package document_scraper

import (
	"context"
	"fmt"
	"strings"
	"time"
	"tm/internal/tender"
	"tm/pkg/ai_summarizer"
	"tm/pkg/logger"
	"tm/pkg/response"
)

// ScrapePortalsProvider fetches supported document scraping portal identifiers.
type ScrapePortalsProvider interface {
	GetScrapePortals(ctx context.Context) (*ai_summarizer.ScrapePortalsResponse, error)
}

// Service defines business logic for the document scraper API
type Service interface {
	// ListPendingTenders retrieves tenders that need document scraping
	ListPendingTenders(ctx context.Context, req DocumentScraperListRequest) (*DocumentScraperListResponse, *response.Meta, error)
	// GetTenderByNoticeID retrieves a specific tender by its notice publication ID
	GetTenderByNoticeID(ctx context.Context, noticeID string) (*DocumentScraperTenderResponse, error)
}

type service struct {
	tenderRepo      tender.TenderRepository
	portalsProvider ScrapePortalsProvider
	logger          logger.Logger
}

// NewService creates a new document scraper service
func NewService(tenderRepo tender.TenderRepository, portalsProvider ScrapePortalsProvider, logger logger.Logger) Service {
	return &service{
		tenderRepo:      tenderRepo,
		portalsProvider: portalsProvider,
		logger:          logger,
	}
}

func (s *service) fetchScrapePortals(ctx context.Context) ([]string, error) {
	if s.portalsProvider == nil {
		s.logger.Warn("Scrape portals provider not configured", map[string]interface{}{})
		return nil, ErrScrapePortalsUnavailable
	}

	resp, err := s.portalsProvider.GetScrapePortals(ctx)
	if err != nil {
		s.logger.Error("Failed to fetch scrape portals", map[string]interface{}{
			"error": err.Error(),
		})
		return nil, fmt.Errorf("fetch scrape portals: %w", err)
	}
	if resp == nil {
		return nil, nil
	}

	portals := make([]string, 0, len(*resp))
	for _, portal := range *resp {
		if p := strings.TrimSpace(portal); p != "" {
			portals = append(portals, p)
		}
	}
	return portals, nil
}

// ListPendingTenders retrieves tenders that have not yet been scraped for documents.
// Only returns tenders whose document URL matches a portal supported by the AI service.
// By default only tenders with an active publication submission window are included; set IncludeExpired to include expired tenders.
func (s *service) ListPendingTenders(ctx context.Context, req DocumentScraperListRequest) (*DocumentScraperListResponse, *response.Meta, error) {
	req.Normalize()

	if req.CreatedAtFrom != nil && req.CreatedAtTo != nil && *req.CreatedAtFrom > *req.CreatedAtTo {
		return nil, nil, ErrInvalidDateRange
	}

	portals, err := s.fetchScrapePortals(ctx)
	if err != nil {
		return nil, nil, err
	}
	if len(portals) == 0 {
		s.logger.Info("No scrape portals configured; returning empty pending tender list", map[string]interface{}{})
		meta := &response.Meta{Total: 0, Limit: req.Limit, Offset: req.Offset, HasMore: false}
		if meta.Limit > 0 {
			meta.Page = (req.Offset / meta.Limit) + 1
		}
		return &DocumentScraperListResponse{Tenders: []DocumentScraperTenderResponse{}}, meta, nil
	}

	s.logger.Info("Listing pending tenders for document scraper", map[string]interface{}{
		"limit":           req.Limit,
		"offset":          req.Offset,
		"created_at_from": req.CreatedAtFrom,
		"created_at_to":   req.CreatedAtTo,
		"include_expired": req.IncludeExpired,
		"portal_count":    len(portals),
	})

	filter := tender.PendingDocumentScrapeFilter{
		Portals:       portals,
		CreatedAtFrom: req.CreatedAtFrom,
		CreatedAtTo:   req.CreatedAtTo,
		Limit:         req.Limit,
		Skip:          req.Offset,
	}
	if !req.IncludeExpired {
		now := time.Now().Unix()
		filter.MinWindowEnd = &now
	}

	tenders, hasMore, err := s.tenderRepo.GetPendingDocumentScrapeTenders(ctx, filter)
	if err != nil {
		s.logger.Error("Failed to list pending tenders", map[string]interface{}{
			"error": err.Error(),
		})
		return nil, nil, fmt.Errorf("failed to list pending tenders: %w", err)
	}

	if !req.IncludeExpired {
		now := time.Now().Unix()
		tenders = filterActivePublicationWindow(tenders, now)
	}

	result := &DocumentScraperListResponse{
		Tenders: make([]DocumentScraperTenderResponse, len(tenders)),
	}

	for i := range tenders {
		result.Tenders[i] = *BuildDocumentScraperTenderResponse(&tenders[i])
	}

	meta := &response.Meta{
		Total:   len(tenders),
		Limit:   req.Limit,
		Offset:  req.Offset,
		HasMore: hasMore,
	}
	if meta.Limit > 0 {
		meta.Page = (req.Offset / meta.Limit) + 1
	}

	s.logger.Info("Pending tenders retrieved successfully", map[string]interface{}{
		"count":    len(tenders),
		"has_more": hasMore,
	})

	return result, meta, nil
}

// GetTenderByNoticeID retrieves a specific tender by its notice publication ID.
// Only returns tenders with an active publication submission window whose document URL matches a supported scrape portal.
func (s *service) GetTenderByNoticeID(ctx context.Context, noticeID string) (*DocumentScraperTenderResponse, error) {
	s.logger.Info("Getting tender by notice ID for document scraper", map[string]interface{}{
		"notice_id": noticeID,
	})

	portals, err := s.fetchScrapePortals(ctx)
	if err != nil {
		return nil, err
	}

	t, err := s.tenderRepo.GetByNoticePublicationID(ctx, noticeID)
	if err != nil {
		s.logger.Error("Failed to get tender by notice ID", map[string]interface{}{
			"notice_id": noticeID,
			"error":     err.Error(),
		})
		return nil, fmt.Errorf("failed to get tender: %w", err)
	}

	if t == nil {
		return nil, fmt.Errorf("tender not found")
	}

	now := time.Now().Unix()
	if !t.HasActivePublicationWindow(now) || !matchesScrapePortals(documentURL(t), portals) {
		s.logger.Info("Tender filtered out: unsupported portal or publication window closed", map[string]interface{}{
			"notice_id":            noticeID,
			"publication_date":     t.PublicationDate,
			"submission_deadline":  t.SubmissionDeadline,
			"publication_deadline": t.PublicationSubmissionDeadline(),
			"now":                  now,
		})
		return nil, fmt.Errorf("tender not found")
	}

	result := BuildDocumentScraperTenderResponse(t)

	s.logger.Info("Tender retrieved successfully for document scraper", map[string]interface{}{
		"notice_id": noticeID,
		"tender_id": t.ID.Hex(),
	})

	return result, nil
}

func filterActivePublicationWindow(tenders []tender.Tender, now int64) []tender.Tender {
	if len(tenders) == 0 {
		return tenders
	}
	active := make([]tender.Tender, 0, len(tenders))
	for i := range tenders {
		if tenders[i].HasActivePublicationWindow(now) {
			active = append(active, tenders[i])
		}
	}
	return active
}