//! Assorted testing utilities.
//!
//! Most notable things are:
//!
//! * Rich text comparison, which outputs a diff.
//! * Extracting markup (mainly, `$0` markers) out of fixture strings.
//! * marks (see the eponymous module).

pub mod bench_fixture;
mod fixture;
mod assert_linear;

use std::{
    collections::BTreeMap,
    convert::{TryFrom, TryInto},
    env, fs,
    path::{Path, PathBuf},
};

use profile::StopWatch;
use stdx::is_ci;
use text_size::{TextRange, TextSize};

pub use dissimilar::diff as __diff;
pub use rustc_hash::FxHashMap;

pub use crate::{
    assert_linear::AssertLinear,
    fixture::{Fixture, MiniCore},
};

pub const CURSOR_MARKER: &str = "$0";
pub const ESCAPED_CURSOR_MARKER: &str = "\\$0";

/// Asserts that two strings are equal, otherwise displays a rich diff between them.
///
/// The diff shows changes from the "original" left string to the "actual" right string.
///
/// All arguments starting from and including the 3rd one are passed to
/// `eprintln!()` macro in case of text inequality.
#[macro_export]
macro_rules! assert_eq_text {
    ($left:expr, $right:expr) => {
        assert_eq_text!($left, $right,)
    };
    ($left:expr, $right:expr, $($tt:tt)*) => {{
        let left = $left;
        let right = $right;
        if left != right {
            if left.trim() == right.trim() {
                std::eprintln!("Left:\n{:?}\n\nRight:\n{:?}\n\nWhitespace difference\n", left, right);
            } else {
                let diff = $crate::__diff(left, right);
                std::eprintln!("Left:\n{}\n\nRight:\n{}\n\nDiff:\n{}\n", left, right, $crate::format_diff(diff));
            }
            std::eprintln!($($tt)*);
            panic!("text differs");
        }
    }};
}

/// Infallible version of `try_extract_offset()`.
pub fn extract_offset(text: &str) -> (TextSize, String) {
    match try_extract_offset(text) {
        None => panic!("text should contain cursor marker"),
        Some(result) => result,
    }
}

/// Returns the offset of the first occurrence of `$0` marker and the copy of `text`
/// without the marker.
fn try_extract_offset(text: &str) -> Option<(TextSize, String)> {
    let cursor_pos = text.find(CURSOR_MARKER)?;
    let mut new_text = String::with_capacity(text.len() - CURSOR_MARKER.len());
    new_text.push_str(&text[..cursor_pos]);
    new_text.push_str(&text[cursor_pos + CURSOR_MARKER.len()..]);
    let cursor_pos = TextSize::from(cursor_pos as u32);
    Some((cursor_pos, new_text))
}

/// Infallible version of `try_extract_range()`.
pub fn extract_range(text: &str) -> (TextRange, String) {
    match try_extract_range(text) {
        None => panic!("text should contain cursor marker"),
        Some(result) => result,
    }
}

/// Returns `TextRange` between the first two markers `$0...$0` and the copy
/// of `text` without both of these markers.
fn try_extract_range(text: &str) -> Option<(TextRange, String)> {
    let (start, text) = try_extract_offset(text)?;
    let (end, text) = try_extract_offset(&text)?;
    Some((TextRange::new(start, end), text))
}

#[derive(Clone, Copy)]
pub enum RangeOrOffset {
    Range(TextRange),
    Offset(TextSize),
}

impl RangeOrOffset {
    pub fn expect_offset(self) -> TextSize {
        match self {
            RangeOrOffset::Offset(it) => it,
            RangeOrOffset::Range(_) => panic!("expected an offset but got a range instead"),
        }
    }
    pub fn expect_range(self) -> TextRange {
        match self {
            RangeOrOffset::Range(it) => it,
            RangeOrOffset::Offset(_) => panic!("expected a range but got an offset"),
        }
    }
    pub fn range_or_empty(self) -> TextRange {
        match self {
            RangeOrOffset::Range(range) => range,
            RangeOrOffset::Offset(offset) => TextRange::empty(offset),
        }
    }
}

impl From<RangeOrOffset> for TextRange {
    fn from(selection: RangeOrOffset) -> Self {
        match selection {
            RangeOrOffset::Range(it) => it,
            RangeOrOffset::Offset(it) => TextRange::empty(it),
        }
    }
}

/// Extracts `TextRange` or `TextSize` depending on the amount of `$0` markers
/// found in `text`.
///
/// # Panics
/// Panics if no `$0` marker is present in the `text`.
pub fn extract_range_or_offset(text: &str) -> (RangeOrOffset, String) {
    if let Some((range, text)) = try_extract_range(text) {
        return (RangeOrOffset::Range(range), text);
    }
    let (offset, text) = extract_offset(text);
    (RangeOrOffset::Offset(offset), text)
}

/// Extracts ranges, marked with `<tag> </tag>` pairs from the `text`
pub fn extract_tags(mut text: &str, tag: &str) -> (Vec<(TextRange, Option<String>)>, String) {
    let open = format!("<{}", tag);
    let close = format!("</{}>", tag);
    let mut ranges = Vec::new();
    let mut res = String::new();
    let mut stack = Vec::new();
    loop {
        match text.find('<') {
            None => {
                res.push_str(text);
                break;
            }
            Some(i) => {
                res.push_str(&text[..i]);
                text = &text[i..];
                if text.starts_with(&open) {
                    let close_open = text.find('>').unwrap();
                    let attr = text[open.len()..close_open].trim();
                    let attr = if attr.is_empty() { None } else { Some(attr.to_string()) };
                    text = &text[close_open + '>'.len_utf8()..];
                    let from = TextSize::of(&res);
                    stack.push((from, attr));
                } else if text.starts_with(&close) {
                    text = &text[close.len()..];
                    let (from, attr) =
                        stack.pop().unwrap_or_else(|| panic!("unmatched </{}>", tag));
                    let to = TextSize::of(&res);
                    ranges.push((TextRange::new(from, to), attr));
                } else {
                    res.push('<');
                    text = &text['<'.len_utf8()..];
                }
            }
        }
    }
    assert!(stack.is_empty(), "unmatched <{}>", tag);
    ranges.sort_by_key(|r| (r.0.start(), r.0.end()));
    (ranges, res)
}
#[test]
fn test_extract_tags() {
    let (tags, text) = extract_tags(r#"<tag fn>fn <tag>main</tag>() {}</tag>"#, "tag");
    let actual = tags.into_iter().map(|(range, attr)| (&text[range], attr)).collect::<Vec<_>>();
    assert_eq!(actual, vec![("fn main() {}", Some("fn".into())), ("main", None),]);
}

/// Inserts `$0` marker into the `text` at `offset`.
pub fn add_cursor(text: &str, offset: TextSize) -> String {
    let offset: usize = offset.into();
    let mut res = String::new();
    res.push_str(&text[..offset]);
    res.push_str("$0");
    res.push_str(&text[offset..]);
    res
}

/// Extracts `//^^^ some text` annotations.
///
/// A run of `^^^` can be arbitrary long and points to the corresponding range
/// in the line above.
///
/// The `// ^file text` syntax can be used to attach `text` to the entirety of
/// the file.
///
/// Multiline string values are supported:
///
/// // ^^^ first line
/// //   | second line
///
/// Annotations point to the last line that actually was long enough for the
/// range, not counting annotations themselves. So overlapping annotations are
/// possible:
/// ```no_run
/// // stuff        other stuff
/// // ^^ 'st'
/// // ^^^^^ 'stuff'
/// //              ^^^^^^^^^^^ 'other stuff'
/// ```
pub fn extract_annotations(text: &str) -> Vec<(TextRange, String)> {
    let mut res = Vec::new();
    // map from line length to beginning of last line that had that length
    let mut line_start_map = BTreeMap::new();
    let mut line_start: TextSize = 0.into();
    let mut prev_line_annotations: Vec<(TextSize, usize)> = Vec::new();
    for line in text.split_inclusive('\n') {
        let mut this_line_annotations = Vec::new();
        let line_length = if let Some(idx) = line.find("//") {
            let annotation_offset = TextSize::of(&line[..idx + "//".len()]);
            for annotation in extract_line_annotations(&line[idx + "//".len()..]) {
                match annotation {
                    LineAnnotation::Annotation { mut range, content, file } => {
                        range += annotation_offset;
                        this_line_annotations.push((range.end(), res.len()));
                        let range = if file {
                            TextRange::up_to(TextSize::of(text))
                        } else {
                            let line_start = line_start_map.range(range.end()..).next().unwrap();

                            range + line_start.1
                        };
                        res.push((range, content))
                    }
                    LineAnnotation::Continuation { mut offset, content } => {
                        offset += annotation_offset;
                        let &(_, idx) = prev_line_annotations
                            .iter()
                            .find(|&&(off, _idx)| off == offset)
                            .unwrap();
                        res[idx].1.push('\n');
                        res[idx].1.push_str(&content);
                        res[idx].1.push('\n');
                    }
                }
            }
            idx.try_into().unwrap()
        } else {
            TextSize::of(line)
        };

        line_start_map = line_start_map.split_off(&line_length);
        line_start_map.insert(line_length, line_start);

        line_start += TextSize::of(line);

        prev_line_annotations = this_line_annotations;
    }

    res
}

enum LineAnnotation {
    Annotation { range: TextRange, content: String, file: bool },
    Continuation { offset: TextSize, content: String },
}

fn extract_line_annotations(mut line: &str) -> Vec<LineAnnotation> {
    let mut res = Vec::new();
    let mut offset: TextSize = 0.into();
    let marker: fn(char) -> bool = if line.contains('^') { |c| c == '^' } else { |c| c == '|' };
    while let Some(idx) = line.find(marker) {
        offset += TextSize::try_from(idx).unwrap();
        line = &line[idx..];

        let mut len = line.chars().take_while(|&it| it == '^').count();
        let mut continuation = false;
        if len == 0 {
            assert!(line.starts_with('|'));
            continuation = true;
            len = 1;
        }
        let range = TextRange::at(offset, len.try_into().unwrap());
        let next = line[len..].find(marker).map_or(line.len(), |it| it + len);
        let mut content = &line[len..][..next - len];

        let mut file = false;
        if !continuation && content.starts_with("file") {
            file = true;
            content = &content["file".len()..]
        }

        let content = content.trim().to_string();

        let annotation = if continuation {
            LineAnnotation::Continuation { offset: range.end(), content }
        } else {
            LineAnnotation::Annotation { range, content, file }
        };
        res.push(annotation);

        line = &line[next..];
        offset += TextSize::try_from(next).unwrap();
    }

    res
}

#[test]
fn test_extract_annotations_1() {
    let text = stdx::trim_indent(
        r#"
fn main() {
    let (x,     y) = (9, 2);
       //^ def  ^ def
    zoo + 1
} //^^^ type:
  //  | i32

// ^file
    "#,
    );
    let res = extract_annotations(&text)
        .into_iter()
        .map(|(range, ann)| (&text[range], ann))
        .collect::<Vec<_>>();

    assert_eq!(
        res[..3],
        [("x", "def".into()), ("y", "def".into()), ("zoo", "type:\ni32\n".into())]
    );
    assert_eq!(res[3].0.len(), 115);
}

#[test]
fn test_extract_annotations_2() {
    let text = stdx::trim_indent(
        r#"
fn main() {
    (x,   y);
   //^ a
      //  ^ b
  //^^^^^^^^ c
}"#,
    );
    let res = extract_annotations(&text)
        .into_iter()
        .map(|(range, ann)| (&text[range], ann))
        .collect::<Vec<_>>();

    assert_eq!(res, [("x", "a".into()), ("y", "b".into()), ("(x,   y)", "c".into())]);
}

/// Returns `false` if slow tests should not run, otherwise returns `true` and
/// also creates a file at `./target/.slow_tests_cookie` which serves as a flag
/// that slow tests did run.
pub fn skip_slow_tests() -> bool {
    let should_skip = std::env::var("CI").is_err() && std::env::var("RUN_SLOW_TESTS").is_err();
    if should_skip {
        eprintln!("ignoring slow test")
    } else {
        let path = project_root().join("./target/.slow_tests_cookie");
        fs::write(&path, ".").unwrap();
    }
    should_skip
}

/// Returns the path to the root directory of `rust-analyzer` project.
pub fn project_root() -> PathBuf {
    let dir = env!("CARGO_MANIFEST_DIR");
    PathBuf::from(dir).parent().unwrap().parent().unwrap().to_owned()
}

pub fn format_diff(chunks: Vec<dissimilar::Chunk>) -> String {
    let mut buf = String::new();
    for chunk in chunks {
        let formatted = match chunk {
            dissimilar::Chunk::Equal(text) => text.into(),
            dissimilar::Chunk::Delete(text) => format!("\x1b[41m{}\x1b[0m", text),
            dissimilar::Chunk::Insert(text) => format!("\x1b[42m{}\x1b[0m", text),
        };
        buf.push_str(&formatted);
    }
    buf
}

/// Utility for writing benchmark tests.
///
/// A benchmark test looks like this:
///
/// ```
/// #[test]
/// fn benchmark_foo() {
///     if skip_slow_tests() { return; }
///
///     let data = bench_fixture::some_fixture();
///     let analysis = some_setup();
///
///     let hash = {
///         let _b = bench("foo");
///         actual_work(analysis)
///     };
///     assert_eq!(hash, 92);
/// }
/// ```
///
/// * We skip benchmarks by default, to save time.
///   Ideal benchmark time is 800 -- 1500 ms in debug.
/// * We don't count preparation as part of the benchmark
/// * The benchmark itself returns some kind of numeric hash.
///   The hash is used as a sanity check that some code is actually run.
///   Otherwise, it's too easy to win the benchmark by just doing nothing.
pub fn bench(label: &'static str) -> impl Drop {
    struct Bencher {
        sw: StopWatch,
        label: &'static str,
    }

    impl Drop for Bencher {
        fn drop(&mut self) {
            eprintln!("{}: {}", self.label, self.sw.elapsed())
        }
    }

    Bencher { sw: StopWatch::start(), label }
}

/// Checks that the `file` has the specified `contents`. If that is not the
/// case, updates the file and then fails the test.
pub fn ensure_file_contents(file: &Path, contents: &str) {
    if let Err(()) = try_ensure_file_contents(file, contents) {
        panic!("Some files were not up-to-date");
    }
}

/// Checks that the `file` has the specified `contents`. If that is not the
/// case, updates the file and return an Error.
pub fn try_ensure_file_contents(file: &Path, contents: &str) -> Result<(), ()> {
    match std::fs::read_to_string(file) {
        Ok(old_contents) if normalize_newlines(&old_contents) == normalize_newlines(contents) => {
            return Ok(())
        }
        _ => (),
    }
    let display_path = file.strip_prefix(&project_root()).unwrap_or(file);
    eprintln!(
        "\n\x1b[31;1merror\x1b[0m: {} was not up-to-date, updating\n",
        display_path.display()
    );
    if is_ci() {
        eprintln!("    NOTE: run `cargo test` locally and commit the updated files\n");
    }
    if let Some(parent) = file.parent() {
        let _ = std::fs::create_dir_all(parent);
    }
    std::fs::write(file, contents).unwrap();
    Err(())
}

fn normalize_newlines(s: &str) -> String {
    s.replace("\r\n", "\n")
}
