clankerdiff-ratatui 0.1.4

use crate::{
    MarkdownCommitError, MarkdownLayout, MarkdownLayoutOptions, MarkdownRenderer, MarkdownRow,
    MarkdownRowUpdate, MarkdownStreamError, StreamingMarkdownPolicy, StreamingMarkdownState,
};
use clankerdiff_markdown::{MarkdownDocument, MarkdownStream};
use clankerdiff_syntax::SyntaxHighlighter;
use clankerdiff_theme::ReviewTheme;
use ratatui::text::Line;
use std::sync::Arc;

/// A streaming Markdown item plus the host-side row mirror an embedding keeps.
#[derive(Default)]
pub struct MarkdownStreamFixture {
    pub stream: MarkdownStream,
    pub state: StreamingMarkdownState,
    pub options: MarkdownLayoutOptions,
    pub theme: ReviewTheme,
    pub highlighter: SyntaxHighlighter,
    pub host: Vec<Arc<MarkdownRow>>,
    pub revision: u64,
}

impl MarkdownStreamFixture {
    #[must_use]
    pub fn from_source(source: &str) -> Self {
        let mut fixture = Self::default();
        fixture.stream.push(source);
        fixture
    }

    #[must_use]
    pub fn terminal() -> Self {
        Self {
            state: StreamingMarkdownState::new(StreamingMarkdownPolicy::Terminal),
            ..Self::default()
        }
    }

    /// Renders the current stream through the streaming cache.
    pub fn layout(&mut self) -> MarkdownLayout {
        self.try_layout().expect("stream renders")
    }

    pub fn try_layout(&mut self) -> Result<MarkdownLayout, MarkdownStreamError> {
        MarkdownRenderer::new().render_stream_layout(
            &mut self.state,
            &self.stream,
            self.options,
            &self.theme,
            &mut self.highlighter,
        )
    }

    /// Commits every row except the last one when the host mirror exceeds
    /// `capacity`, the way a terminal transcript keeps its live region small.
    pub fn commit_overflow(&mut self, capacity: usize) -> Result<usize, MarkdownCommitError> {
        let committed = self.state.committed_rows();
        let live = self.host.len().saturating_sub(committed);
        if live <= capacity {
            return Ok(0);
        }
        let end = self.host.len() - 1;
        self.state.commit_rows(self.revision, end)?;
        Ok(end - committed)
    }

    #[must_use]
    pub fn with_options(mut self, options: MarkdownLayoutOptions) -> Self {
        self.options = options;
        self
    }

    #[must_use]
    pub fn with_theme(mut self, theme: ReviewTheme) -> Self {
        self.theme = theme;
        self
    }

    pub fn render(&mut self) -> Arc<[Line<'static>]> {
        self.layout().materialize()
    }

    pub fn render_lines(&mut self) -> Arc<[Line<'static>]> {
        MarkdownRenderer::new()
            .render_stream_lines(
                &mut self.state,
                &self.stream,
                self.options,
                &self.theme,
                &mut self.highlighter,
            )
            .expect("stream renders")
    }

    #[must_use]
    pub fn one_shot_lines(&self) -> Arc<[Line<'static>]> {
        MarkdownRenderer::new().render_lines(
            &MarkdownDocument::parse(self.stream.source()),
            self.options,
            &self.theme,
            &mut SyntaxHighlighter::default(),
        )
    }

    /// Renders the current source from scratch, without any streaming cache.
    #[must_use]
    pub fn one_shot(&self) -> MarkdownLayout {
        MarkdownRenderer::new().render_layout(
            &MarkdownDocument::parse(self.stream.source()),
            self.options,
            &self.theme,
            &mut SyntaxHighlighter::default(),
        )
    }

    /// Renders, then applies the row update since the host's revision to `host`.
    pub fn apply_update(&mut self) -> MarkdownRowUpdate {
        self.layout();
        let update = self.state.update_since(self.revision);
        assert!(
            update.first_changed_row >= self.state.committed_rows(),
            "update touched committed rows"
        );
        if update.reset {
            self.host.clear();
        }
        self.host.truncate(update.first_changed_row);
        self.host.extend(update.replacement.iter().cloned());
        self.revision = update.revision;
        update
    }

    #[track_caller]
    pub fn assert_output_equivalent(&mut self) {
        self.apply_update();
        let actual = self.layout();
        let expected = self.one_shot();
        assert_eq!(actual.row_count(), expected.row_count());
        for (index, (actual, expected)) in
            actual.rows().iter().zip(expected.rows().iter()).enumerate()
        {
            assert_eq!(actual.line, expected.line, "row {index}");
            if index >= self.state.committed_rows() {
                assert_eq!(actual, expected, "live row {index}");
            }
        }
        assert!(
            self.host
                .iter()
                .zip(actual.rows().iter())
                .all(|(host, row)| Arc::ptr_eq(host, row))
        );
    }

    /// Panics if the streamed snapshot, the host mirror, or a one-shot render
    /// of the same source disagree.
    #[track_caller]
    pub fn assert_equivalent(&mut self) {
        self.apply_update();
        let actual = self.layout();
        let expected = self.one_shot();
        assert_eq!(
            actual.row_count(),
            expected.row_count(),
            "source: {:?}",
            self.stream.source()
        );
        for (index, (actual, expected)) in
            actual.rows().iter().zip(expected.rows().iter()).enumerate()
        {
            assert_eq!(
                actual,
                expected,
                "row {index}, source: {:?}",
                self.stream.source()
            );
        }
        assert!(
            self.host.iter().eq(actual.rows().iter()),
            "host mirror diverged for source: {:?}",
            self.stream.source()
        );
    }
}