main.py

from fastapi import FastAPI, HTTPException
from fastapi.middleware.cors import CORSMiddleware
import requests
import re
import json
from pydantic import BaseModel

app = FastAPI()

app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"], 
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

class TranscriptRequest(BaseModel):
    url: str

class TranslateRequest(BaseModel):
    text: str
    targetLang: str

def extract_video_id(url: str) -> str:
    pattern = r'(?:youtube\.com\/(?:[^\/]+\/.+\/|(?:v|e(?:mbed)?)\/|.*[?&]v=)|youtu\.be\/)([^"&?\/\s]{11})'
    match = re.search(pattern, url)
    return match.group(1) if match else None

def parse_caption_xml(xml_string: str) -> str:
    text_matches = re.findall(r'<text[^>]*>([^<]*)</text>', xml_string)
    if not text_matches:
        return ""
    full_text = " ".join(text_matches)
    full_text = full_text.replace("&amp;#39;", "'").replace("&amp;quot;", '"').replace("&amp;amp;", "&").replace("&#39;", "'")
    return full_text

def fetch_via_proxy(proxy_base: str, target_url: str, timeout: int = 15) -> requests.Response:
    """Fetches a URL through a public CORS/Web proxy."""
    encoded_url = requests.utils.quote(target_url, safe='')
    proxy_url = f"{proxy_base}{encoded_url}"
    headers = {
        "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36",
        "Accept": "text/html,application/json"
    }
    response = requests.get(proxy_url, headers=headers, timeout=timeout)
    if response.status_code != 200:
        raise Exception(f"Proxy returned status {response.status_code}")
    return response

@app.post("/api/transcript")
async def get_transcript(req: TranscriptRequest):
    video_id = extract_video_id(req.url)
    if not video_id:
        raise HTTPException(status_code=400, detail="Invalid YouTube URL")

    # List of reliable public web proxies
    proxies = [
        "https://api.allorigins.win/raw?url=",
        "https://corsproxy.io/?",
        "https://api.codetabs.com/v1/proxy?quest="
    ]

    for proxy in proxies:
        try:
            print(f"Trying proxy {proxy} for video {video_id}...")
            
            # 1. Fetch YouTube Watch Page HTML via Proxy
            yt_url = f"https://www.youtube.com/watch?v={video_id}"
            response = fetch_via_proxy(proxy, yt_url, timeout=15)
            html = response.text
            
            # 2. Find the ytInitialPlayerResponse JSON in the HTML
            match = re.search(r'ytInitialPlayerResponse\s*=\s*(\{.*?\})\s*;', html, re.DOTALL)
            if not match:
                print(f"Failed to find player data via {proxy}")
                continue
                
            data = json.loads(match.group(1))
            
            # Check playability
            playability = data.get("playabilityStatus", {})
            if playability.get("status") == "ERROR":
                raise Exception(playability.get("reason", "Video unavailable"))
                
            # 3. Extract caption tracks
            caption_tracks = data.get("captions", {}).get("playerCaptionsTracklistRenderer", {}).get("captionTracks", [])
            if not caption_tracks:
                print(f"No captions found via {proxy}")
                continue
                
            # Prefer English, fallback to first available
            selected_track = next((t for t in caption_tracks if t.get("languageCode") == "en"), caption_tracks[0])
            caption_url = selected_track.get("baseUrl")
            if not caption_url:
                continue
                
            print(f"Found captions, fetching XML via proxy...")
            
            # 4. Fetch the actual caption XML via the same proxy
            caption_response = fetch_via_proxy(proxy, caption_url, timeout=10)
            
            # 5. Parse the XML into plain text
            full_text = parse_caption_xml(caption_response.text)
            
            if not full_text.strip():
                continue
                
            print(f"✅ Successfully fetched transcript via {proxy}. Length: {len(full_text)} chars")
            return {"text": full_text}
            
        except Exception as e:
            print(f"❌ Proxy {proxy} failed: {e}")
            continue

    raise HTTPException(status_code=500, detail="Failed to fetch transcript. All proxy methods failed or video has no captions.")

# ========================================================
# TRANSLATE API
# ========================================================
@app.post("/api/translate")
async def translate_text(req: TranslateRequest):
    if not req.text or not req.targetLang:
        raise HTTPException(status_code=400, detail="Missing text or target language")

    try:
        url = f"https://translate.googleapis.com/translate_a/single?client=gtx&sl=auto&tl={req.targetLang}&dt=t"
        res = requests.post(url, 
            headers={
                "Content-Type": "application/x-www-form-urlencoded",
                "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36"
            },
            data=f"q={requests.utils.quote(req.text)}",
            timeout=15
        )

        if res.status_code != 200:
            raise Exception(f"Google API returned {res.status_code}")

        data = res.json()
        translated = "".join([item[0] for item in data[0]])
        return {"translatedText": translated}

    except Exception as e:
        raise HTTPException(status_code=500, detail=f"Translation failed: {str(e)}")

# KEEP-ALIVE ENDPOINT
@app.get("/api/health")
async def health_check():
    return {"status": "ok", "message": "Transcript API is running!"}