite3"
	"github.com/pkg/errors"
)

var (
	//go:embed sqlite_queries/schema.sql
	sqlQuerySchema string

	//go:embed sqlite_queries/entryGetAll.sql
	sqlQueryGetAll string
	//go:embed sqlite_queries/entryCount.sql
	sqlQueryCount string

	//go:embed sqlite_queries/entryNew.sql
	sqlQueryNewEntry string
	//go:embed sqlite_queries/entryUpdate.sql
	sqlQueryUpdateEntry string
	//go:embed sqlite_queries/entryDelete.sql
	sqlQueryDeleteEntry string
	//go:embed sqlite_queries/replyNew.sql
	sqlQueryNewReply string
	//go:embed sqlite_queries/replyUpdate.sql
	sqlQueryUpdateReply string
	//go:embed sqlite_queries/replyDelete.sql
	sqlQueryDeleteReply string
)

var (
	sqlStmtGetAll      *sql.Stmt
	sqlStmtCount       *sql.Stmt
	sqlStmtNewEntry    *sql.Stmt
	sqlStmtUpdateEntry *sql.Stmt
	sqlStmtDeleteEntry *sql.Stmt
	sqlStmtNewReply    *sql.Stmt
	sqlStmtUpdateReply *sql.Stmt
	sqlStmtDeleteReply *sql.Stmt
)

func initSQLiteStatements(db *sql.DB) error {
	db.Exec("PRAGMA foreign_keys = ON;")

	_, err := db.Exec(sqlQuerySchema)
	if err != nil {
		return errors.Wrap(err, "failed to init schema")
	}

	sqlStmtGetAll, err = db.Prepare(sqlQueryGetAll)
	if err != nil {
		return errors.Wrap(err, "failed to prepare sqlQueryGetAll")
	}

	sqlStmtCount, err = db.Prepare(sqlQueryCount)
	if err != nil {
		return errors.Wrap(err, "failed to prepare sqlQueryCount")
	}

	sqlStmtNewEntry, err = db.Prepare(sqlQueryNewEntry)
	if err != nil {
		return errors.Wrap(err, "failed to prepare sqlQueryNewEntry")
	}

	sqlStmtUpdateEntry, err = db.Prepare(sqlQueryUpdateEntry)
	if err != nil {
		return errors.Wrap(err, "failed to prepare sqlQueryUpdateEntry")
	}

	sqlStmtDeleteEntry, err = db.Prepare(sqlQueryDeleteEntry)
	if err != nil {
		return errors.Wrap(err, "failed to prepare sqlQueryDeleteEntry")
	}

	sqlStmtNewReply, err = db.Prepare(sqlQueryNewReply)
	if err != nil {
		return errors.Wrap(err, "failed to prepare sqlQueryNewReply")
	}

	sqlStmtUpdateReply, err = db.Prepare(sqlQueryUpdateReply)
	if err != nil {
		return errors.Wrap(err, "failed to prepare sqlQueryUpdateReply")
	}

	sqlStmtDeleteReply, err = db.Prepare(sqlQueryDeleteReply)
	if err != nil {
		return errors.Wrap(err, "failed to prepare sqlQueryDeleteReply")
	}

	return nil
}

// SQLiteDatabase implements a Guestbook that works with a SQLite DB
// under the hood.
type SQLiteDatabase struct {
	db *sql.DB
}

// NewSQLiteDB returns an instance of a SQLite Guestbook implementation.
func NewSQLiteDB(filePath string) (Guestbook, error) {
	db, err := sql.Open("sqlite3", sqliteDSN(filePath))
	if err != nil {
		return nil, err
	}

	if err := initSQLiteStatements(db); err != nil {
		return nil, err
	}

	return &SQLiteDatabase{db: db}, nil
}

func (d *SQLiteDatabase) Entries(page, pageSize int64) (entries []*Entry, err error) {
	tx, err := d.db.Begin()
	if err != nil {
		return
	}
	defer tx.Rollback()

	rows, err := tx.Stmt(sqlStmtGetAll).Query(pageSize, (page-1)*pageSize)
	if err != nil {
		return
	}
	defer rows.Close()

	for rows.Next() {
		var entry Entry
		var entry_created int64
		var reply_created int64
		var reply_message string
		if err = rows.Scan(
			&entry.ID, &entry_created, &entry.Name,
			&entry.Message, &entry.Website, &entry.HideWebsite,
			&reply_created, &reply_message); err != nil {
			return
		}

		entry.Created = time.Unix(entry_created, 0)
		if err != nil {
			return
		}

		if reply_message != "" {
			if err != nil {
				return nil, err
			}

			entry.Reply = &Reply{
				ID: entry.ID,
				// Created: date,
				Created: time.Unix(reply_created, 0),
				Message: reply_message}
		}

		entries = append(entries, &entry)
	}

	tx.Commit()

	return
}

// Count returns how much entries are in an `entry` table.
func (d *SQLiteDatabase) Count() (count int64, err error) {
	tx, err := d.db.Begin()
	if err != nil {
		return -1, err
	}
	defer tx.Rollback()

	err = tx.Stmt(sqlStmtCount).QueryRow().Scan(&count)
	if err != nil {
		return -1, err
	}

	tx.Commit()

	return count, nil
}

// NewEntry inserts a passed Entry struct and fills its ID field if successful.
func (d *SQLiteDatabase) NewEntry(entry *Entry) error {
	tx, err := d.db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()

	r, err := tx.Stmt(sqlStmtNewEntry).Exec(entry.Created.UTC().Unix(), entry.Name, entry.Message,
		entry.Website, entry.HideWebsite)
	if err != nil {
		return err
	}

	entry.ID, err = r.LastInsertId()
	if err != nil {
		return err
	}

	tx.Commit()

	return nil
}

func (d *SQLiteDatabase) EditEntry(entry *Entry) error {
	tx, err := d.db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()

	_, err = tx.Stmt(sqlStmtUpdateEntry).Exec(entry.Name, entry.Message, entry.Website, entry.HideWebsite, entry.ID)
	if err != nil {
		return err
	}
	tx.Commit()

	return nil
}

func (d *SQLiteDatabase) DeleteEntry(entryID int64) error {
	tx, err := d.db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()

	if _, err = tx.Stmt(sqlStmtDeleteEntry).Exec(entryID); err != nil {
		return err
	}

	tx.Commit()

	return nil
}

func (d *SQLiteDatabase) NewReply(reply *Reply) error {
	tx, err := d.db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()

	_, err = tx.Stmt(sqlStmtNewReply).Exec(reply.ID, reply.Created.UTC().Unix(), reply.Message)
	if err != nil {
		return err
	}

	tx.Commit()

	return nil
}

func (d *SQLiteDatabase) EditReply(reply *Reply) error {
	tx, err := d.db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()

	_, err = tx.Stmt(sqlStmtUpdateReply).Exec(reply.Message, reply.ID)
	if err != nil {
		return err
	}

	tx.Commit()

	return nil
}

func (d *SQLiteDatabase) DeleteReply(entryID int64) error {
	tx, err := d.db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()

	if _, err = tx.Stmt(sqlStmtDeleteReply).Exec(entryID); err != nil {
		return err
	}

	tx.Commit()

	return nil
}

func (d *SQLiteDatabase) Close() error {
	sqlStmtCount.Close()
	sqlStmtDeleteEntry.Close()
	sqlStmtDeleteReply.Close()
	sqlStmtGetAll.Close()
	sqlStmtNewEntry.Close()
	sqlStmtNewReply.Close()
	sqlStmtUpdateEntry.Close()
	sqlStmtUpdateReply.Close()

	return d.db.Close()
}

func sqliteDSN(filePath string) string {
	return fmt.Sprintf("file:%s?_journal=WAL&_mutex=full", filePath)
}