use std::iter;
use uuid::Uuid;

// drops
use rand::prelude::*;
use rand::{thread_rng};
use rand::distributions::{WeightedIndex};

use serde_cbor::{from_slice, to_vec};

use postgres::transaction::Transaction;

use failure::Error;
use failure::err_msg;

use account::Account;
use rpc::{VboxStateParams, VboxAcceptParams, VboxDiscardParams, VboxCombineParams, VboxApplyParams, VboxDropParams};
use skill::{Skill};
use cryp::{cryp_get, cryp_write};

#[derive(Debug,Clone,Copy,PartialEq,Eq,Ord,PartialOrd,Serialize,Deserialize)]
pub enum Var {
    Blue,
    Green,
    Red,

    Attack,
    Block,
    Stun,
    Buff,
    Debuff,

    Strike,
    Blast,
    Heal,
    Throw,
    Hex,
}

impl Var {
    fn is_base(&self) -> bool {
        match self {
            Var::Attack |
            Var::Block |
            Var::Stun |
            Var::Debuff |
            Var::Buff => true,
            _ => false,
        }
    }

    fn skill(&self) -> Result<Skill, Error> {
        match self {
            Var::Attack => Ok(Skill::Attack),
            Var::Block => Ok(Skill::Attack),
            Var::Stun => Ok(Skill::Attack),
            Var::Buff => Ok(Skill::Attack),
            Var::Debuff => Ok(Skill::Attack),

            Var::Strike => Ok(Skill::Attack),
            Var::Blast => Ok(Skill::Blast),
            Var::Heal => Ok(Skill::Heal),
            Var::Throw => Ok(Skill::Throw),
            Var::Hex => Ok(Skill::Hex),
            _ => Err(err_msg("not a usable var"))
        }
    }
}

#[derive(Debug,Clone,Serialize,Deserialize)]
pub struct Vbox {
    pub id: Uuid,
    pub balance: u16,
    pub free: Vec<Var>,
    pub bound: Vec<Var>,
    pub game: Uuid,
    pub account: Uuid,
}

impl Vbox {
    pub fn new(account_id: Uuid, game_id: Uuid) -> Vbox {
        Vbox {
            id: Uuid::new_v4(),
            account: account_id,
            game: game_id,
            free: vec![],
            bound: vec![],
            balance: 0,
        }
    }

    pub fn fill(mut self: Vbox) -> Vbox {
        let vars = vec![
            (Var::Red, 1),
            (Var::Green, 1),
            (Var::Blue, 1),

            (Var::Attack, 1),
            (Var::Block, 1),
            (Var::Buff, 1),
            (Var::Debuff, 1),
            (Var::Stun, 1),
        ];

        self.free = iter::
            repeat_with(|| {
                let mut rng = thread_rng();
                let dist = WeightedIndex::new(vars.iter().map(|item| item.1)).unwrap();
                return vars[dist.sample(&mut rng)].0;
            })
            .take(8)
            .collect::<Vec<Var>>();

        self
    }

    pub fn accept(&mut self, i: usize) -> Result<&mut Vbox, Error> {
        if self.bound.len() > 8 {
            return Err(err_msg("too many vars bound"));
        }

        println!("{:?}", self.free);

        self.free.get(i).ok_or(format_err!("no var at index {:?}", i))?;

        self.bound.push(self.free.remove(i));

        Ok(self)
    }

    pub fn drop(&mut self, i: usize) -> Result<&mut Vbox, Error> {
        self.free.get(i).ok_or(format_err!("no var at index {:?}", i))?;
        self.free.remove(i);
        // balance update
        Ok(self)
    }

    pub fn combine(&mut self, mut indices: Vec<usize>) -> Result<&mut Vbox, Error> {
        if indices.len() != 3 {
            return Err(err_msg("exactly 3 indices required"));
        }

        if !indices.iter().all(|i| self.bound.get(*i).is_some()) {
            return Err(err_msg("var missing index"));
        }

        // have to sort the indices and keep track of the iteration
        // because when removing the elements the array shifts
        indices.sort();
        let mut vars = indices
            .iter()
            .enumerate()
            .map(|(i, index)| {
                self.bound.remove(*index - i)
            })
            .collect::<Vec<Var>>();

        let base_index = vars
            .iter()
            .position(|v| v.is_base())
            .ok_or(err_msg("no base item selected"))?;

        let base = vars.remove(base_index);

        // fold colours into RGB
        let colours = vars
            .iter()
            .fold([0, 0, 0], |mut acc, c| {
                match c {
                    Var::Red => acc[0] += 1,
                    Var::Green => acc[1] += 1,
                    Var::Blue => acc[2] += 1,
                    _ => (),
                };
                acc
            });

        let colour_code = match colours {
            [2,0,0] => "rr",
            [0,2,0] => "gg",
            [0,0,2] => "bb",
            [1,1,0] => "rg",
            [0,1,1] => "gb",
            [1,0,1] => "rb",
            _ => return Err(err_msg("not a combo")),
        };

        let new = match base {
            Var::Attack => match colour_code {
                "rr" => Var::Strike,
                "gg" => Var::Heal,
                "bb" => Var::Blast,
                "rg" => Var::Attack,
                "gb" => Var::Attack,
                "rb" => Var::Attack,
                _ => panic!("missing colour code {:?}", colour_code),
            },
            Var::Block => match colour_code {
                "rr" => Var::Strike,
                "gg" => Var::Heal,
                "bb" => Var::Blast,
                "rg" => Var::Attack,
                "gb" => Var::Attack,
                "rb" => Var::Attack,
                _ => panic!("missing colour code {:?}", colour_code),
            },
            Var::Buff => match colour_code {
                "rr" => Var::Strike,
                "gg" => Var::Heal,
                "bb" => Var::Blast,
                "rg" => Var::Attack,
                "gb" => Var::Attack,
                "rb" => Var::Attack,
                _ => panic!("missing colour code {:?}", colour_code),
            },
            Var::Debuff => match colour_code {
                "rr" => Var::Strike,
                "gg" => Var::Heal,
                "bb" => Var::Blast,
                "rg" => Var::Attack,
                "gb" => Var::Attack,
                "rb" => Var::Attack,
                _ => panic!("missing colour code {:?}", colour_code),
            },
            Var::Stun => match colour_code {
                "rr" => Var::Strike,
                "gg" => Var::Heal,
                "bb" => Var::Blast,
                "rg" => Var::Attack,
                "gb" => Var::Attack,
                "rb" => Var::Attack,
                _ => panic!("missing colour code {:?}", colour_code),
            },
            _ => panic!("wrong base {:?}", base),
        };

        self.bound.push(new);

        Ok(self)
    }
}

pub fn vbox_create(vbox: Vbox, tx: &mut Transaction, account: &Account) -> Result<Vbox, Error> {
    let vbox_bytes = to_vec(&vbox)?;

    let query = "
        INSERT INTO vbox (id, account, game, data)
        VALUES ($1, $2, $3, $4)
        RETURNING id;
    ";

    let result = tx
        .query(query, &[&vbox.id, &account.id, &vbox.game, &vbox_bytes])?;

    result.iter().next().ok_or(format_err!("no vbox written"))?;

    // println!("{:} wrote vbox", vbox.id);

    return Ok(vbox);
}

pub fn vbox_write(vbox: Vbox, tx: &mut Transaction) -> Result<Vbox, Error> {
    let vbox_bytes = to_vec(&vbox)?;

    let query = "
        UPDATE vbox
        SET data = $1
        WHERE id = $2
        RETURNING id, account, data;
    ";

    let result = tx
        .query(query, &[&vbox_bytes, &vbox.id])?;

    let _returned = result.iter().next().expect("no row returned");

    // println!("{:?} wrote vbox", vbox.id);

    return Ok(vbox);
}


pub fn vbox_get(tx: &mut Transaction, game_id: Uuid, account: &Account) -> Result<Vbox, Error> {
    let query = "
        SELECT *
        FROM vbox
        WHERE account = $1
        AND game = $2;
    ";

    let result = tx
        .query(query, &[&account.id, &game_id])?;

    let returned = match result.iter().next() {
        Some(row) => row,
        None => return Err(err_msg("vbox not found")),
    };

    // tells from_slice to cast into a cryp
    let vbox_bytes: Vec<u8> = returned.get("data");
    let vbox = from_slice::<Vbox>(&vbox_bytes)?;

    return Ok(vbox);
}

pub fn vbox_state(params: VboxStateParams, tx: &mut Transaction, account: &Account) -> Result<Vbox, Error> {
    match vbox_get(tx, params.game_id, account) {
        Ok(v) => Ok(v),
        Err(e) => {
            println!("{:?}", e);
            vbox_create(Vbox::new(account.id, params.game_id).fill(), tx, account)
        }
    }
}

pub fn vbox_discard(params: VboxDiscardParams, tx: &mut Transaction, account: &Account) -> Result<Vbox, Error> {
    let vbox = vbox_get(tx, params.game_id, account)?;
    return vbox_write(vbox.fill(), tx);
}

pub fn vbox_accept(params: VboxAcceptParams, tx: &mut Transaction, account: &Account) -> Result<Vbox, Error> {
    let mut vbox = vbox_get(tx, params.game_id, account)?;
    vbox.accept(params.index)?;
    return vbox_write(vbox, tx);
}

pub fn vbox_combine(params: VboxCombineParams, tx: &mut Transaction, account: &Account) -> Result<Vbox, Error> {
    let mut vbox = vbox_get(tx, params.game_id, account)?;
    vbox.combine(params.indices)?;
    return vbox_write(vbox, tx);
}

pub fn vbox_drop(params: VboxDropParams, tx: &mut Transaction, account: &Account) -> Result<Vbox, Error> {
    let mut vbox = vbox_get(tx, params.game_id, account)?;
    vbox.drop(params.index)?;
    return vbox_write(vbox, tx);
}

pub fn vbox_apply(params: VboxApplyParams, tx: &mut Transaction, account: &Account) -> Result<Vbox, Error> {
    let mut vbox = vbox_get(tx, params.game_id, account)?;
    let mut cryp = cryp_get(tx, params.cryp_id, account.id)?;

    let var = vbox.bound.remove(params.index);

    // done here because i teach them a tonne of skills for tests
    let max_skills = 4;
    if cryp.skills.len() >= max_skills {
        return Err(format_err!("cryp at max skills ({:?})", max_skills));
    }

    let skill = var.skill()?;
    cryp = cryp.learn(skill);
    cryp_write(cryp, tx)?;
    return vbox_write(vbox, tx);
}


#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn combine_test() {
        let mut vbox = Vbox::new(Uuid::new_v4(), Uuid::new_v4());
        vbox.bound = vec![Var::Attack, Var::Green, Var::Green];
        vbox.combine(vec![1,2,0]).unwrap();
        assert_eq!(vbox.bound[0], Var::Heal);
    }
}