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

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

use crate::components::{
    Attributes, BlocksTile, BlocksVisibility, Door, EntityMoved, Equipped, Faction, HungerClock,
    HungerState, Item, Player, Pools, Position, Renderable, Target, Vendor, Viewshed, WantsToMelee,
    WantsToPickupItem,
};
use crate::game_log::GameLog;
use crate::raws::{self, Reaction, RAWS};
use crate::{spatial, Map, RunState, State, TileType, VendorMode, WantsToCastSpell, Weapon};

pub fn try_move_player(delta_x: i32, delta_y: i32, ecs: &mut World) -> RunState {
    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::<Attributes>();
    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>();
    let factions = ecs.read_storage::<Faction>();
    let vendors = ecs.read_storage::<Vendor>();
    let mut result = RunState::AwaitingInput;

    let mut swap_entities: Vec<(Entity, i32, i32)> = Vec::new();

    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 RunState::AwaitingInput;
        }
        let destination_idx = map.xy_idx(pos.x + delta_x, pos.y + delta_y);

        result =
            spatial::for_each_tile_content_with_gamemode(destination_idx, |potential_target| {
                if vendors.get(potential_target).is_some() {
                    return Some(RunState::ShowVendor {
                        vendor: potential_target,
                        mode: VendorMode::Sell,
                    });
                }

                let mut hostile = true;
                if combat_stats.get(potential_target).is_some() {
                    if let Some(faction) = factions.get(potential_target) {
                        let reaction = crate::raws::faction_reaction(
                            &faction.name,
                            "Player",
                            &RAWS.lock().unwrap(),
                        );
                        if reaction != Reaction::Attack {
                            hostile = false;
                        }
                    }
                }
                if !hostile {
                    // Note that we want to move the bystander
                    swap_entities.push((potential_target, pos.x, pos.y));

                    // Move the player
                    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("Unable to insert marker");

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

                    return Some(RunState::Ticking);
                } else if combat_stats.get(potential_target).is_some() {
                    wants_to_melee
                        .insert(
                            entity,
                            WantsToMelee {
                                target: potential_target,
                            },
                        )
                        .expect("Add target failed");

                    return Some(RunState::Ticking);
                }

                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;

                    return Some(RunState::Ticking);
                }

                None
            });

        if !spatial::is_blocked(destination_idx) {
            let old_idx = map.xy_idx(pos.x, pos.y);
            pos.x = min(map.width - 1, max(0, pos.x + delta_x));
            pos.y = min(map.height - 1, max(0, pos.y + delta_y));
            let new_idx = map.xy_idx(pos.x, pos.y);
            entity_moved
                .insert(entity, EntityMoved {})
                .expect("Failed to add EntityMoved flag to player");
            spatial::move_entity(entity, old_idx, new_idx);

            viewshed.dirty = true;
            let mut ppos = ecs.write_resource::<Point>();
            ppos.x = pos.x;
            ppos.y = pos.y;
            result = RunState::Ticking;
            match map.tiles[destination_idx] {
                TileType::DownStairs => result = RunState::NextLevel,
                TileType::UpStairs => result = RunState::PreviousLevel,
                _ => {}
            }
        }
    }

    for m in swap_entities.iter() {
        if let Some(their_pos) = positions.get_mut(m.0) {
            let old_idx = map.xy_idx(their_pos.x, their_pos.y);
            their_pos.x = m.1;
            their_pos.y = m.2;
            let new_idx = map.xy_idx(their_pos.x, their_pos.y);
            spatial::move_entity(m.0, old_idx, new_idx);

            result = RunState::Ticking;
        }
    }

    result
}

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
    }
}

pub fn try_previous_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::UpStairs {
        true
    } else {
        let mut gamelog = ecs.fetch_mut::<GameLog>();
        gamelog
            .entries
            .push("There is no way up 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 factions = ecs.read_storage::<Faction>();

    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);
        spatial::for_each_tile_content(idx, |entity_id| match factions.get(entity_id) {
            None => {}
            Some(faction) => {
                let reaction =
                    raws::faction_reaction(&faction.name, "Player", &RAWS.lock().unwrap());
                if reaction == Reaction::Attack {
                    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::<Pools>();
        let pools = health_components.get_mut(*player_entity).unwrap();
        pools.hit_points.current = i32::min(pools.hit_points.current + 1, pools.hit_points.max);

        let mut rng = ecs.fetch_mut::<::rltk::RandomNumberGenerator>();
        if rng.roll_dice(1, 6) == 1 {
            pools.mana.current = i32::min(pools.mana.current + 1, pools.mana.max);
        }
    }

    RunState::Ticking
}

fn use_consumable_hotkey(gs: &mut State, key: i32) -> RunState {
    use crate::components::{Consumable, InBackpack, Ranged, WantsToUseItem};

    let consumables = gs.ecs.read_storage::<Consumable>();
    let backpack = gs.ecs.read_storage::<InBackpack>();
    let player_entity = gs.ecs.fetch::<Entity>();
    let entities = gs.ecs.entities();
    let mut carried_consumables = Vec::new();

    for (entity, carried_by, _consumable) in (&entities, &backpack, &consumables).join() {
        if carried_by.owner == *player_entity {
            carried_consumables.push(entity);
        }
    }

    if (key as usize) < carried_consumables.len() {
        if let Some(ranged) = gs
            .ecs
            .read_storage::<Ranged>()
            .get(carried_consumables[key as usize])
        {
            return RunState::ShowTargeting {
                range: ranged.range,
                item: carried_consumables[key as usize],
            };
        }

        let mut intent = gs.ecs.write_storage::<WantsToUseItem>();
        intent
            .insert(
                *player_entity,
                WantsToUseItem {
                    item: carried_consumables[key as usize],
                    target: None,
                },
            )
            .expect("Unable to insert intent to use item.");

        return RunState::Ticking;
    }

    RunState::Ticking
}

fn use_spell_hotkey(gs: &mut State, key: i32) -> RunState {
    use crate::components::{KnownSpells, Ranged};
    use crate::raws::find_spell_entity;

    let player_entity = gs.ecs.fetch::<Entity>();
    let known_spells_storage = gs.ecs.read_storage::<KnownSpells>();
    let known_spells = &known_spells_storage.get(*player_entity).unwrap().spells;

    if (key as usize) < known_spells.len() {
        let pools = gs.ecs.read_storage::<Pools>();
        let player_pools = pools.get(*player_entity).unwrap();
        if player_pools.mana.current >= known_spells[key as usize].mana_cost {
            if let Some(spell_entity) =
                find_spell_entity(&gs.ecs, &known_spells[key as usize].display_name)
            {
                if let Some(ranged) = gs.ecs.read_storage::<Ranged>().get(spell_entity) {
                    return RunState::ShowTargeting {
                        range: ranged.range,
                        item: spell_entity,
                    };
                }

                let mut intent = gs.ecs.write_storage::<WantsToCastSpell>();
                intent
                    .insert(
                        *player_entity,
                        WantsToCastSpell {
                            spell: spell_entity,
                            target: None,
                        },
                    )
                    .expect("Unable to insert intent to cast spell");

                return RunState::Ticking;
            }
        } else {
            let mut gamelog = gs.ecs.fetch_mut::<GameLog>();
            gamelog.append("You don't have enough mana to cast that!");
        }
    }

    RunState::Ticking
}

fn get_player_target_list(ecs: &mut World) -> Vec<(f32, Entity)> {
    let mut possible_targets = Vec::new();
    let viewsheds = ecs.read_storage::<Viewshed>();
    let player_entity = ecs.fetch::<Entity>();
    let equipped = ecs.read_storage::<Equipped>();
    let weapon = ecs.read_storage::<Weapon>();
    let map = ecs.fetch::<Map>();
    let positions = ecs.read_storage::<Position>();
    let factions = ecs.read_storage::<Faction>();

    for (equipped, weapon) in (&equipped, &weapon).join() {
        if equipped.owner == *player_entity {
            if let Some(range) = weapon.range {
                if let Some(vs) = viewsheds.get(*player_entity) {
                    let player_pos = positions.get(*player_entity).unwrap();

                    for tile_point in vs.visible_tiles.iter() {
                        let tile_idx = map.xy_idx(tile_point.x, tile_point.y);
                        let distance_to_target = DistanceAlg::Pythagoras
                            .distance2d(*tile_point, Point::from(*player_pos));
                        if distance_to_target < range as f32 {
                            spatial::for_each_tile_content(tile_idx, |possible_target| {
                                if possible_target != *player_entity
                                    && factions.get(possible_target).is_some()
                                {
                                    possible_targets.push((distance_to_target, possible_target));
                                }
                            });
                        }
                    }
                }
            }
        }
    }

    possible_targets.sort_by(|a, b| a.0.partial_cmp(&b.0).unwrap());

    possible_targets
}

fn cycle_target(ecs: &mut World) {
    let possible_targets = get_player_target_list(ecs);
    let mut targets = ecs.write_storage::<Target>();
    let entities = ecs.entities();
    let mut current_target: Option<Entity> = None;

    for (e, _t) in (&entities, &targets).join() {
        current_target = Some(e);
    }

    targets.clear();
    if let Some(current_target) = current_target {
        if !possible_targets.len() > 1 {
            let mut index = 0;
            for (i, target) in possible_targets.iter().enumerate() {
                if target.1 == current_target {
                    index = 1;
                }
            }

            if index > possible_targets.len() - 2 {
                targets.insert(possible_targets[0].1, Target {});
            } else {
                targets.insert(possible_targets[index + 1].1, Target {});
            }
        }
    }
}

pub fn end_turn_targeting(ecs: &mut World) {
    let possible_targets = get_player_target_list(ecs);
    let mut targets = ecs.write_storage::<Target>();
    targets.clear();

    if !possible_targets.is_empty() {
        targets
            .insert(possible_targets[0].1, Target {})
            .expect("Failed to insert Target tag");
    }
}

pub fn player_input(gs: &mut State, ctx: &mut Rltk) -> RunState {
    // Hotkeys
    if (ctx.shift || ctx.control) && ctx.key.is_some() {
        let key: Option<i32> = match ctx.key.unwrap() {
            VirtualKeyCode::Key1 => Some(1),
            VirtualKeyCode::Key2 => Some(2),
            VirtualKeyCode::Key3 => Some(3),
            VirtualKeyCode::Key4 => Some(4),
            VirtualKeyCode::Key5 => Some(5),
            VirtualKeyCode::Key6 => Some(6),
            VirtualKeyCode::Key7 => Some(7),
            VirtualKeyCode::Key8 => Some(8),
            VirtualKeyCode::Key9 => Some(9),
            _ => None,
        };

        if let Some(key) = key {
            if ctx.shift {
                return use_consumable_hotkey(gs, key - 1);
            } else if ctx.control {
                return use_spell_hotkey(gs, key - 1);
            }
        }
    }

    // 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 => return try_move_player(0, -1, &mut gs.ecs),

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

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

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

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

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

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

            VirtualKeyCode::Numpad3
            | VirtualKeyCode::PageDown
            | VirtualKeyCode::Key3
            | VirtualKeyCode::N
            | VirtualKeyCode::S => return 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;
                }
            }
            VirtualKeyCode::Comma => {
                if try_previous_level(&mut gs.ecs) {
                    return RunState::PreviousLevel;
                }
            }

            // 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,

            // Cheating!
            VirtualKeyCode::Backslash => return RunState::ShowCheatMenu,

            // Ranged
            VirtualKeyCode::V => {
                cycle_target(&mut gs.ecs);

                return RunState::AwaitingInput;
            }

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

    RunState::Ticking
}