hermes-tdata 0.1.1

//! `TDesktop` client implementation
//!
//! Main entry point for parsing tdata folders.

use std::path::{Path, PathBuf};

use crate::account::Account;
use crate::crypto::AuthKey;
use crate::storage::{
    KeyInfo, decrypt_key_data, get_absolute_path, get_default_tdata_path, read_key_data,
    read_mtp_data,
};
use crate::{DEFAULT_KEY_FILE, Error, Result};

/// Telegram Desktop client representation
///
/// Represents a parsed tdata folder with all its accounts.
#[derive(Debug)]
pub struct TDesktop {
    /// Base path to the tdata folder
    base_path: PathBuf,
    /// Key file name (usually "data")
    key_file: String,
    /// Passcode used for decryption (empty if no passcode)
    passcode: String,
    /// Local encryption key
    local_key: AuthKey,
    /// List of accounts
    accounts: Vec<Account>,
    /// App version from tdata
    app_version: u32,
}

impl TDesktop {
    /// Load `TDesktop` from the default tdata location
    ///
    /// # Returns
    /// - `Ok(TDesktop)` if loading succeeded
    /// - `Err(Error::FolderNotFound)` if the default location doesn't exist
    pub fn from_default() -> Result<Self> {
        let path = get_default_tdata_path()
            .ok_or_else(|| Error::FolderNotFound { path: PathBuf::from("(default tdata path)") })?;

        Self::from_path(path)
    }

    /// Load `TDesktop` from a specific path
    ///
    /// # Arguments
    /// - `path`: Path to the tdata folder
    pub fn from_path<P: AsRef<Path>>(path: P) -> Result<Self> {
        Self::with_options(path, None, None)
    }

    /// Load `TDesktop` with a passcode
    ///
    /// Use this when the tdata is protected with a Local Passcode.
    ///
    /// # Arguments
    /// - `path`: Path to the tdata folder
    /// - `passcode`: The Local Passcode
    pub fn from_path_with_passcode<P: AsRef<Path>>(path: P, passcode: &str) -> Result<Self> {
        Self::with_options(path, Some(passcode), None)
    }

    /// Load `TDesktop` with all options
    ///
    /// # Arguments
    /// - `path`: Path to the tdata folder
    /// - `passcode`: Optional Local Passcode
    /// - `key_file`: Optional key file name (default: "data")
    pub fn with_options<P: AsRef<Path>>(
        path: P,
        passcode: Option<&str>,
        key_file: Option<&str>,
    ) -> Result<Self> {
        let base_path = get_absolute_path(path.as_ref().to_str().unwrap_or(""));

        if !base_path.exists() {
            return Err(Error::FolderNotFound { path: base_path });
        }

        let key_file = key_file.unwrap_or(DEFAULT_KEY_FILE).to_owned();
        let passcode = passcode.unwrap_or("").to_owned();

        // Read and decrypt key data
        let key_data = read_key_data(&base_path, &key_file)?;

        let KeyInfo { local_key, account_indices } =
            decrypt_key_data(&key_data, passcode.as_bytes())?;

        tracing::info!("Loaded key data: {} accounts found", account_indices.len());

        // Load accounts
        let mut accounts = Vec::new();
        for index in account_indices {
            match Self::load_account(&base_path, index, &local_key, &key_file) {
                Ok(account) => {
                    tracing::info!(
                        "Loaded account {}: dc_id={}, user_id={}",
                        index,
                        account.dc_id(),
                        account.user_id()
                    );
                    accounts.push(account);
                },
                Err(e) => {
                    tracing::warn!("Failed to load account {}: {}", index, e);
                },
            }
        }

        if accounts.is_empty() {
            return Err(Error::NoAccounts);
        }

        Ok(Self {
            base_path,
            key_file,
            passcode,
            local_key,
            accounts,
            app_version: key_data.version,
        })
    }

    /// Load a single account
    fn load_account(
        base_path: &Path,
        index: i32,
        local_key: &AuthKey,
        key_file: &str,
    ) -> Result<Account> {
        let mtp_data = read_mtp_data(base_path, index, local_key, key_file)?;

        Ok(Account::new(index, mtp_data.dc_id, mtp_data.user_id, mtp_data.auth_key))
    }

    /// Get the base path to the tdata folder
    #[must_use]
    pub fn base_path(&self) -> &Path {
        &self.base_path
    }

    /// Get the number of accounts
    #[must_use]
    pub const fn accounts_count(&self) -> usize {
        self.accounts.len()
    }

    /// Get all accounts
    #[must_use]
    pub fn accounts(&self) -> &[Account] {
        &self.accounts
    }

    /// Get the main (first) account
    #[must_use]
    pub fn main_account(&self) -> Option<&Account> {
        self.accounts.first()
    }

    /// Get an account by index
    #[must_use]
    pub fn account(&self, index: usize) -> Option<&Account> {
        self.accounts.get(index)
    }

    /// Get the app version
    #[must_use]
    pub const fn app_version(&self) -> u32 {
        self.app_version
    }

    /// Check if the tdata has a passcode
    #[must_use]
    pub const fn has_passcode(&self) -> bool {
        !self.passcode.is_empty()
    }

    /// Get the key file name
    #[must_use]
    pub fn key_file(&self) -> &str {
        &self.key_file
    }

    /// Get the local encryption key
    #[must_use]
    pub const fn local_key(&self) -> &AuthKey {
        &self.local_key
    }
}

/// Builder for `TDesktop` with more control over loading
#[derive(Debug)]
pub struct TDesktopBuilder {
    path: PathBuf,
    passcode: Option<String>,
    key_file: Option<String>,
}

impl TDesktopBuilder {
    /// Create a new builder with the given path
    pub fn new<P: AsRef<Path>>(path: P) -> Self {
        Self { path: path.as_ref().to_path_buf(), passcode: None, key_file: None }
    }

    /// Set the passcode
    pub fn passcode(mut self, passcode: impl Into<String>) -> Self {
        self.passcode = Some(passcode.into());
        self
    }

    /// Set the key file name
    pub fn key_file(mut self, key_file: impl Into<String>) -> Self {
        self.key_file = Some(key_file.into());
        self
    }

    /// Build and load the `TDesktop`
    pub fn build(self) -> Result<TDesktop> {
        TDesktop::with_options(self.path, self.passcode.as_deref(), self.key_file.as_deref())
    }
}

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

    #[test]
    fn test_builder() {
        let builder = TDesktopBuilder::new("/path/to/tdata").passcode("secret").key_file("custom");

        assert_eq!(builder.path, PathBuf::from("/path/to/tdata"));
        assert_eq!(builder.passcode, Some("secret".to_string()));
        assert_eq!(builder.key_file, Some("custom".to_string()));
    }
}