// Savegames: JSON with format tag and version, containing the game state - nothing else. The
// player's settings live in the browser's local storage; settings in older savegames are
// ignored. Only the screenshot scenes (scenes.rs) also carry a camera.

use crate::game::Game;
use crate::render3d::Cam;
use serde::{Deserialize, Serialize};

pub const FORMAT: &str = "dungeoncraft-save";
pub const VERSION: u32 = 2; // 2: variable map size, several portals, packed tiles
pub const AUTOSAVE_KEY: &str = "dc.autosave";

#[derive(Serialize)]
struct SaveOut<'a> {
    format: &'a str,
    version: u32,
    game: &'a Game,
    #[serde(skip_serializing_if = "Option::is_none")]
    camera: Option<&'a Cam>,
}

#[derive(Deserialize)]
struct SaveIn {
    format: String,
    version: u32,
    game: Game,
    camera: Option<Cam>,
}

pub struct Loaded {
    pub game: Game,
    pub camera: Option<Cam>,
}

pub fn to_json(game: &Game) -> String {
    serde_json::to_string(&SaveOut { format: FORMAT, version: VERSION, game, camera: None }).unwrap_or_default()
}

// a screenshot scene: the game and where the camera looks
#[allow(dead_code)] // scenes.rs (tests) only
pub fn to_json_with_camera(game: &Game, camera: &Cam) -> String {
    serde_json::to_string(&SaveOut { format: FORMAT, version: VERSION, game, camera: Some(camera) }).unwrap_or_default()
}

// Err contains a language key describing the problem
pub fn from_bytes(data: &[u8]) -> Result<Loaded, &'static str> {
    let s: SaveIn = serde_json::from_slice(data).map_err(|_| "save.err_invalid")?;
    if s.format != FORMAT {
        return Err("save.err_invalid");
    }
    if s.version > VERSION {
        return Err("save.err_version");
    }
    let mut game = s.game;
    // older saves kept the dwarves on side 4, which is now the fourth master
    if !game.is_master(4) && !game.rivals.iter().any(|r| r.side == 4) {
        for e in game.ents.iter_mut().filter(|e| !e.hero && e.side == 4) {
            e.side = crate::dwarves::DWARF_SIDE;
        }
    }
    game.map.activate();
    game.recount();
    Ok(Loaded { game, camera: s.camera })
}

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

    #[test]
    fn save_roundtrip() {
        let mut g = Game::new(42, 96, 128);
        let (cx, cy) = g.map.core;
        g.mark_rect(cx - 5, cy - 5, cx + 8, cy + 8, true);
        for _ in 0..3000 {
            g.update(0.05);
        }
        let json = to_json(&g);
        println!("savegame size: {} KB", json.len() / 1024);
        let l = from_bytes(json.as_bytes()).expect("load");
        assert_eq!(l.game.time, g.time);
        assert_eq!(l.game.ents.len(), g.ents.len());
        assert_eq!(l.game.gold, g.gold);
        assert!(l.game.map.t.iter().zip(g.map.t.iter()).all(|(a, b)| a.kind == b.kind && a.owner == b.owner && a.marked == b.marked));
        assert!(l.camera.is_none() && !json.contains("\"settings\"") && !json.contains("\"camera\""), "only the game state");
        assert_eq!((l.game.map.w, l.game.map.h), (96, 128));
        assert_eq!(l.game.map.portals.len(), g.map.portals.len());
        assert!(l.game.map.t.iter().zip(g.map.t.iter()).all(|(a, b)| a.var == b.var && a.hp == b.hp && a.food == b.food && a.gold == b.gold));
        // the loaded game keeps running identically
        let mut a = l.game;
        let mut b = g;
        for _ in 0..2000 {
            a.update(0.05);
            b.update(0.05);
        }
        assert_eq!(a.gold, b.gold);
        assert_eq!(a.ents.len(), b.ents.len());
        assert!(from_bytes(b"{\"format\":\"x\"}").is_err());
    }

    #[test]
    fn huge_map() {
        let t0 = std::time::Instant::now();
        let mut g = Game::new(7, 256, 256);
        let gen = t0.elapsed();
        assert_eq!(g.map.portals.len(), 16);
        assert_eq!(g.map.treasures.len(), 0); // knight caves are replaced by dwarf caves
        assert!((1..=4).contains(&g.dwarf_caves.len()));
        let (cx, cy) = g.map.core;
        g.mark_rect(cx - 5, cy - 5, cx + 8, cy + 8, true);
        let t1 = std::time::Instant::now();
        for _ in 0..(120 * 20) {
            g.update(0.05);
        }
        let sim = t1.elapsed();
        let json = to_json(&g);
        println!("256x256: generate {:?}, 2 min simulated in {:?}, savegame {} KB", gen, sim, json.len() / 1024);
        let l = from_bytes(json.as_bytes()).expect("load");
        assert_eq!(l.game.map.t.len(), 256 * 256);
    }

    // writes a savegame shortly before a wave (with planned entry points) when DC_SAVE_OUT is set
    #[test]
    fn dump_entry_warning_save() {
        let Ok(path) = std::env::var("DC_SAVE_OUT") else { return };
        let mut g = Game::new(11, 64, 64);
        for _ in 0..(60 * 20) {
            g.update(0.05);
        }
        g.wave_timer = 31.0;
        for _ in 0..30 {
            g.update(0.05); // the scouts warn 30 s before the wave
        }
        assert!(!g.planned_entries.is_empty());
        let (cx, cy) = g.map.core;
        g.spawn(crate::game::EK::Chainbreaker, false, (cx - 1) as f32 + 0.5, (cy - 1) as f32 + 0.5, 1);
        g.spawn(crate::game::EK::Ogre, false, (cx + 4) as f32 + 0.5, (cy - 1) as f32 + 0.5, 1);
        let (ex, ey) = (cx + 1, cy + 1);
        let mut cam = Cam::new(ex as f32 + 0.5, ey as f32 + 0.5);
        cam.zoom = 12.0;
        std::fs::write(path, to_json_with_camera(&g, &cam)).unwrap();
    }
}