// SPDX-FileCopyrightText: 2026 Stefan Majewsky <majewsky@gmx.net>
// SPDX-License-Identifier: Apache-2.0

package oblast

import (
	"errors"
	"fmt"
	"reflect"
)

// Insert executes an SQL INSERT statement for each of the provided records.
//
// Fields that are declared with the "auto" tag will not be written into the DB,
// and instead their value (as auto-generated by the DB on insert) will be placed in the record.
// On success, returns the original set of records, updated thusly.
//
// Returns an error if [NewStore] was called without the [TableNameIs] option, which is required to generate a query for this method.
func (s Store[R]) Insert(db Handle, records ...R) (returnedRecords []R, returnedError error) {
	// NOTE: This function body should be as short as possible to reduce the binary size after monomorphization.
	//       Any expression that does not depend on type R should be factored out into a reusable function.
	// TODO: minimize

	if s.plan.Insert.Query == "" {
		return nil, errors.New("cannot execute Insert() because query could not be autogenerated")
	}

	var (
		argumentIndexes = s.plan.Insert.ArgumentIndexes
		argumentSlots   = make([]any, len(argumentIndexes))
		scanIndexes     = s.plan.Insert.ScanIndexes
		scanSlots       []any
	)
	if len(scanIndexes) > 0 {
		scanSlots = make([]any, len(scanIndexes))
	}

	stmt, err := db.Prepare(s.plan.Insert.Query)
	if err != nil {
		return nil, fmt.Errorf("during Prepare(): %w", err)
	}
	defer func() {
		returnedError = mergeCloseError("Stmt", returnedError, stmt.Close())
	}()

	for idx := range records {
		v := reflect.ValueOf(&records[idx]).Elem()
		for idx, index := range argumentIndexes {
			argumentSlots[idx] = v.FieldByIndex(index).Addr().Interface()
		}

		if s.dialect.UsesLastInsertID() {
			result, err := stmt.Exec(argumentSlots...)
			if err != nil {
				return nil, fmt.Errorf("during Exec() for record with idx = %d: %w", idx, err)
			}
			id, err := result.LastInsertId()
			if err != nil {
				return nil, fmt.Errorf("during LastInsertId() for record with idx = %d: %w", idx, err)
			}
			if s.plan.FillIDWithSetInt {
				v.FieldByIndex(scanIndexes[0]).SetInt(id)
			} else if s.plan.FillIDWithSetUint {
				if id < 0 {
					return nil, fmt.Errorf("LastInsertId() = %d for record with idx = %d cannot be converted to uint", id, idx)
				}
				v.FieldByIndex(scanIndexes[0]).SetUint(uint64(id))
			}
		} else {
			for idx, index := range scanIndexes {
				scanSlots[idx] = v.FieldByIndex(index).Addr().Interface()
			}
			err := stmt.QueryRow(argumentSlots...).Scan(scanSlots...)
			if err != nil {
				return nil, fmt.Errorf("during QueryRow() for record with idx = %d: %w", idx, err)
			}
		}
	}

	return records, nil
}

// TODO: update

// Delete executes an SQL DELETE statement for each of the provided records, using their primary keys to locate the respective table rows.
//
// Returns an error if [NewStore] was called without the [TableNameIs] or [PrimaryKeyIs] options, which are both required to generate a query for this method.
func (s Store[R]) Delete(db Handle, records ...R) (returnedError error) {
	// NOTE: This function body should be as short as possible to reduce the binary size after monomorphization.
	//       Any expression that does not depend on type R should be factored out into a reusable function.
	// TODO: minimize

	if s.plan.Delete.Query == "" {
		return errors.New("cannot execute Delete() because query could not be autogenerated")
	}

	var (
		argumentIndexes = s.plan.Delete.ArgumentIndexes
		argumentSlots   = make([]any, len(argumentIndexes))
	)

	stmt, err := db.Prepare(s.plan.Delete.Query)
	if err != nil {
		return fmt.Errorf("during Prepare(): %w", err)
	}
	defer func() {
		returnedError = mergeCloseError("Stmt", returnedError, stmt.Close())
	}()

	for idx, r := range records {
		v := reflect.ValueOf(&r).Elem()
		for idx, index := range argumentIndexes {
			argumentSlots[idx] = v.FieldByIndex(index).Addr().Interface()
		}
		_, err := stmt.Exec(argumentSlots...)
		if err != nil {
			return fmt.Errorf("during Exec() for record with idx = %d: %w", idx, err)
		}
	}
	return nil
}