use std::collections::HashSet;
use std::fs::{read_to_string, remove_file};
use std::path::PathBuf;
use std::sync::Mutex;

use obsidian_export::postprocessors::{
    filter_by_tags,
    remove_obsidian_comments,
    softbreaks_to_hardbreaks,
};
use obsidian_export::{Context, Exporter, MarkdownEvents, PostprocessorResult};
use pretty_assertions::assert_eq;
use pulldown_cmark::{CowStr, Event};
use serde_yaml::Value;
use tempfile::TempDir;
use walkdir::WalkDir;

/// This postprocessor replaces any instance of "foo" with "bar" in the note
/// body.
fn foo_to_bar(_ctx: &mut Context, events: &mut MarkdownEvents<'_>) -> PostprocessorResult {
    for event in events.iter_mut() {
        if let Event::Text(text) = event {
            *event = Event::Text(CowStr::from(text.replace("foo", "bar")));
        }
    }
    PostprocessorResult::Continue
}

/// This postprocessor appends "bar: baz" to frontmatter.
fn append_frontmatter(ctx: &mut Context, _events: &mut MarkdownEvents<'_>) -> PostprocessorResult {
    ctx.frontmatter
        .insert(Value::String("bar".into()), Value::String("baz".into()));
    PostprocessorResult::Continue
}

// The purpose of this test to verify the `append_frontmatter` postprocessor is
// called to extend the frontmatter, and the `foo_to_bar` postprocessor is
// called to replace instances of "foo" with "bar" (only in the note body).
#[test]
fn test_postprocessors() {
    let tmp_dir = TempDir::new().expect("failed to make tempdir");
    let mut exporter = Exporter::new(
        PathBuf::from("tests/testdata/input/postprocessors"),
        tmp_dir.path().to_path_buf(),
    );
    exporter.add_postprocessor(&foo_to_bar);
    exporter.add_postprocessor(&append_frontmatter);

    exporter.run().unwrap();

    let expected = read_to_string("tests/testdata/expected/postprocessors/Note.md").unwrap();
    let actual = read_to_string(tmp_dir.path().join(PathBuf::from("Note.md"))).unwrap();
    assert_eq!(expected, actual);
}

#[test]
fn test_postprocessor_stophere() {
    let tmp_dir = TempDir::new().expect("failed to make tempdir");
    let mut exporter = Exporter::new(
        PathBuf::from("tests/testdata/input/postprocessors"),
        tmp_dir.path().to_path_buf(),
    );

    exporter.add_postprocessor(&|_ctx, _mdevents| PostprocessorResult::StopHere);
    exporter.add_embed_postprocessor(&|_ctx, _mdevents| PostprocessorResult::StopHere);
    exporter.add_postprocessor(&|_, _| panic!("should not be called due to above processor"));
    exporter.add_embed_postprocessor(&|_, _| panic!("should not be called due to above processor"));
    exporter.run().unwrap();
}

#[test]
fn test_postprocessor_stop_and_skip() {
    let tmp_dir = TempDir::new().expect("failed to make tempdir");
    let note_path = tmp_dir.path().join(PathBuf::from("Note.md"));

    let mut exporter = Exporter::new(
        PathBuf::from("tests/testdata/input/postprocessors"),
        tmp_dir.path().to_path_buf(),
    );
    exporter.run().unwrap();

    assert!(note_path.exists());
    remove_file(&note_path).unwrap();

    exporter.add_postprocessor(&|_ctx, _mdevents| PostprocessorResult::StopAndSkipNote);
    exporter.run().unwrap();

    assert!(!note_path.exists());
}

#[test]
fn test_postprocessor_change_destination() {
    let tmp_dir = TempDir::new().expect("failed to make tempdir");
    let original_note_path = tmp_dir.path().join(PathBuf::from("Note.md"));
    let mut exporter = Exporter::new(
        PathBuf::from("tests/testdata/input/postprocessors"),
        tmp_dir.path().to_path_buf(),
    );
    exporter.run().unwrap();

    assert!(original_note_path.exists());
    remove_file(&original_note_path).unwrap();

    exporter.add_postprocessor(&|ctx, _mdevents| {
        ctx.destination.set_file_name("MovedNote.md");
        PostprocessorResult::Continue
    });
    exporter.run().unwrap();

    let new_note_path = tmp_dir.path().join(PathBuf::from("MovedNote.md"));
    assert!(!original_note_path.exists());
    assert!(new_note_path.exists());
}

// Ensure postprocessor type definition has proper lifetimes to allow state
// (here: `parents`) to be passed in. Otherwise, this fails with an error like:
//     error[E0597]: `parents` does not live long enough
//     cast requires that `parents` is borrowed for `'static`
#[test]
#[allow(clippy::significant_drop_tightening)]
fn test_postprocessor_stateful_callback() {
    let tmp_dir = TempDir::new().expect("failed to make tempdir");
    let mut exporter = Exporter::new(
        PathBuf::from("tests/testdata/input/postprocessors"),
        tmp_dir.path().to_path_buf(),
    );

    let parents: Mutex<HashSet<PathBuf>> = Mutex::default();
    let callback = |ctx: &mut Context, _mdevents: &mut MarkdownEvents<'_>| -> PostprocessorResult {
        parents
            .lock()
            .unwrap()
            .insert(ctx.destination.parent().unwrap().to_path_buf());
        PostprocessorResult::Continue
    };
    exporter.add_postprocessor(&callback);

    exporter.run().unwrap();

    let expected = tmp_dir.path();

    let parents = parents.lock().unwrap();
    println!("{parents:?}");
    assert_eq!(1, parents.len());
    assert!(parents.contains(expected));
}

// The purpose of this test to verify the `append_frontmatter` postprocessor is
// called to extend the frontmatter, and the `foo_to_bar` postprocessor is
// called to replace instances of "foo" with "bar" (only in the note body).
#[test]
fn test_embed_postprocessors() {
    let tmp_dir = TempDir::new().expect("failed to make tempdir");
    let mut exporter = Exporter::new(
        PathBuf::from("tests/testdata/input/postprocessors"),
        tmp_dir.path().to_path_buf(),
    );
    exporter.add_embed_postprocessor(&foo_to_bar);
    // Should have no effect with embeds:
    exporter.add_embed_postprocessor(&append_frontmatter);

    exporter.run().unwrap();

    let expected =
        read_to_string("tests/testdata/expected/postprocessors/Note_embed_postprocess_only.md")
            .unwrap();
    let actual = read_to_string(tmp_dir.path().join(PathBuf::from("Note.md"))).unwrap();
    assert_eq!(expected, actual);
}

// When StopAndSkipNote is used with an embed_preprocessor, it should skip the
// embedded note but continue with the rest of the note.
#[test]
fn test_embed_postprocessors_stop_and_skip() {
    let tmp_dir = TempDir::new().expect("failed to make tempdir");
    let mut exporter = Exporter::new(
        PathBuf::from("tests/testdata/input/postprocessors"),
        tmp_dir.path().to_path_buf(),
    );
    exporter.add_embed_postprocessor(&|_ctx, _mdevents| PostprocessorResult::StopAndSkipNote);

    exporter.run().unwrap();

    let expected =
        read_to_string("tests/testdata/expected/postprocessors/Note_embed_stop_and_skip.md")
            .unwrap();
    let actual = read_to_string(tmp_dir.path().join(PathBuf::from("Note.md"))).unwrap();
    assert_eq!(expected, actual);
}

// This test verifies that the context which is passed to an embed postprocessor
// is actually correct. Primarily, this means the frontmatter should reflect
// that of the note being embedded as opposed to the frontmatter of the root
// note.
#[test]
#[allow(clippy::manual_assert)]
fn test_embed_postprocessors_context() {
    let tmp_dir = TempDir::new().expect("failed to make tempdir");
    let mut exporter = Exporter::new(
        PathBuf::from("tests/testdata/input/postprocessors"),
        tmp_dir.path().to_path_buf(),
    );

    exporter.add_postprocessor(&|ctx, _mdevents| {
        if ctx.current_file() != &PathBuf::from("Note.md") {
            return PostprocessorResult::Continue;
        }
        let is_root_note = ctx
            .frontmatter
            .get(Value::String("is_root_note".into()))
            .unwrap();
        if is_root_note != &Value::Bool(true) {
            // NOTE: Test failure may not give output consistently because the test binary
            // affects how output is captured and printed in the thread running
            // this postprocessor. Just run the test a couple times until the
            // error shows up.
            panic!(
                "postprocessor: expected is_root_note in {} to be true, got false",
                &ctx.current_file().display()
            );
        }
        PostprocessorResult::Continue
    });
    exporter.add_embed_postprocessor(&|ctx, _mdevents| {
        let is_root_note = ctx
            .frontmatter
            .get(Value::String("is_root_note".into()))
            .unwrap();
        if is_root_note == &Value::Bool(true) {
            // NOTE: Test failure may not give output consistently because the test binary
            // affects how output is captured and printed in the thread running
            // this postprocessor. Just run the test a couple times until the
            // error shows up.
            panic!(
                "embed_postprocessor: expected is_root_note in {} to be false, got true",
                &ctx.current_file().display()
            );
        }
        PostprocessorResult::Continue
    });

    exporter.run().unwrap();
}

#[test]
fn test_softbreaks_to_hardbreaks() {
    let tmp_dir = TempDir::new().expect("failed to make tempdir");
    let mut exporter = Exporter::new(
        PathBuf::from("tests/testdata/input/postprocessors"),
        tmp_dir.path().to_path_buf(),
    );
    exporter.add_postprocessor(&softbreaks_to_hardbreaks);
    exporter.run().unwrap();

    let expected =
        read_to_string("tests/testdata/expected/postprocessors/hard_linebreaks.md").unwrap();
    let actual = read_to_string(tmp_dir.path().join(PathBuf::from("hard_linebreaks.md"))).unwrap();
    assert_eq!(expected, actual);
}

#[test]
fn test_filter_by_tags() {
    let tmp_dir = TempDir::new().expect("failed to make tempdir");
    let mut exporter = Exporter::new(
        PathBuf::from("tests/testdata/input/filter-by-tags"),
        tmp_dir.path().to_path_buf(),
    );
    let filter_by_tags = filter_by_tags(
        vec!["private".into(), "no-export".into()],
        vec!["export".into()],
    );
    exporter.add_postprocessor(&filter_by_tags);
    exporter.run().unwrap();

    let walker = WalkDir::new("tests/testdata/expected/filter-by-tags/")
        // Without sorting here, different test runs may trigger the first assertion failure in
        // unpredictable order.
        .sort_by(|a, b| a.file_name().cmp(b.file_name()))
        .into_iter();
    for entry in walker {
        let entry = entry.unwrap();
        if entry.metadata().unwrap().is_dir() {
            continue;
        };
        let filename = entry.file_name().to_string_lossy().into_owned();
        let expected = read_to_string(entry.path()).unwrap_or_else(|_| {
            panic!(
                "failed to read {} from testdata/expected/filter-by-tags",
                entry.path().display()
            )
        });
        let actual = read_to_string(tmp_dir.path().join(PathBuf::from(&filename)))
            .unwrap_or_else(|_| panic!("failed to read {} from temporary exportdir", filename));

        assert_eq!(
            expected, actual,
            "{} does not have expected content",
            filename
        );
    }
}

#[test]
fn test_remove_obsidian_comments() {
    let tmp_dir = TempDir::new().expect("failed to make tempdir");
    let mut exporter = Exporter::new(
        PathBuf::from("tests/testdata/input/remove-comments/"),
        tmp_dir.path().to_path_buf(),
    );
    exporter.add_postprocessor(&remove_obsidian_comments);
    exporter.run().unwrap();

    let expected =
        read_to_string("tests/testdata/expected/remove-comments/test_comments.md").unwrap();
    let actual = read_to_string(tmp_dir.path().join(PathBuf::from("test_comments.md"))).unwrap();

    assert_eq!(expected, actual);
}