mc-classic-js 0.1.3

mod random_level_worker;
mod random;

use rusqlite::{Connection, Result};

use serde::{Deserialize, Serialize};
use serde_json;

use snap;
use snap::raw::{Decoder, Encoder};

use std::collections::HashMap;
use std::fs;

/**

 * JSLevel struct stores the object format of a
 * classic js level of type:
 * {"worldSeed":0,"changedBlocks":{},"worldSize":128,"version":1}
 * References the ChangedBlocks struct
 * worldSeed: This is the seed of the world
 * changedBlocks: This is an array of all changedBlocks in the world
 * worldSize: This is the width/length of the world, must be 128, 256, or 512
 * version: Yeah, I have no clue what this is, but it's seemingly always 1 so...
 */
#[derive(Serialize, Deserialize)]
pub struct JSLevel {
    worldSeed: i64,
    changedBlocks: HashMap<String,ChangedBlocks>,
    worldSize: i32,
    version: u8
}

impl JSLevel {
    pub fn new (worldSeed: i64, changedBlocks: HashMap<String,ChangedBlocks>, worldSize: i32, version: u8) -> Self {
        JSLevel { worldSeed, changedBlocks, worldSize, version } 
    }
}

/**

 * ChangedBlocks struct stores the json object of type:
 * p0_0_0: {a: 0, bt: 0}
 * This object is used inside the savedGame object to keep track
 * of each changed block in the world:
 * p0_0_0: position of block in world, where px_y_z
 * a: 0 if block does match natural generation / 1 if block does not match natural generation
 * bt: type of block
 */
#[derive(Serialize, Deserialize)]
pub struct ChangedBlocks {a: u8, bt: u8}
impl ChangedBlocks { pub fn new (a: u8, bt: u8) -> Self {ChangedBlocks { a, bt }}}

/**

 * LocalStorage struct stores input from localStorage db files
 * key: "savedGame"
 * utf16_length: Length of uncompressed value
 * conversion_type: 1
 * compression_type: 1
 * value: The actual savedGame, so the actual world
 */
pub struct LocalStorage {
    key: String,
    utf16_length: i32,
    conversion_type: i32,
    compression_type: i32,
    last_access_time: i32,
    value: Vec<u8>
}

/**

 * Following function accepts a world size and seed,
 * and then passes them to the js world generation 
 * functionality, and then returns the output as a Vec<>
 */
pub fn get_tile_map (world_size: i32, seed: i64) -> Vec<u8> {
    let y: i32 = 64;
    let level: HashMap<usize, u8> = random_level_worker::start_generation(world_size, seed); //Generating hashmap of all tiles in the world
    let mut tile_map: Vec<u8> = Vec::new();

    for i in 0..world_size * y * world_size {
        tile_map.push(level.get(&(i as usize)).copied().unwrap_or(0)); //Copying hashmap to vec
    }

    return tile_map
}

/**

 * Converts a json string in the savedGame format into
 * a JSLevel struct
 */
pub fn deserialize_saved_game (json_string: String) -> JSLevel {
    let level: JSLevel = serde_json::from_str(&json_string).unwrap();
    return level;
}

/**

 * Following function accepts a level in the JS form, a tile_map, and optimization and
 * writes it into the classic javascript object format
 */
pub fn serialize_saved_game (level: JSLevel, tile_map: Vec<u8>, opt: u8) -> String {

    //Assigning x, y, and z of world
    let x: i32 = level.worldSize;
    let y: i32 = 64;
    let z: i32 = level.worldSize;
    let tile_map1 = get_tile_map(level.worldSize, level.worldSeed);

    let mut output: String = String::from("{"); //Opening json object

    output += &format!(r#""worldSeed":{},"#,level.worldSeed.to_string()); //Adding seed key value pair

    //Adding changed blocks key value pair
    output += r#""changedBlocks":"#; //Adding blocks key
    output += "{"; //Opening block values object

    //Variables for the tiles and a value
    let mut t: u8;
    let mut t1: u8;
    let mut a: u8; //a = 0 if changed block matches generation, a = 1 if changed block does not match generation

    //Iterating through all blocks
    //Tilemaps are stored in X,Z,Y format, where [0] is X:0, Y:0, Z:0 & [1] is X:1, Y:0, Z:0 etc.
    let mut flag: bool = false;
    for i in 0..y {
        for j in 0..z {
            for k in 0..x {

                /* Following code block will be more useful once a changed blocks hashmap is implemented */

                //Setting tile for changed block and checking whether it matches tile generated by seed
                let mut flag1 = false;
                let key: String = String::from(format!(r#""p{}_{}_{}":"#,k,i,j));
                let bt: u8 = level.changedBlocks.get(&key).unwrap_or(&ChangedBlocks::new(1,255)).bt;
                t = tile_map[((i*z*x) + (j*x) + k) as usize];
                t1 = tile_map1[((i*z*x) + (j*x) + k) as usize];
                if bt != 255 { t = bt }
                if t == t1 { a = 0 } else { a = 1 } //a = 0 if changed block matches generation, a = 1 if changed block does not match generation

                //If opt == 2 the tile must differ from natural generation to write to array
                //If opt == 1 either the tile differs from natural generation or it is already considered a changed block to write to array
                //If opt == 0 tile is written to array
                //Default value should be 1 or 2, opt 0 is storage intensive and causes unnecessary lag
                if (opt == 2 && a == 1) || (opt == 1 && (bt != 255 || a == 1)) || opt == 0 { flag1 = true }
                
                if flag1 {
                    //Creating key for changed block
                    output += &key;

                    //Creating value for changed block
                    output += "{";
                    output += &format!(r#""a":{},"bt":{}"#,a,t);
                    output += "},";

                    flag = true;
                }

            }
        }
    }

    if flag {output.pop();} //Removing extra comma
    output += "},"; //Closing Changed Blocks object

    output += &format!{r#""worldSize":{},"#,level.worldSize}; //Adding world size key value pair
    output += &format!{r#""version":{}"#,level.version}; //Adding version key value pair

    output += "}"; //Closing json object
    return output;

}

/**

 * Following function takes a seed and creates a JSLevel from this seed,
 * and then compares it agains the given tilemap to create a json formatted
 * JS world save
 */
pub fn serialize_saved_game_from_seed (seed: i64, tile_map: Vec<u8>) -> String {

    let world_size: i32 = ((tile_map.len()/64) as f64).sqrt() as i32;
    let changed_blocks: HashMap<String, ChangedBlocks> = HashMap::new();
    let level = JSLevel::new(seed, changed_blocks, world_size, 1);

    return serialize_saved_game(level, tile_map, 2);
}

/**

 * Following function opens an sqlite database at the provided path,
 * then retreives the savedGame object, and then decompresses it 
 * before returning it
 */
pub fn read_saved_game (file_path: String) -> Result<String> {

    let conn: Connection = Connection::open(file_path)?;

    let mut stmt = conn.prepare(
        "SELECT * FROM data where key=?1;"
    )?;

    //Iterating through the database
    let entries = stmt.query_map(["savedGame"], |row| Ok(
        LocalStorage {
            key: row.get(0)?,
            utf16_length: row.get(1)?,
            conversion_type: row.get(2)?,
            compression_type: row.get(3)?,
            last_access_time: row.get(4)?,
            value: row.get(5)?,
        }
    ))?;

    //Retreiving the compressed save game object and length
    let mut compressed_saved_game: Vec<u8> = Vec::new();
    let mut decompressed_length: i32 = 0;
    for entry in entries {
        let local: LocalStorage = entry.unwrap();
        if local.key == "savedGame" {
            compressed_saved_game = local.value;
            decompressed_length = local.utf16_length;
            break;
        }
    }

    //Creating an array with the correct length for storing the decompressed bytes
    let mut decompressed: Vec<u8> = Vec::new();
    for _ in 0..decompressed_length {
        decompressed.push(0);
    }

    //Decompressing using snappy compression
    Decoder::decompress(&mut Decoder::new(), &compressed_saved_game, &mut decompressed).unwrap();

    //Converting the character codes to characters
    let mut characters: Vec<char> = Vec::new();
    for ch in decompressed {
        characters.push(ch as char)
    }

    //Returning the characters as a string
    Ok(characters.iter().collect())

}

/**

 * Following function accepts a path to a db file, and a 
 * json string. The json string is parsed as the value and
 * compressed using snappy compression, and is then passed
 * to the db and saved. Note this only applies to Firefox,
 * as firefox is the only browser that I know of that uses
 * this structure. Chromium support in the future...
 */
pub fn write_saved_game (file_path: String, json_string: String) -> Result<()> {

    //Converting the json_string into an array of chars
    let characters: Vec<char> = json_string.chars().collect();
    let utf16_length: i32  = characters.len() as i32;

    //Converting chars to u8
    let mut decompressed: Vec<u8> = Vec::new();
    for ch in characters {
        decompressed.push(ch as u8);
    }

    //Creating the output array
    let max_comp_length = snap::raw::max_compress_len(decompressed.len());
    let mut compressed: Vec<u8> = Vec::new();
    for _ in 0..max_comp_length {
        compressed.push(0);
    }

    //Compressing and cleaning the compressed value
    Encoder::compress(&mut Encoder::new(), &decompressed, & mut compressed).unwrap();
    let mut b: u8 = 0;
    while b == 0 {
        b = compressed.pop().unwrap();
    }
    compressed.push(b);

    let conn: Connection = Connection::open(file_path)?;

    //Creates the localStorage data table inside the database if it does not exist
    conn.execute(
        "CREATE TABLE if not exists data ( 
        key TEXT PRIMARY KEY, 
        utf16_length INTEGER NOT NULL, 
        conversion_type INTEGER NOT NULL, 
        compression_type INTEGER NOT NULL, 
        last_access_time INTEGER NOT NULL DEFAULT 0, 
        value BLOB NOT NULL)", 
        []
    )?;

    //Inserting the savedGame into the database
    let mut stmt = conn.prepare("INSERT OR REPLACE INTO data (key, utf16_length, conversion_type, compression_type, value) values (?1, ?2, ?3, ?4, ?5)" )?;

    stmt.execute(("savedGame", utf16_length, 1, 1, compressed));

    Ok(())

}

/**

 * Following function excepts a file location and a world save formatted as a 
 * json string. It then creates a localStorage.setItem() command for the key
 * savedGame, in order for it to be copy pasted into a browser console to 
 * insert the world save
 */
pub fn write_saved_game_command (file: String, json_string: String) -> String {
    let open: String = String::from(r#"localStorage.setItem("savedGame", `"#); //Opening command for localStorage
    let close: String = String::from(r#"`)"#); //Closing command for localStorage

    let output: String = String::from(format!{r"{open}{json_string}{close}"});

    if file != "" {fs::write(file, output.clone()).expect("Error when writing to file")} //Attempting to write localStorage command to file

    return output;

}