package admin

import (
	"context"
	"encoding/json"
	"errors"
	"regexp"
	"strings"
	"unicode/utf8"

	"github.com/google/uuid"
	"github.com/jackc/pgx/v5"

	"github.com/yuxingu/digital-psychology/apps/api/internal/repository"
)

var (
	ErrInvalidFeedSlot  = errors.New("invalid feed slot")
	ErrFeedSlotConflict = errors.New("feed slot code conflict")
	slotCodeRe          = regexp.MustCompile(`^[a-z][a-z0-9_]{1,62}$`)
	slotKeyRe           = regexp.MustCompile(`^[a-z][a-z0-9_.]{1,62}$`)
)

// FeedSlotWriteBody is JSON for create/update.
type FeedSlotWriteBody struct {
	Code      string `json:"code"`
	Title     string `json:"title"`
	SlotKey   string `json:"slot_key"`
	Placement string `json:"placement"`
	Active    bool   `json:"active"`
}

// CreateFeedSlot validates, inserts, audits.
func (s *Service) CreateFeedSlot(ctx context.Context, adminID uuid.UUID, body FeedSlotWriteBody) (*repository.FeedSlotRow, error) {
	in, err := normalizeFeedSlotWrite(body)
	if err != nil {
		return nil, err
	}
	meta, _ := json.Marshal(map[string]any{"code": in.Code, "active": in.Active})
	row, err := s.Repo.CreateFeedSlotWithAudit(ctx, adminID, in, meta)
	if repository.FeedSlotCodeConflict(err) {
		return nil, ErrFeedSlotConflict
	}
	return row, err
}

// UpdateFeedSlot validates, updates, audits.
func (s *Service) UpdateFeedSlot(ctx context.Context, adminID, id uuid.UUID, body FeedSlotWriteBody) (*repository.FeedSlotRow, error) {
	in, err := normalizeFeedSlotWrite(body)
	if err != nil {
		return nil, err
	}
	meta, _ := json.Marshal(map[string]any{"code": in.Code, "active": in.Active})
	row, err := s.Repo.UpdateFeedSlotWithAudit(ctx, adminID, id, in, meta)
	if errors.Is(err, pgx.ErrNoRows) {
		return nil, ErrFeedSlotNotFound
	}
	if repository.FeedSlotCodeConflict(err) {
		return nil, ErrFeedSlotConflict
	}
	return row, err
}

func normalizeFeedSlotWrite(body FeedSlotWriteBody) (repository.FeedSlotWriteInput, error) {
	code := strings.TrimSpace(body.Code)
	title := strings.TrimSpace(body.Title)
	slotKey := strings.TrimSpace(body.SlotKey)
	placement := strings.TrimSpace(body.Placement)
	if !slotCodeRe.MatchString(code) || !slotKeyRe.MatchString(slotKey) {
		return repository.FeedSlotWriteInput{}, ErrInvalidFeedSlot
	}
	if title == "" || utf8.RuneCountInString(title) > 128 {
		return repository.FeedSlotWriteInput{}, ErrInvalidFeedSlot
	}
	if _, ok := bannerPlacements[placement]; !ok {
		return repository.FeedSlotWriteInput{}, ErrInvalidFeedSlot
	}
	return repository.FeedSlotWriteInput{
		Code: code, Title: title, SlotKey: slotKey, Placement: placement, Active: body.Active,
	}, nil
}