// Copyright 2015-2019 Parity Technologies (UK) Ltd.
// This file is part of Parity Ethereum.

// Parity Ethereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Parity Ethereum is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with Parity Ethereum.  If not, see <http://www.gnu.org/licenses/>.

//! Ethcore client application.

#![warn(missing_docs)]

extern crate ctrlc;
extern crate dir;
extern crate fdlimit;
#[macro_use]
extern crate log;
extern crate ansi_term;
extern crate panic_hook;
extern crate parity_daemonize;
extern crate parity_ethereum;
extern crate parking_lot;

extern crate ethcore_logger;
#[cfg(windows)]
extern crate winapi;

use std::{
    env,
    ffi::OsString,
    fs::{create_dir_all, metadata, remove_file, File},
    io::{Read, Write},
    path::PathBuf,
    process,
    sync::{
        atomic::{AtomicBool, Ordering},
        Arc,
    },
};

use ansi_term::Colour;
use ctrlc::CtrlC;
use dir::default_hypervisor_path;
use ethcore_logger::setup_log;
use fdlimit::raise_fd_limit;
use parity_daemonize::AsHandle;
use parity_ethereum::{start, ExecutionAction};
use parking_lot::{Condvar, Mutex};

const PLEASE_RESTART_EXIT_CODE: i32 = 69;
const PARITY_EXECUTABLE_NAME: &str = "parity";

#[derive(Debug)]
enum Error {
    BinaryNotFound,
    ExitCode(i32),
    Restart,
    Unknown,
}

fn update_path(name: &str) -> PathBuf {
    let mut dest = default_hypervisor_path();
    dest.push(name);
    dest
}

fn latest_exe_path() -> Result<PathBuf, Error> {
    File::open(update_path("latest"))
        .and_then(|mut f| {
            let mut exe_path = String::new();
            trace!(target: "updater", "latest binary path: {:?}", f);
            f.read_to_string(&mut exe_path)
                .map(|_| update_path(&exe_path))
        })
        .or(Err(Error::BinaryNotFound))
}

fn latest_binary_is_newer(
    current_binary: &Option<PathBuf>,
    latest_binary: &Option<PathBuf>,
) -> bool {
    match (
        current_binary
            .as_ref()
            .and_then(|p| metadata(p.as_path()).ok())
            .and_then(|m| m.modified().ok()),
        latest_binary
            .as_ref()
            .and_then(|p| metadata(p.as_path()).ok())
            .and_then(|m| m.modified().ok()),
    ) {
        (Some(latest_exe_time), Some(this_exe_time)) if latest_exe_time > this_exe_time => true,
        _ => false,
    }
}

fn set_spec_name_override(spec_name: &str) {
    if let Err(e) = create_dir_all(default_hypervisor_path()).and_then(|_| {
        File::create(update_path("spec_name_override"))
            .and_then(|mut f| f.write_all(spec_name.as_bytes()))
    }) {
        warn!(
            "Couldn't override chain spec: {} at {:?}",
            e,
            update_path("spec_name_override")
        );
    }
}

fn take_spec_name_override() -> Option<String> {
    let p = update_path("spec_name_override");
    let r = File::open(p.clone()).ok().and_then(|mut f| {
        let mut spec_name = String::new();
        f.read_to_string(&mut spec_name).ok().map(|_| spec_name)
    });
    let _ = remove_file(p);
    r
}

#[cfg(windows)]
fn global_cleanup() {
    // We need to cleanup all sockets before spawning another Parity process. This makes sure everything is cleaned up.
    // The loop is required because of internal reference counter for winsock dll. We don't know how many crates we use do
    // initialize it. There's at least 2 now.
    for _ in 0..10 {
        unsafe {
            ::winapi::um::winsock2::WSACleanup();
        }
    }
}

#[cfg(not(windows))]
fn global_init() {}

#[cfg(windows)]
fn global_init() {
    // When restarting in the same process this reinits windows sockets.
    unsafe {
        const WS_VERSION: u16 = 0x202;
        let mut wsdata: ::winapi::um::winsock2::WSADATA = ::std::mem::zeroed();
        ::winapi::um::winsock2::WSAStartup(WS_VERSION, &mut wsdata);
    }
}

#[cfg(not(windows))]
fn global_cleanup() {}

// Starts parity binary installed via `parity-updater` and returns the code it exits with.
fn run_parity() -> Result<(), Error> {
    global_init();

    let prefix = vec![
        OsString::from("--can-restart"),
        OsString::from("--force-direct"),
    ];

    let res: Result<(), Error> = latest_exe_path().and_then(|exe| {
        process::Command::new(exe)
            .args(
                &(env::args_os()
                    .skip(1)
                    .chain(prefix.into_iter())
                    .collect::<Vec<_>>()),
            )
            .status()
            .ok()
            .map_or(Err(Error::Unknown), |es| {
                match es.code() {
                    // Process success
                    Some(0) => Ok(()),
                    // Please restart
                    Some(PLEASE_RESTART_EXIT_CODE) => Err(Error::Restart),
                    // Process error code `c`
                    Some(c) => Err(Error::ExitCode(c)),
                    // Unknown error, couldn't determine error code
                    _ => Err(Error::Unknown),
                }
            })
    });

    global_cleanup();
    res
}

#[derive(Debug)]
/// Status used to exit or restart the program.
struct ExitStatus {
    /// Whether the program panicked.
    panicking: bool,
    /// Whether the program should exit.
    should_exit: bool,
    /// Whether the program should restart.
    should_restart: bool,
    /// If a restart happens, whether a new chain spec should be used.
    spec_name_override: Option<String>,
}

// Run `locally installed version` of parity (i.e, not installed via `parity-updater`)
// Returns the exit error code.
fn main_direct(force_can_restart: bool) -> i32 {
    global_init();

    let mut conf = {
        let args = std::env::args().collect::<Vec<_>>();
        parity_ethereum::Configuration::parse_cli(&args).unwrap_or_else(|e| e.exit())
    };

    let logger = setup_log(&conf.logger_config()).unwrap_or_else(|e| {
        eprintln!("{}", e);
        process::exit(2)
    });

    if let Some(spec_override) = take_spec_name_override() {
        conf.args.arg_chain = spec_override;
    }

    // FIXME: `pid_file` shouldn't need to cloned here
    // see: `https://github.com/paritytech/parity-daemonize/pull/13` for more info
    let handle = if let Some(pid) = conf.args.arg_daemon_pid_file.clone() {
        info!(
            "{}",
            Colour::Blue.paint("starting in daemon mode").to_string()
        );
        let _ = std::io::stdout().flush();

        match parity_daemonize::daemonize(pid) {
            Ok(h) => Some(h),
            Err(e) => {
                error!("{}", Colour::Red.paint(format!("{}", e)));
                return 1;
            }
        }
    } else {
        None
    };

    let can_restart = force_can_restart || conf.args.flag_can_restart;

    // increase max number of open files
    raise_fd_limit();

    let exit = Arc::new((
        Mutex::new(ExitStatus {
            panicking: false,
            should_exit: false,
            should_restart: false,
            spec_name_override: None,
        }),
        Condvar::new(),
    ));

    // Double panic can happen. So when we lock `ExitStatus` after the main thread is notified, it cannot be locked
    // again.
    let exiting = Arc::new(AtomicBool::new(false));

    let exec = if can_restart {
        start(
            conf,
            logger,
            {
                let e = exit.clone();
                let exiting = exiting.clone();
                move |new_chain: String| {
                    if !exiting.swap(true, Ordering::SeqCst) {
                        *e.0.lock() = ExitStatus {
                            panicking: false,
                            should_exit: true,
                            should_restart: true,
                            spec_name_override: Some(new_chain),
                        };
                        e.1.notify_all();
                    }
                }
            },
            {
                let e = exit.clone();
                let exiting = exiting.clone();
                move || {
                    if !exiting.swap(true, Ordering::SeqCst) {
                        *e.0.lock() = ExitStatus {
                            panicking: false,
                            should_exit: true,
                            should_restart: true,
                            spec_name_override: None,
                        };
                        e.1.notify_all();
                    }
                }
            },
        )
    } else {
        trace!(target: "mode", "Not hypervised: not setting exit handlers.");
        start(conf, logger, move |_| {}, move || {})
    };

    let res = match exec {
        Ok(result) => match result {
            ExecutionAction::Instant(Some(s)) => {
                println!("{}", s);
                0
            }
            ExecutionAction::Instant(None) => 0,
            ExecutionAction::Running(client) => {
                panic_hook::set_with({
                    let e = exit.clone();
                    let exiting = exiting.clone();
                    move |panic_msg| {
                        warn!("Panic occured, see stderr for details");
                        eprintln!("{}", panic_msg);
                        if !exiting.swap(true, Ordering::SeqCst) {
                            *e.0.lock() = ExitStatus {
                                panicking: true,
                                should_exit: true,
                                should_restart: false,
                                spec_name_override: None,
                            };
                            e.1.notify_all();
                        }
                    }
                });

                CtrlC::set_handler({
                    let e = exit.clone();
                    let exiting = exiting.clone();
                    move || {
                        if !exiting.swap(true, Ordering::SeqCst) {
                            *e.0.lock() = ExitStatus {
                                panicking: false,
                                should_exit: true,
                                should_restart: false,
                                spec_name_override: None,
                            };
                            e.1.notify_all();
                        }
                    }
                });

                // so the client has started successfully
                // if this is a daemon, detach from the parent process
                if let Some(mut handle) = handle {
                    handle.detach()
                }

                // Wait for signal
                let mut lock = exit.0.lock();
                if !lock.should_exit {
                    let _ = exit.1.wait(&mut lock);
                }

                client.shutdown();

                if lock.should_restart {
                    if let Some(ref spec_name) = lock.spec_name_override {
                        set_spec_name_override(&spec_name.clone());
                    }
                    PLEASE_RESTART_EXIT_CODE
                } else {
                    if lock.panicking {
                        1
                    } else {
                        0
                    }
                }
            }
        },
        Err(err) => {
            // error occured during start up
            // if this is a daemon, detach from the parent process
            if let Some(mut handle) = handle {
                handle.detach_with_msg(format!("{}", Colour::Red.paint(&err)))
            }
            eprintln!("{}", err);
            1
        }
    };

    global_cleanup();
    res
}

fn println_trace_main(s: String) {
    if env::var("RUST_LOG")
        .ok()
        .and_then(|s| s.find("main=trace"))
        .is_some()
    {
        println!("{}", s);
    }
}

macro_rules! trace_main {
	($arg:expr) => (println_trace_main($arg.into()));
	($($arg:tt)*) => (println_trace_main(format!("{}", format_args!($($arg)*))));
}

fn main() {
    panic_hook::set_abort();

    // the user has specified to run its originally installed binary (not via `parity-updater`)
    let force_direct = std::env::args().any(|arg| arg == "--force-direct");

    // absolute path to the current `binary`
    let exe_path = std::env::current_exe().ok();

    // the binary is named `target/xx/yy`
    let development = exe_path
        .as_ref()
        .and_then(|p| {
            p.parent()
                .and_then(|p| p.parent())
                .and_then(|p| p.file_name())
                .map(|n| n == "target")
        })
        .unwrap_or(false);

    // the binary is named `parity`
    let same_name = exe_path.as_ref().map_or(false, |p| {
        p.file_stem().map_or(false, |n| n == PARITY_EXECUTABLE_NAME)
    });

    trace_main!(
        "Starting up {} (force-direct: {}, development: {}, same-name: {})",
        std::env::current_exe()
            .ok()
            .map_or_else(|| "<unknown>".into(), |x| format!("{}", x.display())),
        force_direct,
        development,
        same_name
    );

    if !force_direct && !development && same_name {
        // Try to run the latest installed version of `parity`,
        // Upon failure it falls back to the locally installed version of `parity`
        // Everything run inside a loop, so we'll be able to restart from the child into a new version seamlessly.
        loop {
            // `Path` to the latest downloaded binary
            let latest_exe = latest_exe_path().ok();

            // `Latest´ binary exist
            let have_update = latest_exe.as_ref().map_or(false, |p| p.exists());

            // Canonicalized path to the current binary is not the same as to latest binary
            let canonicalized_path_not_same = exe_path.as_ref().map_or(false, |exe| {
                latest_exe.as_ref().map_or(false, |lexe| {
                    exe.canonicalize().ok() != lexe.canonicalize().ok()
                })
            });

            // Downloaded `binary` is newer
            let update_is_newer = latest_binary_is_newer(&latest_exe, &exe_path);
            trace_main!(
                "Starting... (have-update: {}, non-updated-current: {}, update-is-newer: {})",
                have_update,
                canonicalized_path_not_same,
                update_is_newer
            );

            let exit_code = if have_update && canonicalized_path_not_same && update_is_newer {
                trace_main!(
                    "Attempting to run latest update ({})...",
                    latest_exe
                        .as_ref()
                        .expect(
                            "guarded by have_update; latest_exe must exist for have_update; qed"
                        )
                        .display()
                );
                match run_parity() {
                    Ok(_) => 0,
                    // Restart parity
                    Err(Error::Restart) => PLEASE_RESTART_EXIT_CODE,
                    // Fall back to local version
                    Err(e) => {
                        error!(target: "updater", "Updated binary could not be executed error: {:?}. Falling back to local version", e);
                        main_direct(true)
                    }
                }
            } else {
                trace_main!("No latest update. Attempting to direct...");
                main_direct(true)
            };
            trace_main!("Latest binary exited with exit code: {}", exit_code);
            if exit_code != PLEASE_RESTART_EXIT_CODE {
                trace_main!("Quitting...");
                process::exit(exit_code);
            }
            trace!(target: "updater", "Re-running updater loop");
        }
    } else {
        trace_main!("Running direct");
        // Otherwise, we're presumably running the version we want. Just run and fall-through.
        process::exit(main_direct(false));
    }
}