// Copyright 2015 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.

extern crate rustfmt;
extern crate diff;
extern crate regex;
extern crate term;

use std::collections::HashMap;
use std::fs;
use std::io::{self, Read, BufRead, BufReader};
use std::path::{Path, PathBuf};

use rustfmt::*;
use rustfmt::filemap::{write_system_newlines, FileMap};
use rustfmt::config::{Config, ReportTactic, WriteMode};
use rustfmt::rustfmt_diff::*;

const DIFF_CONTEXT_SIZE: usize = 3;

fn get_path_string(dir_entry: io::Result<fs::DirEntry>) -> String {
    let path = dir_entry.expect("Couldn't get DirEntry").path();

    path.to_str().expect("Couldn't stringify path").to_owned()
}

// Integration tests. The files in the tests/source are formatted and compared
// to their equivalent in tests/target. The target file and config can be
// overriden by annotations in the source file. The input and output must match
// exactly.
// FIXME(#28) would be good to check for error messages and fail on them, or at
// least report.
#[test]
fn system_tests() {
    // Get all files in the tests/source directory.
    let files = fs::read_dir("tests/source").expect("Couldn't read source dir");
    // Turn a DirEntry into a String that represents the relative path to the
    // file.
    let files = files.map(get_path_string);
    let (_reports, count, fails) = check_files(files, None);

    // Display results.
    println!("Ran {} system tests.", count);
    assert!(fails == 0, "{} system tests failed", fails);
}

// Do the same for tests/coverage-source directory
// the only difference is the coverage mode
#[test]
fn coverage_tests() {
    let files = fs::read_dir("tests/coverage-source").expect("Couldn't read source dir");
    let files = files.map(get_path_string);
    let (_reports, count, fails) = check_files(files, Some(WriteMode::Coverage));

    println!("Ran {} tests in coverage mode.", count);
    assert!(fails == 0, "{} tests failed", fails);
}

#[test]
fn checkstyle_test() {
    let filename = "tests/source/fn-single-line.rs";
    let expected_filename = "tests/writemode/checkstyle.xml";
    assert_output(filename, expected_filename, Some(WriteMode::Checkstyle));
}


// Helper function for comparing the results of rustfmt
// to a known output file generated by one of the write modes.
fn assert_output(source: &str, expected_filename: &str, write_mode: Option<WriteMode>) {
    let config = read_config(&source, write_mode);
    let (file_map, _report) = format_file(source, &config);

    // Populate output by writing to a vec.
    let mut out = vec![];
    let _ = filemap::write_all_files(&file_map, &mut out, &config);
    let output = String::from_utf8(out).unwrap();

    let mut expected_file = fs::File::open(&expected_filename).expect("Couldn't open target");
    let mut expected_text = String::new();
    expected_file.read_to_string(&mut expected_text)
                 .expect("Failed reading target");

    let compare = make_diff(&expected_text, &output, DIFF_CONTEXT_SIZE);
    if compare.len() > 0 {
        let mut failures = HashMap::new();
        failures.insert(source.to_string(), compare);
        print_mismatches(failures);
        assert!(false, "Text does not match expected output");
    }
}

// Idempotence tests. Files in tests/target are checked to be unaltered by
// rustfmt.
#[test]
fn idempotence_tests() {
    // Get all files in the tests/target directory.
    let files = fs::read_dir("tests/target")
                    .expect("Couldn't read target dir")
                    .map(get_path_string);
    let (_reports, count, fails) = check_files(files, None);

    // Display results.
    println!("Ran {} idempotent tests.", count);
    assert!(fails == 0, "{} idempotent tests failed", fails);
}

// Run rustfmt on itself. This operation must be idempotent. We also check that
// no warnings are emitted.
#[test]
fn self_tests() {
    let files = fs::read_dir("src/bin")
                    .expect("Couldn't read src dir")
                    .chain(fs::read_dir("tests").expect("Couldn't read tests dir"))
                    .map(get_path_string);
    // Hack because there's no `IntoIterator` impl for `[T; N]`.
    let files = files.chain(Some("src/lib.rs".to_owned()).into_iter());

    let (reports, count, fails) = check_files(files, None);
    let mut warnings = 0;

    // Display results.
    println!("Ran {} self tests.", count);
    assert!(fails == 0, "{} self tests failed", fails);

    for format_report in reports {
        println!("{}", format_report);
        warnings += format_report.warning_count();
    }

    assert!(warnings == 0,
            "Rustfmt's code generated {} warnings",
            warnings);
}

// For each file, run rustfmt and collect the output.
// Returns the number of files checked and the number of failures.
fn check_files<I>(files: I, write_mode: Option<WriteMode>) -> (Vec<FormatReport>, u32, u32)
    where I: Iterator<Item = String>
{
    let mut count = 0;
    let mut fails = 0;
    let mut reports = vec![];

    for file_name in files.filter(|f| f.ends_with(".rs")) {
        println!("Testing '{}'...", file_name);

        match idempotent_check(file_name, write_mode) {
            Ok(report) => reports.push(report),
            Err(msg) => {
                print_mismatches(msg);
                fails += 1;
            }
        }

        count += 1;
    }

    (reports, count, fails)
}

fn print_mismatches(result: HashMap<String, Vec<Mismatch>>) {
    let mut t = term::stdout().unwrap();

    for (file_name, diff) in result {
        print_diff(diff,
                   |line_num| format!("\nMismatch at {}:{}:", file_name, line_num));
    }

    assert!(t.reset().unwrap());
}

fn read_config(filename: &str, write_mode: Option<WriteMode>) -> Config {
    let sig_comments = read_significant_comments(&filename);
    let mut config = get_config(sig_comments.get("config").map(|x| &(*x)[..]));

    for (key, val) in &sig_comments {
        if key != "target" && key != "config" {
            config.override_value(key, val);
        }
    }

    // Don't generate warnings for to-do items.
    config.report_todo = ReportTactic::Never;

    if let Some(mode) = write_mode {
        config.write_mode = mode
    }

    config
}

fn format_file<P: Into<PathBuf>>(filename: P, config: &Config) -> (FileMap, FormatReport) {
    let input = Input::File(filename.into());
    format_input(input, &config)
}

pub fn idempotent_check(filename: String,
                        write_mode: Option<WriteMode>)
                        -> Result<FormatReport, HashMap<String, Vec<Mismatch>>> {
    let sig_comments = read_significant_comments(&filename);
    let config = read_config(&filename, write_mode);
    let (file_map, format_report) = format_file(filename, &config);

    let mut write_result = HashMap::new();
    for (filename, text) in file_map.iter() {
        let mut v = Vec::new();
        // Won't panic, as we're not doing any IO.
        write_system_newlines(&mut v, text, &config).unwrap();
        // Won't panic, we are writing correct utf8.
        let one_result = String::from_utf8(v).unwrap();
        write_result.insert(filename.clone(), one_result);
    }

    let target = sig_comments.get("target").map(|x| &(*x)[..]);

    handle_result(write_result, target, write_mode).map(|_| format_report)
}

// Reads test config file from comments and reads its contents.
fn get_config(config_file: Option<&str>) -> Config {
    let config_file_name = match config_file {
        None => return Default::default(),
        Some(file_name) => {
            let mut full_path = "tests/config/".to_owned();
            full_path.push_str(&file_name);
            full_path
        }
    };

    let mut def_config_file = fs::File::open(config_file_name).expect("Couldn't open config");
    let mut def_config = String::new();
    def_config_file.read_to_string(&mut def_config).expect("Couldn't read config");

    Config::from_toml(&def_config)
}

// Reads significant comments of the form: // rustfmt-key: value
// into a hash map.
fn read_significant_comments(file_name: &str) -> HashMap<String, String> {
    let file = fs::File::open(file_name).expect(&format!("Couldn't read file {}", file_name));
    let reader = BufReader::new(file);
    let pattern = r"^\s*//\s*rustfmt-([^:]+):\s*(\S+)";
    let regex = regex::Regex::new(&pattern).expect("Failed creating pattern 1");

    // Matches lines containing significant comments or whitespace.
    let line_regex = regex::Regex::new(r"(^\s*$)|(^\s*//\s*rustfmt-[^:]+:\s*\S+)")
                         .expect("Failed creating pattern 2");

    reader.lines()
          .map(|line| line.expect("Failed getting line"))
          .take_while(|line| line_regex.is_match(&line))
          .filter_map(|line| {
              regex.captures_iter(&line).next().map(|capture| {
                  (capture.at(1).expect("Couldn't unwrap capture").to_owned(),
                   capture.at(2).expect("Couldn't unwrap capture").to_owned())
              })
          })
          .collect()
}

// Compare output to input.
// TODO: needs a better name, more explanation.
fn handle_result(result: HashMap<String, String>,
                 target: Option<&str>,
                 write_mode: Option<WriteMode>)
                 -> Result<(), HashMap<String, Vec<Mismatch>>> {
    let mut failures = HashMap::new();

    for (file_name, fmt_text) in result {
        // If file is in tests/source, compare to file with same name in tests/target.
        let target = get_target(&file_name, target, write_mode);
        let mut f = fs::File::open(&target).expect("Couldn't open target");

        let mut text = String::new();
        f.read_to_string(&mut text).expect("Failed reading target");

        if fmt_text != text {
            let diff = make_diff(&text, &fmt_text, DIFF_CONTEXT_SIZE);
            assert!(!diff.is_empty(),
                    "Empty diff? Maybe due to a missing a newline at the end of a file?");
            failures.insert(file_name, diff);
        }
    }

    if failures.is_empty() {
        Ok(())
    } else {
        Err(failures)
    }
}

// Map source file paths to their target paths.
fn get_target(file_name: &str, target: Option<&str>, write_mode: Option<WriteMode>) -> String {
    let file_path = Path::new(file_name);
    let (source_path_prefix, target_path_prefix) = match write_mode {
        Some(WriteMode::Coverage) => {
            (Path::new("tests/coverage-source/"), "tests/coverage-target/")
        }
        _ => (Path::new("tests/source/"), "tests/target/"),
    };

    if file_path.starts_with(source_path_prefix) {
        let mut components = file_path.components();
        // Can't skip(2) as the resulting iterator can't as_path()
        components.next();
        components.next();

        let new_target = match components.as_path().to_str() {
            Some(string) => string,
            None => file_name,
        };
        let base = target.unwrap_or(new_target);

        format!("{}{}", target_path_prefix, base)
    } else {
        file_name.to_owned()
    }
}

#[test]
fn rustfmt_diff_make_diff_tests() {
    let diff = make_diff("a\nb\nc\nd", "a\ne\nc\nd", 3);
    assert_eq!(diff,
               vec![Mismatch {
                        line_number: 1,
                        lines: vec![DiffLine::Context("a".into()),
                                    DiffLine::Resulting("b".into()),
                                    DiffLine::Expected("e".into()),
                                    DiffLine::Context("c".into()),
                                    DiffLine::Context("d".into())],
                    }]);
}