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 (
	ErrInvalidScaleDefinition  = errors.New("invalid scale definition")
	ErrScaleDefinitionConflict = errors.New("scale slug conflict")
	scaleSlugRe                = regexp.MustCompile(`^[a-z][a-z0-9-]{1,62}$`)
)

// ScaleDefinitionWriteBody is explore-side JSON (no status).
type ScaleDefinitionWriteBody struct {
	Slug        string `json:"slug"`
	Title       string `json:"title"`
	Description string `json:"description"`
}

// CreateScaleDefinition creates draft metadata.
func (s *Service) CreateScaleDefinition(ctx context.Context, adminID uuid.UUID, body ScaleDefinitionWriteBody) (*repository.ScaleAdminItem, error) {
	if s.Scales == nil {
		return nil, errors.New("scales unavailable")
	}
	in, err := normalizeScaleDefinitionWrite(body)
	if err != nil {
		return nil, err
	}
	meta, _ := json.Marshal(map[string]any{"slug": in.Slug})
	row, err := s.Scales.CreateScaleDefinitionWithAudit(ctx, adminID, in, meta)
	if repository.ScaleSlugConflict(err) {
		return nil, ErrScaleDefinitionConflict
	}
	return row, err
}

// UpdateScaleDefinition updates metadata; preserves status.
func (s *Service) UpdateScaleDefinition(ctx context.Context, adminID, id uuid.UUID, body ScaleDefinitionWriteBody) (*repository.ScaleAdminItem, error) {
	if s.Scales == nil {
		return nil, errors.New("scales unavailable")
	}
	in, err := normalizeScaleDefinitionWrite(body)
	if err != nil {
		return nil, err
	}
	meta, _ := json.Marshal(map[string]any{"slug": in.Slug})
	row, err := s.Scales.UpdateScaleDefinitionWithAudit(ctx, adminID, id, in, meta)
	if errors.Is(err, pgx.ErrNoRows) {
		return nil, ErrScaleNotFound
	}
	if repository.ScaleSlugConflict(err) {
		return nil, ErrScaleDefinitionConflict
	}
	return row, err
}

func normalizeScaleDefinitionWrite(body ScaleDefinitionWriteBody) (repository.ScaleDefinitionWriteInput, error) {
	slug := strings.TrimSpace(body.Slug)
	title := strings.TrimSpace(body.Title)
	desc := strings.TrimSpace(body.Description)
	if !scaleSlugRe.MatchString(slug) {
		return repository.ScaleDefinitionWriteInput{}, ErrInvalidScaleDefinition
	}
	if title == "" || utf8.RuneCountInString(title) > 128 {
		return repository.ScaleDefinitionWriteInput{}, ErrInvalidScaleDefinition
	}
	if utf8.RuneCountInString(desc) > 512 {
		return repository.ScaleDefinitionWriteInput{}, ErrInvalidScaleDefinition
	}
	return repository.ScaleDefinitionWriteInput{Slug: slug, Title: title, Description: desc}, nil
}