"""
BabelDOC with Agentic AI - MCP Server
PDF Translation with Layout Preservation + Google Drive Integration
"""

import os
import re
import json
import base64
import httpx
from pathlib import Path
from typing import Optional, Tuple, List
from datetime import datetime

from fastmcp import FastMCP

# Google Drive OAuth
try:
    from google.oauth2.credentials import Credentials
    from google_auth_oauthlib.flow import InstalledAppFlow
    from google.auth.transport.requests import Request
    from googleapiclient.discovery import build
    from googleapiclient.http import MediaFileUpload, MediaIoBaseDownload
    import io
    GOOGLE_AVAILABLE = True
except ImportError:
    GOOGLE_AVAILABLE = False

# Constants
MAX_PAGES = 20  # Test phase limit
GRADIO_URL = "http://127.0.0.1:7860"
OUTPUT_DIR = Path.home() / "Downloads" / "BabelDocs"
OUTPUT_DIR.mkdir(parents=True, exist_ok=True)

# Google Drive OAuth config
GDRIVE_SCOPES = ['https://www.googleapis.com/auth/drive']
GDRIVE_OAUTH_PATH = Path(os.getenv(
    "GDRIVE_OAUTH_CREDENTIALS",
    Path.home() / "Downloads" / "gcp-oauth.keys.json"
))
GDRIVE_TOKEN_PATH = OUTPUT_DIR / "gdrive_token.json"

# Modal endpoints (set BABELDOCS_MODAL_URL env var)
MODAL_BASE_URL = os.getenv("BABELDOCS_MODAL_URL")
if not MODAL_BASE_URL:
    raise ValueError("BABELDOCS_MODAL_URL environment variable is required")
MODAL_TRANSLATE_URL = f"{MODAL_BASE_URL}-babeldocstranslator-api.modal.run"
MODAL_HEALTH_URL = f"{MODAL_BASE_URL}-babeldocstranslator-health.modal.run"

SUPPORTED_LANGUAGES = {
    "en": "English", "fr": "French", "es": "Spanish", "de": "German",
    "it": "Italian", "pt": "Portuguese", "zh": "Chinese", "ja": "Japanese",
    "ko": "Korean", "ru": "Russian", "ar": "Arabic",
}


# === Helper Functions ===

async def _warmup_modal():
    """Wake up Modal container."""
    try:
        async with httpx.AsyncClient(timeout=10.0) as client:
            await client.get(MODAL_HEALTH_URL)
    except:
        pass


def _count_pdf_pages(pdf_bytes: bytes) -> int:
    """Count pages in PDF."""
    try:
        import fitz
        doc = fitz.open(stream=pdf_bytes, filetype="pdf")
        count = len(doc)
        doc.close()
        return count
    except ImportError:
        content = pdf_bytes.decode('latin-1', errors='ignore')
        return content.count('/Type /Page') - content.count('/Type /Pages')


def _extract_gdrive_file_id(url: str) -> Optional[str]:
    """Extract file ID from Google Drive URL."""
    patterns = [
        r'/file/d/([a-zA-Z0-9_-]+)',
        r'id=([a-zA-Z0-9_-]+)',
        r'/open\?id=([a-zA-Z0-9_-]+)',
        r'^([a-zA-Z0-9_-]{25,})$',
    ]
    for pattern in patterns:
        match = re.search(pattern, url)
        if match:
            return match.group(1)
    return None


def _get_gdrive_credentials():
    """Get or refresh Google Drive credentials."""
    if not GOOGLE_AVAILABLE:
        return None, "Google libraries not installed"
    if not GDRIVE_OAUTH_PATH.exists():
        return None, f"OAuth credentials not found at {GDRIVE_OAUTH_PATH}"

    creds = None
    if GDRIVE_TOKEN_PATH.exists():
        try:
            creds = Credentials.from_authorized_user_file(str(GDRIVE_TOKEN_PATH), GDRIVE_SCOPES)
        except:
            pass

    if not creds or not creds.valid:
        if creds and creds.expired and creds.refresh_token:
            try:
                creds.refresh(Request())
            except:
                creds = None

        if not creds:
            try:
                flow = InstalledAppFlow.from_client_secrets_file(str(GDRIVE_OAUTH_PATH), GDRIVE_SCOPES)
                for port in [8101, 8102, 8103, 0]:
                    try:
                        creds = flow.run_local_server(port=port, open_browser=True, bind_addr="127.0.0.1")
                        break
                    except OSError:
                        if port == 0:
                            raise
            except Exception as e:
                return None, f"OAuth failed: {str(e)}"

        with open(GDRIVE_TOKEN_PATH, 'w') as token:
            token.write(creds.to_json())

    return creds, None


def _upload_to_gdrive(file_path: str, folder_id: Optional[str] = None) -> Tuple[Optional[str], Optional[str]]:
    """Upload file to Google Drive. Returns (file_id, error)."""
    creds, error = _get_gdrive_credentials()
    if error:
        return None, error

    try:
        service = build('drive', 'v3', credentials=creds)
        file_metadata = {'name': Path(file_path).name}
        if folder_id:
            file_metadata['parents'] = [folder_id]

        media = MediaFileUpload(file_path, mimetype='application/pdf', resumable=True)
        file = service.files().create(body=file_metadata, media_body=media, fields='id, webViewLink').execute()
        return file.get('id'), None
    except Exception as e:
        return None, f"Upload failed: {str(e)}"


def _list_gdrive_folders() -> Tuple[Optional[List[dict]], Optional[str]]:
    """List folders in Google Drive."""
    creds, error = _get_gdrive_credentials()
    if error:
        return None, error

    try:
        service = build('drive', 'v3', credentials=creds)
        results = service.files().list(
            q="mimeType='application/vnd.google-apps.folder' and trashed=false",
            fields='files(id, name)', pageSize=50
        ).execute()
        return results.get('files', []), None
    except Exception as e:
        return None, f"Failed to list folders: {str(e)}"


def _list_gdrive_files(folder_id: Optional[str] = None, file_type: Optional[str] = None) -> Tuple[Optional[List[dict]], Optional[str]]:
    """List files in Google Drive."""
    creds, error = _get_gdrive_credentials()
    if error:
        return None, error

    try:
        service = build('drive', 'v3', credentials=creds)
        query_parts = ["trashed=false"]
        if folder_id:
            query_parts.append(f"'{folder_id}' in parents")
        if file_type == "pdf":
            query_parts.append("mimeType='application/pdf'")
        elif file_type == "folder":
            query_parts.append("mimeType='application/vnd.google-apps.folder'")

        results = service.files().list(
            q=" and ".join(query_parts),
            fields='files(id, name, mimeType, size, webViewLink)',
            pageSize=100, orderBy='modifiedTime desc'
        ).execute()
        return results.get('files', []), None
    except Exception as e:
        return None, f"Failed to list files: {str(e)}"


def _search_gdrive_files(query: str, file_type: Optional[str] = None) -> Tuple[Optional[List[dict]], Optional[str]]:
    """Search files in Google Drive by name."""
    creds, error = _get_gdrive_credentials()
    if error:
        return None, error

    try:
        service = build('drive', 'v3', credentials=creds)
        query_parts = [f"name contains '{query}'", "trashed=false"]
        if file_type == "pdf":
            query_parts.append("mimeType='application/pdf'")

        results = service.files().list(
            q=" and ".join(query_parts),
            fields='files(id, name, mimeType, size, webViewLink)',
            pageSize=50, orderBy='modifiedTime desc'
        ).execute()
        return results.get('files', []), None
    except Exception as e:
        return None, f"Search failed: {str(e)}"


def _download_gdrive_file(file_id: str, destination: Optional[str] = None) -> Tuple[Optional[str], Optional[str]]:
    """Download file from Google Drive."""
    creds, error = _get_gdrive_credentials()
    if error:
        return None, error

    try:
        service = build('drive', 'v3', credentials=creds)
        file_metadata = service.files().get(fileId=file_id, fields='name').execute()
        filename = file_metadata.get('name', f'download_{file_id}')

        dest_path = Path(destination) / filename if destination else OUTPUT_DIR / filename

        request = service.files().get_media(fileId=file_id)
        file_handle = io.BytesIO()
        downloader = MediaIoBaseDownload(file_handle, request)
        done = False
        while not done:
            _, done = downloader.next_chunk()

        dest_path.parent.mkdir(parents=True, exist_ok=True)
        dest_path.write_bytes(file_handle.getvalue())
        return str(dest_path), None
    except Exception as e:
        return None, f"Download failed: {str(e)}"


async def _get_pdf_bytes(source: str) -> Tuple[bytes, str, Optional[str]]:
    """Get PDF bytes from local file or Google Drive URL. Returns (bytes, source_name, error)."""
    # Google Drive URL
    if "drive.google.com" in source or "docs.google.com" in source:
        file_id = _extract_gdrive_file_id(source)
        if not file_id:
            return b"", "", "Invalid Google Drive URL"

        local_path, error = _download_gdrive_file(file_id)
        if error:
            return b"", "", error

        pdf_bytes = Path(local_path).read_bytes()
        return pdf_bytes, f"Google Drive: {Path(local_path).name}", None

    # Just file ID
    if re.match(r'^[a-zA-Z0-9_-]{25,}$', source):
        local_path, error = _download_gdrive_file(source)
        if error:
            return b"", "", error

        pdf_bytes = Path(local_path).read_bytes()
        return pdf_bytes, f"Google Drive: {Path(local_path).name}", None

    # Local file
    pdf_path = Path(source)
    if not pdf_path.exists():
        return b"", "", f"File not found: {source}"
    if pdf_path.suffix.lower() != ".pdf":
        return b"", "", "File must be a PDF"

    return pdf_path.read_bytes(), pdf_path.name, None


# === MCP Server ===

mcp = FastMCP(
    name="babeldocs",
    instructions=f"""PDF translation with layout preservation + Google Drive integration.

Max {MAX_PAGES} pages. For larger PDFs use Gradio at {GRADIO_URL}

WORKFLOW:
1. search_gdrive("filename") - Find PDF
2. download_from_gdrive(file_id) - Download
3. translate_pdf(path, "fr") - Translate
4. upload_to_gdrive(path, folder_id) - Upload

Or all-in-one: translate_and_upload(source, "fr", folder_id)

Output: {OUTPUT_DIR}
"""
)


@mcp.tool()
async def translate_pdf(source: str, target_lang: str = "fr") -> dict:
    """Translate PDF with layout preservation. Returns single translated file."""
    await _warmup_modal()

    try:
        pdf_bytes, source_name, error = await _get_pdf_bytes(source)
        if error:
            return {"success": False, "message": error}

        page_count = _count_pdf_pages(pdf_bytes)
        if page_count > MAX_PAGES:
            return {
                "success": False,
                "message": f"PDF has {page_count} pages (max {MAX_PAGES}). Use Gradio: {GRADIO_URL}"
            }

        if target_lang not in SUPPORTED_LANGUAGES:
            return {"success": False, "message": f"Unsupported language: {target_lang}"}

        # Call Modal
        payload = {
            "pdf_base64": base64.b64encode(pdf_bytes).decode("utf-8"),
            "target_lang": target_lang,
            "no_dual": True,
            "no_mono": False,
        }

        async with httpx.AsyncClient(timeout=900.0, follow_redirects=True) as client:
            response = await client.post(MODAL_TRANSLATE_URL, json=payload)
            response.raise_for_status()
            result = response.json()

        if not result.get("success"):
            return {"success": False, "message": result.get("message", "Translation failed")}

        # Get mono_img (priority) or mono
        pdf_data = result.get("mono_img_pdf_base64") or result.get("mono_pdf_base64")
        if not pdf_data:
            return {"success": False, "message": "No output PDF generated"}

        # Build output filename
        timestamp = datetime.now().strftime("%Y%m%d_%H%M%S")
        if source_name.startswith("Google Drive:"):
            output_filename = f"translated_{timestamp}.{target_lang}.pdf"
        else:
            original_name = Path(source_name).stem
            output_filename = f"{original_name}_translated.{target_lang}.pdf"

        output_path = OUTPUT_DIR / output_filename
        output_path.write_bytes(base64.b64decode(pdf_data))

        return {
            "success": True,
            "message": f"Translated to {SUPPORTED_LANGUAGES[target_lang]}",
            "source": source_name,
            "page_count": page_count,
            "output_file": str(output_path),
            "filename": output_filename,
            "stats": result.get("stats", {}),
        }

    except httpx.TimeoutException:
        return {"success": False, "message": "Translation timed out (max 15 min)"}
    except Exception as e:
        return {"success": False, "message": f"Error: {str(e)}"}


@mcp.tool()
async def translate_and_upload(source: str, target_lang: str = "fr", folder_id: Optional[str] = None) -> dict:
    """Translate PDF and upload to Google Drive."""
    result = await translate_pdf(source, target_lang)
    if not result.get("success"):
        return result

    file_id, error = _upload_to_gdrive(result["output_file"], folder_id)
    if error:
        return {"success": False, "message": error, "local_file": result["output_file"]}

    return {
        "success": True,
        "message": f"Translated and uploaded to Google Drive",
        "source": result.get("source"),
        "page_count": result.get("page_count"),
        "gdrive_id": file_id,
        "gdrive_link": f"https://drive.google.com/file/d/{file_id}/view",
        "local_file": result["output_file"],
    }


@mcp.tool()
async def check_pdf(source: str) -> dict:
    """Check if PDF can be translated (page count)."""
    await _warmup_modal()

    try:
        pdf_bytes, source_name, error = await _get_pdf_bytes(source)
        if error:
            return {"success": False, "message": error}

        page_count = _count_pdf_pages(pdf_bytes)
        can_translate = page_count <= MAX_PAGES

        return {
            "success": True,
            "source": source_name,
            "pages": page_count,
            "size_mb": round(len(pdf_bytes) / (1024 * 1024), 2),
            "can_translate": can_translate,
            "message": f"Ready ({page_count} pages)" if can_translate else f"Too large ({page_count} > {MAX_PAGES})"
        }
    except Exception as e:
        return {"success": False, "message": f"Error: {str(e)}"}


@mcp.tool()
async def get_supported_languages() -> dict:
    """Get supported languages."""
    return {"languages": SUPPORTED_LANGUAGES, "default": "fr"}


@mcp.tool()
async def upload_to_gdrive(file_path: str, folder_id: Optional[str] = None) -> dict:
    """Upload file to Google Drive."""
    if not GOOGLE_AVAILABLE:
        return {"success": False, "message": "Google libraries not installed"}

    path = Path(file_path)
    if not path.exists():
        return {"success": False, "message": f"File not found: {file_path}"}

    file_id, error = _upload_to_gdrive(file_path, folder_id)
    if error:
        return {"success": False, "message": error}

    return {
        "success": True,
        "message": f"Uploaded {path.name}",
        "file_id": file_id,
        "web_link": f"https://drive.google.com/file/d/{file_id}/view",
    }


@mcp.tool()
async def list_gdrive_folders() -> dict:
    """List Google Drive folders."""
    if not GOOGLE_AVAILABLE:
        return {"success": False, "message": "Google libraries not installed"}

    folders, error = _list_gdrive_folders()
    if error:
        return {"success": False, "message": error}

    return {"success": True, "folders": folders, "count": len(folders)}


@mcp.tool()
async def list_gdrive_files(folder_id: Optional[str] = None, file_type: Optional[str] = None) -> dict:
    """List files in Google Drive."""
    if not GOOGLE_AVAILABLE:
        return {"success": False, "message": "Google libraries not installed"}

    files, error = _list_gdrive_files(folder_id, file_type)
    if error:
        return {"success": False, "message": error}

    for f in files:
        if f.get('size'):
            f['size_mb'] = round(int(f['size']) / (1024 * 1024), 2)

    return {"success": True, "files": files, "count": len(files)}


@mcp.tool()
async def search_gdrive(query: str, file_type: Optional[str] = None) -> dict:
    """Search Google Drive by filename."""
    if not GOOGLE_AVAILABLE:
        return {"success": False, "message": "Google libraries not installed"}

    files, error = _search_gdrive_files(query, file_type)
    if error:
        return {"success": False, "message": error}

    for f in files:
        if f.get('size'):
            f['size_mb'] = round(int(f['size']) / (1024 * 1024), 2)

    return {"success": True, "query": query, "files": files, "count": len(files)}


@mcp.tool()
async def download_from_gdrive(file_id: str) -> dict:
    """Download file from Google Drive."""
    if not GOOGLE_AVAILABLE:
        return {"success": False, "message": "Google libraries not installed"}

    local_path, error = _download_gdrive_file(file_id)
    if error:
        return {"success": False, "message": error}

    return {
        "success": True,
        "message": f"Downloaded to {local_path}",
        "local_path": local_path,
        "filename": Path(local_path).name,
    }


if __name__ == "__main__":
    mcp.run()