use std::path::Path;
use std::sync::Mutex;
use std::time::{Duration, SystemTime};

use color_eyre::Result;
use lazy_static::lazy_static;
use rocket::serde::json::Json;
use rocket::tokio::fs::File;
use rocket::tokio::io::AsyncReadExt;
use rocket::tokio::select;
use rocket::tokio::time::sleep;
use rocket::{get, routes};
use serde::{Deserialize, Serialize};
use url::{ParseError, Url};

/// The interval between data polls
///
/// This depends on with which interval Autaurco processes new information from the invertor.
const POLL_INTERVAL: u64 = 300;

/// The base URL of My Autarco site
const BASE_URL: &'static str = "https://my.autarco.com";

fn login_url() -> Result<Url, ParseError> {
    Url::parse(&format!("{}/auth/login", BASE_URL))
}

fn api_url(site_id: &str, endpoint: &str) -> Result<Url, ParseError> {
    Url::parse(&format!(
        "{}/api/site/{}/kpis/{}",
        BASE_URL, site_id, endpoint
    ))
}

/// The configuration for the My Autarco site
#[derive(Debug, Deserialize)]
struct Config {
    /// The username of the account to login with
    username: String,
    /// The password of the account to login with
    password: String,
    /// The Autarco site ID to track
    site_id: String,
}

async fn load_config() -> Result<Config> {
    let config_file_name = Path::new(env!("CARGO_MANIFEST_DIR")).join("autarco.toml");
    let mut file = File::open(config_file_name).await?;

    let mut contents = String::new();
    file.read_to_string(&mut contents).await?;
    let config = toml::from_str(&contents)?;

    Ok(config)
}

/// The current photovoltaic invertor status.
#[derive(Clone, Copy, Debug, Serialize)]
struct Status {
    /// Current power production (W)
    current_w: u32,
    /// Total energy produced since installation (kWh)
    total_kwh: u32,
    /// Timestamp of last update
    last_updated: u64,
}

lazy_static! {
    /// The concurrently accessible current status
    static ref STATUS: Mutex<Option<Status>> = Mutex::new(None);
}

/// The energy data returnes by the energy API endpoint
#[derive(Debug, Deserialize)]
struct ApiEnergy {
    /// Total energy produced today (kWh)
    pv_today: u32,
    /// Total energy produced this month (kWh)
    pv_month: u32,
    /// Total energy produced since installation (kWh)
    pv_to_date: u32,
}

///  The power data returned by the power API endpoint
#[derive(Debug, Deserialize)]
struct ApiPower {
    /// Current power production (W)
    pv_now: u32,
}

async fn login(config: &Config, client: &reqwest::Client) -> Result<()> {
    let params = [
        ("username", &config.username),
        ("password", &config.password),
    ];
    client.post(login_url()?).form(&params).send().await?;

    Ok(())
}

async fn update(config: &Config, client: &reqwest::Client, last_updated: u64) -> Result<Status> {
    // Retrieve the data from the API endpoints
    let api_energy_url = api_url(&config.site_id, "energy")?;
    let api_energy: ApiEnergy = client.get(api_energy_url).send().await?.json().await?;

    let api_power_url = api_url(&config.site_id, "power")?;
    let api_power: ApiPower = client.get(api_power_url).send().await?.json().await?;

    let current_w = api_power.pv_now;
    let total_kwh = api_energy.pv_to_date;

    // Update the status
    Ok(Status {
        current_w,
        total_kwh,
        last_updated,
    })
}

async fn update_loop() -> Result<()> {
    let config = load_config().await?;
    let client = reqwest::ClientBuilder::new().cookie_store(true).build()?;

    // Go to the My Autarco site and login
    println!("⚡ Logging in...");
    login(&config, &client).await?;

    let mut last_updated = 0;
    loop {
        // Wake up every second and check if there is something to do (quit or update).
        sleep(Duration::from_secs(1)).await;

        let timestamp = SystemTime::now()
            .duration_since(SystemTime::UNIX_EPOCH)
            .unwrap()
            .as_secs();
        if timestamp - last_updated < POLL_INTERVAL {
            continue;
        }

        // TODO: Relogin if the cookie expired?
        // TODO: Handle errors instead of panicing!
        let status = update(&config, &client, timestamp).await?;
        last_updated = timestamp;

        println!("⚡ Updated status to: {:#?}", status);
        let mut status_guard = STATUS.lock().expect("Status mutex was poisoned");
        status_guard.replace(status);
    }
}

#[get("/", format = "application/json")]
async fn status() -> Option<Json<Status>> {
    let status_guard = STATUS.lock().expect("Status mutex was poisoined");
    status_guard.map(|status| Json(status))
}

#[rocket::main]
async fn main() -> Result<()> {
    color_eyre::install()?;

    let rocket = rocket::build().mount("/", routes![status]).ignite().await?;
    let shutdown = rocket.shutdown();

    let updater = rocket::tokio::spawn(update_loop());

    select! {
        result = rocket.launch() => {
            result?;
        },
        result = updater => {
            shutdown.notify();
            result??;
        }
    }

    Ok(())
}