//! Rules the map generator has to keep for every seed.

use grovewright_core::map::{Map, Pos, Terrain};
use grovewright_core::mapgen::{
    generate_test_map, outcrop_origin, spawn_pos, HARD_ROCK_DISTANCE, OUTCROP_SIZE,
    SPAWN_CLEARING_RADIUS, TEST_MAP_SIZE,
};

/// Number of seeds every rule is checked against.
const SEEDS: u64 = 300;

fn terrain_at(map: &Map, x: i32, y: i32) -> Terrain {
    map.get(Pos::new(x, y))
        .expect("position is on the map")
        .terrain
}

#[test]
fn the_same_seed_gives_the_same_map() {
    assert_eq!(generate_test_map(42), generate_test_map(42));
}

#[test]
fn different_seeds_give_different_maps() {
    assert_ne!(generate_test_map(1), generate_test_map(2));
}

#[test]
fn the_map_has_the_test_size() {
    let map = generate_test_map(0);
    assert_eq!((map.width(), map.height()), (TEST_MAP_SIZE, TEST_MAP_SIZE));
}

#[test]
fn bedrock_forms_the_border_and_nothing_else() {
    let last = TEST_MAP_SIZE as i32 - 1;
    for seed in 0..SEEDS {
        let map = generate_test_map(seed);
        for y in 0..=last {
            for x in 0..=last {
                let on_border = x == 0 || y == 0 || x == last || y == last;
                let is_bedrock = terrain_at(&map, x, y) == Terrain::Bedrock;
                assert_eq!(is_bedrock, on_border, "seed {seed}, tile {x}/{y}");
            }
        }
    }
}

#[test]
fn the_spawn_clearing_is_open_ground() {
    for seed in 0..SEEDS {
        let map = generate_test_map(seed);
        let spawn = spawn_pos(&map);
        for dy in -SPAWN_CLEARING_RADIUS..=SPAWN_CLEARING_RADIUS {
            for dx in -SPAWN_CLEARING_RADIUS..=SPAWN_CLEARING_RADIUS {
                if dx * dx + dy * dy > SPAWN_CLEARING_RADIUS * SPAWN_CLEARING_RADIUS {
                    continue;
                }
                let terrain = terrain_at(&map, spawn.x + dx, spawn.y + dy);
                assert_eq!(terrain, Terrain::Ground, "seed {seed}, offset {dx}/{dy}");
            }
        }
    }
}

#[test]
fn a_soft_rock_outcrop_lies_next_to_the_clearing() {
    for seed in 0..SEEDS {
        let map = generate_test_map(seed);
        let spawn = spawn_pos(&map);
        let origin = outcrop_origin(&map);
        assert_eq!(origin.x - spawn.x, SPAWN_CLEARING_RADIUS + 2, "seed {seed}");
        for y in origin.y..origin.y + OUTCROP_SIZE {
            for x in origin.x..origin.x + OUTCROP_SIZE {
                assert_eq!(
                    terrain_at(&map, x, y),
                    Terrain::SoftRock,
                    "seed {seed}, tile {x}/{y}"
                );
            }
        }
    }
}

#[test]
fn hard_rock_appears_only_far_from_the_spawn_point() {
    let last = TEST_MAP_SIZE as i32 - 1;
    for seed in 0..SEEDS {
        let map = generate_test_map(seed);
        let spawn = spawn_pos(&map);
        for y in 1..last {
            for x in 1..last {
                let far = (x - spawn.x).abs().max((y - spawn.y).abs()) >= HARD_ROCK_DISTANCE;
                match terrain_at(&map, x, y) {
                    Terrain::HardRock => assert!(far, "seed {seed}: hard rock near spawn"),
                    Terrain::SoftRock => assert!(!far, "seed {seed}: soft rock far out"),
                    Terrain::Ground | Terrain::Bedrock => {}
                }
            }
        }
    }
}

#[test]
fn every_map_mixes_rock_and_open_ground() {
    for seed in 0..SEEDS {
        let map = generate_test_map(seed);
        let total = map.tiles().len();
        let rock = map
            .tiles()
            .iter()
            .filter(|tile| !tile.terrain.is_walkable())
            .count();
        let percent = rock * 100 / total;
        assert!(
            (20..=80).contains(&percent),
            "seed {seed}: {percent} percent rock"
        );
        let hard = map
            .tiles()
            .iter()
            .filter(|tile| tile.terrain == Terrain::HardRock)
            .count();
        assert!(hard > 0, "seed {seed}: no hard rock");
    }
}

#[test]
fn no_generated_tile_starts_damaged() {
    let map = generate_test_map(5);
    assert!(map.tiles().iter().all(|tile| tile.damage == 0));
}