use std::cmp::{max, min};

use ::rltk::{Point, Rltk, VirtualKeyCode};
use ::specs::prelude::*;

use crate::components::{
    BlocksTile, BlocksVisibility, CombatStats, Door, EntityMoved, HungerClock, HungerState, Item,
    Monster, Player, Position, Renderable, Viewshed, WantsToMelee, WantsToPickupItem,
};
use crate::game_log::GameLog;
use crate::{Map, RunState, State, TileType};

pub fn try_move_player(delta_x: i32, delta_y: i32, ecs: &mut World) {
    let mut positions = ecs.write_storage::<Position>();
    let players = ecs.read_storage::<Player>();
    let mut viewsheds = ecs.write_storage::<Viewshed>();
    let entities = ecs.entities();
    let combat_stats = ecs.read_storage::<CombatStats>();
    let map = ecs.fetch::<Map>();
    let mut wants_to_melee = ecs.write_storage::<WantsToMelee>();
    let mut entity_moved = ecs.write_storage::<EntityMoved>();
    let mut doors = ecs.write_storage::<Door>();
    let mut blocks_visibility = ecs.write_storage::<BlocksVisibility>();
    let mut blocks_movement = ecs.write_storage::<BlocksTile>();
    let mut renderables = ecs.write_storage::<Renderable>();

    for (entity, _player, pos, viewshed) in
        (&entities, &players, &mut positions, &mut viewsheds).join()
    {
        if pos.x + delta_x < 1
            || pos.x + delta_x > map.width - 1
            || pos.y + delta_y < 1
            || pos.y + delta_y > map.height - 1
        {
            return;
        }
        let destination_idx = map.xy_idx(pos.x + delta_x, pos.y + delta_y);

        for potential_target in map.tile_content[destination_idx].iter() {
            if let Some(_target) = combat_stats.get(*potential_target) {
                wants_to_melee
                    .insert(
                        entity,
                        WantsToMelee {
                            target: *potential_target,
                        },
                    )
                    .expect("Add target failed");
                return;
            }

            if let Some(door) = doors.get_mut(*potential_target) {
                door.open = true;
                blocks_visibility.remove(*potential_target);
                blocks_movement.remove(*potential_target);

                let glyph = renderables.get_mut(*potential_target).unwrap();
                glyph.glyph = rltk::to_cp437('/');
                viewshed.dirty = true;
            }
        }

        if !map.blocked[destination_idx] {
            pos.x = min(map.width - 1, max(0, pos.x + delta_x));
            pos.y = min(map.height - 1, max(0, pos.y + delta_y));
            entity_moved
                .insert(entity, EntityMoved {})
                .expect("Failed to add EntityMoved flag to player");

            viewshed.dirty = true;
            let mut ppos = ecs.write_resource::<Point>();
            ppos.x = pos.x;
            ppos.y = pos.y;
        }
    }
}

pub fn try_next_level(ecs: &mut World) -> bool {
    let player_pos = ecs.fetch::<Point>();
    let map = ecs.fetch::<Map>();
    let player_idx = map.xy_idx(player_pos.x, player_pos.y);

    if map.tiles[player_idx] == TileType::DownStairs {
        true
    } else {
        let mut gamelog = ecs.fetch_mut::<GameLog>();
        gamelog
            .entries
            .push("There is no way down from here.".to_string());
        false
    }
}

fn get_item(ecs: &mut World) {
    let player_pos = ecs.fetch::<Point>();
    let player_entity = ecs.fetch::<Entity>();
    let entities = ecs.entities();
    let items = ecs.read_storage::<Item>();
    let positions = ecs.read_storage::<Position>();
    let mut gamelog = ecs.fetch_mut::<GameLog>();

    let mut target_item: Option<Entity> = None;
    for (item_entity, _item, position) in (&entities, &items, &positions).join() {
        if position.x == player_pos.x && position.y == player_pos.y {
            target_item = Some(item_entity);
        }
    }

    match target_item {
        None => gamelog
            .entries
            .push("There is nothing here to pick up.".to_string()),
        Some(item) => {
            let mut pickup = ecs.write_storage::<WantsToPickupItem>();
            pickup
                .insert(
                    *player_entity,
                    WantsToPickupItem {
                        collected_by: *player_entity,
                        item,
                    },
                )
                .expect("Unable to pick up item?!");
        }
    }
}

fn skip_turn(ecs: &mut World) -> RunState {
    let player_entity = ecs.fetch::<Entity>();
    let viewshed_components = ecs.read_storage::<Viewshed>();
    let monsters = ecs.read_storage::<Monster>();

    let worldmap_resource = ecs.fetch::<Map>();

    let mut can_heal = true;
    let viewshed = viewshed_components.get(*player_entity).unwrap();
    for tile in viewshed.visible_tiles.iter() {
        let idx = worldmap_resource.xy_idx(tile.x, tile.y);
        for entity_id in worldmap_resource.tile_content[idx].iter() {
            match monsters.get(*entity_id) {
                None => {}
                Some(_) => {
                    can_heal = false;
                }
            }
        }
    }

    // Don't allow healing when hungry or starving
    let hunger_clocks = ecs.read_storage::<HungerClock>();
    if let Some(hc) = hunger_clocks.get(*player_entity) {
        match hc.state {
            HungerState::Hungry => can_heal = false,
            HungerState::Starving => can_heal = false,
            _ => {}
        }
    }

    if can_heal {
        let mut health_components = ecs.write_storage::<CombatStats>();
        let player_hp = health_components.get_mut(*player_entity).unwrap();
        player_hp.hp = i32::min(player_hp.hp + 1, player_hp.max_hp);
    }

    RunState::PlayerTurn
}

pub fn player_input(gs: &mut State, ctx: &mut Rltk) -> RunState {
    // Mac OS is special when it comes to the numpad. Instead of reporting
    // the keys as Numpad-specific numbers, it reports the number row scan
    // codes. The quick fix is to match on both types of number scan codes.
    match ctx.key {
        None => return RunState::AwaitingInput, // Nothing happened
        Some(key) => match key {
            // Cardinal directions
            VirtualKeyCode::Up
            | VirtualKeyCode::Numpad8
            | VirtualKeyCode::Key8
            | VirtualKeyCode::K => try_move_player(0, -1, &mut gs.ecs),

            VirtualKeyCode::Down
            | VirtualKeyCode::Numpad2
            | VirtualKeyCode::Key2
            | VirtualKeyCode::J => try_move_player(0, 1, &mut gs.ecs),

            VirtualKeyCode::Left
            | VirtualKeyCode::Numpad4
            | VirtualKeyCode::Key4
            | VirtualKeyCode::H => try_move_player(-1, 0, &mut gs.ecs),

            VirtualKeyCode::Right
            | VirtualKeyCode::Numpad6
            | VirtualKeyCode::Key6
            | VirtualKeyCode::L => try_move_player(1, 0, &mut gs.ecs),

            // Diagonals
            VirtualKeyCode::Numpad7
            | VirtualKeyCode::Key7
            | VirtualKeyCode::U
            | VirtualKeyCode::Q => try_move_player(-1, -1, &mut gs.ecs),

            VirtualKeyCode::Numpad9
            | VirtualKeyCode::Key9
            | VirtualKeyCode::Y
            | VirtualKeyCode::W => try_move_player(1, -1, &mut gs.ecs),

            VirtualKeyCode::Numpad1
            | VirtualKeyCode::Key1
            | VirtualKeyCode::B
            | VirtualKeyCode::A => try_move_player(-1, 1, &mut gs.ecs),

            VirtualKeyCode::Numpad3
            | VirtualKeyCode::Key3
            | VirtualKeyCode::N
            | VirtualKeyCode::S => try_move_player(1, 1, &mut gs.ecs),

            // Skip Turn
            VirtualKeyCode::Numpad5 | VirtualKeyCode::Key5 | VirtualKeyCode::Space => {
                return skip_turn(&mut gs.ecs)
            }

            // Level changes
            VirtualKeyCode::Period => {
                if try_next_level(&mut gs.ecs) {
                    return RunState::NextLevel;
                }
            }

            // Item management
            VirtualKeyCode::G => get_item(&mut gs.ecs),
            VirtualKeyCode::I => return RunState::ShowInventory,
            VirtualKeyCode::D => return RunState::ShowDropItem,
            VirtualKeyCode::R => return RunState::ShowRemoveItem,

            // Save and Quit
            VirtualKeyCode::Escape => return RunState::SaveGame,

            _ => return RunState::AwaitingInput,
        },
    }

    RunState::PlayerTurn
}