use std::sync::Arc;

use crate::dynamic_data::script_handling::ScriptSource;
use crate::dynamic_data::{Battle, Pokemon};
use crate::dynamic_data::{ExecutingMove, HitData};
use crate::script_hook;
use crate::static_data::{MoveCategory, Statistic};

/// A damage library holds the functions related to the calculation of damage. As this can change in
/// different generations and implementations, this is handled through a trait.
pub trait DamageLibrary: std::fmt::Debug {
    /// Calculate the damage for a given hit on a Pokemon.
    fn get_damage(
        &self,
        executing_move: &ExecutingMove,
        target: &Arc<Pokemon>,
        hit_number: u8,
        hit_data: &HitData,
    ) -> u32;

    /// Calculate the base power for a given hit on a Pokemon.
    fn get_base_power(
        &self,
        executing_move: &ExecutingMove,
        target: &Arc<Pokemon>,
        hit_number: u8,
        hit_data: &HitData,
    ) -> u8;

    /// Returns whether a specified hit should be critical or not.
    fn is_critical(
        &self,
        battle: &Battle,
        executing_move: &ExecutingMove,
        target: &Arc<Pokemon>,
        hit_number: u8,
    ) -> bool;
}

/// The implementation of a Damage Library for generation 7.
#[derive(Debug)]
pub struct Gen7DamageLibrary {
    /// Defines whether or not a random damage modifier is applied to damage (0.85 - 1.00).
    has_randomness: bool,
}

impl Gen7DamageLibrary {
    /// Creates a new generation 7 damage library. `has_randomness` defines whether a random damage
    /// modifier (0.85x - 1.00x) is applied to the calculated damage.
    pub fn new(has_randomness: bool) -> Self {
        Self { has_randomness }
    }

    /// Calculates the modifier applied to damage from the statistics of the relevant Pokemon.
    fn get_stat_modifier(
        &self,
        executing_move: &ExecutingMove,
        target: &Arc<Pokemon>,
        hit_number: u8,
        hit_data: &HitData,
    ) -> f32 {
        let user = executing_move.user();
        let offensive_stat;
        let defensive_stat;
        // Get the relevant stats based on the move category.
        if executing_move.use_move().category() == MoveCategory::Physical {
            offensive_stat = Statistic::Attack;
            defensive_stat = Statistic::Defense;
        } else {
            offensive_stat = Statistic::SpecialAttack;
            defensive_stat = Statistic::SpecialDefense;
        }
        // Check if we can bypass the defensive stat boost on the target. We default to this if the
        // move is critical, and the target has a defensive stat boost of > 0, but a script is
        // allowed to change this.
        let mut bypass_defensive_stat_boost = hit_data.is_critical() && target.stat_boost(defensive_stat) > 0;
        script_hook!(
            bypass_defensive_stat_boost,
            executing_move,
            executing_move,
            target,
            hit_number,
            &mut bypass_defensive_stat_boost
        );
        // Check if we can bypass the offensive stat boost on the user. We default to this if the
        // move is critical, and the user has an offensive stat boost of < 0, but a script is
        // allowed to change this.
        let mut bypass_offensive_stat_boost = hit_data.is_critical() && user.stat_boost(offensive_stat) > 0;
        script_hook!(
            bypass_offensive_stat_boost,
            executing_move,
            executing_move,
            target,
            hit_number,
            &mut bypass_offensive_stat_boost
        );

        // Get the unboosted stat if we bypass the stat boost, otherwise get the boosted stat.
        let mut defensive_stat = if bypass_defensive_stat_boost {
            target.flat_stats().get_stat(offensive_stat)
        } else {
            target.boosted_stats().get_stat(offensive_stat)
        };

        let mut offensive_stat = if bypass_offensive_stat_boost {
            user.flat_stats().get_stat(offensive_stat)
        } else {
            user.boosted_stats().get_stat(offensive_stat)
        };

        // Allow scripts to modify the raw values we use for the damage modifier.
        script_hook!(
            change_defensive_stat_value,
            executing_move,
            executing_move,
            target,
            hit_number,
            &mut defensive_stat
        );
        script_hook!(
            change_offensive_stat_value,
            executing_move,
            executing_move,
            target,
            hit_number,
            &mut offensive_stat
        );

        // Calculate the effective stat modifier.
        let mut stat_modifier = offensive_stat as f32 / defensive_stat as f32;
        script_hook!(
            change_damage_stat_modifier,
            executing_move,
            executing_move,
            target,
            hit_number,
            &mut stat_modifier
        );

        stat_modifier
    }

    /// Gets the damage modifier. This is a value that defaults to 1.0, but can be modified by scripts
    /// to apply a raw modifier to the damage.
    fn get_damage_modifier(
        &self,
        executing_move: &ExecutingMove,
        target: &Arc<Pokemon>,
        hit_number: u8,
        _hit_data: &HitData,
    ) -> f32 {
        let mut modifier = 1.0;
        script_hook!(
            change_damage_modifier,
            executing_move,
            executing_move,
            target,
            hit_number,
            &mut modifier
        );
        modifier
    }
}

impl DamageLibrary for Gen7DamageLibrary {
    fn get_damage(
        &self,
        executing_move: &ExecutingMove,
        target: &Arc<Pokemon>,
        hit_number: u8,
        hit_data: &HitData,
    ) -> u32 {
        if executing_move.use_move().category() == MoveCategory::Status {
            return 0;
        }

        let level_modifier = ((2.0 * executing_move.user().level() as f32) / 5.0).floor() + 2.0;
        let base_power = hit_data.base_power();
        let stat_modifier = self.get_stat_modifier(executing_move, target, hit_number, hit_data);
        let damage_modifier = self.get_damage_modifier(executing_move, target, hit_number, hit_data);

        let mut float_damage = (level_modifier * base_power as f32).floor();
        float_damage = (float_damage * stat_modifier).floor();
        float_damage = (float_damage / 50.0).floor() + 2.0;
        float_damage = (float_damage * damage_modifier).floor();
        if executing_move.target_count() > 1 {
            float_damage = (float_damage * 0.75).floor();
        }
        if hit_data.is_critical() {
            let mut crit_modifier = 1.5;
            script_hook!(
                change_critical_modifier,
                executing_move,
                executing_move,
                target,
                hit_number,
                &mut crit_modifier
            );
            float_damage = (float_damage * crit_modifier).floor();
        }

        if self.has_randomness {
            let random_percentage = 85 + executing_move.user().get_battle().unwrap().random().get_between(0, 16);
            float_damage = (float_damage * (random_percentage as f32 / 100.0)).floor();
        }

        if executing_move.user().types().contains(&hit_data.move_type()) {
            let mut stab_modifier = 1.5;
            script_hook!(
                change_stab_modifier,
                executing_move,
                executing_move,
                target,
                hit_number,
                &mut stab_modifier
            );
            float_damage = (float_damage * stab_modifier).floor();
        }

        float_damage = (float_damage * hit_data.effectiveness()).floor();
        let mut damage = if float_damage <= 0.0 {
            if hit_data.effectiveness() == 0.0 {
                0
            } else {
                1
            }
        } else if float_damage >= u32::MAX as f32 {
            u32::MAX
        } else {
            float_damage as u32
        };

        script_hook!(
            change_damage,
            executing_move,
            executing_move,
            target,
            hit_number,
            &mut damage
        );
        script_hook!(
            change_incoming_damage,
            target,
            executing_move,
            target,
            hit_number,
            &mut damage
        );
        damage
    }

    fn get_base_power(
        &self,
        executing_move: &ExecutingMove,
        target: &Arc<Pokemon>,
        hit_number: u8,
        _hit_data: &HitData,
    ) -> u8 {
        if executing_move.use_move().category() == MoveCategory::Status {
            return 0;
        }

        let mut base_power = executing_move.use_move().base_power();
        script_hook!(
            change_base_power,
            executing_move,
            executing_move,
            target,
            hit_number,
            &mut base_power
        );
        base_power
    }

    fn is_critical(
        &self,
        battle: &Battle,
        executing_move: &ExecutingMove,
        target: &Arc<Pokemon>,
        hit_number: u8,
    ) -> bool {
        // Status moves can't be critical.
        if executing_move.use_move().category() == MoveCategory::Status {
            return false;
        }
        // Get the critical stage from scripts.
        let mut crit_stage = 0;
        script_hook!(
            change_critical_stage,
            executing_move,
            executing_move,
            target,
            hit_number,
            &mut crit_stage
        );
        // Crit stage is an unsigned byte, so we only care about values of 0 or higher.
        // For a critical stage of 3+ we always return true.
        match crit_stage {
            0 => battle.random().get_max(24) == 0,
            1 => battle.random().get_max(8) == 0,
            2 => battle.random().get_max(2) == 0,
            _ => true,
        }
    }
}