use std::error::Error;
use std::fmt;
use std::io;
use std::ops::Deref;

use command_runner::CommandRunner;
use resources::Resource;
use symbols::file::File as FileSymbol;
use symbols::{Action, OwnedSymbolAction, Symbol, SymbolAction, SymbolRunner};

#[derive(Debug)]
pub enum NginxServerError<E: Error> {
  ExecError(E),
  GenericError,
}

impl From<io::Error> for NginxServerError<io::Error> {
  fn from(err: io::Error) -> NginxServerError<io::Error> {
    NginxServerError::ExecError(err)
  }
}

impl<E: Error> Error for NginxServerError<E> {
  fn description(&self) -> &str {
    match self {
      NginxServerError::ExecError(ref e) => e.description(),
      NginxServerError::GenericError => "Generic error",
    }
  }
  fn cause(&self) -> Option<&dyn Error> {
    match self {
      NginxServerError::ExecError(ref e) => Some(e),
      _ => None,
    }
  }
}

impl<E: Error> fmt::Display for NginxServerError<E> {
  fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
    write!(f, "{}", self.description())
  }
}

pub struct NginxServer<'a, C: 'a + CommandRunner, T>
where
  T: Deref<Target = str>,
{
  command_runner: &'a C,
  file: FileSymbol<T, String>,
}

use std::borrow::Cow;

pub fn server_config(domain: &str, content: &str) -> String {
  format!(
    "server {{
    listen                  443 ssl http2;
    server_name             {0};
    include                 \"snippets/acme-challenge.conf\";

    ssl_certificate         /etc/ssl/local_certs/{0}.chained.crt;
    ssl_certificate_key     /etc/ssl/private/{0}.key;
    add_header              Strict-Transport-Security \"max-age=31536000\";

    {1}
}}

# Redirect all HTTP links to the matching HTTPS page
server {{
    listen                  80;
    server_name             {0};
    include                 \"snippets/acme-challenge.conf\";

    location / {{
      return 301 https://$host$request_uri;
    }}
}}
",
    domain, content
  )
}

pub fn php_server_config_snippet<'a>(
  socket_path: Cow<'a, str>,
  static_path: Cow<'a, str>,
) -> String {
  format!(
    "
    root                {};
    index               index.html index.php;
    location ~ [^/]\\.php(/|$) {{
      fastcgi_pass      unix:{};
      include           \"snippets/fastcgi-php.conf\";
    }}",
    static_path, socket_path
  )
}

pub trait SocketSpec {
  fn to_nginx(&self) -> String;
}

impl SocketSpec for &str {
  fn to_nginx(&self) -> String {
    format!("unix:{}:", self)
  }
}

pub struct LocalTcpSocket(usize);

impl LocalTcpSocket {
  pub fn new(x: usize) -> Self {
    LocalTcpSocket(x)
  }
}

impl SocketSpec for LocalTcpSocket {
  fn to_nginx(&self) -> String {
    format!("localhost:{}", self.0)
  }
}

impl<'a, C: CommandRunner> NginxServer<'a, C, String> {
  pub fn new_redir(domain: &'a str, target: &'a str, command_runner: &'a C) -> Self {
    let content = server_config(
      domain,
      &format!(
        "location / {{
  return 301 $scheme://{}$request_uri;
}}",
        target
      ),
    );
    NginxServer::new(domain, content, command_runner)
  }

  pub fn new_proxy<S: SocketSpec>(
    domain: &'a str,
    socket_path: S,
    static_path: &'a str,
    command_runner: &'a C,
  ) -> Self {
    let proxy_content = format!(
      "location / {{
  try_files             $uri @proxy;
}}

location @proxy {{
  include               fastcgi_params;
  proxy_pass            http://{};
  proxy_redirect        off;
}}",
      socket_path.to_nginx()
    );

    let content = server_config(
      domain,
      &format!(
        "
    root                    {};
    {}
",
        static_path, proxy_content
      ),
    );
    NginxServer::new(domain, content, command_runner)
  }

  pub fn new_php(
    domain: &'a str,
    socket_path: Cow<'a, str>,
    static_path: Cow<'a, str>,
    command_runner: &'a C,
    additional_config: &'a str,
  ) -> Self {
    let content = server_config(
      domain,
      &(php_server_config_snippet(socket_path, static_path) + additional_config),
    );
    NginxServer::new(domain, content, command_runner)
  }

  pub fn new_static(domain: &'a str, static_path: &'a str, command_runner: &'a C) -> Self {
    let content = server_config(
      domain,
      &format!(
        "
    root                    {};
    try_files $uri $uri/ $uri.html =404;
",
        static_path
      ),
    );
    NginxServer::new(domain, content, command_runner)
  }

  pub fn new(domain: &'a str, content: String, command_runner: &'a C) -> Self {
    let file_path = String::from("/etc/nginx/sites-enabled/") + domain;
    NginxServer {
      command_runner,
      file: FileSymbol::new(file_path, content),
    }
  }
}

impl<'a, C: CommandRunner, T> Symbol for NginxServer<'a, C, T>
where
  T: Deref<Target = str>,
{
  fn target_reached(&self) -> Result<bool, Box<dyn Error>> {
    if !self.file.target_reached()? {
      return Ok(false);
    }
    // TODO: Could try to find out if the server is in the live config
    Ok(true)
  }

  fn execute(&self) -> Result<(), Box<dyn Error>> {
    self.file.execute()?;
    self
      .command_runner
      .run_successfully("systemctl", &["reload-or-restart", "nginx"])
  }

  fn get_prerequisites(&self) -> Vec<Resource> {
    self.file.get_prerequisites()
  }

  fn as_action<'b>(&'b self, runner: &'b dyn SymbolRunner) -> Box<dyn Action + 'b> {
    Box::new(SymbolAction::new(runner, self))
  }

  fn into_action<'b>(self: Box<Self>, runner: &'b dyn SymbolRunner) -> Box<dyn Action + 'b>
  where
    Self: 'b,
  {
    Box::new(OwnedSymbolAction::new(runner, *self))
  }
}

impl<'a, C: CommandRunner, T> fmt::Display for NginxServer<'a, C, T>
where
  T: Deref<Target = str>,
{
  fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
    write!(f, "Nginx server config")
  }
}