notescraft/crates/engine/tests/json_undo.rs

//! Acceptance: a JSON format or minify rewrite is ONE undo step.
//!
//! `json.format_block` and `json.minify_block` go through `Session::lint_commit`, which edits
//! the open buffer as a single replacement: one `buffer.undo` takes the whole format back,
//! `buffer.redo` re-applies it, and unsaved edits elsewhere in the note survive. Without an
//! open buffer the same edit is one atomic write, and formatting an already formatted block
//! reports `changed: false` and leaves the file untouched. For comparison, `block.turn_into`
//! and `block.move` are checked to be one undo step as well.

mod common;

use common::{TempVault, on_disk, seed, temp_vault};
use notescraft_engine::{Registry, Session, register_core};
use serde_json::{Value, json};

/// The fixture note: one fenced JSON block with compact JSON.
const NOTE: &str = "# T\n\n```json\n{\"b\":1,\"a\":[1e5]}\n```\n";

/// The same note with the JSON pretty-printed; the ONLY change a format makes.
const FORMATTED: &str = "# T\n\n```json\n{\n  \"b\": 1,\n  \"a\": [\n    1e5\n  ]\n}\n```\n";

/// A vault with `n.md` holding `note`, a registry with the core commands, and an open session.
fn setup(name: &str, note: &str) -> (Registry<Session>, Session, TempVault) {
    let vault = temp_vault(name);
    seed(vault.path(), &[("n.md", note)]);
    let mut registry = Registry::new();
    register_core(&mut registry).expect("register");
    let session = Session::open(vault.path()).expect("open");
    (registry, session, vault)
}

/// Runs `id` on the session, panicking with the error instead of returning a bare `Err`.
fn run(registry: &Registry<Session>, session: &mut Session, id: &str, params: &Value) -> Value {
    registry.run(id, session, params).unwrap_or_else(|error| panic!("{id}: {error:?}"))
}

/// The current text of the `n.md` buffer.
fn text(session: &Session) -> String {
    session.buffer("n.md").expect("the buffer is open").text().to_owned()
}

/// One `json.format_block` is one undo step: undo restores the exact original, redo re-applies
/// it, and a later `json.minify_block` is one undo step too.
#[test]
fn json_format_and_minify_are_one_undo_step_each() {
    let (registry, mut session, vault) = setup("json-undo", NOTE);
    run(&registry, &mut session, "buffer.open", &json!({ "path": "n.md" }));

    let result = run(&registry, &mut session, "json.format_block", &json!({ "path": "n.md", "index": 1 }));
    assert_eq!(result["changed"], json!(true));
    assert_eq!(text(&session), FORMATTED);
    assert_eq!(on_disk(vault.path(), "n.md"), NOTE, "a buffer edit is not a save");

    let result = run(&registry, &mut session, "buffer.undo", &json!({ "path": "n.md" }));
    assert_eq!(result["undone"], json!(true));
    assert_eq!(text(&session), NOTE, "ONE undo restores the exact original text");
    assert_eq!(result["dirty"], json!(false), "the buffer is back to the saved bytes");
    let result = run(&registry, &mut session, "buffer.undo", &json!({ "path": "n.md" }));
    assert_eq!(result["undone"], json!(false), "the format was ONE step: nothing more to undo");

    let result = run(&registry, &mut session, "buffer.redo", &json!({ "path": "n.md" }));
    assert_eq!(result["redone"], json!(true));
    assert_eq!(text(&session), FORMATTED, "ONE redo re-applies the format");

    let result = run(&registry, &mut session, "json.minify_block", &json!({ "path": "n.md", "index": 1 }));
    assert_eq!(result["changed"], json!(true));
    assert_eq!(text(&session), NOTE, "the minified body is the original compact body");
    run(&registry, &mut session, "buffer.undo", &json!({ "path": "n.md" }));
    assert_eq!(text(&session), FORMATTED, "the minify is ONE undo step, not more");
}

/// For comparison: `block.turn_into` and `block.move` are one undo step each in an open buffer.
#[test]
fn turn_into_and_move_are_one_undo_step_each() {
    const PROSE: &str = "# Title\n\nFirst para\n\nSecond para\n";
    let (registry, mut session, _vault) = setup("block-undo-turn", PROSE);
    run(&registry, &mut session, "buffer.open", &json!({ "path": "n.md" }));
    run(&registry, &mut session, "block.turn_into", &json!({ "path": "n.md", "index": 1, "target": "heading2" }));
    assert_eq!(text(&session), "# Title\n\n## First para\n\nSecond para\n");
    run(&registry, &mut session, "buffer.undo", &json!({ "path": "n.md" }));
    assert_eq!(text(&session), PROSE, "ONE undo restores the original");
    let result = run(&registry, &mut session, "buffer.undo", &json!({ "path": "n.md" }));
    assert_eq!(result["undone"], json!(false), "the turn into was ONE step");

    let (registry, mut session, _vault) = setup("block-undo-move", PROSE);
    run(&registry, &mut session, "buffer.open", &json!({ "path": "n.md" }));
    run(&registry, &mut session, "block.move", &json!({ "path": "n.md", "index": 2, "direction": "up" }));
    assert_eq!(text(&session), "# Title\n\nSecond para\n\nFirst para\n");
    run(&registry, &mut session, "buffer.undo", &json!({ "path": "n.md" }));
    assert_eq!(text(&session), PROSE, "ONE undo restores the original");
}

/// A buffer with unsaved user edits elsewhere keeps them: the format touches only the JSON
/// block, and one undo removes only the format.
#[test]
fn format_keeps_unsaved_edits_elsewhere_in_the_buffer() {
    const ORIGINAL: &str = "# T\n\nIntro\n\n```json\n{\"b\":1,\"a\":[1e5]}\n```\n";
    const EDITED: &str = "# T\n\nOutro\n\n```json\n{\"b\":1,\"a\":[1e5]}\n```\n";
    let (registry, mut session, vault) = setup("json-undo-dirty", ORIGINAL);
    run(&registry, &mut session, "buffer.open", &json!({ "path": "n.md" }));
    let start = text(&session).find("Intro").unwrap_or_default();
    let end = start.saturating_add("Intro".len());
    session.buffer_mut("n.md").expect("the buffer is open").edit(start..end, "Outro").expect("user edit");
    assert_eq!(text(&session), EDITED);

    let result = run(&registry, &mut session, "json.format_block", &json!({ "path": "n.md", "index": 2 }));
    assert_eq!(result["changed"], json!(true));
    assert_eq!(text(&session), "# T\n\nOutro\n\n```json\n{\n  \"b\": 1,\n  \"a\": [\n    1e5\n  ]\n}\n```\n");
    assert_eq!(on_disk(vault.path(), "n.md"), ORIGINAL, "nothing is saved behind the user's back");

    run(&registry, &mut session, "buffer.undo", &json!({ "path": "n.md" }));
    assert_eq!(text(&session), EDITED, "undo removes only the format, the user edit stays");
    run(&registry, &mut session, "buffer.redo", &json!({ "path": "n.md" }));
    assert_eq!(text(&session), "# T\n\nOutro\n\n```json\n{\n  \"b\": 1,\n  \"a\": [\n    1e5\n  ]\n}\n```\n");
}

/// Without an open buffer the format is one write: an already formatted block reports
/// `changed: false` and leaves the file bytes and mtime untouched.
#[test]
fn format_without_an_open_buffer_writes_the_file_once() {
    let (registry, mut session, vault) = setup("json-no-buffer", NOTE);
    let result = run(&registry, &mut session, "json.format_block", &json!({ "path": "n.md", "index": 1 }));
    assert_eq!(result["changed"], json!(true));
    assert_eq!(on_disk(vault.path(), "n.md"), FORMATTED, "the format reached the disk");
    let mtime = std::fs::metadata(vault.path().join("n.md")).and_then(|meta| meta.modified()).expect("mtime");

    let result = run(&registry, &mut session, "json.format_block", &json!({ "path": "n.md", "index": 1 }));
    assert_eq!(result["changed"], json!(false), "the block is already formatted");
    assert_eq!(on_disk(vault.path(), "n.md"), FORMATTED, "the bytes are identical");
    let again = std::fs::metadata(vault.path().join("n.md")).and_then(|meta| meta.modified()).expect("mtime");
    assert_eq!(again, mtime, "an unchanged format does not rewrite the file");
}

/// A CRLF note keeps CRLF everywhere, also inside the formatted JSON (no mixed line endings).
#[test]
fn format_in_a_crlf_note_keeps_crlf_outside_the_json() {
    const CRLF: &str = "# T\r\n\r\n```json\r\n{\"b\":1,\"a\":[1e5]}\r\n```\r\n";
    let (registry, mut session, _vault) = setup("json-crlf", CRLF);
    run(&registry, &mut session, "buffer.open", &json!({ "path": "n.md" }));
    let result = run(&registry, &mut session, "json.format_block", &json!({ "path": "n.md", "index": 1 }));
    assert_eq!(result["changed"], json!(true));
    let after = text(&session);
    assert_eq!(after, "# T\r\n\r\n```json\r\n{\r\n  \"b\": 1,\r\n  \"a\": [\r\n    1e5\r\n  ]\r\n}\r\n```\r\n");
    assert!(after.starts_with("# T\r\n\r\n```json\r\n"), "the lines outside the JSON keep CRLF");
    run(&registry, &mut session, "buffer.undo", &json!({ "path": "n.md" }));
    assert_eq!(text(&session), CRLF, "ONE undo restores the CRLF original");
}