use clap::{Parser, Subcommand};

use std::collections::HashSet;

use std::fs;
use std::io::{self, Write, BufRead};
use std::path::Path;


const STORAGE_FOLDER: &str = "storage";
const STORAGE_PATH: &str = "storage/db.mps"; // TODO: concat from STORAGE_FOLDER


type DB = HashSet<String>;


#[derive(Parser)]
#[command(name = "mps", version = "0.0.1", about = "MyPasswordStorage: Tool for storing your passwords locally with git synchronization")]
struct Cli {
    #[command(subcommand)]
    command: Option<Commands>,
}

#[derive(Subcommand)]
enum Commands {
    
    /// Initialisation of storage and config, use this in first time of usage of mps
    Init,

    /// Adds new item with unique id to the db
    Add {
        #[arg(value_name="item_id")]
        id: String
    },
    
    /// Lists all ids stored in db
    List
    
}

fn read_db() -> io::Result<DB> {
    let file = fs::File::open(STORAGE_PATH)?;
    let reader = io::BufReader::new(file);
    let mut db = DB::new();
    for line in reader.lines() {
        match line {
            Ok(content) => {
                db.insert(content);
            },
            Err(e) => {
                eprintln!("Error reading line , {}", e);
            }
        }
    }
    Ok(db)
}

fn is_inited() -> bool {
    let path = Path::new(STORAGE_FOLDER);
    return path.exists();
}

fn init() -> io::Result<()> {
    if is_inited() {
        return Err(io::Error::new(io::ErrorKind::AlreadyExists, "Reinitialization attempted"));
    }
    fs::create_dir(STORAGE_FOLDER)?;
    println!("Storage folder created");

    fs::File::create(STORAGE_PATH)?;
    println!("Storage db created");
    println!("Initialization complete."); 
    println!("Now it's required to add folder `{}` under git manually. Don't worry it's going to be encrypted", STORAGE_FOLDER);
    Ok(())
}

fn add(id: &String) -> io::Result<()> {
    let db = read_db()?;
    if db.contains(id) {
        // TODO: ask to edit existing in outer function which invoked this one
        return Err(io::Error::new(
            io::ErrorKind::InvalidInput,
            format!("Dublicate item id: {}. Item id's must be unique.", id)
        ))
    }
    let mut file = fs::OpenOptions::new()
        .write(true)
        .append(true)
        .open(STORAGE_PATH)?;

    writeln!(file, "{}", id)?;
    Ok(())
}

fn list() -> io:: Result<()> {
    let db = read_db()?;
    for item in db.iter() {
        println!("{}", item);
    }
    Ok(())
}

fn main() -> io::Result<()> {
    let cli = Cli::parse();
    match &cli.command {
        Some(Commands::Init) => {
            init()?;
        }
        Some(Commands::Add{ id }) => {
            add(id)?;
        }
        Some(Commands::List) => {
            list()?;
        }
        None => {
            if !is_inited() {
                print!("Do you want to init your storage? [Y/n] ");
                io::stdout().flush().expect("Failed to flush stdout");
                let mut input = String::new();
                io::stdin()
                    .read_line(&mut input)
                    .expect("Failed to read answer");
                let input = input.trim().to_lowercase();
                match input.as_str() {
                    "y" => init()?,
                    "n" => {
                        println!("mps can work only when storage inited.");
                        println!("Hint: you cant do");
                        println!("  git clone <your_storage_git_url> {}", STORAGE_FOLDER);
                        println!("to init manually your storage and config")
                    },
                    _ => init()?,
                }
            } else {
                println!("login, not implemented yet")
            }
        }
    }
    Ok(())
}