/* Copyright (C) 2017 Open Information Security Foundation
 *
 * You can copy, redistribute or modify this Program under the terms of
 * the GNU General Public License version 2 as published by the Free
 * Software Foundation.
 *
 * This program 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
 * version 2 along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */

extern crate libc;

use std::ffi::CString;
use std::path::Path;

use core::*;

#[derive(Debug)]
pub enum Level {
    NotSet = -1,
    None = 0,
    Emergency,
    Alert,
    Critical,
    Error,
    Warning,
    Notice,
    Info,
    Perf,
    Config,
    Debug,
}

pub static mut LEVEL: i32 = Level::NotSet as i32;

pub fn get_log_level() -> i32 {
    unsafe {
        LEVEL
    }
}

fn basename(filename: &str) -> &str {
    let path = Path::new(filename);
    for os_str in path.file_name() {
        for basename in os_str.to_str() {
            return basename;
        }
    }
    return filename;
}

pub fn sclog(level: Level, file: &str, line: u32, function: &str,
         code: i32, message: &str)
{
    let filename = basename(file);
    sc_log_message(level,
                   filename,
                   line,
                   function,
                   code,
                   message);
}

/// Return the function name, but for now just return <rust> as Rust
/// has no macro to return the function name, but may in the future,
/// see: https://github.com/rust-lang/rfcs/pull/1719
macro_rules!function {
    () => {{ "<rust>" }}
}

#[macro_export]
macro_rules!do_log {
    ($level:expr, $file:expr, $line:expr, $function:expr, $code:expr,
     $($arg:tt)*) => {
        if get_log_level() >= $level as i32 {
            sclog($level, $file, $line, $function, $code,
                  &(format!($($arg)*)));
        }
    }
}

#[macro_export]
macro_rules!SCLogNotice {
    ($($arg:tt)*) => {
        do_log!(Level::Notice, file!(), line!(), function!(), 0, $($arg)*);
    }
}

#[macro_export]
macro_rules!SCLogInfo {
    ($($arg:tt)*) => {
        do_log!(Level::Info, file!(), line!(), function!(), 0, $($arg)*);
    }
}

#[macro_export]
macro_rules!SCLogPerf {
    ($($arg:tt)*) => {
        do_log!(Level::Perf, file!(), line!(), function!(), 0, $($arg)*);
    }
}

#[macro_export]
macro_rules!SCLogConfig {
    ($($arg:tt)*) => {
        do_log!(Level::Config, file!(), line!(), function!(), 0, $($arg)*);
    }
}

// Debug mode: call C SCLogDebug
#[cfg(feature = "debug")]
#[macro_export]
macro_rules!SCLogDebug {
    ($($arg:tt)*) => {
        do_log!(Level::Debug, file!(), line!(), function!(), 0, $($arg)*);
    }
}

// Release mode: ignore arguments
// Use a reference to avoid moving values.
#[cfg(not(feature = "debug"))]
#[macro_export]
macro_rules!SCLogDebug {
    ($last:expr) => { let _ = &$last; let _ = Level::Debug; };
    ($one:expr, $($arg:tt)*) => { let _ = &$one; SCLogDebug!($($arg)*); };
}

#[no_mangle]
pub extern "C" fn rs_log_set_level(level: i32) {
    unsafe {
        LEVEL = level;
    }
}

pub fn log_set_level(level: Level) {
    rs_log_set_level(level as i32);
}

/// SCLogMessage wrapper. If the Suricata C context is not registered
/// a more basic log format will be used (for example, when running
/// Rust unit tests).
pub fn sc_log_message(level: Level,
                      filename: &str,
                      line: libc::c_uint,
                      function: &str,
                      code: libc::c_int,
                      message: &str) -> libc::c_int
{
    unsafe {
        if let Some(c) = SC {
            return (c.SCLogMessage)(
                level as i32,
                to_safe_cstring(filename).as_ptr(),
                line,
                to_safe_cstring(function).as_ptr(),
                code,
                to_safe_cstring(message).as_ptr());
        }
    }

    // Fall back if the Suricata C context is not registered which is
    // the case when Rust unit tests are running.
    //
    // We don't log the time right now as I don't think it can be done
    // with Rust 1.7.0 without using an external crate. With Rust
    // 1.8.0 and newer we can unix UNIX_EPOCH.elapsed() to get the
    // unix time.
    println!("{}:{} <{:?}> -- {}", filename, line, level, message);
    return 0;
}

// Convert a &str into a CString by first stripping NUL bytes.
fn to_safe_cstring(val: &str) -> CString {
    let mut safe = Vec::with_capacity(val.len());
    for c in val.as_bytes() {
        if *c != 0 {
            safe.push(*c);
        }
    }
    match CString::new(safe) {
        Ok(cstr) => cstr,
        _ => {
            CString::new("<failed to encode string>").unwrap()
        }
    }
}