use std::ops::{Deref, DerefMut};
use std::sync::atomic::{AtomicBool, AtomicU32, Ordering};
use std::sync::Arc;

use atomig::Atomic;
use parking_lot::RwLock;

use crate::dynamic_data::choices::TurnChoice;
use crate::dynamic_data::event_hooks::{Event, EventHook};
use crate::dynamic_data::models::battle_party::BattleParty;
use crate::dynamic_data::models::battle_random::BattleRandom;
use crate::dynamic_data::models::battle_side::BattleSide;
use crate::dynamic_data::models::pokemon::Pokemon;
use crate::dynamic_data::ChoiceQueue;
use crate::dynamic_data::DynamicLibrary;
use crate::dynamic_data::Script;
use crate::dynamic_data::ScriptSet;
use crate::dynamic_data::VolatileScriptsOwner;
use crate::dynamic_data::{is_valid_target, ScriptWrapper};
use crate::dynamic_data::{ScriptCategory, ScriptSource, ScriptSourceData};
use crate::{script_hook, PkmnResult, StringKey};

/// A pokemon battle, with any amount of sides and pokemon per side.
#[derive(Debug)]
#[cfg_attr(feature = "wasm", derive(unique_type_id_derive::UniqueTypeId))]
pub struct Battle {
    /// The library the battle uses for handling.
    library: Arc<DynamicLibrary>,
    /// A list of all different parties in the battle.
    parties: Vec<BattleParty>,
    /// Whether or not Pokemon can flee from the battle.
    can_flee: bool,
    /// The number of sides in the battle. Typically 2.
    number_of_sides: u8,
    /// The number of Pokemon that can be on each side.
    pokemon_per_side: u8,
    /// A list of all sides in the battle.
    sides: Vec<BattleSide>,
    /// The RNG used for the battle.
    random: BattleRandom,
    /// A queue of the yet to be executed choices in a turn.
    current_turn_queue: RwLock<Option<ChoiceQueue>>,
    /// Whether or not the battle has ended.
    has_ended: AtomicBool,
    /// The eventual result of the battle. Inconclusive until the battle is ended.
    result: RwLock<BattleResult>,
    /// The handler to send all events to.
    event_hook: EventHook,
    /// The index of the current turn. 0 until all choices
    current_turn: AtomicU32,
    /// All the volatile scripts attached to a Pokemon
    volatile_scripts: Arc<ScriptSet>,
    /// The time the last turn took to run. Defaults to 0.
    last_turn_time: Atomic<u64>,
    /// Data required for this script to be a script source.
    script_source_data: RwLock<ScriptSourceData>,
}

impl Battle {
    /// Initializes a new battle.
    pub fn new(
        library: Arc<DynamicLibrary>,
        parties: Vec<BattleParty>,
        can_flee: bool,
        number_of_sides: u8,
        pokemon_per_side: u8,
        random_seed: Option<u128>,
    ) -> Self {
        // If no seed was passed, we use the current time as seed for the RNG, otherwise we use the
        // seed.
        let random = if let Some(seed) = random_seed {
            BattleRandom::new_with_seed(seed)
        } else {
            BattleRandom::default()
        };
        let mut sides = Vec::with_capacity(number_of_sides as usize);
        for i in 0..number_of_sides {
            sides.push(BattleSide::new(i, pokemon_per_side));
        }

        let mut battle = Self {
            library,
            parties,
            can_flee,
            number_of_sides,
            pokemon_per_side,
            sides,
            random,
            current_turn_queue: RwLock::new(None),
            has_ended: AtomicBool::new(false),
            result: RwLock::new(BattleResult::Inconclusive),
            event_hook: Default::default(),
            current_turn: AtomicU32::new(0),
            volatile_scripts: Default::default(),
            last_turn_time: Default::default(),
            script_source_data: Default::default(),
        };

        let ptr: *mut Battle = &mut battle;
        for side in &mut battle.sides {
            side.set_battle(ptr);
        }

        battle
    }

    /// The library the battle uses for handling.
    pub fn library(&self) -> &Arc<DynamicLibrary> {
        &self.library
    }
    /// A list of all different parties in the battle.
    pub fn parties(&self) -> &Vec<BattleParty> {
        &self.parties
    }
    /// Whether or not Pokemon can flee from the battle.
    pub fn can_flee(&self) -> bool {
        self.can_flee
    }
    /// The number of sides in the battle. Typically 2.
    pub fn number_of_sides(&self) -> u8 {
        self.number_of_sides
    }
    /// The number of Pokemon that can be on each side.
    pub fn pokemon_per_side(&self) -> u8 {
        self.pokemon_per_side
    }
    /// A list of all sides in the battle.
    pub fn sides(&self) -> &Vec<BattleSide> {
        &self.sides
    }
    /// A mutable list of all sides in the battle.
    pub fn sides_mut(&mut self) -> &mut Vec<BattleSide> {
        &mut self.sides
    }
    /// The RNG used for the battle.
    pub fn random(&self) -> &BattleRandom {
        &self.random
    }
    /// Whether or not the battle has ended.
    pub fn has_ended(&self) -> bool {
        self.has_ended.load(Ordering::Relaxed)
    }
    /// The eventual result of the battle. Inconclusive until the battle is ended.
    pub fn result(&self) -> BattleResult {
        *self.result.read()
    }
    /// The handler to send all events to.
    pub fn event_hook(&self) -> &EventHook {
        &self.event_hook
    }
    /// The index of the current turn. 0 until all choices
    pub fn current_turn(&self) -> u32 {
        self.current_turn.load(Ordering::Relaxed)
    }
    /// The time the last turn took to run. Defaults to 0.
    pub fn last_turn_time(&self) -> u64 {
        self.last_turn_time.load(Ordering::Relaxed)
    }
    /// A queue of the yet to be executed choices in a turn.
    pub fn current_turn_queue(&self) -> &RwLock<Option<ChoiceQueue>> {
        &self.current_turn_queue
    }

    /// Get a Pokemon on the battlefield, on a specific side and an index on that side.
    pub fn get_pokemon(&self, side: u8, index: u8) -> Option<Arc<Pokemon>> {
        let side = self.sides.get(side as usize);
        side?;
        let pokemon_read_lock = side.unwrap().pokemon();
        let pokemon = pokemon_read_lock.get(index as usize);
        pokemon?;
        pokemon.unwrap().clone()
    }

    /// Returns whether a slot on the battlefield can still be filled. If no party is responsible
    /// for that slot, or a party is responsible, but has no remaining Pokemon to throw out anymore,
    /// this returns false.
    pub fn can_slot_be_filled(&self, side: u8, index: u8) -> bool {
        for party in &self.parties {
            if party.is_responsible_for_index(side, index) && party.has_pokemon_not_in_field() {
                return true;
            }
        }
        false
    }

    /// Validates whether the battle is still in a non-ended state. If the battle has ended, this
    /// properly sets who has won etc.
    pub fn validate_battle_state(&self) {
        // If we've already ended, we dont need to run this.
        if self.has_ended() {
            return;
        }
        let mut surviving_side_exists = false;
        let mut winning_side = None;
        for (side_index, side) in self.sides.iter().enumerate() {
            // If any side has fled, the battle end.
            if side.has_fled_battle() {
                let _w = self.result.write();
                unsafe {
                    self.result.data_ptr().replace(BattleResult::Inconclusive);
                }
                self.has_ended.store(true, Ordering::SeqCst);
                return;
            }
            // If the side is not defeated
            if !side.is_defeated() {
                // More than 1 surviving side. Battle is not ended
                if surviving_side_exists {
                    return;
                }
                surviving_side_exists = true;
                winning_side = Some(side_index as u8);
            }
        }
        // Everyone died :(
        if !surviving_side_exists {
            let _w = self.result.write();
            unsafe {
                self.result.data_ptr().replace(BattleResult::Inconclusive);
            }
        }
        // Someone survived, they won!
        else {
            let _w = self.result.write();
            unsafe {
                self.result
                    .data_ptr()
                    .replace(BattleResult::Conclusive(winning_side.unwrap()));
            }
        }
        self.has_ended.store(true, Ordering::SeqCst);
    }

    /// Checks whether a choice is actually possible.
    pub fn can_use(&self, choice: &TurnChoice) -> bool {
        // If the user is not usable, we obviously can;t use the choice.
        if !choice.user().is_usable() {
            return false;
        }
        if let TurnChoice::Move(data) = choice {
            // TODO: Hook to change number of PP needed.
            if data.used_move().remaining_pp() < 1 {
                return false;
            }
            if !is_valid_target(
                data.target_side(),
                data.target_index(),
                data.used_move().move_data().target(),
                choice.user().deref(),
            ) {
                return false;
            }
        }
        true
    }

    /// Try and set the choice for the battle. If the choice is not valid, this returns false.
    pub fn try_set_choice(&mut self, choice: TurnChoice) -> PkmnResult<bool> {
        if !self.can_use(&choice) {
            return Ok(false);
        }
        if !choice.user().is_on_battlefield() {
            return Ok(false);
        }
        let side = choice.user().get_battle_side_index();
        if side.is_none() {
            return Ok(false);
        }
        self.sides[side.unwrap() as usize].set_choice(choice);
        self.check_choices_set_and_run()?;
        Ok(true)
    }

    /// Checks to see whether all Pokemon on the field have set their choices. If so, we then run
    /// the turn.
    fn check_choices_set_and_run(&self) -> PkmnResult<()> {
        for side in &self.sides {
            if !side.all_choices_set() {
                return Ok(());
            }
            if !side.all_slots_filled() {
                return Ok(());
            }
        }
        let start_time = chrono::Utc::now();
        let mut choices = Vec::with_capacity(self.number_of_sides as usize * self.pokemon_per_side as usize);
        for side in &self.sides {
            let mut side_choices = side.choices().write();
            for choice_opt in side_choices.deref_mut() {
                if choice_opt.is_none() {
                    panic!("Choice was none, but all choices were set? Logic error.");
                }
                let mut choice = choice_opt.as_mut().unwrap();
                let c = choice.deref();
                if let TurnChoice::Move(data) = c {
                    let mut change_priority = data.priority();
                    script_hook!(change_priority, c, c, &mut change_priority);
                    if change_priority != data.priority() {
                        if let TurnChoice::Move(data) = choice.deref_mut() {
                            *data.priority_mut() = change_priority;
                        }
                    }
                }

                let mut speed = choice.speed();
                let c = choice.deref();
                script_hook!(change_speed, c, c, &mut speed);
                *choice.speed_mut() = speed;

                choice.set_random_value(self.random.get() as u32);
                choices.push(choice_opt.take());
            }
            // Drop the lock guard, as we need to write into it in reset_choices.
            drop(side_choices);
            side.reset_choices();
        }
        self.current_turn.fetch_add(1, Ordering::SeqCst);

        choices.sort_unstable_by(|a, b| b.cmp(a));
        self.current_turn_queue.write().replace(ChoiceQueue::new(choices));

        {
            self.run_turn()?;
        }

        self.current_turn_queue.write().take();
        self.event_hook.trigger(Event::EndTurn);
        let end_time = chrono::Utc::now();
        let time = end_time - start_time;
        self.last_turn_time
            .store(time.num_nanoseconds().unwrap() as u64, Ordering::SeqCst);
        Ok(())
    }
}

impl VolatileScriptsOwner for Battle {
    fn volatile_scripts(&self) -> &Arc<ScriptSet> {
        &self.volatile_scripts
    }

    fn load_volatile_script(&self, key: &StringKey) -> PkmnResult<Option<Arc<dyn Script>>> {
        self.library.load_script(self.into(), ScriptCategory::Battle, key)
    }
}

impl ScriptSource for Battle {
    fn get_script_count(&self) -> usize {
        1
    }

    fn get_script_source_data(&self) -> &RwLock<ScriptSourceData> {
        &self.script_source_data
    }

    fn get_own_scripts(&self, scripts: &mut Vec<ScriptWrapper>) {
        scripts.push((&self.volatile_scripts).into());
    }

    fn collect_scripts(&self, scripts: &mut Vec<ScriptWrapper>) {
        self.get_own_scripts(scripts);
    }
}

/// The result of a battle.
#[derive(Debug, Copy, Clone)]
pub enum BattleResult {
    /// The battle has no winner. Either the battle has not ended, or everyone is dead, or one of
    /// the parties has ran away.
    Inconclusive,
    /// The battle has a winner, with the inner value being the index of the side that has won.
    Conclusive(u8),
}