package transformers

import (
	"context"
	"fmt"
	"strings"
	"time"

	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/azure"
	"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"
	"github.com/google/uuid"
	"github.com/sirupsen/logrus"
)

func computeTransformationPlan(columns []models.ColumnType) []etl.ColumnTransformPlan {
	var plan []etl.ColumnTransformPlan

	for i, col := range columns {
		switch col.SystemType() {
		case "uniqueidentifier":
			plan = append(plan, etl.ColumnTransformPlan{
				Index: i,
				Fn: func(v any) (any, error) {
					if b, ok := v.([]byte); ok && b != nil {
						return mssqlUuidToBigEndian(b)
					}
					return v, nil
				},
			})

		case "geometry", "geography":
			plan = append(plan, etl.ColumnTransformPlan{
				Index: i,
				Fn: func(v any) (any, error) {
					if b, ok := v.([]byte); ok && b != nil {
						return wkbToEwkbWithSrid(b, 4326)
					}
					return v, nil
				},
			})

		case "datetime", "datetime2":
			plan = append(plan, etl.ColumnTransformPlan{
				Index: i,
				Fn: func(v any) (any, error) {
					if t, ok := v.(time.Time); ok {
						return ensureUTC(t), nil
					}
					return v, nil
				},
			})
		}
	}

	return plan
}

func computeStorageTransformationPlan(
	ctx context.Context,
	azureClient *azure.Client,
	toStorage config.ToStorageConfig,
	sourceColumns []models.ColumnType,
	sourceTable config.SourceTableInfo,
) []etl.ColumnTransformPlan {
	if azureClient == nil || len(toStorage.Columns) == 0 {
		return nil
	}

	colIndex := make(map[string]int, len(sourceColumns))
	for i, col := range sourceColumns {
		colIndex[strings.ToUpper(col.Name())] = i
	}

	var plan []etl.ColumnTransformPlan
	for _, storageCol := range toStorage.Columns {
		if storageCol.Mode != "REFERENCE_ONLY" {
			logrus.Warnf("to_storage: unsupported mode %q for column %s — skipping", storageCol.Mode, storageCol.Source)
			continue
		}

		idx, ok := colIndex[strings.ToUpper(storageCol.Source)]
		if !ok {
			logrus.Warnf("to_storage: source column %q not found in source schema — skipping", storageCol.Source)
			continue
		}

		sourceColName := storageCol.Source
		schema := sourceTable.Schema
		table := sourceTable.Table

		plan = append(plan, etl.ColumnTransformPlan{
			Index: idx,
			Fn: func(v any) (any, error) {
				if v == nil {
					return nil, nil
				}
				b, ok := v.([]byte)
				if !ok {
					logrus.Warnf("to_storage: expected []byte for %s.%s.%s, got %T — passing through",
						schema, table, sourceColName, v)
					return v, nil
				}
				// start := time.Now()
				blobPath := fmt.Sprintf("%s/%s/%s", schema, table, uuid.New().String())
				blobURL, err := azureClient.UploadAndGetURL(ctx, blobPath, b)
				if err != nil {
					return nil, &custom_errors.JobError{
						Msg:  fmt.Sprintf("Error uploading %s.%s.%s", schema, table, sourceColName),
						Prev: err,
					}
				}

				// logrus.Debugf(`Succesfully uploaded "%s", (%vms)`, blobURL, time.Since(start).Milliseconds())
				return blobURL, nil
			},
		})
	}
	return plan
}