// #![cfg_attr(not(feature = "simulator"), no_main)]

use core::{
    iter::Chain,
    ops::{Deref, DerefMut, Range},
};

use alloc::{
    borrow::Cow,
    boxed::Box,
    ffi::CString,
    string::{String, ToString},
    vec,
    vec::Vec,
};
use chrono::{DateTime, NaiveDateTime};
use ekv::{Database, MountError, flash::PageID};
use embassy_embedded_hal::{adapter::BlockingAsync, flash::partition::Partition};
use embassy_sync::blocking_mutex::raw::{CriticalSectionRawMutex, RawMutex};
use embassy_time::{Duration, Instant};
use embedded_storage_async::nor_flash::{NorFlash, ReadNorFlash};
use esp_hal::rng::Trng;
use esp_storage::FlashStorage;
use itertools::Itertools;
use log::{info, warn};
use rmk::futures::TryFutureExt;
use serde::{Deserialize, Serialize};
use slint::SharedString;
use spectre_api_sys::{
    SpectreAlgorithm, SpectreCounter, SpectreKeyPurpose, SpectreResultType, SpectreUserKey,
};

#[cfg(feature = "limit-fps")]
use crate::FRAME_DURATION_MIN;
use crate::{
    SIGNAL_LCD_SUBMIT, SIGNAL_UI_RENDER,
    db::{AcidDatabase, DbKey, DbPathSpectreUsers, PartitionAcid},
    ui::backend::SlintBackend,
    util::DurationExt,
};

pub mod backend;
pub mod window_adapter;

slint::include_modules!();

#[derive(Deserialize, Serialize, Clone, Debug, PartialEq, Eq)]
struct SpectreUsersConfig {
    users: Vec<SpectreUserConfig>,
}

#[derive(Deserialize, Serialize, Clone, Debug, PartialEq, Eq)]
struct SpectreUserConfig {
    username: String,
}

trait ReprConvert: Copy {
    type Repr: Copy;

    fn into_repr(self) -> Self::Repr;
    fn from_repr(repr: Self::Repr) -> Self;
}

impl ReprConvert for SpectreAlgorithm {
    type Repr = u32;

    fn from_repr(repr: Self::Repr) -> Self {
        unsafe { core::mem::transmute::<Self::Repr, Self>(repr) }
    }

    fn into_repr(self) -> Self::Repr {
        self as Self::Repr
    }
}

impl ReprConvert for SpectreResultType {
    type Repr = u32;

    fn from_repr(repr: Self::Repr) -> Self {
        unsafe { core::mem::transmute::<Self::Repr, Self>(repr) }
    }

    fn into_repr(self) -> Self::Repr {
        self as Self::Repr
    }
}

mod with_repr {
    use serde::{Deserialize, Deserializer, Serializer};

    use super::ReprConvert;

    pub fn serialize<T, S>(value: &T, serializer: S) -> Result<S::Ok, S::Error>
    where
        T: ReprConvert<Repr = u32>,
        S: Serializer,
    {
        serializer.serialize_u32(value.into_repr())
    }

    pub fn deserialize<'de, T, D>(deserializer: D) -> Result<T, D::Error>
    where
        T: ReprConvert<Repr = u32>,
        D: Deserializer<'de>,
    {
        <u32 as Deserialize>::deserialize(deserializer).map(T::from_repr)
    }
}

#[derive(Deserialize, Serialize, Clone, Debug, PartialEq, Eq)]
struct SpectreSiteConfig {
    #[serde(with = "with_repr")]
    algorithm: SpectreAlgorithm,
    counter: SpectreCounter::Type,
    #[serde(rename = "type")]
    #[serde(with = "with_repr")]
    result_type: SpectreResultType,
    password: Option<String>,
    #[serde(with = "with_repr")]
    login_type: SpectreResultType,
    login_name: Option<String>,
    uses: u32,
    last_used: NaiveDateTime,
}

#[derive(Clone, Debug, PartialEq, Eq)]
struct SpectreSite {
    username: String,
    site_name: String,
    config: SpectreSiteConfig,
}

#[embassy_executor::task]
pub async fn run_renderer_task(backend: SlintBackend, flash_part_acid: PartitionAcid) {
    let db = AcidDatabase::mount(flash_part_acid).await;

    let value = SpectreUsersConfig {
        users: vec![SpectreUserConfig {
            username: "test".to_string(),
        }],
    };

    {
        let mut write = db.write_transaction().await;
        write
            .write(
                &DbKey::new(DbPathSpectreUsers),
                &postcard::to_allocvec(&value).unwrap(),
            )
            .await
            .unwrap();
        write.commit().await.unwrap();
    }

    let read_value = {
        let read = db.read_transaction().await;
        // TODO: https://github.com/embassy-rs/ekv/issues/20
        let mut buffer = Vec::new();
        let length = read
            .read(&DbKey::new(DbPathSpectreUsers), &mut buffer)
            .await
            .unwrap();
        buffer.resize(length, 0);
        read.read(&DbKey::new(DbPathSpectreUsers), &mut buffer)
            .await
            .unwrap();

        postcard::from_bytes::<SpectreUsersConfig>(&buffer).unwrap()
    };

    assert_eq!(value, read_value, "values do not match");

    // TODO:
    // * Store a config as a versioned postcard-serialized struct
    // * Store accounts and sites as ranges in the DB

    slint::platform::set_platform(Box::new(backend)).expect("backend already initialized");

    let main = AppWindow::new().unwrap();

    main.on_accepted(|string| {
        warn!("Accepted: {string}");
        let Ok(c_string) = CString::new(&*string) else {
            warn!("String cannot be converted to a C string: {string:?}");
            return;
        };
        unsafe {
            let user_key_start = Instant::now();
            let user_key = &*spectre_api_sys::spectre_user_key(
                c"test".as_ptr(),
                c_string.as_ptr(),
                SpectreAlgorithm::Current,
            );
            let user_key_duration = Instant::now().duration_since(user_key_start);
            warn!(
                "User key derived in {} seconds:\n{user_key:02x?}",
                user_key_duration.display_as_secs()
            );
            let site_key_start = Instant::now();
            let site_key = &*spectre_api_sys::spectre_site_key(
                user_key as *const SpectreUserKey,
                c"example.org".as_ptr(),
                SpectreCounter::Initial,
                SpectreKeyPurpose::Authentication,
                c"".as_ptr(),
            );
            let site_key_duration = Instant::now().duration_since(site_key_start);
            warn!(
                "Site key derived in {} seconds:\n{site_key:02x?}",
                site_key_duration.display_as_secs()
            );

            // TODO: Free memory
        }
    });

    run_event_loop(main).await;
}

/// Instead of having a `loop` in the non-async `SlintBackend::run_event_loop`, we achieve
/// async by having only one iteration of the loop run, and `await`ing here.
/// The following block is analogous to `main.run()`.
async fn run_event_loop(main: AppWindow) {
    main.show().unwrap();

    loop {
        slint::run_event_loop().unwrap();
        SIGNAL_LCD_SUBMIT.signal(());
        #[cfg(feature = "limit-fps")]
        embassy_time::Timer::after(FRAME_DURATION_MIN).await;
        SIGNAL_UI_RENDER.wait().await;
    }

    #[expect(unreachable_code)]
    main.hide().unwrap();
}