use rayon::iter::ParallelIterator;
use rayon::iter::IndexedParallelIterator;
use std::sync::Arc;
use std::time::Instant;
use chrono::{DateTime, Utc};
use log::info;
use parking_lot::Mutex;
use rayon::prelude::IntoParallelRefIterator;
use rhai::{Engine, Scope};
use crate::app::AppState;
use crate::core::srs::{OrderMode, OrderModule, RandomSRSModule, SRSModule, SemiRandomSRSModule, WordOpenMode, WorstWordsSRSModule, FADE_PER_DAY, MAX_SCORE};
use crate::data_provider::card_stats::{load_stats_of_deck, update_stat_score};
use crate::data_provider::history::{push_note};
use crate::data::entities::*;
use crate::data::Id;

#[derive(Clone)]
pub struct DeckSettings {
    pub id: Id,
    pub name: String,
    pub forward: String,
    pub backward: String,
    pub filter: String,
    pub count: Option<usize>,
    pub open_mode: OrderMode,
}
impl DeckSettings {
    pub(crate) fn with_name(name: String) -> DeckSettings {
        DeckSettings {
            id: 0.into(),
            name,
            forward: "".to_string(),
            backward: "".to_string(),
            filter: "true".to_string(),
            count: None,
            open_mode: OrderMode::Default,
        }
    }
    pub fn check_filter(&self) -> bool {
        let time = Instant::now();
        let engine = Engine::new();
        let ast = engine.compile(&self.filter);
        info!("Compile time is {:?}", time.elapsed());
        ast.is_ok()
    }
    pub fn get_word_list(&self, state: &AppState) -> Vec<usize> {
        let time = Instant::now();
        let mut list = vec![];
        let engine = Engine::new();

        let ast = engine.compile(&self.filter);
        if let Ok(ast) = ast {
            let groups = &state.word_groups;

            list = state
                .dictionary
                .par_iter()
                .enumerate()
                .filter(|(_, word)| {
                    let mut more = rhai::Map::new();
                    for iced in &word.additional {
                        more.insert(iced.0.clone().into(), iced.1.clone().into());
                    }
                    let mut scope = Scope::new();
                    scope
                        .push_constant("id", word.id.0 as i64)
                        .push_constant("key", word.key.clone())
                        .push_constant("value", word.value.clone())
                        .push_constant("tags", word.tags.clone())
                        .push_constant("more", more)
                        .push_constant(
                            "group",
                            groups
                                .iter()
                                .find(|g| g.id == word.group_id)
                                .cloned()
                                .unwrap()
                                .name,
                        );

                    let result = engine.eval_ast_with_scope::<bool>(&mut scope, &ast);
                    result.is_ok() && result.unwrap()
                })
                .map(|(index, _)| index)
                .collect();

            info!("Collecting available words is {:?}", time.elapsed());

            list
        } else {
            list
        }
    }
    pub fn require_speech(&self) -> bool {
        self.forward == "speech" || self.backward == "speech"
    }
}

#[derive(Clone)]
pub struct DeckData {
    pub(crate) words: Vec<WordData>,
    pub(crate) set: Vec<CardStatistics>,
    current_word_index: Option<usize>,
    state: Arc<Mutex<AppState>>,
    order_module: OrderModule,
    settings: DeckSettings,
}
impl DeckData {
    pub fn new(settings: &DeckSettings, state: Arc<Mutex<AppState>>) -> Self {
        let state_for = state.clone();
        let state_locked = state.lock();

        let stats = load_stats_of_deck(settings, &state_locked.connection);
        let words = stats
            .iter()
            .map(|stat| {
                state_locked
                    .dictionary
                    .binary_search_by_key(&stat.word_id, |w| w.id)
                    .unwrap()
            })
            .map(|index| &state_locked.dictionary[index])
            .cloned()
            .collect();

        Self {
            set: stats,
            words,
            current_word_index: None,
            state: state_for,
            order_module: match settings.open_mode {
                OrderMode::Default => OrderModule::SemiRandomSRS(SemiRandomSRSModule::new()),
                OrderMode::TrainWorstFirst => {
                    OrderModule::WorstWordsSRS(WorstWordsSRSModule::new())
                }
                OrderMode::FullRandom => OrderModule::RandomSRS(RandomSRSModule::new()),
            },
            settings: settings.clone(),
        }
    }

    pub fn next(&mut self) -> (WordData, CardStatistics) {
        let index = match self.order_module.clone() {
            OrderModule::SemiRandomSRS(mut module) => {
                if !module.initialized {
                    module.init(self)
                }
                let index = module.next(self);
                self.order_module = OrderModule::SemiRandomSRS(module);
                index
            }
            OrderModule::RandomSRS(mut module) => {
                if !module.initialized {
                    module.init(self)
                }
                let index = module.next(self);
                self.order_module = OrderModule::RandomSRS(module);
                index
            }
            OrderModule::WorstWordsSRS(mut module) => {
                if !module.initialized {
                    module.init(self)
                }
                let index = module.next(self);
                self.order_module = OrderModule::WorstWordsSRS(module);
                index
            }
        };

        self.current_word_index = Some(index);
        (self.words[index].clone(), self.set[index].clone())
    }
    pub fn open(&mut self, status: WordOpenMode) {
        if self.current_word_index.is_none() {
            return;
        }
        let index = self.current_word_index.unwrap();

        let word : &mut CardStatistics = &mut self.set[index];
        let old_score = word.score;
        word.update(status);
        let new_score = word.score;

        match self.order_module {
            OrderModule::SemiRandomSRS(ref mut module) => {
                module.open(status, index, word);
            }
            OrderModule::RandomSRS(ref mut module) => {
                module.open(status, index, word);
            }
            OrderModule::WorstWordsSRS(ref mut module) => {
                module.open(status, index, word);
            }
        }
        update_stat_score(word, &self.state.lock().connection);
        let _ = push_note(
            self.settings.id,
            HistoryItem {
                timestamp: Utc::now(),
                word_id: word.word_id,
                mode: status,
                before: old_score,
                after: new_score,
            },
        );
    }
    pub fn len(&self) -> usize {
        self.set.len()
    }
}

#[derive(Clone, PartialEq)]
pub struct CardStatistics {
    pub id: Id,
    pub word_id: Id,
    pub set_id: Id,
    pub last_open: DateTime<Utc>,
    pub score: u8,
}
impl CardStatistics {
    pub fn update(&mut self, status: WordOpenMode) {
        match status {
            WordOpenMode::Easy => {
                self.score = (self.calculated_score() + 5.0).round() as u8;
            }
            WordOpenMode::Ok => self.score = (self.calculated_score() + 2.0).round() as u8,
            WordOpenMode::Hard => {
                self.score = (self.calculated_score() * 0.75).round() as u8;
            }
            WordOpenMode::None => {
                self.score = (self.calculated_score() * 0.4) as u8;
            }
        }

        self.score = self.score.clamp(1, MAX_SCORE);
        self.last_open = Utc::now();
    }

    pub fn calculated_score(&self) -> f32 {
        let time = Utc::now() - self.last_open;
        let days = time.num_days();
        let multiplier = FADE_PER_DAY.powi(days as i32);
        (self.score as f32 * multiplier).max(1.0)
    }
}