feat: add Facebook video extractor

internal/extractors/facebook/main.go

@@ -0,0 +1,104 @@
+package facebook
+
+import (
+	"fmt"
+	"regexp"
+
+	"github.com/govdbot/govd/internal/database"
+	"github.com/govdbot/govd/internal/models"
+	"github.com/govdbot/govd/internal/networking"
+)
+
+var facebookHost = []string{"facebook"}
+
+var ShareExtractor = &models.Extractor{
+	ID:          "facebook",
+	DisplayName: "Facebook (Share)",
+
+	URLPattern: regexp.MustCompile(`https?://(?:(?:www|m)\.)?facebook\.com/share/(?:r|v|p)/(?P<id>[a-zA-Z0-9]+)`),
+	Host:       facebookHost,
+
+	Redirect: true,
+
+	GetFunc: func(ctx *models.ExtractorContext) (*models.ExtractorResponse, error) {
+		finalURL, err := ctx.FetchLocation(
+			ctx.ContentURL,
+			&networking.RequestParams{Headers: webHeaders},
+		)
+		if err != nil {
+			return nil, fmt.Errorf("failed to follow share redirect: %w", err)
+		}
+		return &models.ExtractorResponse{URL: finalURL}, nil
+	},
+}
+
+var Extractor = &models.Extractor{
+	ID:          "facebook",
+	DisplayName: "Facebook",
+
+	URLPattern: regexp.MustCompile(
+		`https?://(?:(?:www|m|mbasic)\.)?facebook\.com/` +
+			`(?:watch/?\?(?:[^&]*&)*v=|(?:reel|videos?|posts?)/|[^/]+/(?:videos|posts|reels?)/)` +
+			`(?P<id>[a-zA-Z0-9]+)`,
+	),
+	Host: facebookHost,
+
+	GetFunc: func(ctx *models.ExtractorContext) (*models.ExtractorResponse, error) {
+		media, err := GetMedia(ctx)
+		if err != nil {
+			return nil, err
+		}
+		return &models.ExtractorResponse{
+			Media: media,
+		}, nil
+	},
+}
+
+func GetMedia(ctx *models.ExtractorContext) (*models.Media, error) {
+	if ctx.HTTPClient.Cookies == nil {
+		return nil, fmt.Errorf("auth cookies are required for facebook")
+	}
+	videoData, err := GetVideoData(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get video data: %w", err)
+	}
+	return buildMedia(ctx, videoData)
+}
+
+func buildMedia(ctx *models.ExtractorContext, data *VideoData) (*models.Media, error) {
+	media := ctx.NewMedia()
+	if data.Title != "" {
+		media.SetCaption(data.Title)
+	}
+
+	item := media.NewItem()
+	var formats []*models.MediaFormat
+
+	if data.HDURL != "" {
+		formats = append(formats, &models.MediaFormat{
+			FormatID:   "hd",
+			Type:       database.MediaTypeVideo,
+			VideoCodec: database.MediaCodecAvc,
+			AudioCodec: database.MediaCodecAac,
+			URL:        []string{data.HDURL},
+			Width:      data.Width,
+			Height:     data.Height,
+		})
+	}
+	if data.SDURL != "" {
+		formats = append(formats, &models.MediaFormat{
+			FormatID:   "sd",
+			Type:       database.MediaTypeVideo,
+			VideoCodec: database.MediaCodecAvc,
+			AudioCodec: database.MediaCodecAac,
+			URL:        []string{data.SDURL},
+		})
+	}
+
+	if len(formats) == 0 {
+		return nil, fmt.Errorf("no video formats found")
+	}
+
+	item.AddFormats(formats...)
+	return media, nil
+}

internal/extractors/facebook/models.go

@@ -0,0 +1,10 @@
+package facebook
+
+// VideoData holds extracted video information from Facebook page HTML.
+type VideoData struct {
+	HDURL  string
+	SDURL  string
+	Title  string
+	Width  int32
+	Height int32
+}

internal/extractors/facebook/util.go

@@ -0,0 +1,173 @@
+package facebook
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"net/http"
+	"regexp"
+	"strings"
+	"unicode/utf8"
+
+	"github.com/govdbot/govd/internal/logger"
+	"github.com/govdbot/govd/internal/models"
+	"github.com/govdbot/govd/internal/networking"
+)
+
+var webHeaders = map[string]string{
+	"User-Agent":                "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36",
+	"Accept":                    "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
+	"Accept-Language":           "en-US,en;q=0.5",
+	"Sec-Fetch-Dest":            "document",
+	"Sec-Fetch-Mode":            "navigate",
+	"Sec-Fetch-Site":            "none",
+	"Sec-Fetch-User":            "?1",
+	"Upgrade-Insecure-Requests": "1",
+}
+
+var (
+	hdURLPattern = regexp.MustCompile(
+		`"progressive_url"\s*:\s*"([^"\\]*(?:\\.[^"\\]*)*)"\s*,\s*"failure_reason"\s*:\s*[^,]+\s*,\s*"metadata"\s*:\s*\{\s*"quality"\s*:\s*"HD"\s*\}`,
+	)
+	sdURLPattern = regexp.MustCompile(
+		`"progressive_url"\s*:\s*"([^"\\]*(?:\\.[^"\\]*)*)"\s*,\s*"failure_reason"\s*:\s*[^,]+\s*,\s*"metadata"\s*:\s*\{\s*"quality"\s*:\s*"SD"\s*\}`,
+	)
+	titlePattern = regexp.MustCompile(
+		`"title"\s*:\s*\{\s*"text"\s*:\s*"([^"\\]*(?:\\.[^"\\]*)*)"`,
+	)
+)
+
+func GetVideoData(ctx *models.ExtractorContext) (*VideoData, error) {
+	contentURL := strings.Replace(ctx.ContentURL, "m.facebook.com", "www.facebook.com", 1)
+	contentURL = strings.Replace(contentURL, "mbasic.facebook.com", "www.facebook.com", 1)
+
+	// convert watch URLs to reel permalink,
+	// /watch/?v=XXX pages return wrong video data when scraped
+	if strings.Contains(contentURL, "/watch") && ctx.ContentID != "" {
+		contentURL = "https://www.facebook.com/reel/" + ctx.ContentID
+	}
+
+	resp, err := ctx.Fetch(
+		http.MethodGet,
+		contentURL,
+		&networking.RequestParams{
+			Headers: webHeaders,
+		},
+	)
+	if err != nil {
+		return nil, fmt.Errorf("failed to send request: %w", err)
+	}
+	defer resp.Body.Close()
+
+	logger.WriteFile("fb_response", resp)
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("failed to get page: %s", resp.Status)
+	}
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read response body: %w", err)
+	}
+
+	return parseVideoFromBody(body, ctx.ContentID)
+}
+
+func parseVideoFromBody(body []byte, videoID string) (*VideoData, error) {
+	data := &VideoData{}
+
+	// find the section belonging to the requested video
+	section := findVideoSection(body, videoID)
+	if section == nil {
+		// fall back to full body for reel/post pages with a single video
+		section = body
+	}
+
+	if match := hdURLPattern.FindSubmatch(section); len(match) >= 2 {
+		data.HDURL = unescapeFacebookURL(string(match[1]))
+	}
+	if match := sdURLPattern.FindSubmatch(section); len(match) >= 2 {
+		data.SDURL = unescapeFacebookURL(string(match[1]))
+	}
+	// title can be anywhere in the page
+	if match := titlePattern.FindSubmatch(body); len(match) >= 2 {
+		data.Title = unescapeUnicode(string(match[1]))
+	}
+
+	if data.HDURL == "" && data.SDURL == "" {
+		return nil, fmt.Errorf("no video URLs found in page")
+	}
+
+	return data, nil
+}
+
+// findVideoSection returns the slice of body containing the video delivery
+// data for the given videoID, anchored by dash_mpd_debug.mpd?v=VIDEO_ID
+// and bounded by the closing "id":"VIDEO_ID".
+func findVideoSection(body []byte, videoID string) []byte {
+	if videoID == "" {
+		return nil
+	}
+
+	anchor := []byte("dash_mpd_debug.mpd?v=" + videoID)
+	start := bytes.Index(body, anchor)
+	if start == -1 {
+		return nil
+	}
+
+	remaining := body[start:]
+
+	// look for "id":"VIDEO_ID" which closes the videoDeliveryResponseResult block
+	endMarker := []byte(`"id":"` + videoID + `"`)
+	endIdx := bytes.Index(remaining, endMarker)
+	if endIdx > 0 {
+		return remaining[:endIdx+len(endMarker)]
+	}
+
+	// fallback: take a generous window
+	maxLen := 20000
+	if maxLen > len(remaining) {
+		maxLen = len(remaining)
+	}
+	return remaining[:maxLen]
+}
+
+func unescapeFacebookURL(s string) string {
+	s = strings.ReplaceAll(s, `\/`, "/")
+	s = unescapeUnicode(s)
+	return s
+}
+
+func unescapeUnicode(s string) string {
+	var b strings.Builder
+	b.Grow(len(s))
+
+	for i := 0; i < len(s); {
+		if i+5 < len(s) && s[i] == '\\' && s[i+1] == 'u' {
+			var r rune
+			valid := true
+			for j := 2; j < 6; j++ {
+				r <<= 4
+				c := s[i+j]
+				switch {
+				case c >= '0' && c <= '9':
+					r |= rune(c - '0')
+				case c >= 'a' && c <= 'f':
+					r |= rune(c - 'a' + 10)
+				case c >= 'A' && c <= 'F':
+					r |= rune(c - 'A' + 10)
+				default:
+					valid = false
+				}
+			}
+			if valid && utf8.ValidRune(r) {
+				b.WriteRune(r)
+				i += 6
+				continue
+			}
+		}
+		b.WriteByte(s[i])
+		i++
+	}
+	return b.String()
+}

internal/extractors/main.go

@@ -1,6 +1,7 @@
 package extractors
 
 import (
+	"github.com/govdbot/govd/internal/extractors/facebook"
 	"github.com/govdbot/govd/internal/extractors/instagram"
 	"github.com/govdbot/govd/internal/extractors/ninegag"
 	"github.com/govdbot/govd/internal/extractors/pinterest"
@@ -14,6 +15,8 @@ import (
 )
 
 var Extractors = []*models.Extractor{
+	facebook.ShareExtractor,
+	facebook.Extractor,
 	tiktok.Extractor,
 	tiktok.VMExtractor,
 	soundcloud.Extractor,