package sqlite

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

	"git.arav.su/Arav/justguestbook/guestbook"
	_ "github.com/mattn/go-sqlite3"
	"github.com/pkg/errors"
)

var (
	//go:embed queries/schema.sql
	querySchema string

	//go:embed queries/entryGetAll.sql
	queryGetAll string
	//go:embed queries/entryCount.sql
	queryCount string

	//go:embed queries/entryNew.sql
	queryNewEntry string
	//go:embed queries/entryUpdate.sql
	queryUpdateEntry string
	//go:embed queries/entryDelete.sql
	queryDeleteEntry string
	//go:embed queries/replyNew.sql
	queryNewReply string
	//go:embed queries/replyUpdate.sql
	queryUpdateReply string
	//go:embed queries/replyDelete.sql
	queryDeleteReply string
)

var (
	stmtGetAll      *sql.Stmt
	stmtCount       *sql.Stmt
	stmtNewEntry    *sql.Stmt
	stmtUpdateEntry *sql.Stmt
	stmtDeleteEntry *sql.Stmt
	stmtNewReply    *sql.Stmt
	stmtUpdateReply *sql.Stmt
	stmtDeleteReply *sql.Stmt
)

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

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

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

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

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

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

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

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

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

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

	return nil
}

type SQLiteDatabase struct {
	db *sql.DB
}

func New(filePath string) (*SQLiteDatabase, error) {
	db, err := sql.Open("sqlite3", dsn(filePath))
	if err != nil {
		return nil, err
	}

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

	return &SQLiteDatabase{db: db}, nil
}

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

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

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

		entry.Created, err = time.Parse(guestbook.DateFormat, entry_created)
		if err != nil {
			return
		}

		if reply_message.Valid /* reply_created is also valid if reply is */ {
			date, err := time.Parse(guestbook.DateFormat, reply_created.String)
			if err != nil {
				return nil, err
			}

			entry.Reply = &guestbook.Reply{
				ID:      entry.ID,
				Created: date,
				Message: reply_message.String}
		}

		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(stmtCount).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 *guestbook.Entry) error {
	tx, err := d.db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()

	r, err := tx.Stmt(stmtNewEntry).Exec(entry.Created.Format(guestbook.DateFormat), 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
}

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

	row := tx.Stmt(stmtUpdateEntry).QueryRow(entry.Name, entry.Message, entry.Website, entry.HideWebsite, entry.ID)
	if row.Err() != nil {
		return row.Err()
	}
	tx.Commit()

	return nil
}

func (d *SQLiteDatabase) DeleteEntry(entryID int64) (int64, error) {
	tx, err := d.db.Begin()
	if err != nil {
		return -1, err
	}
	defer tx.Rollback()

	res, err := tx.Stmt(stmtDeleteEntry).Exec(entryID)
	if err != nil {
		return -1, err
	}

	c, err := res.RowsAffected()
	if err != nil {
		return -1, err
	}

	tx.Commit()

	return c, nil
}

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

	_, err = tx.Stmt(stmtNewReply).Exec(reply.ID, reply.Created.Format(guestbook.DateFormat), reply.Message)
	if err != nil {
		return err
	}

	tx.Commit()

	return nil
}

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

	row := tx.Stmt(stmtUpdateReply).QueryRow(
		reply.Created.Format(guestbook.DateFormat), reply.Message, reply.ID)
	if row.Err() != nil {
		return row.Err()
	}

	tx.Commit()

	return nil
}

func (d *SQLiteDatabase) DeleteReply(entryID int64) (int64, error) {
	tx, err := d.db.Begin()
	if err != nil {
		return -1, err
	}
	defer tx.Rollback()

	res, err := tx.Stmt(stmtDeleteReply).Exec(entryID)
	if err != nil {
		return -1, err
	}

	ra, err := res.RowsAffected()
	if err != nil {
		return -1, err
	}

	tx.Commit()

	return ra, nil
}

func (d *SQLiteDatabase) Close() error {
	stmtCount.Close()
	stmtDeleteEntry.Close()
	stmtDeleteReply.Close()
	stmtGetAll.Close()
	stmtNewEntry.Close()
	stmtNewReply.Close()
	stmtUpdateEntry.Close()
	stmtUpdateReply.Close()

	return d.db.Close()
}

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