//! Rendering and routing tests (MJB-HLR-012, MJB-HLR-019).
//!
//! These use ratatui's `TestBackend` to render into an in-memory cell grid and
//! assert on what a user would actually see, rather than declaring the
//! presentation layer "verified manually".

use mojibake::{
    components::{Component, buffer::BufferComponent},
    config::Config,
};
use ratatui::{Terminal, backend::TestBackend};

fn default_config() -> Config {
    toml::from_str(include_str!("../.config/config.toml")).expect("built-in config must parse")
}

/// Render `text` into a `w`×`h` grid and return the rows as strings.
fn render(text: &str, w: u16, h: u16) -> (Vec<String>, tempfile::TempDir) {
    let dir = tempfile::tempdir().unwrap();
    let path = dir.path().join("f.txt");
    std::fs::write(&path, text).unwrap();

    let mut component = BufferComponent::new(default_config(), Some(path)).unwrap();
    let mut terminal = Terminal::new(TestBackend::new(w, h)).unwrap();
    terminal
        .draw(|frame| component.draw(frame, frame.area()).unwrap())
        .unwrap();

    let buffer = terminal.backend().buffer().clone();
    let rows = (0..h)
        .map(|y| {
            (0..w)
                .map(|x| buffer.cell((x, y)).map(|c| c.symbol()).unwrap_or(" "))
                .collect::<String>()
                .trim_end()
                .to_owned()
        })
        .collect();
    (rows, dir)
}

#[test]
fn mjb_llr_200_renders_the_file_contents() {
    let (rows, _d) = render("hello world\nsecond line\n", 40, 8);
    let joined = rows.join("\n");
    assert!(
        joined.contains("hello world"),
        "file contents must be on screen, got:\n{joined}"
    );
    assert!(joined.contains("second line"));
}

/// MJB-LLR-200, MJB-HLR-012: only lines intersecting the viewport are drawn.
/// A 1000-line file in an 8-row terminal must not show line 500.
#[test]
fn mjb_llr_200_renders_only_the_visible_window() {
    let text: String = (0..1000).map(|i| format!("line{i}\n")).collect();
    let (rows, _d) = render(&text, 40, 8);
    let joined = rows.join("\n");

    assert!(joined.contains("line0"), "the top of the file is visible");
    assert!(
        !joined.contains("line500"),
        "a line far outside the viewport must not be rendered"
    );
    assert!(
        !joined.contains("line999"),
        "nor the last line of the file"
    );
}

#[test]
fn mjb_llr_200_line_numbers_are_shown_in_the_gutter() {
    let (rows, _d) = render("alpha\nbeta\n", 40, 8);
    assert!(rows[0].starts_with('1'), "row 0 gutter, got {:?}", rows[0]);
    assert!(rows[1].starts_with('2'), "row 1 gutter, got {:?}", rows[1]);
}

/// MJB-LLR-201: the block cursor is drawn with a distinct style.
#[test]
fn mjb_llr_201_cursor_is_styled_distinctly() {
    let dir = tempfile::tempdir().unwrap();
    let path = dir.path().join("f.txt");
    std::fs::write(&path, "abc\n").unwrap();

    let mut component = BufferComponent::new(default_config(), Some(path)).unwrap();
    let mut terminal = Terminal::new(TestBackend::new(20, 5)).unwrap();
    terminal
        .draw(|frame| component.draw(frame, frame.area()).unwrap())
        .unwrap();

    let buffer = terminal.backend().buffer().clone();
    // The gutter is two cells wide for a 1-line file ("1" + space), so the
    // first text cell holds the cursor.
    let gutter = 2u16;
    let cursor_cell = buffer.cell((gutter, 0)).unwrap();
    let plain_cell = buffer.cell((gutter + 1, 0)).unwrap();

    assert_eq!(cursor_cell.symbol(), "a");
    assert_ne!(
        (cursor_cell.fg, cursor_cell.bg),
        (plain_cell.fg, plain_cell.bg),
        "the cursor cell must be styled differently from ordinary text"
    );
}

/// MJB-LLR-202: the status line reports mode, file name and position.
#[test]
fn mjb_llr_202_status_line_shows_mode_and_path() {
    let (rows, _d) = render("abc\n", 60, 6);
    let status = &rows[rows.len() - 2];

    assert!(status.contains("NOR"), "mode indicator, got {status:?}");
    assert!(status.contains("f.txt"), "file name, got {status:?}");
    assert!(status.contains("1:1"), "cursor position, got {status:?}");
}

#[test]
fn mjb_llr_202_status_line_marks_an_unmodified_file() {
    let (rows, _d) = render("abc\n", 60, 6);
    let status = &rows[rows.len() - 2];
    assert!(
        !status.contains("[+]"),
        "a freshly opened file is not modified, got {status:?}"
    );
}

#[test]
fn mjb_llr_202_scratch_buffer_is_labelled() {
    let mut component = BufferComponent::new(default_config(), None).unwrap();
    let mut terminal = Terminal::new(TestBackend::new(40, 5)).unwrap();
    terminal
        .draw(|frame| component.draw(frame, frame.area()).unwrap())
        .unwrap();

    let buffer = terminal.backend().buffer().clone();
    let status: String = (0..40)
        .map(|x| buffer.cell((x, 3)).map(|c| c.symbol()).unwrap_or(" "))
        .collect();
    assert!(
        status.contains("[scratch]"),
        "a buffer with no path must say so, got {status:?}"
    );
}

/// MJB-HLR-019: no trace of the removed template widgets.
#[test]
fn mjb_llr_204_no_fps_counter_or_hello_world_is_rendered() {
    let (rows, _d) = render("some content\n", 80, 12);
    let joined = rows.join("\n").to_lowercase();

    assert!(!joined.contains("hello world"), "placeholder widget removed");
    assert!(!joined.contains("fps"), "frame-rate counter removed");
    assert!(
        !joined.contains("ticks/sec"),
        "frame-rate counter removed"
    );
}

/// MJB-LLR-203: a key matching the `Global` keymap is consumed by `App` and
/// never reaches the buffer.
///
/// Verified at the component boundary: `Ctrl-c` is bound globally to `Quit`,
/// and the buffer must not treat it as text even in insert mode. If routing
/// regressed and the key were forwarded, insert mode would type a `c`.
#[test]
fn mjb_llr_203_globally_bound_key_is_not_typed_as_text() {
    use crossterm::event::{KeyCode, KeyEvent, KeyModifiers};

    let dir = tempfile::tempdir().unwrap();
    let path = dir.path().join("f.txt");
    std::fs::write(&path, "").unwrap();

    let mut component = BufferComponent::new(default_config(), Some(path)).unwrap();
    component
        .handle_key_event(KeyEvent::new(KeyCode::Char('i'), KeyModifiers::empty()))
        .unwrap();
    component
        .handle_key_event(KeyEvent::new(KeyCode::Char('c'), KeyModifiers::CONTROL))
        .unwrap();

    assert_eq!(
        component.buffer().document.text().to_string(),
        "",
        "ctrl-c must never insert a literal 'c'"
    );
}

/// MJB-LLR-205: no per-tick key state remains, so a chord cannot be broken by
/// the passage of time or by intervening frames.
#[test]
fn mjb_llr_205_pending_chord_survives_redraws() {
    use crossterm::event::{KeyCode, KeyEvent, KeyModifiers};

    let dir = tempfile::tempdir().unwrap();
    let path = dir.path().join("f.txt");
    std::fs::write(&path, "aaa\nbbb\nccc\n").unwrap();

    let mut component = BufferComponent::new(default_config(), Some(path)).unwrap();
    let mut terminal = Terminal::new(TestBackend::new(40, 8)).unwrap();

    let k = |c| KeyEvent::new(KeyCode::Char(c), KeyModifiers::empty());

    component.handle_key_event(k('j')).unwrap();
    component.handle_key_event(k('j')).unwrap();
    // Begin the `gg` chord...
    component.handle_key_event(k('g')).unwrap();

    // ...then redraw repeatedly, which is what the tick used to interrupt.
    for _ in 0..10 {
        terminal
            .draw(|frame| component.draw(frame, frame.area()).unwrap())
            .unwrap();
    }

    component.handle_key_event(k('g')).unwrap();

    let buf = component.buffer();
    assert_eq!(
        buf.document.range().cursor(buf.document.slice()),
        0,
        "gg must still resolve after many redraws"
    );
}

/// MJB-LLR-098: a viewport too small to hold the status rows must not panic.
#[test]
fn mjb_llr_098_tiny_viewport_renders_without_panicking() {
    for (w, h) in [(1u16, 1u16), (2, 2), (1, 3), (80, 2)] {
        let _ = render("content\nmore content\n", w, h);
    }
}

#[test]
fn mjb_llr_200_empty_file_renders_without_panicking() {
    let (rows, _d) = render("", 40, 6);
    assert!(!rows.is_empty());
}

#[test]
fn mjb_llr_200_wide_characters_render() {
    let (rows, _d) = render("文字化け\n", 40, 6);
    let joined = rows.join("\n");
    // A wide character occupies two terminal cells; ratatui fills the second
    // with a continuation space, so the glyphs are not contiguous in the
    // reconstructed row. Check for each one.
    for c in "文字化け".chars() {
        assert!(
            joined.contains(c),
            "wide character {c:?} must render, got {rows:?}"
        );
    }
}

/// MJB-LLR-025: a wide character must advance the reported column by two, not
/// by one character or by three bytes.
#[test]
fn mjb_llr_025_wide_characters_advance_two_columns() {
    let dir = tempfile::tempdir().unwrap();
    let path = dir.path().join("f.txt");
    std::fs::write(&path, "文字\n").unwrap();

    let mut component = BufferComponent::new(default_config(), Some(path)).unwrap();
    // Move right one grapheme, then read the reported column off the status line.
    component
        .handle_key_event(crossterm::event::KeyEvent::new(
            crossterm::event::KeyCode::Char('l'),
            crossterm::event::KeyModifiers::empty(),
        ))
        .unwrap();

    let mut terminal = Terminal::new(TestBackend::new(60, 6)).unwrap();
    terminal
        .draw(|frame| component.draw(frame, frame.area()).unwrap())
        .unwrap();

    let buffer = terminal.backend().buffer().clone();
    let status: String = (0..60)
        .map(|x| buffer.cell((x, 4)).map(|c| c.symbol()).unwrap_or(" "))
        .collect();
    assert!(
        status.contains("1:3"),
        "one wide character past the start is column 3, got {status:?}"
    );
}