// Savegames: JSON with format tag and version, containing the game state, the camera
// and the player's settings (settings are always applied when a savegame is loaded).

use crate::game::Game;
use crate::render3d::Cam;
use crate::settings::Settings;
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,
    camera: &'a Cam,
    settings: &'a Settings,
}

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

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

pub fn to_json(game: &Game, camera: &Cam, settings: &Settings) -> String {
    serde_json::to_string(&SaveOut { format: FORMAT, version: VERSION, game, camera, settings }).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;
    game.map.activate();
    game.recount();
    Ok(Loaded { game, camera: s.camera, settings: s.settings })
}

#[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 cam = Cam::new(10.0, 20.0);
        let mut settings = Settings::default();
        settings.language = "de".into();
        let json = to_json(&g, &cam, &settings);
        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_eq!(l.settings.unwrap().language, "de");
        assert_eq!(l.camera.unwrap().tx, 10.0);
        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, &Cam::new(0.0, 0.0), &Settings::default());
        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(&g, &cam, &Settings { language: "en".into(), ..Settings::default() })).unwrap();
    }
}