/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

use crate::NotifierEvent;
use crate::WindowWrapper;
use std::collections::{HashMap, HashSet};
use std::fs::File;
use std::io::{BufRead, BufReader};
use std::io::{Read, Write};
use std::path::{Path, PathBuf};
use std::sync::mpsc::Receiver;
use crate::wrench::{Wrench, WrenchThing};
use crate::yaml_frame_reader::YamlFrameReader;
use webrender::DebugFlags;
use webrender::render_api::DebugCommand;

const COLOR_DEFAULT: &str = "\x1b[0m";
const COLOR_RED: &str = "\x1b[31m";
const COLOR_GREEN: &str = "\x1b[32m";
const COLOR_MAGENTA: &str = "\x1b[95m";

const MIN_SAMPLE_COUNT: usize = 50;
const SAMPLE_EXCLUDE_COUNT: usize = 10;

pub struct Benchmark {
    pub test: PathBuf,
}

pub struct BenchmarkManifest {
    pub benchmarks: Vec<Benchmark>,
}

impl BenchmarkManifest {
    pub fn new(manifest: &Path) -> BenchmarkManifest {
        let dir = manifest.parent().unwrap();
        let f =
            File::open(manifest).unwrap_or_else(|_| panic!("couldn't open manifest: {}", manifest.display()));
        let file = BufReader::new(&f);

        let mut benchmarks = Vec::new();

        for line in file.lines() {
            let l = line.unwrap();

            // strip the comments
            let s = &l[0 .. l.find('#').unwrap_or(l.len())];
            let s = s.trim();
            if s.is_empty() {
                continue;
            }

            let mut items = s.split_whitespace();

            match items.next() {
                Some("include") => {
                    let include = dir.join(items.next().unwrap());

                    benchmarks.append(&mut BenchmarkManifest::new(include.as_path()).benchmarks);
                }
                Some(name) => {
                    let test = dir.join(name);
                    benchmarks.push(Benchmark { test });
                }
                _ => panic!(),
            };
        }

        BenchmarkManifest {
            benchmarks,
        }
    }
}

#[derive(Clone, Serialize, Deserialize)]
struct TestProfileRange {
    min: u64,
    avg: u64,
    max: u64,
}

#[derive(Clone, Serialize, Deserialize)]
struct TestProfile {
    name: String,
    backend_time_ns: TestProfileRange,
    composite_time_ns: TestProfileRange,
    paint_time_ns: TestProfileRange,
    draw_calls: usize,
}

impl TestProfile {
    fn csv_header() -> String {
        "name,\
        backend_time_ns min, avg, max,\
        composite_time_ns min, avg, max,\
        paint_time_ns min, avg, max,\
        draw_calls\n".to_string()
    }

    fn convert_to_csv(&self) -> String {
        format!("{},\
                 {},{},{},\
                 {},{},{},\
                 {},{},{},\
                 {}\n",
                self.name,
                self.backend_time_ns.min,   self.backend_time_ns.avg,   self.backend_time_ns.max,
                self.composite_time_ns.min, self.composite_time_ns.avg, self.composite_time_ns.max,
                self.paint_time_ns.min,     self.paint_time_ns.avg,     self.paint_time_ns.max,
                self.draw_calls)
    }
}

#[derive(Serialize, Deserialize)]
struct Profile {
    tests: Vec<TestProfile>,
}

impl Profile {
    fn new() -> Profile {
        Profile { tests: Vec::new() }
    }

    fn add(&mut self, profile: TestProfile) {
        self.tests.push(profile);
    }

    fn save(&self, filename: &str, as_csv: bool) {
        let mut file = File::create(&filename).unwrap();
        if as_csv {
            file.write_all(&TestProfile::csv_header().into_bytes()).unwrap();
            for test in &self.tests {
                file.write_all(&test.convert_to_csv().into_bytes()).unwrap();
            }
        } else {
            let s = serde_json::to_string_pretty(self).unwrap();
            file.write_all(&s.into_bytes()).unwrap();
            file.write_all(b"\n").unwrap();
        }
    }

    fn load(filename: &str) -> Profile {
        let mut file = File::open(&filename).unwrap();
        let mut string = String::new();
        file.read_to_string(&mut string).unwrap();
        serde_json::from_str(&string).expect("Unable to load profile!")
    }

    fn build_set_and_map_of_tests(&self) -> (HashSet<String>, HashMap<String, TestProfile>) {
        let mut hash_set = HashSet::new();
        let mut hash_map = HashMap::new();

        for test in &self.tests {
            hash_set.insert(test.name.clone());
            hash_map.insert(test.name.clone(), test.clone());
        }

        (hash_set, hash_map)
    }
}

pub struct PerfHarness<'a> {
    wrench: &'a mut Wrench,
    window: &'a mut WindowWrapper,
    rx: Receiver<NotifierEvent>,
    warmup_frames: usize,
    sample_count: usize,
}

impl<'a> PerfHarness<'a> {
    pub fn new(wrench: &'a mut Wrench,
               window: &'a mut WindowWrapper,
               rx: Receiver<NotifierEvent>,
               warmup_frames: Option<usize>,
               sample_count: Option<usize>) -> Self {
        PerfHarness {
            wrench,
            window,
            rx,
            warmup_frames: warmup_frames.unwrap_or(0usize),
            sample_count: sample_count.unwrap_or(MIN_SAMPLE_COUNT),
        }
    }

    pub fn run(mut self, base_manifest: &Path, filename: &str, as_csv: bool) {
        let manifest = BenchmarkManifest::new(base_manifest);

        let mut profile = Profile::new();

        for t in manifest.benchmarks {
            let stats = self.render_yaml(t.test.as_path());
            profile.add(stats);
        }

        profile.save(filename, as_csv);
    }

    fn render_yaml(&mut self, filename: &Path) -> TestProfile {
        let mut reader = YamlFrameReader::new(filename);

        // Loop until we get a reasonable number of CPU and GPU
        // frame profiles. Then take the mean.
        let mut cpu_frame_profiles = Vec::new();
        let mut gpu_frame_profiles = Vec::new();

        let mut debug_flags = DebugFlags::empty();
        debug_flags.set(DebugFlags::GPU_TIME_QUERIES | DebugFlags::GPU_SAMPLE_QUERIES, true);
        self.wrench.api.send_debug_cmd(DebugCommand::SetFlags(debug_flags));

        let mut frame_count = 0;

        while cpu_frame_profiles.len() < self.sample_count ||
            gpu_frame_profiles.len() < self.sample_count
        {
            reader.do_frame(self.wrench);
            self.rx.recv().unwrap();
            self.wrench.render();
            self.window.swap_buffers();
            let (cpu_profiles, gpu_profiles) = self.wrench.get_frame_profiles();
            if frame_count >= self.warmup_frames {
                cpu_frame_profiles.extend(cpu_profiles);
                gpu_frame_profiles.extend(gpu_profiles);
            }
            frame_count += 1;
        }

        // Ensure the draw calls match in every sample.
        let draw_calls = cpu_frame_profiles[0].draw_calls;
        let draw_calls_same =
            cpu_frame_profiles
                .iter()
                .all(|s| s.draw_calls == draw_calls);

        // this can be normal in cases where some elements are cached (eg. linear
        // gradients), but print a warning in case it's not (which could make the
        // benchmark produce unexpected results).
        if !draw_calls_same {
            println!("Warning: not every frame has the same number of draw calls");
        }

        let composite_time_ns = extract_sample(&mut cpu_frame_profiles, |a| a.composite_time_ns);
        let paint_time_ns = extract_sample(&mut gpu_frame_profiles, |a| a.paint_time_ns);
        let backend_time_ns = extract_sample(&mut cpu_frame_profiles, |a| a.backend_time_ns);

        TestProfile {
            name: filename.to_str().unwrap().to_string(),
            composite_time_ns,
            paint_time_ns,
            backend_time_ns,
            draw_calls,
        }
    }
}

// returns min, average, max, after removing the lowest and highest SAMPLE_EXCLUDE_COUNT
// samples (each).
fn extract_sample<F, T>(profiles: &mut [T], f: F) -> TestProfileRange
where
    F: Fn(&T) -> u64,
{
    let mut samples: Vec<u64> = profiles.iter().map(f).collect();
    samples.sort_unstable();
    let useful_samples = &samples[SAMPLE_EXCLUDE_COUNT .. samples.len() - SAMPLE_EXCLUDE_COUNT];
    let total_time: u64 = useful_samples.iter().sum();
    TestProfileRange {
        min: useful_samples[0],
        avg: total_time / useful_samples.len() as u64,
        max: useful_samples[useful_samples.len()-1]
    }
}

fn select_color(base: f32, value: f32) -> &'static str {
    let tolerance = base * 0.1;
    if (value - base).abs() < tolerance {
        COLOR_DEFAULT
    } else if value > base {
        COLOR_RED
    } else {
        COLOR_GREEN
    }
}

pub fn compare(first_filename: &str, second_filename: &str) {
    let profile0 = Profile::load(first_filename);
    let profile1 = Profile::load(second_filename);

    let (set0, map0) = profile0.build_set_and_map_of_tests();
    let (set1, map1) = profile1.build_set_and_map_of_tests();

    print!("+------------------------------------------------");
    println!("+--------------+------------------+------------------+");
    print!("|  Test name                                     ");
    println!("| Draw Calls   | Composite (ms)   | Paint (ms)       |");
    print!("+------------------------------------------------");
    println!("+--------------+------------------+------------------+");

    for test_name in set0.symmetric_difference(&set1) {
        println!(
            "| {}{:47}{}|{:14}|{:18}|{:18}|",
            COLOR_MAGENTA,
            test_name,
            COLOR_DEFAULT,
            " -",
            " -",
            " -"
        );
    }

    for test_name in set0.intersection(&set1) {
        let test0 = &map0[test_name];
        let test1 = &map1[test_name];

        let composite_time0 = test0.composite_time_ns.avg as f32 / 1000000.0;
        let composite_time1 = test1.composite_time_ns.avg as f32 / 1000000.0;

        let paint_time0 = test0.paint_time_ns.avg as f32 / 1000000.0;
        let paint_time1 = test1.paint_time_ns.avg as f32 / 1000000.0;

        let draw_calls_color = match test0.draw_calls.cmp(&test1.draw_calls) {
            std::cmp::Ordering::Equal => COLOR_DEFAULT,
            std::cmp::Ordering::Greater => COLOR_GREEN,
            std::cmp::Ordering::Less => COLOR_RED,
        };

        let composite_time_color = select_color(composite_time0, composite_time1);
        let paint_time_color = select_color(paint_time0, paint_time1);

        let draw_call_string = format!(" {} -> {}", test0.draw_calls, test1.draw_calls);
        let composite_time_string = format!(" {:.2} -> {:.2}", composite_time0, composite_time1);
        let paint_time_string = format!(" {:.2} -> {:.2}", paint_time0, paint_time1);

        println!(
            "| {:47}|{}{:14}{}|{}{:18}{}|{}{:18}{}|",
            test_name,
            draw_calls_color,
            draw_call_string,
            COLOR_DEFAULT,
            composite_time_color,
            composite_time_string,
            COLOR_DEFAULT,
            paint_time_color,
            paint_time_string,
            COLOR_DEFAULT
        );
    }

    print!("+------------------------------------------------");
    println!("+--------------+------------------+------------------+");
}