use std::fmt::Display;
use std::mem;
use std::path::Path;
use std::rc::Rc;
use std::sync::Arc;

use limbo_core::Database;
use rand::{Rng, SeedableRng};
use rand_chacha::ChaCha8Rng;

use crate::model::table::Table;

use crate::runner::io::SimulatorIO;

use super::cli::SimulatorCLI;

pub(crate) struct SimulatorEnv {
    pub(crate) opts: SimulatorOpts,
    pub(crate) tables: Vec<Table>,
    pub(crate) connections: Vec<SimConnection>,
    pub(crate) io: Arc<SimulatorIO>,
    pub(crate) db: Arc<Database>,
    pub(crate) rng: ChaCha8Rng,
}

impl SimulatorEnv {
    pub(crate) fn clone_without_connections(&self) -> Self {
        SimulatorEnv {
            opts: self.opts.clone(),
            tables: self.tables.clone(),
            connections: (0..self.connections.len())
                .map(|_| SimConnection::Disconnected)
                .collect(),
            io: self.io.clone(),
            db: self.db.clone(),
            rng: self.rng.clone(),
        }
    }
}

impl SimulatorEnv {
    pub(crate) fn new(seed: u64, cli_opts: &SimulatorCLI, db_path: &Path) -> Self {
        let mut rng = ChaCha8Rng::seed_from_u64(seed);

        let (create_percent, read_percent, write_percent, delete_percent, drop_percent) = {
            let total = 100.0;

            let read_percent = rng.gen_range(0.0..=total);
            let write_percent = total - read_percent;

            // Create percent should be 5-15% of the write percent
            let create_percent = rng.gen_range(0.05..=0.15) * write_percent;
            // Drop percent should be 2-5% of the write percent
            let drop_percent = rng.gen_range(0.02..=0.05) * write_percent;
            // Delete percent should be 10-20% of the write percent
            let delete_percent = rng.gen_range(0.1..=0.2) * write_percent;

            let write_percent = write_percent - create_percent - delete_percent - drop_percent;

            (
                create_percent,
                read_percent,
                write_percent,
                delete_percent,
                drop_percent,
            )
        };

        let opts = SimulatorOpts {
            ticks: rng.gen_range(cli_opts.minimum_tests..=cli_opts.maximum_tests),
            max_connections: 1, // TODO: for now let's use one connection as we didn't implement
            // correct transactions processing
            max_tables: rng.gen_range(0..128),
            create_percent,
            read_percent,
            write_percent,
            delete_percent,
            drop_percent,
            page_size: 4096, // TODO: randomize this too
            max_interactions: rng.gen_range(cli_opts.minimum_tests..=cli_opts.maximum_tests),
            max_time_simulation: cli_opts.maximum_time,
        };

        let io = Arc::new(SimulatorIO::new(seed, opts.page_size).unwrap());

        // Remove existing database file if it exists
        if db_path.exists() {
            std::fs::remove_file(db_path).unwrap();
        }

        let wal_path = db_path.with_extension("db-wal");
        if wal_path.exists() {
            std::fs::remove_file(wal_path).unwrap();
        }

        let db = match Database::open_file(io.clone(), db_path.to_str().unwrap(), false) {
            Ok(db) => db,
            Err(e) => {
                panic!("error opening simulator test file {:?}: {:?}", db_path, e);
            }
        };

        let connections = (0..opts.max_connections)
            .map(|_| SimConnection::Disconnected)
            .collect::<Vec<_>>();

        SimulatorEnv {
            opts,
            tables: Vec::new(),
            connections,
            rng,
            io,
            db,
        }
    }
}

pub trait ConnectionTrait
where
    Self: std::marker::Sized + Clone,
{
    fn is_connected(&self) -> bool;
    fn disconnect(&mut self);
}

pub(crate) enum SimConnection {
    LimboConnection(Rc<limbo_core::Connection>),
    SQLiteConnection(rusqlite::Connection),
    Disconnected,
}

impl SimConnection {
    pub(crate) fn is_connected(&self) -> bool {
        match self {
            SimConnection::LimboConnection(_) | SimConnection::SQLiteConnection(_) => true,
            SimConnection::Disconnected => false,
        }
    }
    pub(crate) fn disconnect(&mut self) {
        let conn = mem::replace(self, SimConnection::Disconnected);

        match conn {
            SimConnection::LimboConnection(conn) => {
                conn.close().unwrap();
            }
            SimConnection::SQLiteConnection(conn) => {
                conn.close().unwrap();
            }
            SimConnection::Disconnected => {}
        }
    }
}

impl Display for SimConnection {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            SimConnection::LimboConnection(_) => {
                write!(f, "LimboConnection")
            }
            SimConnection::SQLiteConnection(_) => {
                write!(f, "SQLiteConnection")
            }
            SimConnection::Disconnected => {
                write!(f, "Disconnected")
            }
        }
    }
}

#[derive(Debug, Clone)]
pub(crate) struct SimulatorOpts {
    pub(crate) ticks: usize,
    pub(crate) max_connections: usize,
    pub(crate) max_tables: usize,
    // this next options are the distribution of workload where read_percent + write_percent +
    // delete_percent == 100%
    pub(crate) create_percent: f64,
    pub(crate) read_percent: f64,
    pub(crate) write_percent: f64,
    pub(crate) delete_percent: f64,
    pub(crate) drop_percent: f64,
    pub(crate) max_interactions: usize,
    pub(crate) page_size: usize,
    pub(crate) max_time_simulation: usize,
}