/// HTTP handler for POST /memory/visualize endpoint.
///
/// Serves graph visualization queries with pagination support.
/// Used for testing queries and understanding context depth impact.

use actix_web::{web, HttpRequest, HttpResponse};
use serde_json::json;

use crate::query::visualize::{VisualizeRequest, GraphVisualizer};
use crate::jwt_validator::validate_token;
use crate::rate_limiter::RateLimiter;

/// POST /memory/visualize
///
/// Query knowledge graph around a search query, with pagination.
///
/// # Request
/// ```json
/// {
///   "project": "poimen",
///   "query": "kubernetes troubleshooting",
///   "depth": 2,
///   "limit": 50,
///   "page": 1,
///   "include_low_confidence": false
/// }
/// ```
///
/// # Response (200 OK)
/// ```json
/// {
///   "query": "kubernetes troubleshooting",
///   "project": "poimen",
///   "pagination": {
///     "page": 1,
///     "limit": 50,
///     "total_nodes": 487,
///     "total_pages": 10,
///     "has_next": true,
///     "has_prev": false
///   },
///   "depth_breakdown": {
///     "depth_0": 12,
///     "depth_1": 234,
///     "depth_2": 241
///   },
///   "nodes": [...],
///   "edges": [...],
///   "performance": {
///     "query_time_ms": 145,
///     "depth_1_time_ms": 45,
///     "depth_2_time_ms": 100,
///     "total_time_ms": 157
///   },
///   "recommendations": [
///     {
///       "issue": "high_result_count",
///       "suggestion": "Try depth=1 to reduce from 487→234 nodes",
///       "expected_latency_ms": 95
///     }
///   ]
/// }
/// ```
pub async fn handle_visualize(
    req: HttpRequest,
    body: web::Json<VisualizeRequest>,
    rate_limiter: web::Data<RateLimiter>,
) -> HttpResponse {
    // 1. Extract and validate token
    let token = match extract_bearer_token(&req) {
        Ok(t) => t,
        Err(e) => {
            return error_response(401, "unauthorized", &format!("Missing token: {}", e));
        }
    };
    
    let claims = match validate_token(&token) {
        Ok(c) => c,
        Err(e) => {
            return error_response(401, "unauthorized", &format!("Invalid token: {}", e));
        }
    };
    
    // 2. Check rate limit (visualize: 100/hour)
    let user_id = &claims.sub;
    if !rate_limiter.check_limit(user_id, "visualize", 100) {
        return error_response(
            429,
            "rate_limit_exceeded",
            "Visualize limit: 100/hour",
        );
    }
    
    // 3. Validate request
    if body.project.is_empty() || body.query.is_empty() {
        return error_response(400, "invalid_request", "Missing project or query");
    }
    
    // 4. Check project access
    // TODO: Verify user has access to this project via RBAC
    
    // 5. Execute visualization query
    let response = match GraphVisualizer::visualize(&body, "").await {
        Ok(r) => r,
        Err(e) => {
            return error_response(500, "internal_error", &format!("Visualization failed: {}", e));
        }
    };
    
    // 6. Return response
    HttpResponse::Ok().json(json!({
        "query": response.query,
        "project": response.project,
        "pagination": response.pagination,
        "depth_breakdown": {
            "depth_0": response.depth_breakdown.depth_0,
            "depth_1": response.depth_breakdown.depth_1,
            "depth_2": response.depth_breakdown.depth_2,
            "depth_3": response.depth_breakdown.depth_3,
        },
        "nodes": response.nodes,
        "edges": response.edges,
        "performance": {
            "query_time_ms": response.performance.query_time_ms,
            "depth_times_ms": response.performance.depth_times_ms,
            "total_time_ms": response.performance.total_time_ms,
        },
        "recommendations": response.recommendations,
    }))
}

/// GET /memory/visualize/layouts
///
/// Return available layout algorithms for graph visualization.
pub async fn handle_visualize_layouts() -> HttpResponse {
    HttpResponse::Ok().json(json!({
        "layouts": [
            {
                "id": "force",
                "name": "Force-Directed",
                "description": "Physics simulation (good for dense graphs)",
                "params": {
                    "strength": -30,
                    "distance": 100
                }
            },
            {
                "id": "hierarchy",
                "name": "Hierarchical",
                "description": "Top-down tree layout",
                "params": {
                    "gap": 40
                }
            },
            {
                "id": "circular",
                "name": "Circular",
                "description": "Nodes on a circle",
                "params": {
                    "radius": 200
                }
            }
        ]
    }))
}

/// GET /memory/visualize/styles
///
/// Return node/edge styling presets.
pub async fn handle_visualize_styles() -> HttpResponse {
    HttpResponse::Ok().json(json!({
        "node_colors": {
            "person": "#4CAF50",
            "tool": "#2196F3",
            "concept": "#9C27B0",
            "location": "#FF9800",
            "organization": "#F44336",
            "event": "#FFC107"
        },
        "edge_styles": {
            "high_confidence": {
                "stroke": "#333",
                "strokeWidth": 3,
                "animated": true
            },
            "medium_confidence": {
                "stroke": "#666",
                "strokeWidth": 2,
                "animated": false
            },
            "low_confidence": {
                "stroke": "#999",
                "strokeWidth": 1,
                "strokeDasharray": "5,5"
            },
            "contradiction": {
                "stroke": "#F44336",
                "strokeWidth": 3,
                "animated": true
            },
            "under_review": {
                "stroke": "#FFC107",
                "strokeWidth": 2,
                "strokeDasharray": "3,3"
            }
        }
    }))
}

// ─────────────────────────────────────────────────────────────────────────────

fn extract_bearer_token(req: &HttpRequest) -> Result<String, String> {
    let header = req
        .headers()
        .get("Authorization")
        .and_then(|v| v.to_str().ok())
        .ok_or("Missing Authorization header")?;
    
    if !header.starts_with("Bearer ") {
        return Err("Invalid Authorization format".to_string());
    }
    
    Ok(header[7..].to_string())
}

fn error_response(status: u16, code: &str, message: &str) -> HttpResponse {
    let status_code = actix_web::http::StatusCode::from_u16(status)
        .unwrap_or(actix_web::http::StatusCode::INTERNAL_SERVER_ERROR);
    
    HttpResponse::build(status_code).json(json!({
        "error": code,
        "message": message,
        "request_id": uuid::Uuid::new_v4().to_string(),
    }))
}

#[cfg(test)]
mod tests {
    use super::*;
    
    #[test]
    fn test_extract_bearer_token_valid() {
        // Mock request with Bearer token
        // Note: This is simplified; real test would use actix test utilities
        let token = "eyJ0eXAiOiJKV1QiLCJhbGc...";
        let header = format!("Bearer {}", token);
        assert!(header.starts_with("Bearer "));
    }
    
    #[test]
    fn test_error_response_400() {
        let resp = error_response(400, "bad_request", "Invalid input");
        assert_eq!(resp.status(), actix_web::http::StatusCode::BAD_REQUEST);
    }
    
    #[test]
    fn test_error_response_401() {
        let resp = error_response(401, "unauthorized", "Invalid token");
        assert_eq!(resp.status(), actix_web::http::StatusCode::UNAUTHORIZED);
    }
}