// Run with go run ./examples/transactions. Uses a deterministic demonstration
// driver, no external database and no actual uploaded files.
package main

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

	"git.yuntuo.hk/k2safe/go-omni/database"
)

func main() {
	failure := errors.New("demonstration failure")
	for _, name := range []string{"success", "beginFailure", "workFailure", "rollbackFailure", "commitRejected", "commitAcknowledgementLost"} {
		driver := &demoConnector{}
		var workErr error
		switch name {
		case "beginFailure":
			driver.beginErr = failure
		case "workFailure":
			workErr = failure
		case "rollbackFailure":
			workErr, driver.rollbackErr = failure, failure
		case "commitRejected":
			driver.commitErr = failure
		case "commitAcknowledgementLost":
			driver.commitErr, driver.persistBeforeError = failure, true
		}
		pool := &database.DB{DB: sql.OpenDB(driver)}
		err := pool.InTx(context.Background(), nil, func(tx *sql.Tx) error {
			if _, err := tx.ExecContext(context.Background(), "INSERT demonstration record"); err != nil {
				return err
			}
			return workErr
		})
		_ = pool.Close()
		if err == nil {
			fmt.Printf("%s: committed, stored=%t\n", name, driver.stored.Load())
			continue
		}
		var txErr *database.TxError
		if !errors.As(err, &txErr) || !errors.Is(err, failure) {
			panic("transaction phase or original cause lost")
		}
		// A project decides whether cleanup is appropriate for its own operation.
		// Unknown outcomes must not be treated as evidence that no record exists.
		cleanup := txErr.Outcome == database.TxOutcomeNotStarted || txErr.Outcome == database.TxOutcomeRolledBack
		if cleanup && driver.stored.Load() {
			panic("unsafe cleanup decision")
		}
		fmt.Printf("%s: stage=%s outcome=%s stored=%t cleanup=%t\n", name, txErr.Stage, txErr.Outcome, driver.stored.Load(), cleanup)
	}
}