// Wood, the second resource. Underground it comes from giant mushrooms (few, growing back
// slowly), above ground from trees (many). Pit imps fell them like they dig (mark them with the
// pick); the wood goes to the master at once. Wooden bridges, wooden drawbridges and wooden
// doors cost wood; stone bridges, iron and magic doors do not.

use crate::game::*;
use crate::map::*;
use serde::{Deserialize, Serialize};

// every master starts with a little wood
pub const WOOD_START: f32 = 12.0;
// wood from one giant mushroom / one tree
pub const WOOD_MUSHROOM: f32 = 4.0;
pub const WOOD_TREE: f32 = 3.0;
// strikes a plant takes
pub const MUSHROOM_HP: f32 = 4.0;
#[allow(dead_code)] // trees come with the surface world
pub const TREE_HP: f32 = 6.0;
// seconds until a felled giant mushroom sprouts again, and from sprout to fully grown
pub const REGROW: f32 = 90.0;
pub const GROW_TIME: f32 = 300.0;
// wood a wooden bridge tile, a wooden drawbridge tile and a wooden door cost
pub const BRIDGE_WOOD: f32 = 2.0;
pub const DRAWBRIDGE_WOOD: f32 = 4.0;
pub const DOOR_WOOD: f32 = 3.0;
// mushroom groves of a random map: one per this many map tiles (at least 2, at most 6)
const GROVE_SHARE: usize = 2200;
const GROVE_RADIUS: i32 = 4;

#[derive(Clone, Debug, Default, Serialize, Deserialize)]
pub struct WoodWork {
    pub regrow: Vec<(usize, f32)>, // felled mushroom tile, seconds until it sprouts again
    #[serde(default)]
    pub growing: Vec<usize>, // giant mushrooms still growing (Tile::food: growth left)
}

// open ground of nobody (or a grove's moss)
fn open_ground(t: &Tile) -> bool {
    (t.kind == Kind::Floor && t.owner == Owner::None) || t.kind == Kind::Grove
}

// a tile where a plant may stand: all eight neighbours open, no other plant next to it (so a
// plant never closes a corridor)
fn lonely_spot(map: &Map, x: i32, y: i32) -> bool {
    if !inb(x, y) || !open_ground(&map.t[idx(x, y)]) {
        return false;
    }
    DIR8.iter().all(|&(dx, dy)| map.get(x + dx, y + dy).map_or(false, |n| n.walkable() && !n.bridge() && n.kind != Kind::Door && !n.plant()))
}

impl Game {
    // mushroom groves in the open caverns of a random map (deterministic, from the seed): mossy
    // ground nobody can claim, giant mushrooms in a loose grid that grow back when felled
    pub fn grow_mushrooms(&mut self, seed: u32) {
        let mut rng = Rng(seed.wrapping_mul(0x9e37_79b9) ^ 0x6d2b_79f5 | 1);
        let (cx, cy) = (self.map.core.0 + 1, self.map.core.1 + 1);
        let open = |g: &Game, x: i32, y: i32| inb(x, y) && !g.map.sky(idx(x, y)) && open_ground(&g.map.t[idx(x, y)]) && !g.map.t[idx(x, y)].bridge();
        // centres: open ground with open ground all around, away from the heart
        let r = GROVE_RADIUS;
        let centres: Vec<usize> = (0..self.map.t.len())
            .filter(|&i| {
                let (x, y) = xy(i);
                (x - cx).abs().max((y - cy).abs()) > 12 && (-2..=2).all(|dy| (-2..=2).all(|dx| open(self, x + dx, y + dy)))
            })
            .collect();
        let want = (self.map.t.len() / GROVE_SHARE).clamp(2, 6);
        let mut groves: Vec<(i32, i32)> = Vec::new();
        let mut tries = 0;
        while groves.len() < want && tries < 200 && !centres.is_empty() {
            tries += 1;
            let (x, y) = xy(centres[(rng.next() as usize) % centres.len()]);
            if groves.iter().any(|&(gx, gy)| (gx - x).abs().max((gy - y).abs()) < 3 * r) {
                continue;
            }
            groves.push((x, y));
        }
        for &(gx, gy) in &groves {
            // the moss: the open ground of a rough disc
            for y in gy - r..=gy + r {
                for x in gx - r..=gx + r {
                    let d2 = (x - gx).pow(2) + (y - gy).pow(2);
                    if d2 <= r * r + (hash32(x, y) % 3) as i32 - 1 && open(self, x, y) {
                        let t = &mut self.map.t[idx(x, y)];
                        t.kind = Kind::Grove;
                        t.owner = Owner::None;
                    }
                }
            }
            // the mushrooms: every other tile in both directions, some still growing
            for y in gy - r + 1..gy + r {
                for x in gx - r + 1..gx + r {
                    if (x - gx) % 2 != 0 || (y - gy) % 2 != 0 {
                        continue;
                    }
                    let i = idx(x, y);
                    if self.map.t[i].kind != Kind::Grove || !lonely_spot(&self.map, x, y) || self.ents.iter().any(|e| e.alive && e.tile() == i) {
                        continue;
                    }
                    let left = if rng.f() < 0.6 { 0.0 } else { rng.f() };
                    self.plant_mushroom(i, left);
                }
            }
        }
    }

    // a giant mushroom on tile i; `left`: how much of its growth is still to come (0 = grown)
    pub fn plant_mushroom(&mut self, i: usize, left: f32) {
        let grove = self.map.t[i].kind == Kind::Grove || self.map.t[i].res & MUSH_GROVE != 0;
        let t = &mut self.map.t[i];
        t.kind = Kind::Mushroom;
        t.owner = Owner::None;
        t.hp = MUSHROOM_HP;
        t.marked = false;
        t.food = left.clamp(0.0, 1.0);
        t.res = if grove { MUSH_GROVE } else { 0 };
        if t.food > 0.0 && !self.woodwork.growing.contains(&i) {
            self.woodwork.growing.push(i);
        }
    }

    // an imp felled the plant at tile i: wood for its master, a mushroom grows back later
    pub(crate) fn felled(&mut self, i: usize) {
        let kind = self.map.t[i].kind;
        let wood = if kind == Kind::Tree { WOOD_TREE } else { WOOD_MUSHROOM };
        self.wood += wood;
        self.count(crate::stats::WOOD, wood);
        if kind == Kind::Mushroom {
            self.woodwork.regrow.push((i, REGROW));
        }
        let (x, y) = xy(i);
        self.fx(5, x as f32 + 0.5, y as f32 + 0.5, 0.0, 0.0, 0.5, 0xff3070a0);
    }

    // pays wood; false (and nothing paid) if there is not enough
    pub fn spend_wood(&mut self, n: f32) -> bool {
        if self.wood + 1e-3 < n {
            return false;
        }
        self.wood = (self.wood - n).max(0.0);
        true
    }

    // the shared step: young mushrooms grow, felled ones sprout again where there is room
    pub(crate) fn update_wood(&mut self, dt: f32) {
        let mut k = 0;
        while k < self.woodwork.growing.len() {
            let i = self.woodwork.growing[k];
            let t = &mut self.map.t[i];
            if t.kind != Kind::Mushroom {
                self.woodwork.growing.swap_remove(k);
                continue;
            }
            t.food = (t.food - dt / GROW_TIME).max(0.0);
            if t.food <= 0.0 {
                self.woodwork.growing.swap_remove(k);
            } else {
                k += 1;
            }
        }
        let mut k = 0;
        while k < self.woodwork.regrow.len() {
            self.woodwork.regrow[k].1 -= dt;
            if self.woodwork.regrow[k].1 > 0.0 {
                k += 1;
                continue;
            }
            let i = self.woodwork.regrow[k].0;
            let (x, y) = xy(i);
            if lonely_spot(&self.map, x, y) && !self.ents.iter().any(|e| e.alive && e.tile() == i) {
                // a sprout: it takes GROW_TIME until it can be felled again
                self.plant_mushroom(i, 1.0);
                self.woodwork.regrow.swap_remove(k);
            } else if !open_ground(&self.map.t[i]) {
                // built over or claimed: it does not come back
                self.woodwork.regrow.swap_remove(k);
            } else {
                self.woodwork.regrow[k].1 = 30.0;
                k += 1;
            }
        }
    }
}

fn hash32(x: i32, y: i32) -> u32 {
    let h = (x as u32).wrapping_mul(2654435761) ^ (y as u32).wrapping_mul(2246822519);
    (h ^ (h >> 15)).wrapping_mul(2246822519) >> 7
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn random_maps_have_mushroom_groves() {
        let g = Game::new(9, 96, 96);
        let groves = g.map.t.iter().filter(|t| t.kind == Kind::Grove).count();
        let n = g.map.t.iter().filter(|t| t.kind == Kind::Mushroom).count();
        assert!(groves >= 30, "{} grove tiles", groves);
        assert!(n >= 6, "{} mushrooms", n);
        assert!((g.wood - WOOD_START).abs() < 1e-3);
        // none closes a corridor: every neighbour is open ground; all stand in a grove
        for i in 0..g.map.t.len() {
            if g.map.t[i].kind == Kind::Mushroom {
                let (x, y) = xy(i);
                assert!(DIR8.iter().all(|&(dx, dy)| g.map.get(x + dx, y + dy).map_or(false, |n| n.walkable())));
                assert!(g.map.t[i].res & MUSH_GROVE != 0);
            }
        }
    }

    #[test]
    fn grove_mushrooms_grow_slowly_are_felled_only_when_grown_and_come_back() {
        let mut g = Game::new(9, 96, 96);
        let i = g.map.t.iter().position(|t| t.kind == Kind::Mushroom && t.grown()).unwrap();
        assert!(g.map.t[i].diggable());
        let w0 = g.wood;
        g.felled(i);
        g.dig_out(i);
        assert_eq!(g.wood, w0 + WOOD_MUSHROOM);
        assert_eq!(g.map.t[i].kind, Kind::Grove, "the moss stays");
        // the grove can't be claimed or marked
        let (x, y) = xy(i);
        g.mark_rect(x, y, x, y, true);
        assert!(!g.map.t[i].marked);
        assert!(!g.claimable(i, 1));
        // it sprouts again: small, and not to be felled yet
        let idx_r = g.woodwork.regrow.iter().position(|r| r.0 == i).unwrap();
        g.woodwork.regrow[idx_r].1 = 0.01;
        g.update_wood(0.05);
        assert_eq!(g.map.t[i].kind, Kind::Mushroom, "a sprout");
        assert!(!g.map.t[i].grown() && !g.map.t[i].diggable());
        g.mark_rect(x, y, x, y, true);
        assert!(!g.map.t[i].marked, "a young mushroom can't be marked");
        // halfway
        for _ in 0..(GROW_TIME as usize / 2) {
            g.update_wood(1.0);
        }
        assert!(!g.map.t[i].grown() && g.map.t[i].growth() > 0.4);
        for _ in 0..(GROW_TIME as usize / 2 + 2) {
            g.update_wood(1.0);
        }
        assert!(g.map.t[i].grown() && g.map.t[i].diggable(), "fully grown: ready to fell");
        assert!(g.spend_wood(3.0) && !g.spend_wood(1000.0));
    }
}