use crate::config::Config;
use crate::memory::{self, Memory, MemoryCategory};
use crate::providers::{self, Provider};
use anyhow::Result;
use std::sync::Arc;
use tokio::io::{AsyncReadExt, AsyncWriteExt};
use tokio::net::TcpListener;

/// Run a minimal HTTP gateway (webhook + health check)
/// Zero new dependencies — uses raw TCP + tokio.
#[allow(clippy::too_many_lines)]
pub async fn run_gateway(host: &str, port: u16, config: Config) -> Result<()> {
    let addr = format!("{host}:{port}");
    let listener = TcpListener::bind(&addr).await?;

    let provider: Arc<dyn Provider> = Arc::from(providers::create_provider(
        config.default_provider.as_deref().unwrap_or("openrouter"),
        config.api_key.as_deref(),
    )?);
    let model = config
        .default_model
        .clone()
        .unwrap_or_else(|| "anthropic/claude-sonnet-4-20250514".into());
    let temperature = config.default_temperature;
    let mem: Arc<dyn Memory> = Arc::from(memory::create_memory(
        &config.memory,
        &config.workspace_dir,
        config.api_key.as_deref(),
    )?);

    // Extract webhook secret for authentication
    let webhook_secret: Option<Arc<str>> = config
        .channels_config
        .webhook
        .as_ref()
        .and_then(|w| w.secret.as_deref())
        .map(Arc::from);

    // ── Tunnel ────────────────────────────────────────────────
    let tunnel = crate::tunnel::create_tunnel(&config.tunnel)?;
    let mut tunnel_url: Option<String> = None;

    if let Some(ref tun) = tunnel {
        println!("🔗 Starting {} tunnel...", tun.name());
        match tun.start(host, port).await {
            Ok(url) => {
                println!("🌐 Tunnel active: {url}");
                tunnel_url = Some(url);
            }
            Err(e) => {
                println!("⚠️  Tunnel failed to start: {e}");
                println!("   Falling back to local-only mode.");
            }
        }
    }

    println!("🦀 ZeroClaw Gateway listening on http://{addr}");
    if let Some(ref url) = tunnel_url {
        println!("  🌐 Public URL: {url}");
    }
    println!("  POST /webhook  — {{\"message\": \"your prompt\"}}");
    println!("  GET  /health   — health check");
    if webhook_secret.is_some() {
        println!("  🔒 Webhook authentication: ENABLED (X-Webhook-Secret header required)");
    } else {
        println!(
            "  ⚠️  Webhook authentication: DISABLED (set [channels.webhook] secret to enable)"
        );
    }
    println!("  Press Ctrl+C to stop.\n");

    loop {
        let (mut stream, peer) = listener.accept().await?;
        let provider = provider.clone();
        let model = model.clone();
        let mem = mem.clone();
        let auto_save = config.memory.auto_save;
        let secret = webhook_secret.clone();

        tokio::spawn(async move {
            let mut buf = vec![0u8; 8192];
            let n = match stream.read(&mut buf).await {
                Ok(n) if n > 0 => n,
                _ => return,
            };

            let request = String::from_utf8_lossy(&buf[..n]);
            let first_line = request.lines().next().unwrap_or("");
            let parts: Vec<&str> = first_line.split_whitespace().collect();

            if let [method, path, ..] = parts.as_slice() {
                tracing::info!("{peer} → {method} {path}");
                handle_request(
                    &mut stream,
                    method,
                    path,
                    &request,
                    &provider,
                    &model,
                    temperature,
                    &mem,
                    auto_save,
                    secret.as_ref(),
                )
                .await;
            } else {
                let _ = send_response(&mut stream, 400, "Bad Request").await;
            }
        });
    }
}

/// Extract a header value from a raw HTTP request.
fn extract_header<'a>(request: &'a str, header_name: &str) -> Option<&'a str> {
    let lower_name = header_name.to_lowercase();
    for line in request.lines() {
        if let Some((key, value)) = line.split_once(':') {
            if key.trim().to_lowercase() == lower_name {
                return Some(value.trim());
            }
        }
    }
    None
}

#[allow(clippy::too_many_arguments)]
async fn handle_request(
    stream: &mut tokio::net::TcpStream,
    method: &str,
    path: &str,
    request: &str,
    provider: &Arc<dyn Provider>,
    model: &str,
    temperature: f64,
    mem: &Arc<dyn Memory>,
    auto_save: bool,
    webhook_secret: Option<&Arc<str>>,
) {
    match (method, path) {
        ("GET", "/health") => {
            let body = serde_json::json!({
                "status": "ok",
                "version": env!("CARGO_PKG_VERSION"),
                "memory": mem.name(),
                "memory_healthy": mem.health_check().await,
            });
            let _ = send_json(stream, 200, &body).await;
        }

        ("POST", "/webhook") => {
            // Authenticate webhook requests if a secret is configured
            if let Some(secret) = webhook_secret {
                let header_val = extract_header(request, "X-Webhook-Secret");
                match header_val {
                    Some(val) if val == secret.as_ref() => {}
                    _ => {
                        tracing::warn!(
                            "Webhook: rejected request — invalid or missing X-Webhook-Secret"
                        );
                        let err = serde_json::json!({"error": "Unauthorized — invalid or missing X-Webhook-Secret header"});
                        let _ = send_json(stream, 401, &err).await;
                        return;
                    }
                }
            }
            handle_webhook(
                stream,
                request,
                provider,
                model,
                temperature,
                mem,
                auto_save,
            )
            .await;
        }

        _ => {
            let body = serde_json::json!({
                "error": "Not found",
                "routes": ["GET /health", "POST /webhook"]
            });
            let _ = send_json(stream, 404, &body).await;
        }
    }
}

async fn handle_webhook(
    stream: &mut tokio::net::TcpStream,
    request: &str,
    provider: &Arc<dyn Provider>,
    model: &str,
    temperature: f64,
    mem: &Arc<dyn Memory>,
    auto_save: bool,
) {
    let body_str = request
        .split("\r\n\r\n")
        .nth(1)
        .or_else(|| request.split("\n\n").nth(1))
        .unwrap_or("");

    let Ok(parsed) = serde_json::from_str::<serde_json::Value>(body_str) else {
        let err = serde_json::json!({"error": "Invalid JSON. Expected: {\"message\": \"...\"}"});
        let _ = send_json(stream, 400, &err).await;
        return;
    };

    let Some(message) = parsed.get("message").and_then(|v| v.as_str()) else {
        let err = serde_json::json!({"error": "Missing 'message' field in JSON"});
        let _ = send_json(stream, 400, &err).await;
        return;
    };

    if auto_save {
        let _ = mem
            .store("webhook_msg", message, MemoryCategory::Conversation)
            .await;
    }

    match provider.chat(message, model, temperature).await {
        Ok(response) => {
            let body = serde_json::json!({"response": response, "model": model});
            let _ = send_json(stream, 200, &body).await;
        }
        Err(e) => {
            let err = serde_json::json!({"error": format!("LLM error: {e}")});
            let _ = send_json(stream, 500, &err).await;
        }
    }
}

async fn send_response(
    stream: &mut tokio::net::TcpStream,
    status: u16,
    body: &str,
) -> std::io::Result<()> {
    let reason = match status {
        200 => "OK",
        400 => "Bad Request",
        404 => "Not Found",
        500 => "Internal Server Error",
        _ => "Unknown",
    };
    let response = format!(
        "HTTP/1.1 {status} {reason}\r\nContent-Type: text/plain\r\nContent-Length: {}\r\nConnection: close\r\n\r\n{body}",
        body.len()
    );
    stream.write_all(response.as_bytes()).await
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn extract_header_finds_value() {
        let req =
            "POST /webhook HTTP/1.1\r\nHost: localhost\r\nX-Webhook-Secret: my-secret\r\n\r\n{}";
        assert_eq!(extract_header(req, "X-Webhook-Secret"), Some("my-secret"));
    }

    #[test]
    fn extract_header_case_insensitive() {
        let req = "POST /webhook HTTP/1.1\r\nx-webhook-secret: abc123\r\n\r\n{}";
        assert_eq!(extract_header(req, "X-Webhook-Secret"), Some("abc123"));
    }

    #[test]
    fn extract_header_missing_returns_none() {
        let req = "POST /webhook HTTP/1.1\r\nHost: localhost\r\n\r\n{}";
        assert_eq!(extract_header(req, "X-Webhook-Secret"), None);
    }

    #[test]
    fn extract_header_trims_whitespace() {
        let req = "POST /webhook HTTP/1.1\r\nX-Webhook-Secret:   spaced   \r\n\r\n{}";
        assert_eq!(extract_header(req, "X-Webhook-Secret"), Some("spaced"));
    }

    #[test]
    fn extract_header_first_match_wins() {
        let req = "POST /webhook HTTP/1.1\r\nX-Webhook-Secret: first\r\nX-Webhook-Secret: second\r\n\r\n{}";
        assert_eq!(extract_header(req, "X-Webhook-Secret"), Some("first"));
    }

    #[test]
    fn extract_header_empty_value() {
        let req = "POST /webhook HTTP/1.1\r\nX-Webhook-Secret:\r\n\r\n{}";
        assert_eq!(extract_header(req, "X-Webhook-Secret"), Some(""));
    }

    #[test]
    fn extract_header_colon_in_value() {
        let req = "POST /webhook HTTP/1.1\r\nAuthorization: Bearer sk-abc:123\r\n\r\n{}";
        // split_once on ':' means only the first colon splits key/value
        assert_eq!(
            extract_header(req, "Authorization"),
            Some("Bearer sk-abc:123")
        );
    }

    #[test]
    fn extract_header_different_header() {
        let req = "POST /webhook HTTP/1.1\r\nContent-Type: application/json\r\nX-Webhook-Secret: mysecret\r\n\r\n{}";
        assert_eq!(
            extract_header(req, "Content-Type"),
            Some("application/json")
        );
        assert_eq!(extract_header(req, "X-Webhook-Secret"), Some("mysecret"));
    }

    #[test]
    fn extract_header_from_empty_request() {
        assert_eq!(extract_header("", "X-Webhook-Secret"), None);
    }

    #[test]
    fn extract_header_newline_only_request() {
        assert_eq!(extract_header("\r\n\r\n", "X-Webhook-Secret"), None);
    }
}

async fn send_json(
    stream: &mut tokio::net::TcpStream,
    status: u16,
    body: &serde_json::Value,
) -> std::io::Result<()> {
    let reason = match status {
        200 => "OK",
        400 => "Bad Request",
        404 => "Not Found",
        500 => "Internal Server Error",
        _ => "Unknown",
    };
    let json = serde_json::to_string(body).unwrap_or_default();
    let response = format!(
        "HTTP/1.1 {status} {reason}\r\nContent-Type: application/json\r\nContent-Length: {}\r\nConnection: close\r\n\r\n{json}",
        json.len()
    );
    stream.write_all(response.as_bytes()).await
}