mod dem;

use axum::{
    extract::{Extension, Path, Query, State},
    http::StatusCode,
    response::{IntoResponse, Response},
    routing::get,
    Json, Router,
};
use axum_macros::debug_handler;
use std::env;

use serde::ser::SerializeSeq;
use serde::{Deserialize, Deserializer, Serialize};
use serde_qs::axum::{QsQueryConfig, QsQueryRejection};
use tower_http::trace::TraceLayer;
use tower_http::{
    services::ServeDir,
    trace::{self},
};
use tracing::{error, info, Level};

use dem::DatasetRepository;

const DEFAULT_DATA_DIR: &str = "/data";
const DEFAULT_PORT: &str = "3000";

#[derive(Deserialize, Debug)]
struct Opts {
    #[serde(default, deserialize_with = "empty_string_as_none")]
    json: bool,
}

#[derive(Deserialize, Debug)]
struct JsParams {
    #[serde(default, deserialize_with = "deserialize_array")]
    pts: Vec<(f64, f64)>,
}

#[derive(Serialize, Debug)]
struct JsResult {
    #[serde(serialize_with = "serialize_vec_round")]
    elevations: Vec<Option<f64>>,
}

fn serialize_vec_round<S>(v: &Vec<Option<f64>>, s: S) -> Result<S::Ok, S::Error>
where
    S: serde::Serializer,
{
    let mut sv = s.serialize_seq(Some(v.len()))?;
    for e in v {
        match e {
            None => sv.serialize_element(&e)?,
            Some(x) => {
                // Round the f64 to 1 decimal place. This is ugly as shit.
                let fmt = format!("{:.1}", x);
                let xx = fmt.parse::<f64>().unwrap();
                sv.serialize_element(&xx)?;
            }
        };
    }
    sv.end()
}

fn deserialize_array<'de, D>(deserializer: D) -> Result<Vec<(f64, f64)>, D::Error>
where
    D: Deserializer<'de>,
{
    let s = String::deserialize(deserializer)?;
    let result: Result<Vec<(f64, f64)>, serde_json::Error> = serde_json::from_str(&s);
    match result {
        Ok(x) => Ok(x),
        Err(e) => Err(serde::de::Error::custom(
            "Invalid array: ".to_string() + &e.to_string(),
        )),
    }
}

fn empty_string_as_none<'de, D>(de: D) -> Result<bool, D::Error>
where
    D: Deserializer<'de>,
{
    let opt = Option::<String>::deserialize(de)?;
    match opt.as_deref() {
        None => Ok(false),
        Some("") => Ok(true),
        Some(x) => Ok(x != "false"),
    }
}

#[tokio::main]
async fn main() {
    // initialize tracing
    tracing_subscriber::fmt::init();

    let config = load_config().unwrap();
    let cache = DatasetRepository::new(config.basedir);

    let serve_dir = ServeDir::new("assets");

    let app = Router::<DatasetRepository>::new()
        .route("/v1/elevation/:lat/:lon", get(get_elevation))
        .route("/v1/elevation", get(get_elevation_js))
        .nest_service("/", serve_dir)
        .with_state(cache)
        .layer(
            TraceLayer::new_for_http()
                .make_span_with(trace::DefaultMakeSpan::new().level(Level::DEBUG))
                .on_response(trace::DefaultOnResponse::new().level(Level::DEBUG)),
        )
        .layer(Extension(QsQueryConfig::new(5, false).error_handler(
            |err| {
                QsQueryRejection::new(
                    format!("Get fucked: {}", err),
                    StatusCode::UNPROCESSABLE_ENTITY,
                )
            },
        )));

    let host = format!("[::]:{}", config.port);
    info!("Will start server on {host}");

    let listener = tokio::net::TcpListener::bind(host).await.unwrap();
    axum::serve(listener, app).await.unwrap();
}

#[debug_handler]
async fn get_elevation(
    State(dsr): State<DatasetRepository>,
    query_opts: Query<Opts>,
    Path((lat, lon)): Path<(f64, f64)>,
) -> Response {
    println!("lat: {}, lon: {}", lat, lon);
    println!("query_opts: {:?}", query_opts);

    let ele;
    match dem::elevation_from_coordinates(&dsr, lat, lon).await {
        Ok(x) => match x {
            Some(el) => ele = el,
            None => ele = 0.,
        },
        Err(e) => {
            return e.to_string().into_response();
        }
    }

    #[derive(Serialize)]
    struct Ele {
        elevation: f64,
    }

    if query_opts.json {
        let r = Ele { elevation: ele };
        Json(r).into_response()
    } else {
        format!("{}", ele).into_response()
    }
}

#[debug_handler]
async fn get_elevation_js(
    State(dsr): State<DatasetRepository>,
    Query(params): Query<JsParams>,
) -> Response {
    let mut response = JsResult { elevations: vec![] };
    for pt in params.pts {
        let ele = dem::elevation_from_coordinates(&dsr, pt.0, pt.1).await;
        match ele {
            Ok(x) => response.elevations.push(x),
            Err(e) => {
                error!("Error: {e}");
                response.elevations.push(None);
            }
        }
    }
    Json(response).into_response()
}

fn load_config() -> Result<Config, env::VarError> {
    Ok(Config {
        basedir: env::var("DEM_LOCATION").unwrap_or_else(|_| DEFAULT_DATA_DIR.to_string()),
        port: env::var("HTTP_PORT").unwrap_or_else(|_| DEFAULT_PORT.to_string()),
    })
}
struct Config {
    basedir: String,
    port: String,
}