use std::collections::HashMap;
use std::sync::Arc;
use std::time::Instant;
use tokio::sync::Mutex;

use russh::server::Handle;
use russh::ChannelId;

use crate::db::{GameDb, SavedPlayer};
use crate::world::{Attitude, Object, World};

#[derive(Clone)]
pub struct PlayerStats {
    pub max_hp: i32,
    pub hp: i32,
    pub attack: i32,
    pub defense: i32,
    pub level: i32,
    pub xp: i32,
    pub xp_to_next: i32,
}

pub struct Player {
    pub name: String,
    pub race_id: String,
    pub class_id: String,
    pub room_id: String,
    pub stats: PlayerStats,
    pub inventory: Vec<Object>,
    pub equipped_weapon: Option<Object>,
    pub equipped_armor: Option<Object>,
}

impl Player {
    pub fn effective_attack(&self) -> i32 {
        let bonus = self.equipped_weapon.as_ref().and_then(|w| w.stats.damage).unwrap_or(0);
        self.stats.attack + bonus
    }

    pub fn effective_defense(&self) -> i32 {
        let bonus = self.equipped_armor.as_ref().and_then(|a| a.stats.armor).unwrap_or(0);
        self.stats.defense + bonus
    }
}

pub struct CombatState {
    pub npc_id: String,
}

pub struct NpcInstance {
    pub hp: i32,
    pub alive: bool,
    pub death_time: Option<Instant>,
}

pub struct PlayerConnection {
    pub player: Player,
    pub channel: ChannelId,
    pub handle: Handle,
    pub combat: Option<CombatState>,
}

pub struct GameState {
    pub world: World,
    pub db: Arc<dyn GameDb>,
    pub players: HashMap<usize, PlayerConnection>,
    pub npc_instances: HashMap<String, NpcInstance>,
}

pub type SharedState = Arc<Mutex<GameState>>;

impl GameState {
    pub fn new(world: World, db: Arc<dyn GameDb>) -> Self {
        let mut npc_instances = HashMap::new();
        for npc in world.npcs.values() {
            if let Some(ref combat) = npc.combat {
                npc_instances.insert(npc.id.clone(), NpcInstance {
                    hp: combat.max_hp, alive: true, death_time: None,
                });
            }
        }
        GameState { world, db, players: HashMap::new(), npc_instances }
    }

    pub fn spawn_room(&self) -> &str {
        &self.world.spawn_room
    }

    // Get effective attitude of an NPC towards a specific player
    pub fn npc_attitude_toward(&self, npc_id: &str, player_name: &str) -> Attitude {
        if let Some(val) = self.db.get_attitude(player_name, npc_id) {
            return Attitude::from_value(val);
        }
        self.world.get_npc(npc_id)
            .map(|n| n.base_attitude)
            .unwrap_or(Attitude::Neutral)
    }

    pub fn npc_attitude_value(&self, npc_id: &str, player_name: &str) -> i32 {
        if let Some(val) = self.db.get_attitude(player_name, npc_id) {
            return val;
        }
        self.world.get_npc(npc_id)
            .map(|n| n.base_attitude.default_value())
            .unwrap_or(0)
    }

    pub fn shift_attitude(&self, npc_id: &str, player_name: &str, delta: i32) {
        let current = self.npc_attitude_value(npc_id, player_name);
        let new_val = (current + delta).clamp(-100, 100);
        self.db.save_attitude(player_name, npc_id, new_val);
    }

    // Shift attitude for all NPCs in the same faction
    pub fn shift_faction_attitude(&self, faction: &str, player_name: &str, delta: i32) {
        for npc in self.world.npcs.values() {
            if npc.faction.as_deref() == Some(faction) {
                self.shift_attitude(&npc.id, player_name, delta);
            }
        }
    }

    pub fn create_new_player(
        &mut self, id: usize, name: String, race_id: String, class_id: String,
        channel: ChannelId, handle: Handle,
    ) {
        let room_id = self.world.spawn_room.clone();
        let race = self.world.races.iter().find(|r| r.id == race_id);
        let class = self.world.classes.iter().find(|c| c.id == class_id);

        let (base_hp, base_atk, base_def) = match class {
            Some(c) => (c.base_stats.max_hp, c.base_stats.attack, c.base_stats.defense),
            None => (100, 10, 10),
        };
        let (con_mod, str_mod, dex_mod) = match race {
            Some(r) => (r.stats.constitution, r.stats.strength, r.stats.dexterity),
            None => (0, 0, 0),
        };

        let max_hp = base_hp + con_mod * 5;
        let attack = base_atk + str_mod + dex_mod / 2;
        let defense = base_def + con_mod / 2;

        let stats = PlayerStats {
            max_hp, hp: max_hp, attack, defense, level: 1, xp: 0, xp_to_next: 100,
        };

        self.players.insert(id, PlayerConnection {
            player: Player { name, race_id, class_id, room_id, stats, inventory: Vec::new(), equipped_weapon: None, equipped_armor: None },
            channel, handle, combat: None,
        });
    }

    pub fn load_existing_player(
        &mut self, id: usize, saved: SavedPlayer, channel: ChannelId, handle: Handle,
    ) {
        let inventory: Vec<Object> = serde_json::from_str(&saved.inventory_json).unwrap_or_default();
        let equipped_weapon: Option<Object> = saved.equipped_weapon_json.as_deref().and_then(|j| serde_json::from_str(j).ok());
        let equipped_armor: Option<Object> = saved.equipped_armor_json.as_deref().and_then(|j| serde_json::from_str(j).ok());

        // Validate room still exists, else spawn
        let room_id = if self.world.rooms.contains_key(&saved.room_id) {
            saved.room_id
        } else {
            self.world.spawn_room.clone()
        };

        let stats = PlayerStats {
            max_hp: saved.max_hp, hp: saved.hp, attack: saved.attack, defense: saved.defense,
            level: saved.level, xp: saved.xp, xp_to_next: saved.level * 100,
        };

        self.players.insert(id, PlayerConnection {
            player: Player {
                name: saved.name, race_id: saved.race_id, class_id: saved.class_id,
                room_id, stats, inventory, equipped_weapon, equipped_armor,
            },
            channel, handle, combat: None,
        });
    }

    pub fn save_player_to_db(&self, player_id: usize) {
        if let Some(conn) = self.players.get(&player_id) {
            let p = &conn.player;
            let inv_json = serde_json::to_string(&p.inventory).unwrap_or_else(|_| "[]".into());
            let weapon_json = p.equipped_weapon.as_ref().map(|w| serde_json::to_string(w).unwrap_or_else(|_| "null".into()));
            let armor_json = p.equipped_armor.as_ref().map(|a| serde_json::to_string(a).unwrap_or_else(|_| "null".into()));

            self.db.save_player(&SavedPlayer {
                name: p.name.clone(), race_id: p.race_id.clone(), class_id: p.class_id.clone(),
                room_id: p.room_id.clone(), level: p.stats.level, xp: p.stats.xp,
                hp: p.stats.hp, max_hp: p.stats.max_hp, attack: p.stats.attack,
                defense: p.stats.defense, inventory_json: inv_json,
                equipped_weapon_json: weapon_json, equipped_armor_json: armor_json,
            });
        }
    }

    pub fn remove_player(&mut self, id: usize) -> Option<PlayerConnection> {
        self.save_player_to_db(id);
        self.players.remove(&id)
    }

    pub fn players_in_room(&self, room_id: &str, exclude_id: usize) -> Vec<&PlayerConnection> {
        self.players.iter()
            .filter(|(&id, conn)| conn.player.room_id == room_id && id != exclude_id)
            .map(|(_, conn)| conn).collect()
    }

    pub fn check_respawns(&mut self) {
        let now = Instant::now();
        for (npc_id, instance) in self.npc_instances.iter_mut() {
            if instance.alive { continue; }
            let npc = match self.world.npcs.get(npc_id) { Some(n) => n, None => continue };
            let respawn_secs = match npc.respawn_secs { Some(s) => s, None => continue };
            if let Some(death_time) = instance.death_time {
                if now.duration_since(death_time).as_secs() >= respawn_secs {
                    if let Some(ref combat) = npc.combat {
                        instance.hp = combat.max_hp;
                        instance.alive = true;
                        instance.death_time = None;
                    }
                }
            }
        }
    }

    pub fn check_level_up(&mut self, player_id: usize) -> Option<String> {
        let conn = self.players.get_mut(&player_id)?;
        let player = &mut conn.player;
        if player.stats.xp < player.stats.xp_to_next { return None; }

        player.stats.xp -= player.stats.xp_to_next;
        player.stats.level += 1;
        player.stats.xp_to_next = player.stats.level * 100;

        let class = self.world.classes.iter().find(|c| c.id == player.class_id);
        let (hp_g, atk_g, def_g) = match class {
            Some(c) => (c.growth.hp_per_level, c.growth.attack_per_level, c.growth.defense_per_level),
            None => (10, 2, 1),
        };
        player.stats.max_hp += hp_g;
        player.stats.hp = player.stats.max_hp;
        player.stats.attack += atk_g;
        player.stats.defense += def_g;

        Some(format!("You are now level {}! HP:{} ATK:{} DEF:{}", player.stats.level, player.stats.max_hp, player.stats.attack, player.stats.defense))
    }
}