package rules

import (
	"context"
	"fmt"
	"net/http"
	"net/url"
	"strings"
	"time"
)

// URLMetadata contains metadata extracted from a URL via HEAD request
type URLMetadata struct {
	Domain   string
	MimeType string
	Headers  http.Header
}

// AnalyzeURL performs a HEAD request to the URL and extracts metadata
func AnalyzeURL(ctx context.Context, urlStr string) (*URLMetadata, error) {
	// Parse URL to extract domain
	parsedURL, err := url.Parse(urlStr)
	if err != nil {
		return nil, fmt.Errorf("failed to parse URL: %w", err)
	}

	domain := parsedURL.Host
	// Remove port if present
	if idx := strings.Index(domain, ":"); idx != -1 {
		domain = domain[:idx]
	}

	// Create HTTP client with timeout
	client := &http.Client{
		Timeout: 30 * time.Second,
	}

	// Create HEAD request
	req, err := http.NewRequestWithContext(ctx, http.MethodHead, urlStr, nil)
	if err != nil {
		return nil, fmt.Errorf("failed to create HEAD request: %w", err)
	}

	// Set user agent
	req.Header.Set("User-Agent", "Hako/1.0")

	// Perform HEAD request
	resp, err := client.Do(req)
	if err != nil {
		return nil, fmt.Errorf("HEAD request failed: %w", err)
	}
	defer func() { _ = resp.Body.Close() }()

	// Extract MIME type from Content-Type header
	mimeType := resp.Header.Get("Content-Type")
	// Remove charset and other parameters (e.g., "text/html; charset=utf-8" -> "text/html")
	if idx := strings.Index(mimeType, ";"); idx != -1 {
		mimeType = strings.TrimSpace(mimeType[:idx])
	}

	return &URLMetadata{
		Domain:   domain,
		MimeType: mimeType,
		Headers:  resp.Header,
	}, nil
}