package storage

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

	"github.com/go-mysql-org/go-mysql/mysql"

	"dashboard-cdc-worker/internal/config"
)

const serviceName = "dashboard-cdc-worker"

type MySQLRepository struct {
	db  *sql.DB
	cfg config.Config
}

func NewMySQLRepository(db *sql.DB, cfg config.Config) *MySQLRepository {
	return &MySQLRepository{db: db, cfg: cfg}
}

func (r *MySQLRepository) WithTx(ctx context.Context, fn func(*sql.Tx) error) error {
	tx, err := r.db.BeginTx(ctx, &sql.TxOptions{Isolation: sql.LevelReadCommitted})
	if err != nil {
		return err
	}
	if err := fn(tx); err != nil {
		_ = tx.Rollback()
		return err
	}
	return tx.Commit()
}

func (r *MySQLRepository) LoadCheckpoint(ctx context.Context) (mysql.Position, bool, error) {
	var file string
	var pos uint32
	err := r.db.QueryRowContext(ctx, `
SELECT binlog_file, binlog_pos
FROM dashboard_cdc_checkpoint
WHERE service_name = ?
`, serviceName).Scan(&file, &pos)
	if err == sql.ErrNoRows {
		return mysql.Position{}, false, nil
	}
	if err != nil {
		return mysql.Position{}, false, err
	}
	return mysql.Position{Name: file, Pos: pos}, true, nil
}

func (r *MySQLRepository) SaveCheckpoint(ctx context.Context, pos mysql.Position) error {
	_, err := r.db.ExecContext(ctx, `
INSERT INTO dashboard_cdc_checkpoint (service_name, binlog_file, binlog_pos, updated_at)
VALUES (?, ?, ?, NOW())
ON DUPLICATE KEY UPDATE
  binlog_file = VALUES(binlog_file),
  binlog_pos = VALUES(binlog_pos),
  updated_at = NOW()
`, serviceName, pos.Name, pos.Pos)
	return err
}

func (r *MySQLRepository) MarkEventApplied(ctx context.Context, tx *sql.Tx, eventKey string, source string) (bool, error) {
	result, err := tx.ExecContext(ctx, `
INSERT IGNORE INTO dashboard_cdc_event_dedup (event_key, source, created_at)
VALUES (?, ?, NOW())
`, eventKey, source)
	if err != nil {
		return false, err
	}
	affected, err := result.RowsAffected()
	if err != nil {
		return false, err
	}
	return affected > 0, nil
}

func execAll(ctx context.Context, db *sql.DB, statements []string) error {
	for _, stmt := range statements {
		if _, err := db.ExecContext(ctx, stmt); err != nil {
			return fmt.Errorf("exec schema failed: %w; sql=%s", err, stmt)
		}
	}
	return nil
}