package adapter

import (
	"cmp"
	"context"
	"encoding/json"
	"fmt"
	"slices"

	"entgo.io/ent/dialect/sql"

	"github.com/openmeterio/openmeter/openmeter/ent/db"
	taxcodedb "github.com/openmeterio/openmeter/openmeter/ent/db/taxcode"
	"github.com/openmeterio/openmeter/openmeter/taxcode"
	"github.com/openmeterio/openmeter/pkg/clock"
	"github.com/openmeterio/openmeter/pkg/framework/entutils"
	"github.com/openmeterio/openmeter/pkg/models"
	"github.com/openmeterio/openmeter/pkg/pagination"
)

func (a *adapter) CreateTaxCode(ctx context.Context, input taxcode.CreateTaxCodeInput) (taxcode.TaxCode, error) {
	if err := input.Validate(); err != nil {
		return taxcode.TaxCode{}, err
	}

	return entutils.TransactingRepo(ctx, a, func(ctx context.Context, a *adapter) (taxcode.TaxCode, error) {
		query := a.db.TaxCode.Create().
			SetNamespace(input.Namespace).
			SetKey(input.Key).
			SetName(input.Name).
			SetNillableDescription(input.Description).
			SetMetadata(input.Metadata).
			SetAnnotations(input.Annotations)

		if len(input.AppMappings) > 0 {
			query = query.SetAppMappings(&input.AppMappings)
		}

		entity, err := query.Save(ctx)
		if err != nil {
			if db.IsConstraintError(err) {
				return taxcode.TaxCode{}, models.NewGenericConflictError(fmt.Errorf("tax code with the same key already exists"))
			}

			return taxcode.TaxCode{}, fmt.Errorf("failed to create tax code: %w", err)
		}

		return MapTaxCodeFromEntity(entity)
	})
}

func (a *adapter) UpdateTaxCode(ctx context.Context, input taxcode.UpdateTaxCodeInput) (taxcode.TaxCode, error) {
	if err := input.Validate(); err != nil {
		return taxcode.TaxCode{}, err
	}

	return entutils.TransactingRepo(ctx, a, func(ctx context.Context, a *adapter) (taxcode.TaxCode, error) {
		query := a.db.TaxCode.UpdateOneID(input.ID).
			Where(taxcodedb.NamespaceEQ(input.Namespace)).
			Where(taxcodedb.DeletedAtIsNil()).
			SetName(input.Name).
			SetNillableDescription(input.Description).
			SetMetadata(input.Metadata).
			SetAnnotations(input.Annotations)

		if len(input.AppMappings) > 0 {
			query = query.SetAppMappings(&input.AppMappings)
		} else {
			query = query.ClearAppMappings()
		}

		entity, err := query.Save(ctx)
		if err != nil {
			if db.IsNotFound(err) {
				return taxcode.TaxCode{}, taxcode.NewTaxCodeNotFoundError(input.ID)
			}

			return taxcode.TaxCode{}, fmt.Errorf("failed to update tax code: %w", err)
		}

		return MapTaxCodeFromEntity(entity)
	})
}

func (a *adapter) ListTaxCodes(ctx context.Context, input taxcode.ListTaxCodesInput) (pagination.Result[taxcode.TaxCode], error) {
	if err := input.Validate(); err != nil {
		return pagination.Result[taxcode.TaxCode]{}, err
	}

	return entutils.TransactingRepo(ctx, a, func(ctx context.Context, a *adapter) (pagination.Result[taxcode.TaxCode], error) {
		query := a.db.TaxCode.Query().
			Where(taxcodedb.Namespace(input.Namespace))
		if !input.IncludeDeleted {
			query = query.Where(taxcodedb.DeletedAtIsNil())
		}

		entities, err := query.Paginate(ctx, input.Page)
		if err != nil {
			return pagination.Result[taxcode.TaxCode]{}, fmt.Errorf("failed to list tax codes: %w", err)
		}

		return pagination.MapResultErr(entities, MapTaxCodeFromEntity)
	})
}

func (a *adapter) GetTaxCode(ctx context.Context, input taxcode.GetTaxCodeInput) (taxcode.TaxCode, error) {
	if err := input.Validate(); err != nil {
		return taxcode.TaxCode{}, err
	}

	return entutils.TransactingRepo(ctx, a, func(ctx context.Context, a *adapter) (taxcode.TaxCode, error) {
		query := a.db.TaxCode.Query().
			Where(taxcodedb.Namespace(input.Namespace)).
			Where(taxcodedb.ID(input.ID))
		if !input.IncludeDeleted {
			query = query.Where(taxcodedb.DeletedAtIsNil())
		}

		entity, err := query.Only(ctx)
		if err != nil {
			if db.IsNotFound(err) {
				return taxcode.TaxCode{}, taxcode.NewTaxCodeNotFoundError(input.ID)
			}

			return taxcode.TaxCode{}, fmt.Errorf("failed to get tax code: %w", err)
		}

		return MapTaxCodeFromEntity(entity)
	})
}

func (a *adapter) GetTaxCodeByKey(ctx context.Context, input taxcode.GetTaxCodeByKeyInput) (taxcode.TaxCode, error) {
	if err := input.Validate(); err != nil {
		return taxcode.TaxCode{}, err
	}

	return entutils.TransactingRepo(ctx, a, func(ctx context.Context, a *adapter) (taxcode.TaxCode, error) {
		query := a.db.TaxCode.Query().
			Where(taxcodedb.Namespace(input.Namespace)).
			Where(taxcodedb.Key(input.Key)).
			Where(taxcodedb.DeletedAtIsNil())

		entity, err := query.Only(ctx)
		if err != nil {
			if db.IsNotFound(err) {
				return taxcode.TaxCode{}, taxcode.NewTaxCodeByKeyNotFoundError(input.Key)
			}

			return taxcode.TaxCode{}, fmt.Errorf("failed to get tax code by key: %w", err)
		}

		return MapTaxCodeFromEntity(entity)
	})
}

func (a *adapter) GetTaxCodeByAppMapping(ctx context.Context, input taxcode.GetTaxCodeByAppMappingInput) (taxcode.TaxCode, error) {
	if err := input.Validate(); err != nil {
		return taxcode.TaxCode{}, err
	}

	return entutils.TransactingRepo(ctx, a, func(ctx context.Context, a *adapter) (taxcode.TaxCode, error) {
		// Build a JSONB containment query: app_mappings @> '[{"app_type": "...", "tax_code": "..."}]'
		pattern, err := json.Marshal([]taxcode.TaxCodeAppMapping{
			{AppType: input.AppType, TaxCode: input.TaxCode},
		})
		if err != nil {
			return taxcode.TaxCode{}, fmt.Errorf("failed to marshal app mapping pattern: %w", err)
		}

		entities, err := a.db.TaxCode.Query().
			Where(taxcodedb.Namespace(input.Namespace)).
			Where(taxcodedb.DeletedAtIsNil()).
			Where(func(s *sql.Selector) {
				s.Where(sql.P(func(b *sql.Builder) {
					b.Ident(taxcodedb.FieldAppMappings).WriteString(" @> ").Arg(string(pattern))
				}))
			}).
			All(ctx)
		if err != nil {
			return taxcode.TaxCode{}, fmt.Errorf("failed to get tax code by app mapping: %w", err)
		}

		if len(entities) == 0 {
			return taxcode.TaxCode{}, taxcode.NewTaxCodeByAppMappingNotFoundError(
				string(input.AppType), input.TaxCode,
			)
		}

		slices.SortStableFunc(entities, func(a, b *db.TaxCode) int {
			aManagedBy, _ := a.Annotations.GetString(taxcode.AnnotationKeyManagedBy)
			bManagedBy, _ := b.Annotations.GetString(taxcode.AnnotationKeyManagedBy)

			aSystemManaged := aManagedBy == taxcode.AnnotationValueManagedBySystem
			bSystemManaged := bManagedBy == taxcode.AnnotationValueManagedBySystem

			if aSystemManaged && !bSystemManaged {
				return -1
			}

			if !aSystemManaged && bSystemManaged {
				return 1
			}

			if byCreatedAt := a.CreatedAt.Compare(b.CreatedAt); byCreatedAt != 0 {
				return byCreatedAt
			}

			return cmp.Compare(a.ID, b.ID)
		})

		return MapTaxCodeFromEntity(entities[0])
	})
}

func (a *adapter) DeleteTaxCode(ctx context.Context, input taxcode.DeleteTaxCodeInput) error {
	if err := input.Validate(); err != nil {
		return err
	}

	return entutils.TransactingRepoWithNoValue(ctx, a, func(ctx context.Context, a *adapter) error {
		entity, err := a.db.TaxCode.Query().
			Where(taxcodedb.Namespace(input.Namespace)).
			Where(taxcodedb.ID(input.ID)).
			Only(ctx)
		if err != nil {
			if db.IsNotFound(err) {
				return taxcode.NewTaxCodeNotFoundError(input.ID)
			}

			return fmt.Errorf("failed to get tax code: %w", err)
		}

		if entity.DeletedAt == nil {
			err := a.db.TaxCode.UpdateOneID(input.ID).
				Where(taxcodedb.Namespace(input.Namespace)).
				SetDeletedAt(clock.Now()).
				Exec(ctx)
			if err != nil {
				return fmt.Errorf("failed to delete tax code: %w", err)
			}
		}

		return nil
	})
}