use grovewright_core::command::Command;
use grovewright_core::inventory::ITEM_STONE;
use grovewright_core::map::{Pos, Terrain};
use grovewright_core::mapgen::{outcrop_origin, spawn_pos};
use grovewright_core::player::{
    PlayerId, PlayerKey, MAX_KNOWN_PLAYERS, MAX_NAME_BYTES, MAX_ONLINE_PLAYERS,
};
use grovewright_core::world::{Event, World, DIG_COOLDOWN_TICKS, TICKS_PER_SECOND};

fn key(n: u8) -> PlayerKey {
    [n; 16]
}

fn join(n: u8) -> Command {
    Command::Join {
        key: key(n),
        name: format!("Spieler {n}"),
    }
}

/// A world with one online player, and a soft rock tile to dig at.
fn world_with_player() -> (World, PlayerId, Pos) {
    let mut world = World::new(42);
    world.step(&[join(1)]);
    let rock = outcrop_origin(world.map());
    (world, PlayerId(0), rock)
}

/// Steps without commands until a player who just hit may hit again.
fn wait_for_cooldown(world: &mut World) {
    for _ in 0..DIG_COOLDOWN_TICKS {
        world.step(&[]);
    }
}

#[test]
fn a_new_world_starts_at_tick_zero_without_players() {
    let world = World::new(42);
    assert_eq!(world.seed(), 42);
    assert_eq!(world.tick(), 0);
    assert!(world.players().is_empty());
    assert_eq!(TICKS_PER_SECOND, 20);
}

#[test]
fn step_advances_the_tick() {
    let mut world = World::new(1);
    assert!(world.step(&[]).is_empty());
    assert_eq!(world.tick(), 1);
}

#[test]
fn joining_adds_an_online_player() {
    let mut world = World::new(1);
    let events = world.step(&[join(7)]);
    assert_eq!(
        events,
        vec![Event::PlayerJoined {
            player: PlayerId(0)
        }]
    );
    let player = world.player(PlayerId(0)).unwrap();
    assert!(player.online);
    assert_eq!(player.name, "Spieler 7");
    assert_eq!(world.find_player(&key(7)), Some(PlayerId(0)));
    assert_eq!(world.find_player(&key(8)), None);
    assert!(world.player(PlayerId(1)).is_none());
}

#[test]
fn joining_twice_changes_nothing() {
    let mut world = World::new(1);
    world.step(&[join(7)]);
    assert!(world.step(&[join(7)]).is_empty());
    assert_eq!(world.players().len(), 1);
}

#[test]
fn leaving_and_returning_keeps_the_inventory() {
    let (mut world, id, rock) = world_with_player();
    for _ in 0..3 {
        world.step(&[Command::Dig {
            player: id,
            pos: rock,
        }]);
        wait_for_cooldown(&mut world);
    }
    assert_eq!(world.player(id).unwrap().inventory.count(ITEM_STONE), 1);

    assert_eq!(
        world.step(&[Command::Leave { player: id }]),
        vec![Event::PlayerLeft { player: id }]
    );
    assert!(!world.player(id).unwrap().online);
    assert!(world.step(&[Command::Leave { player: id }]).is_empty());

    assert_eq!(
        world.step(&[join(1)]),
        vec![Event::PlayerJoined { player: id }]
    );
    assert_eq!(world.players().len(), 1);
    assert!(world.player(id).unwrap().online);
    assert_eq!(world.player(id).unwrap().inventory.count(ITEM_STONE), 1);
}

#[test]
fn a_returning_player_can_change_their_name() {
    let (mut world, id, _) = world_with_player();
    world.step(&[Command::Leave { player: id }]);
    world.step(&[Command::Join {
        key: key(1),
        name: "Neuer Name".to_owned(),
    }]);
    assert_eq!(world.player(id).unwrap().name, "Neuer Name");
}

#[test]
fn overlong_names_are_stored_shortened_on_both_join_paths() {
    let mut world = World::new(1);
    world.step(&[Command::Join {
        key: key(1),
        name: "ä".repeat(20),
    }]);
    assert_eq!(world.player(PlayerId(0)).unwrap().name, "ä".repeat(16));

    world.step(&[Command::Leave {
        player: PlayerId(0),
    }]);
    world.step(&[Command::Join {
        key: key(1),
        name: "x".repeat(MAX_NAME_BYTES + 10),
    }]);
    assert_eq!(
        world.player(PlayerId(0)).unwrap().name,
        "x".repeat(MAX_NAME_BYTES)
    );
}

#[test]
fn a_fifth_online_player_is_refused() {
    let mut world = World::new(1);
    for n in 0..MAX_ONLINE_PLAYERS as u8 {
        world.step(&[join(n)]);
    }
    assert_eq!(
        world.step(&[join(99)]),
        vec![Event::JoinRefused { key: key(99) }]
    );
    assert_eq!(world.players().len(), MAX_ONLINE_PLAYERS);

    // A known player who is offline is refused as well while the world is full.
    world.step(&[Command::Leave {
        player: PlayerId(0),
    }]);
    world.step(&[join(50)]);
    assert_eq!(
        world.step(&[join(0)]),
        vec![Event::JoinRefused { key: key(0) }]
    );
}

#[test]
fn the_world_remembers_a_limited_number_of_players() {
    let mut world = World::new(1);
    for n in 0..MAX_KNOWN_PLAYERS as u8 {
        world.step(&[join(n)]);
        world.step(&[Command::Leave {
            player: PlayerId(n),
        }]);
    }
    assert_eq!(world.players().len(), MAX_KNOWN_PLAYERS);
    assert_eq!(
        world.step(&[join(200)]),
        vec![Event::JoinRefused { key: key(200) }]
    );
    assert_eq!(world.players().len(), MAX_KNOWN_PLAYERS);
}

#[test]
fn set_all_offline_marks_every_player_offline() {
    let mut world = World::new(1);
    world.step(&[join(1), join(2)]);
    world.set_all_offline();
    assert!(world.players().iter().all(|player| !player.online));
}

#[test]
fn three_hits_break_soft_rock_and_give_one_stone() {
    let (mut world, id, rock) = world_with_player();
    let dig = [Command::Dig {
        player: id,
        pos: rock,
    }];
    let hit = vec![Event::TileHit {
        player: id,
        pos: rock,
    }];

    assert_eq!(world.step(&dig), hit);
    assert_eq!(world.map().get(rock).unwrap().damage, 1);
    wait_for_cooldown(&mut world);

    assert_eq!(world.step(&dig), hit);
    assert_eq!(world.map().get(rock).unwrap().damage, 2);
    wait_for_cooldown(&mut world);

    assert_eq!(
        world.step(&dig),
        vec![
            Event::TileChanged { pos: rock },
            Event::ItemGained {
                player: id,
                item: ITEM_STONE,
                count: 1
            }
        ]
    );
    let tile = world.map().get(rock).unwrap();
    assert_eq!((tile.terrain, tile.damage), (Terrain::Ground, 0));
    assert_eq!(world.player(id).unwrap().inventory.count(ITEM_STONE), 1);
}

#[test]
fn hits_during_the_cooldown_are_ignored() {
    let (mut world, id, rock) = world_with_player();
    let dig = [Command::Dig {
        player: id,
        pos: rock,
    }];
    world.step(&dig);
    for _ in 1..DIG_COOLDOWN_TICKS {
        assert!(world.step(&dig).is_empty());
    }
    assert_eq!(world.map().get(rock).unwrap().damage, 1);
    assert_eq!(world.step(&dig).len(), 1);
    assert_eq!(world.map().get(rock).unwrap().damage, 2);
}

#[test]
fn two_hits_in_one_tick_count_once() {
    let (mut world, id, rock) = world_with_player();
    let dig = Command::Dig {
        player: id,
        pos: rock,
    };
    let twice = [dig.clone(), dig];
    assert_eq!(world.step(&twice).len(), 1);
    assert_eq!(world.map().get(rock).unwrap().damage, 1);
}

#[test]
fn ground_bedrock_and_positions_off_the_map_cannot_be_dug() {
    let (mut world, id, _) = world_with_player();
    let spawn = spawn_pos(world.map());
    for pos in [
        spawn,
        Pos::new(0, 0),
        Pos::new(-5, 3),
        Pos::new(10_000, 10_000),
    ] {
        let before = world.map().clone();
        let events = world.step(&[Command::Dig { player: id, pos }]);
        assert!(events.is_empty(), "{pos:?}");
        assert_eq!(world.map(), &before, "{pos:?}");
    }
}

#[test]
fn hard_rock_resists_the_stone_pickaxe() {
    let (mut world, id, _) = world_with_player();
    let width = world.map().width() as usize;
    let index = world
        .map()
        .tiles()
        .iter()
        .position(|tile| tile.terrain == Terrain::HardRock)
        .expect("the test map has hard rock");
    let pos = Pos::new((index % width) as i32, (index / width) as i32);

    assert!(world.step(&[Command::Dig { player: id, pos }]).is_empty());
    assert_eq!(world.map().get(pos).unwrap().damage, 0);
}

#[test]
fn unknown_and_offline_players_cannot_dig() {
    let (mut world, id, rock) = world_with_player();
    assert!(world
        .step(&[Command::Dig {
            player: PlayerId(9),
            pos: rock
        }])
        .is_empty());
    world.step(&[Command::Leave { player: id }]);
    assert!(world
        .step(&[Command::Dig {
            player: id,
            pos: rock
        }])
        .is_empty());
    assert_eq!(world.map().get(rock).unwrap().damage, 0);
}

#[test]
fn commands_of_one_tick_are_applied_in_order() {
    let (mut world, id, rock) = world_with_player();
    // Leaving first makes the hit in the same tick invalid.
    let events = world.step(&[
        Command::Leave { player: id },
        Command::Dig {
            player: id,
            pos: rock,
        },
    ]);
    assert_eq!(events, vec![Event::PlayerLeft { player: id }]);
    assert_eq!(world.map().get(rock).unwrap().damage, 0);
}