package transformers

import (
	"context"
	"errors"
	"time"

	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/custom_errors"
	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/etl"
	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
)

const processBatchCtxCheck = 4096

func ProcessBatchWithRetries(
	ctx context.Context,
	batch *models.Batch,
	transformationPlan []etl.ColumnTransformPlan,
	retryConfig config.RetryConfig,
) error {
	for i, rowValues := range batch.Rows {
		if i%processBatchCtxCheck == 0 {
			if err := ctx.Err(); err != nil {
				return err
			}
		}

		for _, task := range transformationPlan {
			val := rowValues[task.Index]
			if val == nil {
				continue
			}

			var lastErr error
			success := false

			for attempt := 0; attempt < retryConfig.Attempts; attempt++ {
				transformed, err := task.Fn(val)
				if err == nil {
					rowValues[task.Index] = transformed
					success = true
					break
				}

				lastErr = err
				if jobError, ok := errors.AsType[*custom_errors.JobError](err); ok {
					if jobError.ShouldCancelJob {
						return jobError
					}
				}

				if attempt == retryConfig.Attempts-1 {
					break
				}

				delay := custom_errors.ComputeBackoffDelay(
					attempt,
					retryConfig.BaseDelayMs,
					retryConfig.MaxDelayMs,
					retryConfig.MaxJitterMs,
				)
				time.Sleep(delay)
			}

			if !success {
				return lastErr
			}
		}
	}

	return nil
}