"""
DSMS Gateway - REST API für dezentrales Speichersystem
Bietet eine vereinfachte API über IPFS für BreakPilot
"""

import os
import json
import httpx
import hashlib
from datetime import datetime
from typing import Optional
from fastapi import FastAPI, HTTPException, UploadFile, File, Header, Depends
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import StreamingResponse
from pydantic import BaseModel
import io

app = FastAPI(
    title="DSMS Gateway",
    description="Dezentrales Daten Speicher System Gateway für BreakPilot",
    version="1.0.0"
)

# CORS Configuration
app.add_middleware(
    CORSMiddleware,
    allow_origins=["http://localhost:8000", "http://backend:8000", "*"],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

# Configuration
IPFS_API_URL = os.getenv("IPFS_API_URL", "http://dsms-node:5001")
IPFS_GATEWAY_URL = os.getenv("IPFS_GATEWAY_URL", "http://dsms-node:8080")
JWT_SECRET = os.getenv("JWT_SECRET", "your-super-secret-jwt-key-change-in-production")


# Models
class DocumentMetadata(BaseModel):
    """Metadaten für gespeicherte Dokumente"""
    document_type: str  # 'legal_document', 'consent_record', 'audit_log'
    document_id: Optional[str] = None
    version: Optional[str] = None
    language: Optional[str] = "de"
    created_at: Optional[str] = None
    checksum: Optional[str] = None
    encrypted: bool = False


class StoredDocument(BaseModel):
    """Antwort nach erfolgreichem Speichern"""
    cid: str  # Content Identifier (IPFS Hash)
    size: int
    metadata: DocumentMetadata
    gateway_url: str
    timestamp: str


class DocumentList(BaseModel):
    """Liste der gespeicherten Dokumente"""
    documents: list
    total: int


# Helper Functions
async def verify_token(authorization: Optional[str] = Header(None)) -> dict:
    """Verifiziert JWT Token (vereinfacht für MVP)"""
    if not authorization:
        raise HTTPException(status_code=401, detail="Authorization header fehlt")

    # In Produktion: JWT validieren
    # Für MVP: Einfache Token-Prüfung
    if not authorization.startswith("Bearer "):
        raise HTTPException(status_code=401, detail="Ungültiges Token-Format")

    return {"valid": True}


async def ipfs_add(content: bytes, pin: bool = True) -> dict:
    """Fügt Inhalt zu IPFS hinzu"""
    async with httpx.AsyncClient(timeout=60.0) as client:
        files = {"file": ("document", content)}
        params = {"pin": str(pin).lower()}

        response = await client.post(
            f"{IPFS_API_URL}/api/v0/add",
            files=files,
            params=params
        )

        if response.status_code != 200:
            raise HTTPException(
                status_code=502,
                detail=f"IPFS Fehler: {response.text}"
            )

        return response.json()


async def ipfs_cat(cid: str) -> bytes:
    """Liest Inhalt von IPFS"""
    async with httpx.AsyncClient(timeout=60.0) as client:
        response = await client.post(
            f"{IPFS_API_URL}/api/v0/cat",
            params={"arg": cid}
        )

        if response.status_code != 200:
            raise HTTPException(
                status_code=404,
                detail=f"Dokument nicht gefunden: {cid}"
            )

        return response.content


async def ipfs_pin_ls() -> list:
    """Listet alle gepinnten Objekte"""
    async with httpx.AsyncClient(timeout=30.0) as client:
        response = await client.post(
            f"{IPFS_API_URL}/api/v0/pin/ls",
            params={"type": "recursive"}
        )

        if response.status_code != 200:
            return []

        data = response.json()
        return list(data.get("Keys", {}).keys())


# API Endpoints
@app.get("/health")
async def health_check():
    """Health Check für DSMS Gateway"""
    try:
        async with httpx.AsyncClient(timeout=5.0) as client:
            response = await client.post(f"{IPFS_API_URL}/api/v0/id")
            ipfs_status = response.status_code == 200
    except Exception:
        ipfs_status = False

    return {
        "status": "healthy" if ipfs_status else "degraded",
        "ipfs_connected": ipfs_status,
        "timestamp": datetime.utcnow().isoformat()
    }


@app.post("/api/v1/documents", response_model=StoredDocument)
async def store_document(
    file: UploadFile = File(...),
    document_type: str = "legal_document",
    document_id: Optional[str] = None,
    version: Optional[str] = None,
    language: str = "de",
    _auth: dict = Depends(verify_token)
):
    """
    Speichert ein Dokument im DSMS.

    - **file**: Das zu speichernde Dokument
    - **document_type**: Typ des Dokuments (legal_document, consent_record, audit_log)
    - **document_id**: Optionale ID des Dokuments
    - **version**: Optionale Versionsnummer
    - **language**: Sprache (default: de)
    """
    content = await file.read()

    # Checksum berechnen
    checksum = hashlib.sha256(content).hexdigest()

    # Metadaten erstellen
    metadata = DocumentMetadata(
        document_type=document_type,
        document_id=document_id,
        version=version,
        language=language,
        created_at=datetime.utcnow().isoformat(),
        checksum=checksum,
        encrypted=False
    )

    # Dokument mit Metadaten als JSON verpacken
    package = {
        "metadata": metadata.model_dump(),
        "content_base64": content.hex(),  # Hex-encodiert für JSON
        "filename": file.filename
    }

    package_bytes = json.dumps(package).encode()

    # Zu IPFS hinzufügen
    result = await ipfs_add(package_bytes)

    cid = result.get("Hash")
    size = int(result.get("Size", 0))

    return StoredDocument(
        cid=cid,
        size=size,
        metadata=metadata,
        gateway_url=f"{IPFS_GATEWAY_URL}/ipfs/{cid}",
        timestamp=datetime.utcnow().isoformat()
    )


@app.get("/api/v1/documents/{cid}")
async def get_document(
    cid: str,
    _auth: dict = Depends(verify_token)
):
    """
    Ruft ein Dokument aus dem DSMS ab.

    - **cid**: Content Identifier (IPFS Hash)
    """
    content = await ipfs_cat(cid)

    try:
        package = json.loads(content)
        metadata = package.get("metadata", {})
        original_content = bytes.fromhex(package.get("content_base64", ""))
        filename = package.get("filename", "document")

        return StreamingResponse(
            io.BytesIO(original_content),
            media_type="application/octet-stream",
            headers={
                "Content-Disposition": f'attachment; filename="{filename}"',
                "X-DSMS-Document-Type": metadata.get("document_type", "unknown"),
                "X-DSMS-Checksum": metadata.get("checksum", ""),
                "X-DSMS-Created-At": metadata.get("created_at", "")
            }
        )
    except json.JSONDecodeError:
        # Wenn es kein DSMS-Paket ist, gib rohen Inhalt zurück
        return StreamingResponse(
            io.BytesIO(content),
            media_type="application/octet-stream"
        )


@app.get("/api/v1/documents/{cid}/metadata")
async def get_document_metadata(
    cid: str,
    _auth: dict = Depends(verify_token)
):
    """
    Ruft nur die Metadaten eines Dokuments ab.

    - **cid**: Content Identifier (IPFS Hash)
    """
    content = await ipfs_cat(cid)

    try:
        package = json.loads(content)
        return {
            "cid": cid,
            "metadata": package.get("metadata", {}),
            "filename": package.get("filename"),
            "size": len(bytes.fromhex(package.get("content_base64", "")))
        }
    except json.JSONDecodeError:
        return {
            "cid": cid,
            "metadata": {},
            "raw_size": len(content)
        }


@app.get("/api/v1/documents", response_model=DocumentList)
async def list_documents(
    _auth: dict = Depends(verify_token)
):
    """
    Listet alle gespeicherten Dokumente auf.
    """
    cids = await ipfs_pin_ls()

    documents = []
    for cid in cids[:100]:  # Limit auf 100 für Performance
        try:
            content = await ipfs_cat(cid)
            package = json.loads(content)
            documents.append({
                "cid": cid,
                "metadata": package.get("metadata", {}),
                "filename": package.get("filename")
            })
        except Exception:
            # Überspringe nicht-DSMS Objekte
            continue

    return DocumentList(
        documents=documents,
        total=len(documents)
    )


@app.delete("/api/v1/documents/{cid}")
async def unpin_document(
    cid: str,
    _auth: dict = Depends(verify_token)
):
    """
    Entfernt ein Dokument aus dem lokalen Pin-Set.
    Das Dokument bleibt im Netzwerk, wird aber bei GC entfernt.

    - **cid**: Content Identifier (IPFS Hash)
    """
    async with httpx.AsyncClient(timeout=30.0) as client:
        response = await client.post(
            f"{IPFS_API_URL}/api/v0/pin/rm",
            params={"arg": cid}
        )

        if response.status_code != 200:
            raise HTTPException(
                status_code=404,
                detail=f"Konnte Pin nicht entfernen: {cid}"
            )

    return {
        "status": "unpinned",
        "cid": cid,
        "message": "Dokument wird bei nächster Garbage Collection entfernt"
    }


@app.post("/api/v1/legal-documents/archive")
async def archive_legal_document(
    document_id: str,
    version: str,
    content: str,
    language: str = "de",
    _auth: dict = Depends(verify_token)
):
    """
    Archiviert eine rechtliche Dokumentversion dauerhaft.
    Speziell für AGB, Datenschutzerklärung, etc.

    - **document_id**: ID des Legal Documents
    - **version**: Versionsnummer
    - **content**: HTML/Markdown Inhalt
    - **language**: Sprache
    """
    # Checksum berechnen
    content_bytes = content.encode('utf-8')
    checksum = hashlib.sha256(content_bytes).hexdigest()

    # Metadaten
    metadata = {
        "document_type": "legal_document",
        "document_id": document_id,
        "version": version,
        "language": language,
        "created_at": datetime.utcnow().isoformat(),
        "checksum": checksum,
        "content_type": "text/html"
    }

    # Paket erstellen
    package = {
        "metadata": metadata,
        "content": content,
        "archived_at": datetime.utcnow().isoformat()
    }

    package_bytes = json.dumps(package, ensure_ascii=False).encode('utf-8')

    # Zu IPFS hinzufügen
    result = await ipfs_add(package_bytes)

    cid = result.get("Hash")

    return {
        "cid": cid,
        "document_id": document_id,
        "version": version,
        "checksum": checksum,
        "archived_at": datetime.utcnow().isoformat(),
        "verification_url": f"{IPFS_GATEWAY_URL}/ipfs/{cid}"
    }


@app.get("/api/v1/verify/{cid}")
async def verify_document(cid: str):
    """
    Verifiziert die Integrität eines Dokuments.
    Öffentlich zugänglich für Audit-Zwecke.

    - **cid**: Content Identifier (IPFS Hash)
    """
    try:
        content = await ipfs_cat(cid)
        package = json.loads(content)

        # Checksum verifizieren
        stored_checksum = package.get("metadata", {}).get("checksum")

        if "content_base64" in package:
            original_content = bytes.fromhex(package["content_base64"])
            calculated_checksum = hashlib.sha256(original_content).hexdigest()
        elif "content" in package:
            calculated_checksum = hashlib.sha256(
                package["content"].encode('utf-8')
            ).hexdigest()
        else:
            calculated_checksum = None

        integrity_valid = (
            stored_checksum == calculated_checksum
            if stored_checksum and calculated_checksum
            else None
        )

        return {
            "cid": cid,
            "exists": True,
            "integrity_valid": integrity_valid,
            "metadata": package.get("metadata", {}),
            "stored_checksum": stored_checksum,
            "calculated_checksum": calculated_checksum,
            "verified_at": datetime.utcnow().isoformat()
        }
    except Exception as e:
        return {
            "cid": cid,
            "exists": False,
            "error": str(e),
            "verified_at": datetime.utcnow().isoformat()
        }


@app.get("/api/v1/node/info")
async def get_node_info():
    """
    Gibt Informationen über den DSMS Node zurück.
    """
    try:
        async with httpx.AsyncClient(timeout=10.0) as client:
            # Node ID
            id_response = await client.post(f"{IPFS_API_URL}/api/v0/id")
            node_info = id_response.json() if id_response.status_code == 200 else {}

            # Repo Stats
            stat_response = await client.post(f"{IPFS_API_URL}/api/v0/repo/stat")
            repo_stats = stat_response.json() if stat_response.status_code == 200 else {}

            return {
                "node_id": node_info.get("ID"),
                "protocol_version": node_info.get("ProtocolVersion"),
                "agent_version": node_info.get("AgentVersion"),
                "repo_size": repo_stats.get("RepoSize"),
                "storage_max": repo_stats.get("StorageMax"),
                "num_objects": repo_stats.get("NumObjects"),
                "addresses": node_info.get("Addresses", [])[:5]  # Erste 5
            }
    except Exception as e:
        return {"error": str(e)}


if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="0.0.0.0", port=8082)
