package home

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

	"github.com/google/uuid"

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

var (
	ErrInvalidTools = errors.New("invalid home tools")
	ErrTooManyTools = errors.New("too many home tools")
)

var pathRe = regexp.MustCompile(`^/[a-zA-Z0-9_./-]{1,120}$`)

var allowedIcons = map[string]struct{}{
	"mbti": {}, "star": {}, "portrait": {}, "rhythm": {}, "synastry": {}, "astro": {},
	"companion": {}, "ask": {}, "cards": {}, "reports": {}, "growth": {}, "relation": {},
}

// Service serves homepage tool catalog.
type Service struct {
	Repo *repository.HomeToolsRepo
}

// ListPublic returns enabled tools.
func (s *Service) ListPublic(ctx context.Context) ([]repository.HomeTool, error) {
	return s.Repo.ListEnabled(ctx)
}

// ListAdmin returns all tools.
func (s *Service) ListAdmin(ctx context.Context) ([]repository.HomeTool, error) {
	return s.Repo.ListAll(ctx)
}

// ReplaceInput is one tool in a PUT body (id optional).
type ReplaceInput struct {
	ID        string  `json:"id"`
	RowIndex  int     `json:"row_index"`
	SortOrder int     `json:"sort_order"`
	Path      string  `json:"path"`
	Icon      string  `json:"icon"`
	Label     string  `json:"label"`
	Badge     *string `json:"badge"`
	BadgeTone *string `json:"badge_tone"`
	Enabled   bool    `json:"enabled"`
}

// Replace validates and replaces all tools.
func (s *Service) Replace(ctx context.Context, items []ReplaceInput) error {
	return s.ReplaceWithAudit(ctx, uuid.Nil, items, nil)
}

// ReplaceWithAudit validates, replaces, and audits in one transaction when adminID set.
func (s *Service) ReplaceWithAudit(
	ctx context.Context,
	adminID uuid.UUID,
	items []ReplaceInput,
	meta json.RawMessage,
) error {
	if len(items) == 0 {
		return ErrInvalidTools
	}
	if len(items) > 24 {
		return ErrTooManyTools
	}
	rows := make([]repository.HomeTool, 0, len(items))
	for _, in := range items {
		t, err := normalizeTool(in)
		if err != nil {
			return err
		}
		rows = append(rows, *t)
	}
	return s.Repo.ReplaceAllWithAudit(ctx, rows, adminID, meta)
}

func normalizeTool(in ReplaceInput) (*repository.HomeTool, error) {
	if in.RowIndex != 1 && in.RowIndex != 2 {
		return nil, ErrInvalidTools
	}
	path := strings.TrimSpace(in.Path)
	if !pathRe.MatchString(path) || strings.Contains(path, "..") {
		return nil, ErrInvalidTools
	}
	icon := strings.TrimSpace(in.Icon)
	if _, ok := allowedIcons[icon]; !ok {
		return nil, ErrInvalidTools
	}
	label := strings.TrimSpace(in.Label)
	n := utf8.RuneCountInString(label)
	if n < 1 || n > 16 {
		return nil, ErrInvalidTools
	}
	var badge, tone *string
	if in.Badge != nil {
		b := strings.TrimSpace(*in.Badge)
		if b != "" {
			if utf8.RuneCountInString(b) > 4 {
				return nil, ErrInvalidTools
			}
			badge = &b
		}
	}
	if in.BadgeTone != nil {
		t := strings.TrimSpace(*in.BadgeTone)
		if t != "" && t != "hot" && t != "new" {
			return nil, ErrInvalidTools
		}
		if t != "" {
			tone = &t
		}
	}
	id := uuid.Nil
	if strings.TrimSpace(in.ID) != "" {
		parsed, err := uuid.Parse(in.ID)
		if err != nil {
			return nil, ErrInvalidTools
		}
		id = parsed
	}
	return &repository.HomeTool{
		ID: id, RowIndex: in.RowIndex, SortOrder: in.SortOrder,
		Path: path, Icon: icon, Label: label, Badge: badge, BadgeTone: tone, Enabled: in.Enabled,
	}, nil
}