package staff

import (
	"context"
	"fmt"
	"io"
	"log"
	"net/http"
	"net/url"
	"regexp"
	"strings"
	"sync"
	"time"

	"github.com/google/uuid"

	"github.com/breakpilot/edu-search-service/internal/database"
)

// StaffCrawler crawls university websites for staff information
type StaffCrawler struct {
	client      *http.Client
	userAgent   string
	rateLimit   time.Duration
	lastFetch   map[string]time.Time
	mu          sync.Mutex
	repo        *database.Repository
	patterns    *UniversityPatterns
}

// CrawlResult contains the result of a staff crawl
type CrawlResult struct {
	UniversityID uuid.UUID
	StaffFound   int
	StaffNew     int
	StaffUpdated int
	Errors       []string
	Duration     time.Duration
}

// NewStaffCrawler creates a new staff crawler
func NewStaffCrawler(repo *database.Repository) *StaffCrawler {
	return &StaffCrawler{
		client: &http.Client{
			Timeout: 30 * time.Second,
			CheckRedirect: func(req *http.Request, via []*http.Request) error {
				if len(via) >= 5 {
					return fmt.Errorf("too many redirects")
				}
				return nil
			},
		},
		userAgent: "BreakPilot-EduBot/1.0 (+https://breakpilot.de/bot)",
		rateLimit: 2 * time.Second, // 0.5 requests/second per domain
		lastFetch: make(map[string]time.Time),
		repo:      repo,
		patterns:  NewUniversityPatterns(),
	}
}

// CrawlUniversity crawls a single university for staff
func (c *StaffCrawler) CrawlUniversity(ctx context.Context, uni *database.University) (*CrawlResult, error) {
	start := time.Now()
	result := &CrawlResult{
		UniversityID: uni.ID,
	}

	log.Printf("Starting staff crawl for %s (%s)", uni.Name, uni.URL)

	// Find staff pages
	staffPages, err := c.findStaffPages(ctx, uni)
	if err != nil {
		result.Errors = append(result.Errors, fmt.Sprintf("Failed to find staff pages: %v", err))
		return result, err
	}

	log.Printf("Found %d potential staff pages for %s", len(staffPages), uni.Name)

	// Crawl each staff page
	for _, pageURL := range staffPages {
		select {
		case <-ctx.Done():
			result.Errors = append(result.Errors, "Crawl cancelled")
			return result, ctx.Err()
		default:
		}

		staffMembers, err := c.extractStaffFromPage(ctx, pageURL, uni)
		if err != nil {
			result.Errors = append(result.Errors, fmt.Sprintf("Error crawling %s: %v", pageURL, err))
			continue
		}

		for _, staff := range staffMembers {
			staff.UniversityID = uni.ID
			staff.SourceURL = &pageURL

			err := c.repo.CreateStaff(ctx, staff)
			if err != nil {
				errMsg := fmt.Sprintf("Error saving staff %s %s: %v", stringValue(staff.FirstName), staff.LastName, err)
				result.Errors = append(result.Errors, errMsg)
				// Log first few errors for debugging
				if len(result.Errors) <= 5 {
					log.Printf("[StaffCrawler] %s", errMsg)
				}
				continue
			}

			result.StaffFound++
			if staff.CreatedAt.Equal(staff.UpdatedAt) {
				result.StaffNew++
			} else {
				result.StaffUpdated++
			}
		}
	}

	result.Duration = time.Since(start)

	// Note: Profile enrichment is now handled by AI (vast.ai)
	// The crawler only extracts profile links, AI extracts detailed data
	log.Printf("Crawl complete. Profile enrichment will be handled by AI extraction.")

	// Update crawl status
	now := time.Now()
	status := &database.UniversityCrawlStatus{
		UniversityID:     uni.ID,
		LastStaffCrawl:   &now,
		StaffCrawlStatus: "completed",
		StaffCount:       result.StaffFound,
		StaffErrors:      result.Errors,
	}
	if err := c.repo.UpdateCrawlStatus(ctx, status); err != nil {
		log.Printf("Warning: Failed to update crawl status: %v", err)
	}

	log.Printf("Completed staff crawl for %s: found=%d, new=%d, updated=%d, errors=%d, duration=%v",
		uni.Name, result.StaffFound, result.StaffNew, result.StaffUpdated, len(result.Errors), result.Duration)

	return result, nil
}

// fetchPage fetches a page with rate limiting
func (c *StaffCrawler) fetchPage(ctx context.Context, urlStr string) ([]byte, error) {
	c.waitForRateLimit(urlStr)

	req, err := http.NewRequestWithContext(ctx, "GET", urlStr, nil)
	if err != nil {
		return nil, err
	}

	req.Header.Set("User-Agent", c.userAgent)
	req.Header.Set("Accept", "text/html,application/xhtml+xml")
	req.Header.Set("Accept-Language", "de-DE,de;q=0.9,en;q=0.8")

	resp, err := c.client.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("HTTP %d", resp.StatusCode)
	}

	// Limit to 10MB
	body, err := io.ReadAll(io.LimitReader(resp.Body, 10*1024*1024))
	if err != nil {
		return nil, err
	}

	return body, nil
}

// waitForRateLimit enforces rate limiting per domain
func (c *StaffCrawler) waitForRateLimit(urlStr string) {
	u, err := url.Parse(urlStr)
	if err != nil {
		return
	}

	host := u.Host

	c.mu.Lock()
	defer c.mu.Unlock()

	if last, ok := c.lastFetch[host]; ok {
		elapsed := time.Since(last)
		if elapsed < c.rateLimit {
			time.Sleep(c.rateLimit - elapsed)
		}
	}

	c.lastFetch[host] = time.Now()
}

// resolveURL resolves a relative URL against a base URL
func resolveURL(baseURL, href string) string {
	if href == "" {
		return ""
	}

	// Already absolute
	if strings.HasPrefix(href, "http://") || strings.HasPrefix(href, "https://") {
		return href
	}

	base, err := url.Parse(baseURL)
	if err != nil {
		return ""
	}

	ref, err := url.Parse(href)
	if err != nil {
		return ""
	}

	return base.ResolveReference(ref).String()
}

// parseName parses a full name into first and last name
func (c *StaffCrawler) parseName(fullName string, person *database.UniversityStaff) {
	// Remove title prefixes - be careful with M.A. and M.Sc. to not match names starting with "Ma"
	// Only match these if followed by a space or dot
	titlePattern := regexp.MustCompile(`(?i)^(Prof\.?\s*|Dr\.?\s*|M\.A\.\s+|M\.Sc\.\s+|Dipl\.?-?\w*\.?\s*|PD\s+)+`)

	title := titlePattern.FindString(fullName)
	if title != "" {
		person.Title = &title
		fullName = strings.TrimSpace(titlePattern.ReplaceAllString(fullName, ""))
	}

	// Clean up
	fullName = strings.TrimSpace(fullName)
	fullName = regexp.MustCompile(`\s+`).ReplaceAllString(fullName, " ")

	parts := strings.Fields(fullName)
	if len(parts) == 0 {
		return
	}

	if len(parts) == 1 {
		person.LastName = parts[0]
	} else {
		// Last word is usually the last name
		person.LastName = parts[len(parts)-1]
		firstName := strings.Join(parts[:len(parts)-1], " ")
		person.FirstName = &firstName
	}
}

// looksLikeName checks if a string looks like a person's name (not a role/function)
func (c *StaffCrawler) looksLikeName(text string) bool {
	text = strings.TrimSpace(text)
	if len(text) < 3 || len(text) > 100 {
		return false
	}

	// Skip common non-name texts
	skipWords := []string{
		"internetkoordinator", "sekretariat", "verwaltung", "büro",
		"übersicht", "kontakt", "impressum", "datenschutz",
		"startseite", "home", "zurück", "mehr",
	}
	lower := strings.ToLower(text)
	for _, skip := range skipWords {
		if strings.Contains(lower, skip) {
			return false
		}
	}

	// Check for common title prefixes that indicate a name
	titlePrefixes := []string{"prof", "dr", "m.a.", "m.sc.", "dipl", "b.a.", "b.sc."}
	for _, prefix := range titlePrefixes {
		if strings.HasPrefix(lower, prefix) {
			return true
		}
	}

	// Check if it has at least two words (first name, last name)
	parts := strings.Fields(text)
	return len(parts) >= 2
}

// looksLikePosition checks if a text looks like a position/title
func (c *StaffCrawler) looksLikePosition(text string) bool {
	text = strings.ToLower(text)
	positionKeywords := []string{
		"professor", "prof.", "dozent", "lektor",
		"wissenschaftlich", "mitarbeiter", "assistent",
		"sekretär", "manager", "leiter", "direktor",
		"researcher", "postdoc", "doktorand", "phd",
		"student", "hilfskraft", "tutor",
	}

	for _, keyword := range positionKeywords {
		if strings.Contains(text, keyword) {
			return true
		}
	}
	return false
}

// classifyPosition classifies a position into a type
func (c *StaffCrawler) classifyPosition(position string) *string {
	pos := strings.ToLower(position)

	var posType string
	switch {
	case strings.Contains(pos, "professor") || strings.Contains(pos, "prof."):
		posType = "professor"
	case strings.Contains(pos, "postdoc") || strings.Contains(pos, "post-doc"):
		posType = "postdoc"
	case strings.Contains(pos, "doktorand") || strings.Contains(pos, "phd") || strings.Contains(pos, "promovend"):
		posType = "phd_student"
	case strings.Contains(pos, "wissenschaftlich") || strings.Contains(pos, "researcher"):
		posType = "researcher"
	case strings.Contains(pos, "sekretär") || strings.Contains(pos, "verwaltung") || strings.Contains(pos, "admin"):
		posType = "admin"
	case strings.Contains(pos, "student") || strings.Contains(pos, "hilfskraft"):
		posType = "student"
	default:
		posType = "staff"
	}

	return &posType
}

// isProfessor checks if a position indicates a professor
func (c *StaffCrawler) isProfessor(position string) bool {
	pos := strings.ToLower(position)
	return strings.Contains(pos, "professor") || strings.Contains(pos, "prof.")
}