use crate::{
    services::{
        comms::broadcast_to_room,
        skills::skill_check_and_grind,
        skills::skill_check_only,
    },
    models::{
        item::{Item, LocationActionType, Subattack, SkillType, DeathData},
        task::{Task, TaskMeta, TaskDetails},
    },
    static_content::{
        possession_type::{WeaponData, possession_data, fist},
        npc::npc_by_code,
        species::species_info_map,
    },
    message_handler::user_commands::{user_error, UResult, drop::consider_expire_job_for_item},
    regular_tasks::{TaskRunContext, TaskHandler},
    DResult,
};
use mockall_double::double;
#[double] use crate::db::DBTrans;
use async_trait::async_trait;
use chrono::Utc;
use async_recursion::async_recursion;
use std::time;
use ansi::ansi;
use rand::prelude::IteratorRandom;
use rand_distr::{Normal, Distribution};

#[derive(Clone)]
pub struct AttackTaskHandler;
#[async_trait]
impl TaskHandler for AttackTaskHandler {
    async fn do_task(&self, ctx: &mut TaskRunContext) -> DResult<Option<time::Duration>> {
        let (ctype, ccode) = ctx.task.meta.task_code.split_once("/")
            .ok_or("Invalid AttackTick task code")?;
        let mut attacker_item = match ctx.trans.find_item_by_type_code(ctype, ccode).await? {
            None => { return Ok(None); } // Player is gone
            Some(item) => (*item).clone()
        };

        let (vtype, vcode) =
            match attacker_item.active_combat.as_ref().and_then(|ac| ac.attacking.as_ref()).and_then(|v| v.split_once("/")) {
                None => return Ok(None),
                Some(x) => x
            };
        let mut victim_item = match ctx.trans.find_item_by_type_code(vtype, vcode).await? {
            None => { return Ok(None); }
            Some(item) => (*item).clone()
        };

        if attacker_item.death_data.is_some() || victim_item.death_data.is_some() {
            return Ok(None)
        }
        
        let weapon = what_wielded(ctx.trans, &attacker_item).await?;
        
        let attack_skill = *attacker_item.total_skills.get(&weapon.uses_skill).unwrap_or(&0.0);
        let victim_dodge_skill = *victim_item.total_skills.get(&SkillType::Dodge).unwrap_or(&0.0);

        let dodge_result = skill_check_and_grind(ctx.trans, &mut victim_item, &SkillType::Dodge,
                                                 attack_skill).await?;
        let user_opt = if ctype == "player" { ctx.trans.find_by_username(ccode).await? } else { None };
        let attack_result = if let Some(user) = user_opt {
            let raw_skill = *user.raw_skills.get(&weapon.uses_skill).unwrap_or(&0.0);
            if raw_skill >= weapon.raw_min_to_learn && raw_skill <= weapon.raw_max_to_learn {
                skill_check_and_grind(ctx.trans, &mut attacker_item, &weapon.uses_skill,
                                      victim_dodge_skill).await?
            } else {
                skill_check_only(&attacker_item, &weapon.uses_skill, victim_dodge_skill)
            }
        } else {
            skill_check_only(&attacker_item, &weapon.uses_skill, victim_dodge_skill)
        };
        
        if dodge_result > attack_result {
            let msg_exp = format!("{} dodges out of the way of {}'s attack.\n",
                                  victim_item.display_for_sentence(true, 1, true),
                                  attacker_item.display_for_sentence(true, 1, false));
            let msg_nonexp = format!("{} dodges out of the way of {}'s attack.\n",
                                     victim_item.display_for_sentence(false, 1, true),
                                     attacker_item.display_for_sentence(false, 1, false));
            broadcast_to_room(ctx.trans, &attacker_item.location, None, &msg_exp, Some(&msg_nonexp)).await?;
            ctx.trans.save_item_model(&attacker_item).await?;
            ctx.trans.save_item_model(&victim_item).await?;
        } else {
            // TODO: Parry system of some kind?

            // Determine body part...
            let part = victim_item.species.sample_body_part();

            // TODO: Armour / soaks
            
            // TODO: Calculate damage etc... and display health impact.
            let mut mean_damage: f64 = weapon.normal_attack_mean_damage;
            for scaling in weapon.normal_attack_skill_scaling.iter() {
                let skill = *attacker_item.total_skills.get(&scaling.skill).unwrap_or(&0.0);
                if skill >= scaling.min_skill {
                    mean_damage += (skill - scaling.min_skill) * scaling.mean_damage_per_point_over_min;
                }
            }
            
            let actual_damage = Normal::new(mean_damage,
                                            weapon.normal_attack_stdev_damage)?
                .sample(&mut rand::thread_rng()).floor().max(1.0) as i64;
            ctx.trans.save_item_model(&attacker_item).await?;
            let msg_exp = weapon.normal_attack_success_message(&attacker_item, &victim_item,
                                                               &part, true);
            let msg_nonexp = weapon.normal_attack_success_message(&attacker_item, &victim_item,
                                                                  &part, false);
            if change_health(ctx.trans, -actual_damage, &mut victim_item, 
                             &msg_exp, &msg_nonexp).await? {
                ctx.trans.save_item_model(&victim_item).await?;
                return Ok(None);
            }
            ctx.trans.save_item_model(&victim_item).await?;
        }

        let msg_exp = &(weapon.normal_attack_start_message(&attacker_item, &victim_item, true) + ".\n");
        let msg_nonexp = &(weapon.normal_attack_start_message(&attacker_item, &victim_item, false) + ".\n");
        broadcast_to_room(ctx.trans, &attacker_item.location, None, msg_exp, Some(msg_nonexp)).await?;
        Ok(Some(attack_speed(&attacker_item)))
    }
}

pub async fn change_health(trans: &DBTrans,
                           change: i64,
                           victim: &mut Item,
                           reason_exp: &str, reason_nonexp: &str) -> DResult<bool> {
    let maxh = max_health(victim);
    let new_health = ((victim.health as i64 + change).max(0) as u64).min(maxh);
    if change >= 0 && new_health == victim.health {
        return Ok(false);
    }
    let colour = if change > 0 { ansi!("<green>") } else { ansi!("<red>") };
    let msg_exp = format!(ansi!("[ {}{}<reset> <bold>{}/{}<reset> ] {}.\n"),
                          colour,
                          change,
                          new_health,
                          max_health(&victim),
                          reason_exp);
    let msg_nonexp =
        format!(ansi!("[ {}{}<reset> <bold>{}/{}<reset> ] {}.\n"),
                colour,
                change,
                new_health,
                maxh,
                reason_nonexp);
    broadcast_to_room(trans, &victim.location, None, &msg_exp, Some(&msg_nonexp)).await?;
    victim.health = new_health;
    if new_health == 0 {
        handle_death(trans, victim).await?;
        Ok(true)
    } else {
        Ok(false)
    }
}

pub async fn consider_reward_for(trans: &DBTrans, by_item: &mut Item, for_item: &Item) -> DResult<()> {
    if by_item.item_type != "player" {
        return Ok(());
    }
    let (session, _) = match trans.find_session_for_player(&by_item.item_code).await? {
        None => return Ok(()),
        Some(r) => r
    };
    if by_item.total_xp >= for_item.total_xp {
        trans.queue_for_session(&session, Some("[You didn't gain any experience for that]\n")).await?;
        return Ok(());
    }
    let xp_gain =
        (((for_item.total_xp - by_item.total_xp) as f64 * 10.0 / (by_item.total_xp + 1) as f64) as u64)
        .min(100);

    if xp_gain == 0 {
        trans.queue_for_session(&session, Some("[You didn't gain any experience for that]\n")).await?;
        return Ok(());
    }

    by_item.total_xp += xp_gain;
    let mut user = match trans.find_by_username(&by_item.item_code).await? {
        None => return Ok(()),
        Some(r) => r
    };
    user.experience.xp_change_for_this_reroll += xp_gain as i64;

    // Now consider kill bonuses...
    if for_item.item_type == "npc" {
        if let Some(npc) = npc_by_code().get(for_item.item_code.as_str()) {
            if let Some(bonus) = &npc.kill_bonus {
                user.credits += bonus.payment;
                trans.queue_for_session(&session, Some(&format!("{}\nYour wristpad beeps for a credit of {} for that.\n", bonus.msg, bonus.payment))).await?;
            }
        }
    }

    trans.save_user_model(&user).await?;
    trans.queue_for_session(&session, Some(&format!("You gained {} experience points!\n", xp_gain))).await?;

    Ok(())
}

pub async fn handle_death(trans: &DBTrans, whom: &mut Item) -> DResult<()> {
    let msg_exp = format!(
        ansi!("<red>{} stiffens and collapses dead.<reset>\n"),
        &whom.display_for_sentence(true, 1, true)
    );
    let msg_nonexp = format!(
        ansi!("<red>{} stiffens and collapses dead.<reset>\n"),
        &whom.display_for_sentence(false, 1, true)
    );
    broadcast_to_room(trans, &whom.location, None, &msg_exp, Some(&msg_nonexp)).await?;

    whom.death_data = Some(DeathData {
        parts_remaining: species_info_map().get(&whom.species)
            .map(|sp| sp.corpse_butchers_into.clone()).unwrap_or_else(|| vec!()),
        ..Default::default()
    });
    if let Some(ac) = &whom.active_combat {
        let at_str = ac.attacking.clone();
        for attacker in ac.attacked_by.clone().iter() {
            if let Some((atype, acode)) = attacker.split_once("/") {
                if let Some(aitem) = trans.find_item_by_type_code(atype, acode).await? {
                    let mut new_aitem = (*aitem).clone();
                    consider_reward_for(trans, &mut new_aitem, &whom).await?;
                    stop_attacking_mut(trans, &mut new_aitem, whom, true).await?;
                    trans.save_item_model(&new_aitem).await?;
                }
            }
        }
        if let Some((vtype, vcode)) = at_str.as_ref().and_then(|a| a.split_once("/")) {
            if let Some(vitem) = trans.find_item_by_type_code(vtype, vcode).await? {
                let mut new_vitem = (*vitem).clone();
                stop_attacking_mut(trans, whom, &mut new_vitem, false).await?;
                trans.save_item_model(&new_vitem).await?;
            }
        }
    }
    if whom.item_type == "npc" {
        trans.upsert_task(&Task {
            meta: TaskMeta {
                task_code: whom.item_code.clone(),
                next_scheduled: Utc::now() + chrono::Duration::seconds(120),
                ..Default::default()
            },
            details: TaskDetails::RecloneNPC {
                npc_code: whom.item_code.clone()
            }
        }).await?;
    } else if whom.item_type == "player" {
        trans.revoke_until_death_consent(&whom.item_code).await?;
    }
    Ok(())
}

pub async fn handle_resurrect(trans: &DBTrans, player: &mut Item) -> DResult<bool> {
    corpsify_item(trans, &player).await?;
    player.death_data = None;
    let lost_xp = (player.total_xp / 200).max(10).min(player.total_xp);
    let (session, _) = match trans.find_session_for_player(&player.item_code).await? {
        None => return Ok(false),
        Some(r) => r
    };
    let mut user = match trans.find_by_username(&player.item_code).await? {
        None => return Ok(false),
        Some(r) => r
    };
    trans.queue_for_session(&session,
                            Some(&format!("You lost {} experience points by dying.\n", lost_xp))).await?;
    player.total_xp -= lost_xp;
    user.experience.xp_change_for_this_reroll -= lost_xp as i64;
    player.health = max_health(&player);
    
    trans.save_user_model(&user).await?;
    Ok(true)
}

pub fn max_health(whom: &Item) -> u64 {
    if whom.item_type == "npc" {
        npc_by_code().get(whom.item_code.as_str())
            .map(|npc| npc.max_health)
            .unwrap_or(24)
    } else if whom.item_type == "player" {
        (22.0 + (whom.total_xp as f64).log(1.4)).min(60.0) as u64
    } else if whom.item_type == "possession" {
        whom.possession_type.as_ref().and_then(|pt| possession_data().get(&pt))
            .map(|poss| poss.max_health)
            .unwrap_or(10)
    } else {
        24
    }
}

pub static TASK_HANDLER: &(dyn TaskHandler + Sync + Send) = &AttackTaskHandler;

pub async fn stop_attacking_mut(trans: &DBTrans, new_by_whom: &mut Item, new_to_whom: &mut Item,
                                auto_refocus: bool) ->
    DResult<()>
{
    trans.delete_task("AttackTick",
                      &format!("{}/{}",
                               new_by_whom.item_type,
                               new_by_whom.item_code)).await?;
    if let Some(ac) = new_to_whom.active_combat.as_mut() {
        let old_attacker = format!("{}/{}", new_by_whom.item_type, new_by_whom.item_code);
        ac.attacked_by.retain(|v| v != &old_attacker);
    }
    if let Some(ac) = new_by_whom.active_combat.as_mut() {
        ac.attacking = None;
        if auto_refocus {
            let old_vic = format!("{}/{}", new_to_whom.item_type, new_to_whom.item_code);
            let new_vic_opt = ac.attacked_by.iter().filter(|i| **i != old_vic).choose(&mut rand::thread_rng());
            if let Some(new_vic) = new_vic_opt {
                if let Some((vtype, vcode)) = new_vic.split_once("/") {
                    if let Some(vic_item) = trans.find_item_by_type_code(vtype, vcode).await? {
                        let mut new_vic_item = (*vic_item).clone();
                        start_attack_mut(trans, new_by_whom, &mut new_vic_item);
                        trans.save_item_model(&new_vic_item).await?;
                    }
                }
            }
        }
    }
    new_by_whom.action_type = LocationActionType::Normal;
    Ok(())
}


pub async fn stop_attacking(trans: &DBTrans, by_whom: &Item, to_whom: &Item) -> DResult<()> {
    let mut new_by_whom = (*by_whom).clone();
    let mut new_to_whom = (*to_whom).clone();
    stop_attacking_mut(trans, &mut new_by_whom, &mut new_to_whom, false).await?;
    trans.save_item_model(&new_by_whom).await?;
    trans.save_item_model(&new_to_whom).await?;
    Ok(())
}

async fn what_wielded(trans: &DBTrans, who: &Item) -> DResult<&'static WeaponData> {
    if let Some(item) = trans.find_by_action_and_location(
        &who.refstr(), &LocationActionType::Wielded).await? {
        if let Some(dat) = item.possession_type.as_ref()
            .and_then(|pt| possession_data().get(&pt))
            .and_then(|pd| pd.weapon_data.as_ref()) {
            return Ok(dat);
        }
    }
    
    // TODO: Search inventory for wielded item first.
    if who.item_type == "npc" {
        if let Some(intrinsic) = npc_by_code().get(who.item_code.as_str())
            .and_then(|npc| npc.intrinsic_weapon.as_ref()) {
            if let Some(weapon) = possession_data().get(intrinsic).and_then(|p| p.weapon_data.as_ref()) {
                return Ok(weapon)
            }
        }
    }
    Ok(fist())
}

fn attack_speed(_who: &Item) -> time::Duration {
    time::Duration::from_secs(5)
}

#[async_recursion]
pub async fn start_attack(trans: &DBTrans, by_whom: &Item, to_whom: &Item) -> UResult<()> {
    let mut by_whom_for_update = by_whom.clone();
    let mut to_whom_for_update = to_whom.clone();
    start_attack_mut(trans, &mut by_whom_for_update, &mut to_whom_for_update).await?;
    trans.save_item_model(&by_whom_for_update).await?;
    trans.save_item_model(&to_whom_for_update).await?;
    Ok(())
}

#[async_recursion]
pub async fn start_attack_mut(trans: &DBTrans, by_whom: &mut Item, to_whom: &mut Item) -> UResult<()> {
    let mut msg_exp = String::new();
    let mut msg_nonexp = String::new();
    let mut verb: String = "attacks".to_string();
    match by_whom.action_type {
        LocationActionType::Sitting | LocationActionType::Reclining => {
            msg_exp.push_str(&format!(ansi!("{} stands up.\n"), &by_whom.display));
            msg_nonexp.push_str(&format!(ansi!("{} stands up.\n"),
                                         by_whom.display_less_explicit.as_ref().unwrap_or(&by_whom.display)));
        },
        LocationActionType::Attacking(_) => {
            match by_whom.active_combat.as_ref().and_then(|ac| ac.attacking.as_ref().and_then(|s| s.split_once("/"))) {
                Some((cur_type, cur_code)) if cur_type == to_whom.item_type && cur_code == to_whom.item_code =>
                    user_error(format!("You're already attacking {}!", to_whom.pronouns.object))?,
                Some((cur_type, cur_code)) => {
                    if let Some(cur_item_arc) = trans.find_item_by_type_code(cur_type, cur_code).await? {
                        stop_attacking(trans, by_whom, &cur_item_arc).await?;
                    }
                }
                _ => {}
            }
            verb = "refocuses ".to_string() + &by_whom.pronouns.possessive + " attacks on";
        },
        _ => {}
    }

    msg_exp.push_str(&format!(
        ansi!("<red>{} {} {}.<reset>\n"),
        &by_whom.display_for_sentence(true, 1, true),
        verb,
        &to_whom.display_for_sentence(true, 1, false))
    );
    msg_nonexp.push_str(&format!(
        ansi!("<red>{} {} {}.<reset>\n"),
        &by_whom.display_for_sentence(false, 1, true),
        verb,
        &to_whom.display_for_sentence(false, 1, false))
    );

    let wielded = what_wielded(trans, by_whom).await?;
    msg_exp.push_str(&(wielded.normal_attack_start_message(by_whom, to_whom, true) + ".\n"));
    msg_nonexp.push_str(&(wielded.normal_attack_start_message(by_whom, to_whom, false) + ".\n"));
    
    broadcast_to_room(trans, &by_whom.location, None::<&Item>, &msg_exp, Some(msg_nonexp.as_str())).await?;

    by_whom.active_combat.get_or_insert_with(|| Default::default()).attacking =
        Some(format!("{}/{}",
                     &to_whom.item_type, &to_whom.item_code));
    by_whom.action_type = LocationActionType::Attacking(Subattack::Normal);
    to_whom.active_combat.get_or_insert_with(|| Default::default()).attacked_by.push(
        format!("{}/{}",
                &by_whom.item_type, &by_whom.item_code)
    );

    trans.upsert_task(&Task {
        meta: TaskMeta {
            task_code: format!("{}/{}", by_whom.item_type, by_whom.item_code),
            next_scheduled: Utc::now() + chrono::Duration::milliseconds(
                attack_speed(by_whom).as_millis() as i64),
            ..Default::default()
        },
        details: TaskDetails::AttackTick
    }).await?;
    // Auto-counterattack if victim isn't busy.
    if to_whom.active_combat.as_ref().and_then(|ac| ac.attacking.as_ref()) == None {
        start_attack_mut(trans, to_whom, by_whom).await?;
    }

    Ok(())
}

pub async fn corpsify_item(trans: &DBTrans, base_item: &Item) -> DResult<()> {
    let mut new_item = base_item.clone();
    new_item.item_type = "corpse".to_owned();
    new_item.item_code = format!("{}", trans.alloc_item_code().await?);
    new_item.is_static = false;
    trans.save_item_model(&new_item).await?;
    trans.upsert_task(&Task {
        meta: TaskMeta {
            task_code: new_item.item_code.clone(),
            next_scheduled: Utc::now() + chrono::Duration::minutes(5),
            ..Default::default()
        },
        details: TaskDetails::RotCorpse { corpse_code: new_item.item_code.clone() }
    }).await?;

    trans.transfer_all_possessions(base_item, &new_item).await?;
    
    Ok(())
}

pub struct NPCRecloneTaskHandler;
#[async_trait]
impl TaskHandler for NPCRecloneTaskHandler {
    async fn do_task(&self, ctx: &mut TaskRunContext) -> DResult<Option<time::Duration>> {
        let npc_code = match &ctx.task.details {
            TaskDetails::RecloneNPC { npc_code } => npc_code.clone(),
            _ => Err("Expected RecloneNPC type")?
        };
        let mut npc_item = match ctx.trans.find_item_by_type_code("npc", &npc_code).await? {
            None => { return Ok(None) },
            Some(r) => (*r).clone()
        };

        let npc = match npc_by_code().get(npc_code.as_str()) {
            None => { return Ok(None) },
            Some(r) => r
        };
        
        if npc_item.death_data.is_none() {
            return Ok(None);
        }

        corpsify_item(ctx.trans, &npc_item).await?;

        npc_item.death_data = None;
        npc_item.health = max_health(&npc_item);
        npc_item.location = npc.spawn_location.to_owned();
        ctx.trans.save_item_model(&npc_item).await?;
        return Ok(None);
    }
}
pub struct RotCorpseTaskHandler;
#[async_trait]
impl TaskHandler for RotCorpseTaskHandler {
    async fn do_task(&self, ctx: &mut TaskRunContext) -> DResult<Option<time::Duration>> {
        let corpse_code = match &ctx.task.details {
            TaskDetails::RotCorpse { corpse_code } => corpse_code.clone(),
            _ => Err("Expected RotCorpse type")?
        };
        let corpse = match ctx.trans.find_item_by_type_code("corpse", &corpse_code).await? {
            None => { return Ok(None) }
            Some(r) => r
        };
        ctx.trans.delete_item("corpse", &corpse_code).await?;
        let msg_exp = format!("{} rots away to nothing.\n",
                              corpse.display_for_sentence(true, 1, true));
        let msg_nonexp = format!("{} rots away to nothing.\n",
                                 corpse.display_for_sentence(false, 1, true));
        
        for item in ctx.trans.find_items_by_location(
            &format!("{}/{}", &corpse.item_type, &corpse.item_code)).await?.into_iter() {
            let mut item_mut = (*item).clone();
            // We only update this to support consider_expire_job - it gets updated in bulk
            // by transfer_all_possession below.
            item_mut.location = corpse.location.clone();
            consider_expire_job_for_item(ctx.trans, &item_mut).await?;
        }
        ctx.trans.transfer_all_possessions_code(
            &format!("{}/{}", &corpse.item_type, &corpse.item_code),
            &corpse.location).await?;
        broadcast_to_room(ctx.trans, &corpse.location, None, &msg_exp, Some(&msg_nonexp)).await?;
        Ok(None)
    }
}
pub static ROT_CORPSE_HANDLER: &'static (dyn TaskHandler + Sync + Send) = &RotCorpseTaskHandler;