#![allow(non_camel_case_types)]

use rustc_data_structures::sync::Lock;

use std::cell::Cell;
use std::fmt::Debug;
use std::time::{Duration, Instant};

use syntax::symbol::{Symbol, sym};
use rustc_macros::HashStable;
use crate::session::Session;

#[cfg(test)]
mod tests;

// The name of the associated type for `Fn` return types.
pub const FN_OUTPUT_NAME: Symbol = sym::Output;

// Useful type to use with `Result<>` indicate that an error has already
// been reported to the user, so no need to continue checking.
#[derive(Clone, Copy, Debug, RustcEncodable, RustcDecodable, HashStable)]
pub struct ErrorReported;

thread_local!(static TIME_DEPTH: Cell<usize> = Cell::new(0));

#[allow(nonstandard_style)]
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct QueryMsg {
    pub query: &'static str,
    pub msg: Option<String>,
}

/// Read the current depth of `time()` calls. This is used to
/// encourage indentation across threads.
pub fn time_depth() -> usize {
    TIME_DEPTH.with(|slot| slot.get())
}

/// Sets the current depth of `time()` calls. The idea is to call
/// `set_time_depth()` with the result from `time_depth()` in the
/// parent thread.
pub fn set_time_depth(depth: usize) {
    TIME_DEPTH.with(|slot| slot.set(depth));
}

pub fn time<T, F>(sess: &Session, what: &str, f: F) -> T where
    F: FnOnce() -> T,
{
    time_ext(sess.time_passes(), what, f)
}

pub fn time_ext<T, F>(do_it: bool, what: &str, f: F) -> T where
    F: FnOnce() -> T,
{
    if !do_it { return f(); }

    let old = TIME_DEPTH.with(|slot| {
        let r = slot.get();
        slot.set(r + 1);
        r
    });

    let start = Instant::now();
    let rv = f();
    let dur = start.elapsed();

    print_time_passes_entry(true, what, dur);

    TIME_DEPTH.with(|slot| slot.set(old));

    rv
}

pub fn print_time_passes_entry(do_it: bool, what: &str, dur: Duration) {
    if !do_it {
        return
    }

    let indentation = TIME_DEPTH.with(|slot| slot.get());

    let mem_string = match get_resident() {
        Some(n) => {
            let mb = n as f64 / 1_000_000.0;
            format!("; rss: {}MB", mb.round() as usize)
        }
        None => String::new(),
    };
    println!("{}time: {}{}\t{}",
             "  ".repeat(indentation),
             duration_to_secs_str(dur),
             mem_string,
             what);
}

// Hack up our own formatting for the duration to make it easier for scripts
// to parse (always use the same number of decimal places and the same unit).
pub fn duration_to_secs_str(dur: Duration) -> String {
    const NANOS_PER_SEC: f64 = 1_000_000_000.0;
    let secs = dur.as_secs() as f64 +
               dur.subsec_nanos() as f64 / NANOS_PER_SEC;

    format!("{:.3}", secs)
}

pub fn to_readable_str(mut val: usize) -> String {
    let mut groups = vec![];
    loop {
        let group = val % 1000;

        val /= 1000;

        if val == 0 {
            groups.push(group.to_string());
            break;
        } else {
            groups.push(format!("{:03}", group));
        }
    }

    groups.reverse();

    groups.join("_")
}

pub fn record_time<T, F>(accu: &Lock<Duration>, f: F) -> T where
    F: FnOnce() -> T,
{
    let start = Instant::now();
    let rv = f();
    let duration = start.elapsed();
    let mut accu = accu.lock();
    *accu = *accu + duration;
    rv
}

// Memory reporting
#[cfg(unix)]
fn get_resident() -> Option<usize> {
    use std::fs;

    let field = 1;
    let contents = fs::read("/proc/self/statm").ok()?;
    let contents = String::from_utf8(contents).ok()?;
    let s = contents.split_whitespace().nth(field)?;
    let npages = s.parse::<usize>().ok()?;
    Some(npages * 4096)
}

#[cfg(windows)]
fn get_resident() -> Option<usize> {
    type BOOL = i32;
    type DWORD = u32;
    type HANDLE = *mut u8;
    use libc::size_t;
    use std::mem;
    #[repr(C)]
    #[allow(non_snake_case)]
    struct PROCESS_MEMORY_COUNTERS {
        cb: DWORD,
        PageFaultCount: DWORD,
        PeakWorkingSetSize: size_t,
        WorkingSetSize: size_t,
        QuotaPeakPagedPoolUsage: size_t,
        QuotaPagedPoolUsage: size_t,
        QuotaPeakNonPagedPoolUsage: size_t,
        QuotaNonPagedPoolUsage: size_t,
        PagefileUsage: size_t,
        PeakPagefileUsage: size_t,
    }
    type PPROCESS_MEMORY_COUNTERS = *mut PROCESS_MEMORY_COUNTERS;
    #[link(name = "psapi")]
    extern "system" {
        fn GetCurrentProcess() -> HANDLE;
        fn GetProcessMemoryInfo(Process: HANDLE,
                                ppsmemCounters: PPROCESS_MEMORY_COUNTERS,
                                cb: DWORD) -> BOOL;
    }
    let mut pmc: PROCESS_MEMORY_COUNTERS = unsafe { mem::zeroed() };
    pmc.cb = mem::size_of_val(&pmc) as DWORD;
    match unsafe { GetProcessMemoryInfo(GetCurrentProcess(), &mut pmc, pmc.cb) } {
        0 => None,
        _ => Some(pmc.WorkingSetSize as usize),
    }
}

pub fn indent<R, F>(op: F) -> R where
    R: Debug,
    F: FnOnce() -> R,
{
    // Use in conjunction with the log post-processor like `src/etc/indenter`
    // to make debug output more readable.
    debug!(">>");
    let r = op();
    debug!("<< (Result = {:?})", r);
    r
}

pub struct Indenter {
    _cannot_construct_outside_of_this_module: (),
}

impl Drop for Indenter {
    fn drop(&mut self) { debug!("<<"); }
}

pub fn indenter() -> Indenter {
    debug!(">>");
    Indenter { _cannot_construct_outside_of_this_module: () }
}
