package dbwrapper

import (
	"context"
	"database/sql"
	"fmt"

	mssql "github.com/microsoft/go-mssqldb"
)

func init() {
	Register("sqlserver", func() DbWrapper {
		return &mssqlDbWrapper{dialect: "sqlserver"}
	})
}

type mssqlRowResult struct {
	row *sql.Row
}

func (mr *mssqlRowResult) Scan(dest ...any) error {
	return mr.row.Scan(dest...)
}

type mssqlRowsResult struct {
	columns []string
	rows    *sql.Rows
}

func (mr *mssqlRowsResult) Close() error {
	return mr.rows.Close()
}

func (mr *mssqlRowsResult) Columns() ([]string, error) {
	if mr.columns != nil {
		return mr.columns, nil
	}

	return mr.rows.Columns()
}

func (mr *mssqlRowsResult) Err() error {
	return mr.rows.Err()
}

func (mr *mssqlRowsResult) Next() bool {
	return mr.rows.Next()
}

func (mr *mssqlRowsResult) Scan(dest ...any) error {
	return mr.rows.Scan(dest...)
}

func (mr *mssqlRowsResult) Values() ([]any, error) {
	columns, err := mr.Columns()
	if err != nil {
		return nil, err
	}

	rowValues := make([]any, len(columns))
	scanArgs := make([]any, len(columns))
	for i := range rowValues {
		scanArgs[i] = &rowValues[i]
	}

	if err := mr.rows.Scan(scanArgs...); err != nil {
		return nil, err
	}

	return rowValues, nil
}

type mssqlDbWrapper struct {
	db      *sql.DB
	dialect string
}

func (mw *mssqlDbWrapper) Connect(ctx context.Context, dbUrl string) error {
	db, err := sql.Open("sqlserver", dbUrl)
	if err != nil {
		return err
	}

	if err := db.PingContext(ctx); err != nil {
		if err := db.Close(); err != nil {
			return err
		}
		return err
	}

	mw.db = db
	return nil
}

func (mw *mssqlDbWrapper) Close() error {
	return mw.db.Close()
}

func (mw *mssqlDbWrapper) Exec(ctx context.Context, query string, args ...any) (ExecResult, error) {
	result, execErr := mw.db.ExecContext(ctx, query, args...)
	if execErr != nil {
		return ExecResult{}, execErr
	}

	affectedRows, err := result.RowsAffected()
	if err != nil {
		return ExecResult{}, err
	}

	return ExecResult{AffectedRows: affectedRows}, nil
}

func (mw *mssqlDbWrapper) GetDialect() string {
	return mw.dialect
}

func (mw *mssqlDbWrapper) Query(ctx context.Context, query string, args ...any) (RowsResult, error) {
	rows, err := mw.db.QueryContext(ctx, query, args...)
	if err != nil {
		return nil, err
	}

	return &mssqlRowsResult{columns: nil, rows: rows}, nil
}

func (mw *mssqlDbWrapper) QueryRow(ctx context.Context, query string, args ...any) RowResult {
	row := mw.db.QueryRowContext(ctx, query, args...)
	return &mssqlRowResult{row: row}
}

func (mw *mssqlDbWrapper) SaveMassive(ctx context.Context, schema string, table string, columnNames []string, rows [][]any) (int64, error) {
	tx, err := mw.db.BeginTx(ctx, nil)
	if err != nil {
		return 0, err
	}

	fullTableName := fmt.Sprintf("[%s].[%s]", schema, table)

	stmt, err := tx.PrepareContext(ctx, mssql.CopyIn(fullTableName, mssql.BulkOptions{}, columnNames...))
	if err != nil {
		tx.Rollback()
		return 0, err
	}

	for _, row := range rows {
		_, err = stmt.ExecContext(ctx, row...)
		if err != nil {
			stmt.Close()
			tx.Rollback()
			return 0, err
		}
	}

	result, err := stmt.ExecContext(ctx)
	if err != nil {
		stmt.Close()
		tx.Rollback()
		return 0, err
	}

	if err := stmt.Close(); err != nil {
		tx.Rollback()
		return 0, err
	}

	if err := tx.Commit(); err != nil {
		return 0, err
	}

	rowsAffected, raErr := result.RowsAffected()
	if raErr != nil {
		return 0, nil
	}

	return rowsAffected, nil
}