package company

import (
	"context"
	"errors"
	"strings"

	"github.com/asaskevich/govalidator"
)

const maxCompanyLinks = 20

// AddLinksResponse is returned after appending links to a company.
type AddLinksResponse struct {
	Links []CompanyLink `json:"links"`
	Added []CompanyLink `json:"added"`
}

// AddLinks appends validated links to a company.
func (s *companyService) AddLinks(ctx context.Context, companyID string, form *AddLinksForm) (*AddLinksResponse, error) {
	if form == nil || len(form.Links) == 0 {
		return nil, errors.New("no links provided")
	}
	if len(form.Links) > maxCompanyLinks {
		return nil, errors.New("too many links in request")
	}

	company, err := s.repository.GetByID(ctx, companyID)
	if err != nil {
		return nil, errors.New("company not found")
	}

	newLinks, err := sanitizeCompanyLinks(convertCompanyLinkForms(form.Links))
	if err != nil {
		return nil, err
	}
	if len(newLinks) == 0 {
		return nil, errors.New("no valid links provided")
	}

	existing := sanitizeStoredCompanyLinks(company.Links)
	merged, added := mergeCompanyLinks(existing, newLinks)
	if len(merged) > maxCompanyLinks {
		return nil, errors.New("company link limit exceeded")
	}

	company.Links = merged
	if err := s.repository.Update(ctx, company); err != nil {
		s.logger.Error("Failed to save company links", map[string]interface{}{
			"error":      err.Error(),
			"company_id": companyID,
		})
		return nil, errors.New("failed to update company links")
	}

	s.logger.Info("Company links added", map[string]interface{}{
		"company_id":   companyID,
		"added_count":  len(added),
		"links_total":  len(company.Links),
	})

	s.triggerAIOnboardingAsync(companyID)

	return &AddLinksResponse{
		Links: company.Links,
		Added: added,
	}, nil
}

func convertCompanyLinkForms(forms []CompanyLinkForm) []CompanyLink {
	if len(forms) == 0 {
		return nil
	}

	links := make([]CompanyLink, 0, len(forms))
	for _, form := range forms {
		links = append(links, CompanyLink{
			URL:   form.URL,
			Title: form.Title,
		})
	}
	return links
}

func sanitizeCompanyLinks(links []CompanyLink) ([]CompanyLink, error) {
	if len(links) == 0 {
		return nil, nil
	}

	sanitized := make([]CompanyLink, 0, len(links))
	for _, link := range links {
		url := strings.TrimSpace(link.URL)
		if url == "" {
			continue
		}
		if !govalidator.IsURL(url) {
			return nil, errors.New("invalid link URL")
		}

		var title *string
		if link.Title != nil {
			trimmed := strings.TrimSpace(*link.Title)
			if trimmed != "" {
				title = &trimmed
			}
		}

		sanitized = append(sanitized, CompanyLink{
			URL:   url,
			Title: title,
		})
	}
	return sanitized, nil
}

func sanitizeStoredCompanyLinks(links []CompanyLink) []CompanyLink {
	sanitized, err := sanitizeCompanyLinks(links)
	if err != nil || len(sanitized) == 0 {
		return nil
	}
	return sanitized
}

func mergeCompanyLinks(existing, additional []CompanyLink) ([]CompanyLink, []CompanyLink) {
	seen := make(map[string]struct{}, len(existing)+len(additional))
	merged := make([]CompanyLink, 0, len(existing)+len(additional))
	added := make([]CompanyLink, 0, len(additional))

	appendUnique := func(items []CompanyLink, trackAdded bool) {
		for _, item := range items {
			key := strings.ToLower(strings.TrimSpace(item.URL))
			if key == "" {
				continue
			}
			if _, ok := seen[key]; ok {
				continue
			}
			seen[key] = struct{}{}
			merged = append(merged, item)
			if trackAdded {
				added = append(added, item)
			}
		}
	}

	appendUnique(existing, false)
	appendUnique(additional, true)
	return merged, added
}

func companyLinkURLs(links []CompanyLink) []string {
	if len(links) == 0 {
		return nil
	}

	urls := make([]string, 0, len(links))
	for _, link := range links {
		url := strings.TrimSpace(link.URL)
		if url != "" {
			urls = append(urls, url)
		}
	}
	return urls
}