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

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

#[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<&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> where C: Deref<Target=str> {
  command_runner: &'a CommandRunner,
  file: FileSymbol<C, Cow<'a, str>>,
}

use std::borrow::Cow;

impl<'a> NginxServer<'a, String> {
  pub fn server_config(domain: &str, content: &str) -> String {
    format!("server {{
    listen                  80;
    server_name             {0};
    include                 \"snippets/acme-challenge.conf\";

    location / {{
      # Redirect all HTTP links to the matching HTTPS page
      return 301 https://$host$request_uri;
    }}
}}

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}
}}
", domain, content)
  }

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

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

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

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

  pub fn new_php(domain: &'a str, socket_path: &'a str, static_path: &'a str, command_runner: &'a CommandRunner) -> Self {
    let content = NginxServer::server_config(domain, &format!("
    root                {};
    index               index.html index.php;
    location ~ [^/]\\.php(/|$) {{
      fastcgi_pass      unix:{};
      include           \"snippets/fastcgi-php.conf\";
    }}
", static_path, socket_path));
    NginxServer::new(domain, content, command_runner)
  }

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

impl<'a, C> Symbol for NginxServer<'a, C> where C: Deref<Target=str> {
  fn target_reached(&self) -> Result<bool, Box<Error>> {
    if !try!(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<Error>> {
    try!(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 SymbolRunner) -> Box<Action + 'b> {
    Box::new(SymbolAction::new(runner, self))
  }

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

impl<'a, C> fmt::Display for NginxServer<'a, C> where C: Deref<Target=str> {
  fn fmt(&self, f: &mut fmt::Formatter) -> Result<(),fmt::Error>{
    write!(f, "Nginx server config")
  }
}