use std::{collections::HashMap, fs::File, path::Path, time::Duration};

use chrono::{DateTime, TimeZone, Utc};
use futures::TryStreamExt;
use indicatif::ProgressBar;
use rand::distributions::{Distribution, WeightedIndex};
use regex::Regex;
use reqwest::{header, ClientBuilder, RequestBuilder, Response};
use serde::{Deserialize, Serialize};
use serde_json::{json, Value};
use sprs::{CsMat, TriMat};
use sqlx::postgres::PgPoolOptions;

#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq, PartialOrd, Ord)]
enum MarkovItem {
    Start,
    Stop,
    Token(u32),
}

impl MarkovItem {
    fn index(self) -> usize {
        match self {
            MarkovItem::Start => 0,
            MarkovItem::Stop => 1,
            MarkovItem::Token(idx) => idx as usize + 2,
        }
    }

    fn required_matrix_size(items: u32) -> usize {
        items as usize + 2
    }

    fn from_usize(ind: usize) -> Self {
        match ind {
            0 => MarkovItem::Start,
            1 => MarkovItem::Stop,
            x => MarkovItem::Token(x.checked_sub(2).unwrap() as u32),
        }
    }
}

#[derive(Debug, Serialize, Deserialize)]
struct State {
    matrix: CsMat<u32>,
    mappings: HashMap<u32, String>,
    reverse_mappings: HashMap<String, u32>,
    fetched_up_to: Option<DateTime<Utc>>,
}

impl State {
    fn new() -> Self {
        let mut tri_mat = TriMat::new((2, 2));
        tri_mat.add_triplet(MarkovItem::Start.index(), MarkovItem::Stop.index(), 1);

        State {
            matrix: tri_mat.to_csr(),
            mappings: HashMap::new(),
            reverse_mappings: HashMap::new(),
            fetched_up_to: None,
        }
    }

    fn generate(&self) -> String {
        let mut rand = rand::thread_rng();
        let mut attempts = 0;

        loop {
            let mut idx = MarkovItem::Start;
            let mut tokens = Vec::new();
            loop {
                if matches!(idx, MarkovItem::Stop) {
                    break;
                }

                let weights = WeightedIndex::new(
                    (0..self.matrix.cols())
                        .map(|j| self.matrix.get(idx.index(), j).copied().unwrap_or_default()),
                )
                .expect("Weighted index failed to create");

                idx = MarkovItem::from_usize(weights.sample(&mut rand));

                if let MarkovItem::Token(ti) = idx {
                    tokens.push(
                        self.mappings
                            .get(&ti)
                            .expect("Item should be present in the mappings map")
                            .clone(),
                    )
                }
            }

            if (tokens.is_empty() || tokens.join(" ").trim().is_empty()) && attempts < 10 {
                attempts += 1;
                continue;
            }

            break tokens.join(" ").replace('@', "@\u{200b}");
        }
    }

    fn insert(&mut self, (tok1, tok2): (Option<&str>, Option<&str>)) {
        let item1 = match tok1 {
            None => MarkovItem::Start,
            Some(t) => match self.reverse_mappings.get(t) {
                Some(i) => MarkovItem::Token(*i),
                None => {
                    let new_idx = self.reverse_mappings.len() as u32;
                    self.reverse_mappings.insert(t.to_owned(), new_idx);
                    self.mappings.insert(new_idx, t.to_owned());

                    MarkovItem::Token(new_idx)
                }
            },
        };

        let item2 = match tok2 {
            None => MarkovItem::Stop,
            Some(t) => match self.reverse_mappings.get(t) {
                Some(i) => MarkovItem::Token(*i),
                None => {
                    let new_idx = self.reverse_mappings.len() as u32;
                    self.reverse_mappings.insert(t.to_owned(), new_idx);
                    self.mappings.insert(new_idx, t.to_owned());

                    MarkovItem::Token(new_idx)
                }
            },
        };

        let mut item_value = 10;

        if matches!(item1, MarkovItem::Start) && matches!(tok2, Some(val) if val.starts_with('@')) {
            item_value /= 3;
        }

        if tok2.is_none() {
            item_value -= 2;
        }

        if let Some(item) = self.matrix.get_mut(item1.index(), item2.index()) {
            *item += item_value;
        } else {
            self.matrix.insert(item1.index(), item2.index(), item_value)
        }
    }

    fn insert_tokens(&mut self, input: &str) {
        let input = input.trim();
        // Remove quotes
        let input = Regex::new(r"> ?.+")
            .unwrap()
            .replace_all(input, "")
            .to_string();

        let regex = Regex::new(r"\s+").unwrap();

        let nasty_words = vec![
            "hitler",
            "natsura",
            "eve@snug",
            "lustlion",
            "abuse",
            "pedophi",
            "murder",
            "transpho",
            "holocaust",
            "cpluspatch",
            "umbrellix",
            "sachi",
            "heonkey",
        ];

        if nasty_words.iter().any(|w| input.to_lowercase().contains(w)) {
            return;
        }

        let mut last = None;
        for tok in regex.split(&input) {
            self.insert((last, Some(tok)));
            last = Some(tok);
        }
        self.insert((last, None));
    }
}

#[tokio::main]
async fn main() {
    dotenvy::dotenv().ok();
    let token = std::env::var("TOKEN").expect("token");

    let path = Path::new("state.msg");

    let progress = ProgressBar::new_spinner();

    let mut state = if path.is_file() {
        let file = File::open(path).unwrap();
        progress.set_message("Loading data...");
        rmp_serde::decode::from_read::<_, State>(progress.wrap_read(file)).unwrap()
    } else {
        State::new()
    };
    progress.disable_steady_tick();

    let pool = PgPoolOptions::new()
        .connect(std::env::var("DATABASE_URL").as_deref().unwrap())
        .await
        .unwrap();

    let note_time_min = state
        .fetched_up_to
        .unwrap_or(Utc.with_ymd_and_hms(2010, 1, 1, 12, 0, 0).unwrap());

    progress.set_message("Fetching notes...");
    let text_stream = sqlx::query!(
        r#"SELECT text, "createdAt" 
        FROM note
        WHERE "note"."userId" = $1 
            AND "note"."createdAt" > $2 
            AND "note"."visibility" IN ('public', 'home') 
            AND ("note"."cw" IS NULL OR LOWER("note"."cw") IN ('', 'gay', 'cursed', 'what', 'shitpost', 'no', 'natty what', 'natty what the fuck'))"#,
        "9awy7u3l76",
        note_time_min
    )
    .fetch(&pool);

    let mut stream = progress.wrap_stream(text_stream);
    let mut cnt = 0;
    while let Ok(Some(item)) = stream.try_next().await.map_err(|e| {
        eprintln!("Error fetching: {}", e);
        e
    }) {
        state.fetched_up_to = Some(item.createdAt);
        state.insert_tokens(item.text.as_deref().unwrap_or_default());
        progress.set_message(item.text.unwrap_or_default().clone());
        cnt += 1;
        progress.tick();
        progress.set_length(cnt);
    }

    let file = File::create(path).unwrap();
    progress.set_message("Saving data...");
    rmp_serde::encode::write(&mut progress.wrap_write(file), &state).unwrap();

    let mut timer = tokio::time::interval(Duration::from_secs(600));

    loop {
        timer.tick().await;

        let text = state.generate();
        println!("Generated: {:?}", text);

        let client = ClientBuilder::new().https_only(true).build().unwrap();
        match client
            .post("https://astolfo.social/api/notes/create")
            .json(&serde_json::json!({
                "text": text,
                "poll": Option::<()>::None,
                "cw": "Automated Markov-Natty post",
                "visibility": "home"
            }))
            .header(header::AUTHORIZATION, &format!("Bearer {}", token))
            .send()
            .await
        {
            Err(e) => eprintln!("Fetch error: {}", e),
            Ok(r) => println!("Response: {:#?}", r.json::<Value>().await),
        }
    }
}