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 (
	ErrInvalidFunnelDefinition  = errors.New("invalid funnel definition")
	ErrFunnelDefinitionConflict = errors.New("funnel definition code conflict")
	funnelDefinitionCodeRe      = regexp.MustCompile(`^[a-z][a-z0-9_]{1,62}$`)
)

// FunnelDefinitionWriteBody is JSON for create/update.
type FunnelDefinitionWriteBody struct {
	Code   string `json:"code"`
	Title  string `json:"title"`
	Active bool   `json:"active"`
}

// CreateFunnelDefinition validates, inserts, audits.
func (s *Service) CreateFunnelDefinition(ctx context.Context, adminID uuid.UUID, body FunnelDefinitionWriteBody) (*repository.FunnelDefinitionRow, error) {
	in, err := normalizeFunnelDefinitionWrite(body)
	if err != nil {
		return nil, err
	}
	meta, _ := json.Marshal(map[string]any{"code": in.Code, "active": in.Active})
	row, err := s.Repo.CreateFunnelDefinitionWithAudit(ctx, adminID, in, meta)
	if repository.FunnelDefinitionCodeConflict(err) {
		return nil, ErrFunnelDefinitionConflict
	}
	return row, err
}

// UpdateFunnelDefinition validates, updates, audits.
func (s *Service) UpdateFunnelDefinition(ctx context.Context, adminID, id uuid.UUID, body FunnelDefinitionWriteBody) (*repository.FunnelDefinitionRow, error) {
	in, err := normalizeFunnelDefinitionWrite(body)
	if err != nil {
		return nil, err
	}
	meta, _ := json.Marshal(map[string]any{"code": in.Code, "active": in.Active})
	row, err := s.Repo.UpdateFunnelDefinitionWithAudit(ctx, adminID, id, in, meta)
	if errors.Is(err, pgx.ErrNoRows) {
		return nil, ErrFunnelDefinitionNotFound
	}
	if repository.FunnelDefinitionCodeConflict(err) {
		return nil, ErrFunnelDefinitionConflict
	}
	return row, err
}

func normalizeFunnelDefinitionWrite(body FunnelDefinitionWriteBody) (repository.FunnelDefinitionWriteInput, error) {
	code := strings.TrimSpace(body.Code)
	title := strings.TrimSpace(body.Title)
	if !funnelDefinitionCodeRe.MatchString(code) {
		return repository.FunnelDefinitionWriteInput{}, ErrInvalidFunnelDefinition
	}
	if title == "" || utf8.RuneCountInString(title) > 128 {
		return repository.FunnelDefinitionWriteInput{}, ErrInvalidFunnelDefinition
	}
	return repository.FunnelDefinitionWriteInput{Code: code, Title: title, Active: body.Active}, nil
}