# =============================================================================
# 📰 Newspaper Article Extractor — FastAPI Backend
# Priority queue: one page at a time, user clicks jump to front
# =============================================================================

import os
import hashlib
import json
import threading
import time
import logging
from pathlib import Path
from collections import deque

from fastapi import FastAPI, UploadFile, File, HTTPException
from fastapi.middleware.cors import CORSMiddleware
import uvicorn

from config import MAX_PDF_PAGES, MAX_PDF_SIZE_MB
from extractor import ExtractionPipeline
from summarizer import NewspaperSummarizer
from rater import ArticleRater

# ---- Logging ----
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger("newspaper_api")

# ---- Config ----
API_KEY = os.environ.get("SAMBANOVA_API_KEY", "")
assert API_KEY, "Set SAMBANOVA_API_KEY environment variable"

UPLOAD_DIR = Path("/tmp/newspaper_uploads")
UPLOAD_DIR.mkdir(exist_ok=True)

QUEUE_DELAY = 5  # seconds between queued jobs to avoid rate limits

# ---- Initialize once ----
pipeline = ExtractionPipeline(api_key=API_KEY)
summarizer = NewspaperSummarizer(api_key=API_KEY)
rater = ArticleRater(api_key=API_KEY)

# ---- Cache ----
extraction_cache = {}      # "hash_pageN" → result
extraction_status = {}     # "hash_pageN" → "queued"/"running"/"done"/"error"
summary_results = {}       # hash → result
summary_status = {}        # hash → "running"/"done"/"error"
file_sections = {}         # hash → {page_num: section_name}

# ---- Priority Queue ----
# The queue processes ONE page at a time. User-requested pages jump to front.
page_queue = deque()       # [(file_hash, page_num, priority), ...]
queue_lock = threading.Lock()
queue_event = threading.Event()  # Signals the worker when new jobs are added
worker_running = False


def get_cache_key(file_hash, page_num):
    return f"{file_hash}_page{page_num}"


def is_page_processed(file_hash, page_num):
    key = get_cache_key(file_hash, page_num)
    return extraction_status.get(key) in ("done", "running")


def enqueue_page(file_hash, page_num, priority="low"):
    """Add a page to the queue. HIGH priority goes to front, LOW to back."""
    key = get_cache_key(file_hash, page_num)

    with queue_lock:
        # Skip if already done or in progress
        if extraction_status.get(key) in ("done", "running"):
            return

        # Remove any existing entry for this page (to re-prioritize)
        items = [(h, p, pr) for h, p, pr in page_queue if not (h == file_hash and p == page_num)]
        page_queue.clear()
        page_queue.extend(items)

        if priority == "high":
            page_queue.appendleft((file_hash, page_num, priority))
        else:
            page_queue.append((file_hash, page_num, priority))

        extraction_status[key] = "queued"

    # Wake up the worker
    queue_event.set()
    ensure_worker_running()


def process_page(file_path, file_hash, page_num):
    """Extract + rate a single page. Called by the queue worker."""
    key = get_cache_key(file_hash, page_num)
    extraction_status[key] = "running"

    try:
        # Extract
        page_idx = page_num - 1
        result, viz_image, regions, is_digital, total_pages = pipeline.extract(
            file_path, page_idx
        )

        if result is None:
            extraction_status[key] = "error"
            extraction_cache[key] = {"error": f"Invalid page. PDF has {total_pages} pages."}
            return

        articles = result.get("articles", [])

        # Rate (text-only call, fast)
        ratings = []
        if articles:
            section = file_sections.get(file_hash, {}).get(page_num, "UNKNOWN")
            logger.info(f"Rating {len(articles)} articles on page {page_num} ({section})")
            ratings = rater.rate(articles, section=section, page_num=page_num)

        response = {
            "page": page_num,
            "pdf_type": "digital" if is_digital else "scanned",
            "total_regions": len(regions) if regions else 0,
            "articles": articles,
            "ratings": ratings,
        }

        extraction_cache[key] = response
        extraction_status[key] = "done"
        logger.info(f"✅ Page {page_num} done ({len(articles)} articles)")

    except Exception as e:
        logger.error(f"Page {page_num} failed: {e}", exc_info=True)
        extraction_status[key] = "error"
        extraction_cache[key] = {"error": str(e)}


def queue_worker():
    """Background worker — processes one page at a time from the queue."""
    global worker_running
    logger.info("Queue worker started")

    while True:
        # Wait for jobs
        queue_event.wait()
        queue_event.clear()

        while True:
            # Get next job
            job = None
            with queue_lock:
                if page_queue:
                    job = page_queue.popleft()

            if job is None:
                break

            file_hash, page_num, priority = job
            file_path = str(UPLOAD_DIR / f"{file_hash}.pdf")

            if not os.path.exists(file_path):
                logger.warning(f"PDF not found for {file_hash}")
                continue

            # Skip if already done
            key = get_cache_key(file_hash, page_num)
            if extraction_status.get(key) == "done":
                continue

            logger.info(f"Processing page {page_num} (priority: {priority})")
            process_page(file_path, file_hash, page_num)

            # Delay between pages to avoid rate limits
            time.sleep(QUEUE_DELAY)

    worker_running = False


def ensure_worker_running():
    """Start the queue worker thread if not already running."""
    global worker_running
    if not worker_running:
        worker_running = True
        thread = threading.Thread(target=queue_worker, daemon=True)
        thread.start()


# ---- Summary (runs independently of queue) ----
def run_summary_background(file_path, file_hash):
    """Run summary in its own thread — doesn't use the page queue."""
    try:
        summary_status[file_hash] = "running"

        # Detect sections first
        sections = summarizer._detect_page_sections(file_path)
        file_sections[file_hash] = sections
        logger.info(f"Sections detected: {sections}")

        # Run summary
        result = summarizer.summarize(file_path)

        summary_results[file_hash] = result
        summary_status[file_hash] = "done"
        logger.info(f"Summary complete: {len(result.get('important_articles', []))} articles")

        # Queue important pages from summary (low priority)
        important_pages = []
        for article in result.get("important_articles", []):
            p = article.get("page")
            if p and p not in important_pages:
                important_pages.append(p)

        for page_num in important_pages[:8]:  # Max 8 important pages
            enqueue_page(file_hash, page_num, priority="low")

    except Exception as e:
        logger.error(f"Summary failed: {e}", exc_info=True)
        summary_status[file_hash] = "error"
        summary_results[file_hash] = {"error": str(e)}


# ---- Helpers ----
def save_upload(upload_file: UploadFile) -> tuple:
    content = upload_file.file.read()
    file_hash = hashlib.md5(content[:10 * 1024 * 1024]).hexdigest()
    file_path = str(UPLOAD_DIR / f"{file_hash}.pdf")
    if not os.path.exists(file_path):
        with open(file_path, "wb") as f:
            f.write(content)
    return file_path, file_hash


def detect_front_and_editorial(file_path, file_hash):
    """Detect front page and editorial page numbers. Returns (front, editorial)."""
    sections = file_sections.get(file_hash, {})

    front_page = 1  # Default to page 1
    editorial_page = None

    for page_num, section in sections.items():
        upper = section.upper()
        if upper in ("FRONT PAGE", "NATIONAL") and page_num <= 2:
            front_page = page_num
        if upper in ("EDITORIAL", "OP-ED", "OPINION") and editorial_page is None:
            editorial_page = page_num

    return front_page, editorial_page


# ---- FastAPI ----
app = FastAPI(title="Newspaper Article Extractor API", version="6.0")

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


@app.get("/health")
def health_check():
    return {"status": "ok"}


@app.post("/upload")
async def upload_pdf(file: UploadFile = File(...)):
    """Upload PDF → validate → start summary → queue front page + editorial."""
    if not file.filename.lower().endswith(".pdf"):
        raise HTTPException(400, "Only PDF files are accepted")

    file_path, file_hash = save_upload(file)

    size_mb = os.path.getsize(file_path) / (1024 * 1024)
    if size_mb > MAX_PDF_SIZE_MB:
        os.remove(file_path)
        raise HTTPException(400, f"PDF is {size_mb:.1f} MB. Max {MAX_PDF_SIZE_MB} MB.")

    try:
        total_pages = pipeline.get_page_count(file_path)
    except Exception as e:
        os.remove(file_path)
        raise HTTPException(400, f"Could not read PDF: {e}")

    if total_pages > MAX_PDF_PAGES:
        os.remove(file_path)
        raise HTTPException(400, f"PDF has {total_pages} pages. Max {MAX_PDF_PAGES}.")

    # Detect sections (instant)
    sections = summarizer._detect_page_sections(file_path)
    file_sections[file_hash] = sections

    # Start summary immediately (separate thread, not in page queue)
    if file_hash not in summary_status:
        thread = threading.Thread(
            target=run_summary_background,
            args=(file_path, file_hash),
            daemon=True,
        )
        thread.start()

    # Queue front page and editorial
    front_page, editorial_page = detect_front_and_editorial(file_path, file_hash)

    enqueue_page(file_hash, front_page, priority="low")
    if editorial_page and editorial_page != front_page:
        enqueue_page(file_hash, editorial_page, priority="low")

    return {
        "file_hash": file_hash,
        "filename": file.filename,
        "size_mb": round(size_mb, 1),
        "total_pages": total_pages,
        "sections": sections,
        "front_page": front_page,
        "editorial_page": editorial_page,
    }


@app.post("/extract/{file_hash}/{page_num}")
def start_extraction(file_hash: str, page_num: int):
    """Start extraction — user-requested page jumps to front of queue."""
    file_path = str(UPLOAD_DIR / f"{file_hash}.pdf")
    if not os.path.exists(file_path):
        raise HTTPException(404, "PDF not found. Please upload again.")

    key = get_cache_key(file_hash, page_num)

    # Already done — return immediately
    if extraction_status.get(key) == "done":
        return {"status": "done", "result": extraction_cache[key]}

    # Already running
    if extraction_status.get(key) == "running":
        return {"status": "running", "message": "Extraction in progress..."}

    # Queue with HIGH priority (jumps to front)
    enqueue_page(file_hash, page_num, priority="high")

    # Also queue next page with low priority
    total_pages = pipeline.get_page_count(file_path)
    next_page = page_num + 1
    if next_page <= total_pages:
        enqueue_page(file_hash, next_page, priority="low")

    return {"status": "started", "message": "Extraction queued with high priority."}


@app.get("/extract/{file_hash}/{page_num}")
def get_extraction(file_hash: str, page_num: int):
    """Poll for extraction results."""
    key = get_cache_key(file_hash, page_num)

    status = extraction_status.get(key)

    if status is None:
        return {"status": "not_started"}

    if status == "queued":
        # Show position in queue
        position = 0
        with queue_lock:
            for i, (h, p, pr) in enumerate(page_queue):
                if h == file_hash and p == page_num:
                    position = i + 1
                    break
        msg = f"Queued (position {position})" if position > 0 else "Queued"
        return {"status": "queued", "message": msg}

    if status == "running":
        return {"status": "running", "message": "Extracting articles..."}

    if status == "error":
        error = extraction_cache.get(key, {}).get("error", "Unknown error")
        return {"status": "error", "message": error}

    # Done
    return {"status": "done", "result": extraction_cache[key]}


@app.get("/summary/{file_hash}")
def get_summary(file_hash: str):
    """Get newspaper summary."""
    status = summary_status.get(file_hash)

    if status is None:
        return {"status": "not_started"}
    if status == "running":
        return {"status": "running", "message": "Scanning newspaper..."}
    if status == "error":
        error = summary_results.get(file_hash, {}).get("error", "Unknown")
        return {"status": "error", "message": error}

    result = summary_results.get(file_hash, {})
    return {
        "status": "done",
        "total_headlines_found": result.get("total_headlines_found", 0),
        "important_articles": result.get("important_articles", []),
    }


@app.get("/queue-status/{file_hash}")
def get_queue_status(file_hash: str):
    """See what's in the queue for this PDF."""
    with queue_lock:
        items = [
            {"page": p, "priority": pr}
            for h, p, pr in page_queue
            if h == file_hash
        ]

    cached = [
        int(key.split("_page")[1])
        for key, status in extraction_status.items()
        if key.startswith(file_hash) and status == "done"
    ]

    return {
        "queued": items,
        "cached_pages": sorted(cached),
    }


@app.get("/layout-image/{file_hash}/{page_num}")
def get_layout_image(file_hash: str, page_num: int):
    """Get annotated layout image as base64 JPEG."""
    import base64
    import io

    file_path = str(UPLOAD_DIR / f"{file_hash}.pdf")
    if not os.path.exists(file_path):
        raise HTTPException(404, "PDF not found.")

    try:
        image, total = pipeline._pdf_page_to_image(file_path, page_num - 1)
        if image is None:
            raise HTTPException(400, f"Invalid page. PDF has {total} pages.")

        regions = pipeline._detect_layout(image)
        viz = pipeline._visualize_layout(image, regions)

        buf = io.BytesIO()
        viz.thumbnail((1400, 1400))
        viz.save(buf, format="JPEG", quality=80)
        return {"image_base64": base64.b64encode(buf.getvalue()).decode()}
    except HTTPException:
        raise
    except Exception as e:
        raise HTTPException(500, str(e))


@app.get("/page-image/{file_hash}/{page_num}")
def get_page_image(file_hash: str, page_num: int):
    """Get clean page image as base64 JPEG."""
    import base64
    import io

    file_path = str(UPLOAD_DIR / f"{file_hash}.pdf")
    if not os.path.exists(file_path):
        raise HTTPException(404, "PDF not found.")

    try:
        image, total = pipeline._pdf_page_to_image(file_path, page_num - 1)
        if image is None:
            raise HTTPException(400, f"Invalid page. PDF has {total} pages.")

        buf = io.BytesIO()
        image.thumbnail((1400, 1400))
        image.save(buf, format="JPEG", quality=80)
        return {"image_base64": base64.b64encode(buf.getvalue()).decode()}
    except HTTPException:
        raise
    except Exception as e:
        raise HTTPException(500, str(e))


# ---- Run ----
if __name__ == "__main__":
    port = int(os.environ.get("PORT", 7860))
    uvicorn.run(app, host="0.0.0.0", port=port)