"""
Graph router for Library Desk API.

Endpoints for Neo4j knowledge graph operations.
"""

from fastapi import APIRouter, HTTPException, Depends, Query
from typing import Optional, List
import logging

from src.models.graph import (
    CypherQueryRequest, CypherQueryResponse,
    UpdateFromPageRequest, GraphUpdateSummary,
    NodeListResponse, GraphNodeDetail,
    MindMapResponse
)
from src.services.graph_service import GraphService
from src.core.dependencies import (
    Neo4jDep, WikiJSDep, verify_api_key, RequiredUserQuery
)

logger = logging.getLogger(__name__)

router = APIRouter(prefix="/graph", tags=["Graph"])


# Dependency to get graph service
def get_graph_service(
    neo4j_client: Neo4jDep,
    wiki_client: WikiJSDep
) -> GraphService:
    """Get graph service instance."""
    return GraphService(neo4j_client, wiki_client)


@router.post("/query", response_model=CypherQueryResponse)
async def execute_cypher_query(
    request: CypherQueryRequest,
    graph_service: GraphService = Depends(get_graph_service),
    api_key: str = Depends(verify_api_key)
):
    """
    Execute a raw Cypher query (ADMIN/DEBUG — read-only, NOT tenant-scoped).

    **Security model:**
    - Write clauses (CREATE/MERGE/DELETE/SET/REMOVE/DROP/DETACH/FOREACH/
      LOAD CSV) and CALL procedures are rejected with 400.
    - Execution happens in a read-only Neo4j session as a hard backstop.
    - Results are NOT restricted to the requesting user's tenant labels —
      scope your own patterns (e.g. match `User_<Tenant>_Document`).
      For tenant-scoped access use /graph/nodes instead.

    **Example Request:**
    ```json
    {
        "query": "MATCH (d:User_Llm_Tester_Document:Document) RETURN d LIMIT 10",
        "parameters": {},
        "user": "<tenant>"
    }
    ```
    """
    try:
        return await graph_service.execute_query(
            query=request.query,
            parameters=request.parameters,
            user=request.user
        )
    except ValueError as e:
        raise HTTPException(status_code=400, detail=str(e))
    except Exception as e:
        logger.error(f"Cypher query failed: {e}", exc_info=True)
        raise HTTPException(status_code=500, detail="Query execution failed")


@router.get("/nodes", response_model=NodeListResponse)
async def list_nodes(
    user: RequiredUserQuery,
    node_type: Optional[str] = Query(default=None, description="Node type filter"),
    limit: int = Query(default=100, ge=1, le=500, description="Maximum nodes"),
    graph_service: GraphService = Depends(get_graph_service),
    api_key: str = Depends(verify_api_key)
):
    """
    List graph nodes for a user.

    Optionally filter by node type (Document, Person, Project, Concept, etc.).

    **Example:** `/graph/nodes?user=<tenant>&node_type=Document&limit=50`
    """
    try:
        return await graph_service.list_nodes(
            user=user,
            node_type=node_type,
            limit=limit
        )
    except Exception as e:
        logger.error(f"Failed to list nodes: {e}", exc_info=True)
        raise HTTPException(status_code=500, detail="Failed to list nodes")


@router.get("/nodes/{node_id}", response_model=GraphNodeDetail)
async def get_node(
    node_id: str,
    user: RequiredUserQuery,
    graph_service: GraphService = Depends(get_graph_service),
    api_key: str = Depends(verify_api_key)
):
    """
    Get detailed information about a graph node.

    Returns the node, its relationships, and connected nodes.

    **Example:** `/graph/nodes/4:abc123def:0?user=<tenant>`
    """
    try:
        node = await graph_service.get_node(node_id, user)
        if not node:
            raise HTTPException(status_code=404, detail=f"Node {node_id} not found")
        return node
    except HTTPException:
        raise
    except Exception as e:
        logger.error(f"Failed to get node {node_id}: {e}", exc_info=True)
        raise HTTPException(status_code=500, detail="Failed to get node")


@router.post("/update-from-page/{page_id}", response_model=GraphUpdateSummary)
async def update_graph_from_page(
    page_id: int,
    user: RequiredUserQuery,
    force_refresh: bool = Query(default=False, description="Force re-extraction"),
    graph_service: GraphService = Depends(get_graph_service),
    api_key: str = Depends(verify_api_key)
):
    """
    Update knowledge graph from a wiki page.

    This endpoint:
    1. Fetches the page from Wiki.js
    2. Extracts entities (people, projects, concepts, technologies)
    3. Creates/updates Document node
    4. Creates entity nodes and MENTIONS relationships
    5. Returns summary of what was updated

    **Use Cases:**
    - Called automatically after page creation/update (via BackgroundTasks)
    - Called manually by user/Librarian to refresh graph
    - Called by Scheduler for batch processing

    **Example:** `POST /graph/update-from-page/4?user=<tenant>`

    **Returns:** Summary with nodes/relationships created and entities extracted
    """
    try:
        summary = await graph_service.update_from_page(
            page_id=page_id,
            user=user,
            force_refresh=force_refresh
        )

        if not summary.success:
            raise HTTPException(
                status_code=500,
                detail=f"Graph update failed: {summary.error_message}"
            )

        return summary

    except HTTPException:
        raise
    except Exception as e:
        logger.error(f"Failed to update graph from page {page_id}: {e}", exc_info=True)
        raise HTTPException(status_code=500, detail="Graph update failed")


@router.post("/mindmap", response_model=MindMapResponse)
async def generate_mindmap(
    user: RequiredUserQuery,
    center_node_id: str = Query(..., description="Central node ID"),
    depth: int = Query(default=2, ge=1, le=5, description="Traversal depth"),
    graph_service: GraphService = Depends(get_graph_service),
    api_key: str = Depends(verify_api_key)
):
    """
    Generate mind map data for visualization.

    Traverses the graph from a center node and returns nodes/links
    in a format suitable for D3.js or similar visualization libraries.

    **Parameters:**
    - `center_node_id`: The node to center the mind map on
    - `depth`: How many hops away from center to include (1-5)
    - `user`: User identifier for scoping

    **Example:** `POST /graph/mindmap?center_node_id=4:abc:0&depth=2`

    **Returns:** Nodes and links for visualization
    """
    try:
        return await graph_service.generate_mindmap(
            center_node_id=center_node_id,
            user=user,
            depth=depth
        )
    except Exception as e:
        logger.error(f"Failed to generate mindmap: {e}", exc_info=True)
        raise HTTPException(status_code=500, detail="Mindmap generation failed")


@router.post("/generate-entity-pages")
async def generate_entity_pages(
    user: RequiredUserQuery,
    min_mentions: int = Query(default=5, ge=1, le=100, description="Minimum mentions threshold"),
    entity_types: Optional[List[str]] = Query(default=None, description="Entity types to process"),
    graph_service: GraphService = Depends(get_graph_service),
    api_key: str = Depends(verify_api_key)
):
    """
    Generate wiki stub pages for graph entities.

    Creates pages in `/entities/{type}/{name}` namespace for entities
    that have been mentioned in multiple documents. This creates a
    bidirectional knowledge graph ↔ wiki synchronization.

    **Threshold:** Entities must be mentioned in at least `min_mentions` documents (default: 5)

    **Auto-stub flow:**
    1. Find entities with >= min_mentions
    2. Check if entity already has a wiki page
    3. If not, create stub page with:
       - List of mentioning documents
       - Related entities (co-occurring)
       - Auto-generated tag to prevent feedback loops

    **Feedback loop protection:** Pages tagged with `entity-stub` skip entity extraction

    **Parameters:**
    - `min_mentions`: Minimum number of document mentions required (default: 5)
    - `entity_types`: List of types to process (default: Person, Technology, Concept, Project)
    - `user`: User identifier for scoping

    **Example:** `POST /graph/generate-entity-pages?min_mentions=3&user=jpmschweitzer`

    **Returns:** Summary with list of pages created and skipped
    """
    try:
        result = await graph_service.generate_entity_stubs(
            user=user,
            min_mentions=min_mentions,
            entity_types=entity_types
        )
        return result
    except Exception as e:
        logger.error(f"Failed to generate entity pages: {e}", exc_info=True)
        raise HTTPException(status_code=500, detail="Entity page generation failed")