use std::path::PathBuf;
use std::fs::File;
use std::io::{Read, Cursor};
use base64::engine::{general_purpose::URL_SAFE, Engine};
use flate2::read::GzDecoder;
use gd_plist::Value;

struct User {
    name: String,
    id: Option<u64>,
}

enum Song {
    Official{id: i32 /*k8*/},
    Newgrounds{id: i32 /*k45*/},
    Unknown
}

struct Level {
    outer: OuterLevel,
    song: Song,
}

#[derive(Debug)]
pub struct OuterLevel {
    name: String, // k2
    revision: Option<i64>, // k46
}

pub fn gd_path() -> PathBuf {
    let mut path_buf = home::home_dir().unwrap();
    #[cfg(unix)]
    path_buf.extend([".local", "share", "Steam", "steamapps", 
                     "compatdata", "322170", "pfx", "drive_c",
                     "users", "steamuser", "AppData", "Local",
                     "GeometryDash"].iter());
    #[cfg(windows)]
    path_buf.extend(["AppData", "Local", "GeometryDash"].iter());
    path_buf
}

struct LevelBuilder {
    name: Option<String>,
    song: Option<Song>,
    revision: Option<i64>,
}

impl Default for LevelBuilder {
    fn default() -> Self {
        Self {name: None, song: None, revision: None}
    }
}

impl LevelBuilder {
    fn new() -> Self {Self::default()}

    fn with_name(&mut self, name: String) {
        self.name = Some(name);
    }

    fn with_song(&mut self, song: Song) {
        self.song = Some(song);
    }

    fn with_revision(&mut self, revision: i64) {
        self.revision = Some(revision);
    }

    fn build_level(self) -> Option<Level> {
        match self {
            Self {
                name: Some(name), 
                song: Some(song), 
                revision,
            } => Some(Level{song, outer: OuterLevel {name, revision}}),
            _ => None,
        }
    }

    fn build_outer_level(self) -> Option<OuterLevel> {
        match self {
            Self {
                name: Some(name), 
                revision,
                ..
            } => Some(OuterLevel {name, revision}),
            _ => None,
        }
    }
}

fn get_local_level_plist() -> Value {
    let raw_save_data = {
        let mut save_file = File::open(gd_path().join("CCLocalLevels.dat")).expect("No save file found!");
        let mut sd = Vec::new();
        save_file.read_to_end(&mut sd).unwrap();
        sd
    };
    let data_post_xor: Vec<u8> = raw_save_data.iter().map(|b| b ^ 11).collect();
    let data_post_b64 = URL_SAFE.decode(data_post_xor).unwrap();
    let mut decoder = GzDecoder::<&[u8]>::new(data_post_b64.as_ref());
    let mut plist = String::new();
    if let Err(_) = decoder.read_to_string(&mut plist) {
        println!("Warning: Game save likely corrupted (gzip decode failed)");
    }
    Value::from_reader(Cursor::new(plist)).unwrap()
}

pub fn get_outer_levels() -> Vec<OuterLevel> {
    let plist = get_local_level_plist();
    let levels: Vec<OuterLevel> = plist.as_dictionary().and_then(|dict| dict.get("LLM_01")).unwrap()
        .as_dictionary().unwrap().into_iter().filter(|(key, _)| key.as_str() != "_isArr").map(|(_, val)| {
            let mut builder = LevelBuilder::new();
            let props = val.as_dictionary().unwrap();
            if let Some(title) = props.get("k2") {
                builder.with_name(title.as_string().unwrap().into());
            }
            if let Some(rev) = props.get("k46") {
                builder.with_revision(rev.as_signed_integer().unwrap().into());
            }
            builder.build_outer_level().unwrap()
        }).collect();
    levels
}