use std::path::PathBuf;
use pronouns_today::PronounList;
use pronouns_today::UserPreferences;
use std::fs::OpenOptions;
use std::fs::File;
use std::io::Write;
use pronouns_today::InstanceSettings;
use argh::FromArgs;
use serde::{Deserialize, Serialize};

#[derive(FromArgs, PartialEq, Debug)]
/// Everything you need to selfhost a pronouns.today server
pub struct PronounsTodayArgs {
	#[argh(subcommand)]
	pub command: SubCommand
}

#[derive(FromArgs, PartialEq, Debug)]
#[argh(subcommand)]
pub enum SubCommand {
	Run(Run),
	#[cfg(feature = "embed_static_assets")]
	DumpStatics(DumpStatics),
}

#[derive(FromArgs, PartialEq, Debug)]
#[cfg(feature = "embed_static_assets")]
#[argh(subcommand, name = "dump-statics")]
/// Dump necessary static files to a directory to be served by a webserver.  Serving
/// static files with a dedicated webserver isn't necessary, but may improve performance.
/// If serving static files, all files should be available under the /static/filename.ext
/// route.
pub struct DumpStatics {
	#[argh(option, default = "String::from(\"./static/\")")]
	/// the directory to write the static files to
	///
	/// Defaults to ./static/
	pub destination: String,
}

#[derive(FromArgs, PartialEq, Debug)]
#[argh(subcommand, name = "run")]
/// Run the server from the specified config file.  Commandline options override config
/// options.
pub struct Run {
	#[cfg_attr(feature = "docker",
			   argh(
				   option,
				   default = "PathBuf::from(\"/data/config.yml\")",
				   short = 'c'))]
	#[cfg_attr(not(feature = "docker"),
			   argh(
				   option,
				   default = "PathBuf::from(\"/etc/pronouns_today.yml\")",
				   short = 'c'))]
	/// path to the config file (generated if needed).  Defaults to
	/// /etc/pronouns_today.yml
	pub config: PathBuf,

	#[argh(switch)]
	/// don't attempt to read or generate a config file, just use command line args.  Missing
	/// options will be filled in using sane defaults
	pub no_read_cfg: bool,

	#[argh(option, short = 'p')]
	/// the port to listen on
	pub port: Option<u16>,

	#[argh(option)]
	/// default pronoun probabilites (formatted as a prefstring, like the ones in the
	/// used in the custom URLs, e.g. "acaqeawdym")
	pub default_prefstr: Option<UserPreferences>,

	#[argh(option)]
	/// the pronouns to be supported by the server.  see configuration file documentation
	/// for warnings when changing this value.  formatted as a list of comma seperated
	/// five-form pronouns, e.g. she/her/her/hers/herself,he/him/his/his/himself
	pub pronouns: Option<PronounList>,
}

impl Run {
	/// Read the config from the provided file, and apply overrides from args
	///
	/// If `--no-read-cfg` was passed, no config file is present, and there aren't
	/// enough args to populate the configuration, returns an [`Err`] with a list of
	/// arguments that were missing.
	pub fn load_config(self) -> Result<Conf, ConfigError> {
		if !self.no_read_cfg {
			match File::open(&self.config) {
				Ok(raw_cfg) => {
					serde_yaml::from_reader(raw_cfg)
						.map_err(ConfigError::MalformedConfig)
				}
				Err(e) if e.kind() == std::io::ErrorKind::NotFound => {
					OpenOptions::new()
						.write(true)
						.create(true)
						.open(&self.config)
						.and_then(|mut c|
							c.write_all(include_bytes!("../assets/default_config.yml"))
						)
						.map_err(ConfigError::IoError)?;
					Err(ConfigError::ConfigCreated(self.config.clone()))
				}
				Err(e) => {
					Err(ConfigError::IoError(e))
				}
			}
		} else {
            Ok(Conf::default())
		}.map(|config| config.update_with(self))
	}
}

#[derive(Clone, Serialize, Deserialize, Debug)]
/// A parsed config file for Pronouns.Today web
pub struct Conf {

	#[serde(flatten)]
	/// General settings for the pronouns.today library
	pub instance_settings: InstanceSettings,

	/// The port for the server to bind to.  Defaults to 1312
	pub port: u16,
}

impl Conf {
	fn update_with(mut self, args: Run) -> Conf {
		self.port = args.port.unwrap_or(self.port);
		self.instance_settings.pronoun_list = args.pronouns.map(Into::into).unwrap_or(self.instance_settings.pronoun_list);
		self
	}
}

impl Default for Conf {
    fn default() -> Self {
        Conf {
            instance_settings: InstanceSettings::default(),
            port: 1312,
        }
    }
}

/// An error occured while trying to load the configuration
pub enum ConfigError {

	/// There wase a problem reading/writing the config file
	IoError(std::io::Error),

	/// There wase a problem deserializing the config file
	MalformedConfig(serde_yaml::Error),

	/// The config file was missing, but has been created
	///
	/// The program should now prompt the user to fill the config in, and then exit.  The
	/// provided [`PathBuf`] contains the path to the new config file
	ConfigCreated(PathBuf),
}