package calendar

import (
	"context"
	"errors"
	"time"

	"github.com/jackc/pgx/v5"
)

var ErrAttachmentNotFound = errors.New("attachment not found")

type Attachment struct {
	ID               string    `json:"id"`
	CalendarItemID   string    `json:"calendar_item_id"`
	OriginalFilename string    `json:"original_filename"`
	StoredFilename   string    `json:"stored_filename"`
	MimeType         string    `json:"mime_type"`
	SizeBytes        int64     `json:"size_bytes"`
	StorageDriver    string    `json:"storage_driver"`
	StoragePath      string    `json:"-"`
	CreatedBy        *string   `json:"created_by"`
	CreatedAt        time.Time `json:"created_at"`
}

type CreateAttachmentInput struct {
	CalendarItemID   string
	OriginalFilename string
	StoredFilename   string
	MimeType         string
	SizeBytes        int64
	StorageDriver    string
	StoragePath      string
	CreatedBy        string
}

func (s Store) CreateAttachment(ctx context.Context, input CreateAttachmentInput) (Attachment, error) {
	row := s.db.QueryRow(ctx, `
		INSERT INTO calendar_item_attachments (
			calendar_item_id,
			original_filename,
			stored_filename,
			mime_type,
			size_bytes,
			storage_driver,
			storage_path,
			created_by
		)
		VALUES ($1::uuid, $2, $3, $4, $5, $6, $7, NULLIF($8, '')::uuid)
		RETURNING
			id::text,
			calendar_item_id::text,
			original_filename,
			stored_filename,
			mime_type,
			size_bytes,
			storage_driver,
			storage_path,
			created_by::text,
			created_at
	`, input.CalendarItemID, input.OriginalFilename, input.StoredFilename, input.MimeType, input.SizeBytes, input.StorageDriver, input.StoragePath, input.CreatedBy)

	return scanAttachment(row)
}

func (s Store) ListAttachments(ctx context.Context, calendarItemID string, viewerUserID string) ([]Attachment, error) {
	rows, err := s.db.Query(ctx, `
		SELECT
			calendar_item_attachments.id::text,
			calendar_item_attachments.calendar_item_id::text,
			calendar_item_attachments.original_filename,
			calendar_item_attachments.stored_filename,
			calendar_item_attachments.mime_type,
			calendar_item_attachments.size_bytes,
			calendar_item_attachments.storage_driver,
			calendar_item_attachments.storage_path,
			calendar_item_attachments.created_by::text,
			calendar_item_attachments.created_at
		FROM calendar_item_attachments
		INNER JOIN calendar_items ON calendar_items.id = calendar_item_attachments.calendar_item_id
		WHERE calendar_item_attachments.calendar_item_id = $1::uuid
		AND (
			$2 = ''
			OR EXISTS (
				SELECT 1
				FROM client_users
				WHERE client_users.client_id = calendar_items.client_id
				AND client_users.user_id = $2::uuid
			)
		)
		ORDER BY calendar_item_attachments.created_at DESC
	`, calendarItemID, viewerUserID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	attachments := []Attachment{}
	for rows.Next() {
		attachment, err := scanAttachment(rows)
		if err != nil {
			return nil, err
		}
		attachments = append(attachments, attachment)
	}

	return attachments, rows.Err()
}

func (s Store) FindAttachment(ctx context.Context, id string, viewerUserID string) (Attachment, error) {
	row := s.db.QueryRow(ctx, `
		SELECT
			calendar_item_attachments.id::text,
			calendar_item_attachments.calendar_item_id::text,
			calendar_item_attachments.original_filename,
			calendar_item_attachments.stored_filename,
			calendar_item_attachments.mime_type,
			calendar_item_attachments.size_bytes,
			calendar_item_attachments.storage_driver,
			calendar_item_attachments.storage_path,
			calendar_item_attachments.created_by::text,
			calendar_item_attachments.created_at
		FROM calendar_item_attachments
		INNER JOIN calendar_items ON calendar_items.id = calendar_item_attachments.calendar_item_id
		WHERE calendar_item_attachments.id = $1::uuid
		AND (
			$2 = ''
			OR EXISTS (
				SELECT 1
				FROM client_users
				WHERE client_users.client_id = calendar_items.client_id
				AND client_users.user_id = $2::uuid
			)
		)
	`, id, viewerUserID)

	return scanAttachment(row)
}

func (s Store) DeleteAttachment(ctx context.Context, id string) (Attachment, error) {
	row := s.db.QueryRow(ctx, `
		DELETE FROM calendar_item_attachments
		WHERE id = $1::uuid
		RETURNING
			id::text,
			calendar_item_id::text,
			original_filename,
			stored_filename,
			mime_type,
			size_bytes,
			storage_driver,
			storage_path,
			created_by::text,
			created_at
	`, id)

	return scanAttachment(row)
}

type attachmentScanner interface {
	Scan(dest ...any) error
}

func scanAttachment(row attachmentScanner) (Attachment, error) {
	var attachment Attachment
	err := row.Scan(
		&attachment.ID,
		&attachment.CalendarItemID,
		&attachment.OriginalFilename,
		&attachment.StoredFilename,
		&attachment.MimeType,
		&attachment.SizeBytes,
		&attachment.StorageDriver,
		&attachment.StoragePath,
		&attachment.CreatedBy,
		&attachment.CreatedAt,
	)
	if errors.Is(err, pgx.ErrNoRows) {
		return Attachment{}, ErrAttachmentNotFound
	}
	if err != nil {
		return Attachment{}, err
	}
	return attachment, nil
}