use crate::api::proxy_client::proxy_client;
use crate::state::AppState;
use axum::{
    body::Bytes,
    extract::{Path, Query, State},
    http::{HeaderMap, Method, StatusCode},
    response::{IntoResponse, Response},
};
use std::collections::HashMap;
use tracing::error;

fn resolve_service_did(did_with_fragment: &str) -> Option<(String, String)> {
    if let Some(without_prefix) = did_with_fragment.strip_prefix("did:web:") {
        let host = without_prefix.split('#').next()?;
        let url = format!("https://{}", host);
        let did_without_fragment = format!("did:web:{}", host);
        Some((url, did_without_fragment))
    } else {
        None
    }
}

pub async fn proxy_handler(
    State(state): State<AppState>,
    Path(method): Path<String>,
    method_verb: Method,
    headers: HeaderMap,
    Query(params): Query<HashMap<String, String>>,
    body: Bytes,
) -> Response {
    let proxy_header = headers
        .get("atproto-proxy")
        .and_then(|h| h.to_str().ok())
        .map(|s| s.to_string());
    let (appview_url, service_aud) = match &proxy_header {
        Some(did_str) => {
            let (url, did_without_fragment) = match resolve_service_did(did_str) {
                Some(resolved) => resolved,
                None => {
                    error!(did = %did_str, "Could not resolve service DID");
                    return (StatusCode::BAD_GATEWAY, "Could not resolve service DID")
                        .into_response();
                }
            };
            (url, Some(did_without_fragment))
        }
        None => {
            let url = match std::env::var("APPVIEW_URL") {
                Ok(url) => url,
                Err(_) => {
                    return (StatusCode::BAD_GATEWAY, "No upstream AppView configured")
                        .into_response();
                }
            };
            let aud = std::env::var("APPVIEW_DID").ok();
            (url, aud)
        }
    };
    let target_url = format!("{}/xrpc/{}", appview_url, method);
    let client = proxy_client();
    let mut request_builder = client.request(method_verb, &target_url).query(&params);
    let mut auth_header_val = headers.get("Authorization").cloned();
    if let Some(aud) = &service_aud
        && let Some(token) = crate::auth::extract_bearer_token_from_header(
            headers.get("Authorization").and_then(|h| h.to_str().ok()),
        )
            && let Ok(auth_user) = crate::auth::validate_bearer_token(&state.db, &token).await
                && let Some(key_bytes) = auth_user.key_bytes
                    && let Ok(new_token) =
                        crate::auth::create_service_token(&auth_user.did, aud, &method, &key_bytes)
                        && let Ok(val) =
                            axum::http::HeaderValue::from_str(&format!("Bearer {}", new_token))
                        {
                            auth_header_val = Some(val);
                        }
    if let Some(val) = auth_header_val {
        request_builder = request_builder.header("Authorization", val);
    }
    for (key, value) in headers.iter() {
        if key != "host" && key != "content-length" && key != "authorization" {
            request_builder = request_builder.header(key, value);
        }
    }
    request_builder = request_builder.body(body);
    match request_builder.send().await {
        Ok(resp) => {
            let status = resp.status();
            let headers = resp.headers().clone();
            let body = match resp.bytes().await {
                Ok(b) => b,
                Err(e) => {
                    error!("Error reading proxy response body: {:?}", e);
                    return (StatusCode::BAD_GATEWAY, "Error reading upstream response")
                        .into_response();
                }
            };
            let mut response_builder = Response::builder().status(status);
            for (key, value) in headers.iter() {
                response_builder = response_builder.header(key, value);
            }
            match response_builder.body(axum::body::Body::from(body)) {
                Ok(r) => r,
                Err(e) => {
                    error!("Error building proxy response: {:?}", e);
                    (StatusCode::INTERNAL_SERVER_ERROR, "Internal Server Error").into_response()
                }
            }
        }
        Err(e) => {
            error!("Error sending proxy request: {:?}", e);
            if e.is_timeout() {
                (StatusCode::GATEWAY_TIMEOUT, "Upstream Timeout").into_response()
            } else {
                (StatusCode::BAD_GATEWAY, "Upstream Error").into_response()
            }
        }
    }
}