//! Configuration

use std::{fmt::Display, fs::File, io::ErrorKind as IoErrorKind};

use serde::{Deserialize, Serialize};

/// Result alias for this module
pub type Result<T> = std::result::Result<T, Error>;

/// Data for a valid login, including access token and homeserver address
#[derive(Serialize, Deserialize, Clone, Debug)]
pub struct Session {
	/// Access token, mxid and device id of the session
	pub session: matrix_sdk::Session,
	/// The address of the homeserver
	pub homeserver: String,
}

impl Session {
	/// Read session data from disk.
	pub fn from_file() -> Result<Option<Session>> {
		let dirs = dirs()?;
		let file = File::open(dirs.data_dir().join("session.json"));
		let file = match file {
			Ok(file) => file,
			Err(e) => {
				return match e.kind() {
					IoErrorKind::NotFound => Ok(None),
					_ => Err(e.into()),
				}
			}
		};
		let session = serde_json::from_reader(file)?;
		Ok(session)
	}

	/// Writes the session data to disk.
	pub fn write(&self) -> Result<()> {
		let dirs = dirs()?;
		std::fs::create_dir_all(dirs.data_dir())?;
		let file = File::create(dirs.data_dir().join("session.json"))?;
		serde_json::to_writer_pretty(file, self)?;
		Ok(())
	}
}

/// Configuration for the application
#[derive(Serialize, Deserialize, Clone, Debug)]
pub struct Config {
	/// The global zoom level.
	pub zoom: f64,
}

impl Config {
	/// Creates a new `Config` with default settings
	pub fn new() -> Config {
		Config { zoom: 1.0 }
	}
}

impl Default for Config {
	fn default() -> Self {
		Self::new()
	}
}

impl Config {
	/// Reads the configuration from disk, or creates a new file with default settings if none
	/// exists
	pub fn from_file() -> Result<Config> {
		let dirs = dirs()?;
		let file = File::open(dirs.config_dir().join("retrix.json"));
		// Create the file if it doesn't exist
		let file = match file {
			Ok(file) => file,
			Err(e) => match e.kind() {
				IoErrorKind::NotFound => {
					let config = Config::default();
					config.write()?;
					return Ok(config);
				}
				_ => return Err(e.into()),
			},
		};
		let config: Config = serde_json::from_reader(file)?;
		Ok(config)
	}

	/// Writes the configuration to disk
	pub fn write(&self) -> Result<()> {
		let dirs = dirs()?;
		std::fs::create_dir_all(dirs.config_dir())?;
		let file = File::create(dirs.config_dir().join("retrix.json"))?;
		serde_json::to_writer_pretty(file, self)?;
		Ok(())
	}
}

/// Generates structure holding paths for config dirs etc.
pub fn dirs() -> Result<dirs::ProjectDirs> {
	dirs::ProjectDirs::from("net.amandag", "", "retrix").ok_or(Error::HomeDir)
}

/// Errors which can happen when handling config files
#[derive(Debug)]
pub enum Error {
	/// An error happened opening or creating a file
	Io(std::io::Error),
	/// (De)serializing a file failed
	Parsing(serde_json::Error),
	/// The home directory couldn't be found
	HomeDir,
}

impl Display for Error {
	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
		match self {
			Error::Io(e) => write!(f, "Error opening file: {}", e),
			Error::Parsing(e) => write!(f, "Error in config file: {}", e),
			Error::HomeDir => write!(f, "Couldn't find home directory"),
		}
	}
}

impl std::error::Error for Error {
	fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
		match *self {
			Error::Io(ref e) => Some(e),
			Error::Parsing(ref e) => Some(e),
			Error::HomeDir => None,
		}
	}
}

impl From<std::io::Error> for Error {
	fn from(e: std::io::Error) -> Self {
		Error::Io(e)
	}
}

impl From<serde_json::Error> for Error {
	fn from(e: serde_json::Error) -> Self {
		Error::Parsing(e)
	}
}