// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

use either::*;
use libc;
use str::StrSlice;

pub trait Logger {
    fn log(&mut self, msg: Either<~str, &'static str>);
}

pub struct StdErrLogger;

impl Logger for StdErrLogger {
    fn log(&mut self, msg: Either<~str, &'static str>) {
        use io::{Writer, WriterUtil};

        if !should_log_console() {
            return;
        }

        let s: &str = match msg {
            Left(ref s) => {
                let s: &str = *s;
                s
            }
            Right(ref s) => {
                let s: &str = *s;
                s
            }
        };

        // Truncate the string
        let buf_bytes = 256;
        if s.len() > buf_bytes {
            let s = s.slice(0, buf_bytes) + "[...]";
            print(s);
        } else {
            print(s)
        };

        fn print(s: &str) {
            let dbg = ::libc::STDERR_FILENO as ::io::fd_t;
            dbg.write_str(s);
            dbg.write_str("\n");
            dbg.flush();
        }
    }
}

/// Configure logging by traversing the crate map and setting the
/// per-module global logging flags based on the logging spec
pub fn init(crate_map: *u8) {
    use os;
    use str::StrSlice;
    use ptr;
    use option::{Some, None};

    let log_spec = os::getenv("RUST_LOG");
    match log_spec {
        Some(spec) => {
            do spec.as_c_str |buf| {
                unsafe { rust_update_log_settings(crate_map, buf) }
            }
        }
        None => {
            unsafe {
                rust_update_log_settings(crate_map, ptr::null());
            }
        }
    }
}

pub fn console_on() { unsafe { rust_log_console_on() } }
pub fn console_off() { unsafe { rust_log_console_off() } }
fn should_log_console() -> bool { unsafe { rust_should_log_console() != 0 } }

extern {
    fn rust_update_log_settings(crate_map: *u8, settings: *libc::c_char);
    fn rust_log_console_on();
    fn rust_log_console_off();
    fn rust_should_log_console() -> libc::uintptr_t;
}