//! The `improvise cmd` / `improvise script` contract, pinned at the process
//! boundary. Why a spawned binary: `context/test-evidence/cli.md`.

use std::path::{Path, PathBuf};
use std::process::{Command, Output};

fn bin() -> &'static str {
    env!("CARGO_BIN_EXE_improvise")
}

struct Scratch(PathBuf);

impl Scratch {
    fn new(tag: &str) -> Self {
        let dir = std::env::temp_dir().join(format!("improv_cli_{tag}-{}", std::process::id()));
        let _ = std::fs::remove_dir_all(&dir);
        std::fs::create_dir_all(&dir).expect("a scratch directory");
        Self(dir)
    }

    fn path(&self, name: &str) -> PathBuf {
        self.0.join(name)
    }
}

impl Drop for Scratch {
    fn drop(&mut self) {
        let _ = std::fs::remove_dir_all(&self.0);
    }
}

fn run_cmd(args: &[&str], file: &Path) -> Output {
    Command::new(bin())
        .arg("cmd")
        .args(args)
        .arg("-f")
        .arg(file)
        .output()
        .expect("the improvise binary runs")
}

fn stderr_of(out: &Output) -> String {
    String::from_utf8_lossy(&out.stderr).to_string()
}

fn stdout_of(out: &Output) -> String {
    String::from_utf8_lossy(&out.stdout).to_string()
}

/// A document with one category, so `add-item` has somewhere legitimate to go.
fn seeded(scratch: &Scratch, name: &str) -> PathBuf {
    let doc = scratch.path(name);
    let out = run_cmd(&["add-category Region"], &doc);
    assert!(doc.exists(), "the seed run wrote a document: {out:?}");
    doc
}

#[test]
fn a_refused_command_says_what_went_wrong() {
    let scratch = Scratch::new("refused");
    let doc = seeded(&scratch, "m.improv");
    let out = run_cmd(&["add-item Nonexistent Thing"], &doc);
    let said = stderr_of(&out);
    assert!(
        !said.trim().is_empty(),
        "a refused command said nothing at all; stdout={:?}",
        stdout_of(&out)
    );
    assert!(
        said.contains("Nonexistent"),
        "the refusal does not name the category that does not exist: {said:?}"
    );
}

/// The rival this separates from: a fix that reports on the happy path and
/// stays silent on the refusal. `context/test-evidence/cli.md`.
#[test]
fn a_command_with_nothing_to_say_says_nothing() {
    let scratch = Scratch::new("quiet");
    let doc = scratch.path("m.improv");
    let out = run_cmd(&["add-category Region"], &doc);
    assert!(
        stderr_of(&out).trim().is_empty(),
        "a command that succeeded with nothing to report spoke anyway: {:?}",
        stderr_of(&out)
    );
    assert!(
        out.status.success(),
        "a command that succeeded did not exit 0"
    );
}

#[test]
fn an_aborted_batch_exits_non_zero_and_says_why() {
    let scratch = Scratch::new("abort");
    let doc = seeded(&scratch, "m.improv");
    let bad = scratch.path("no-such-dir").join("out.improv");
    let out = run_cmd(&[&format!("w {}", bad.display())], &doc);
    let said = stderr_of(&out);
    assert!(
        !said.trim().is_empty(),
        "a failed save said nothing: stdout={:?}",
        stdout_of(&out)
    );
    assert!(
        !out.status.success(),
        "a failed save exited 0; stderr={said:?}"
    );
}

#[test]
fn a_parse_error_still_exits_non_zero() {
    let scratch = Scratch::new("parse");
    let doc = seeded(&scratch, "m.improv");
    let out = run_cmd(&["no-such-command-at-all"], &doc);
    assert!(!out.status.success(), "an unparseable line exited 0");
    assert!(
        stderr_of(&out).contains("no-such-command-at-all"),
        "the parse error does not name the word typed: {:?}",
        stderr_of(&out)
    );
}

/// Diagnostics go to stderr so that stdout stays free for a data output, and
/// so `2>/dev/null` is the whole suppression story. `context/code/cli.md`.
#[test]
fn what_a_command_says_goes_to_stderr_and_stdout_stays_empty() {
    let scratch = Scratch::new("stream");
    let doc = seeded(&scratch, "m.improv");
    let out = run_cmd(&["add-item Nonexistent Thing"], &doc);
    assert!(
        stdout_of(&out).trim().is_empty(),
        "a diagnostic reached stdout: {:?}",
        stdout_of(&out)
    );
    assert!(!stderr_of(&out).trim().is_empty(), "stderr was empty too");
}

#[test]
fn a_script_reports_exactly_as_cmd_does() {
    let scratch = Scratch::new("script");
    let doc = seeded(&scratch, "m.improv");
    let script = scratch.path("s.txt");
    std::fs::write(&script, "# a comment\nadd-item Nonexistent Thing\n").expect("a script file");
    let out = Command::new(bin())
        .arg("script")
        .arg(&script)
        .arg("-f")
        .arg(&doc)
        .output()
        .expect("the improvise binary runs");
    assert!(
        stderr_of(&out).contains("Nonexistent"),
        "`script` swallowed the refusal `cmd` reports: {:?}",
        stderr_of(&out)
    );
}

/// A run that changed nothing must leave the bytes alone: a fixture edited by
/// hand between runs is otherwise silently normalised. `context/code/cli.md`.
#[test]
fn a_run_that_changes_nothing_does_not_rewrite_the_document() {
    let scratch = Scratch::new("noop");
    let doc = seeded(&scratch, "m.improv");
    let before = std::fs::read(&doc).expect("the seeded document");
    let out = run_cmd(&["move-cursor down"], &doc);
    let after = std::fs::read(&doc).expect("the document after a view-only command");
    assert_eq!(
        before,
        after,
        "a view-only command rewrote the document; stderr={:?}",
        stderr_of(&out)
    );
}

/// The reported instance: `1e20` is expanded to its twenty digits by a run that
/// was asked to change nothing at all.
#[test]
fn a_no_op_run_leaves_an_unnormalised_literal_alone() {
    let scratch = Scratch::new("literal");
    let doc = scratch.path("m.improv");
    std::fs::write(
        &doc,
        "v2025-04-09\n# Big\nInitial View: Default\n\n\
         ## View: Default\nRegion: row\n_Measure: column\n\n\
         ## Category: Region\n- North\n\n\
         ## Category: _Measure\n- Score\n\n\
         ## Data\nRegion=North, _Measure=Score = 1e20\n",
    )
    .expect("a hand-written document");
    let before = std::fs::read_to_string(&doc).expect("the document");
    assert!(before.contains("1e20"), "the fixture itself is wrong");
    let out = run_cmd(&["move-cursor down"], &doc);
    let after = std::fs::read_to_string(&doc).expect("the document after");
    assert!(
        after.contains("1e20"),
        "a no-op run normalised the literal; stderr={:?}, after={after:?}",
        stderr_of(&out)
    );
}

#[test]
fn the_cmd_help_does_not_advertise_a_language_it_refuses() {
    for sub in ["cmd", "script"] {
        let out = Command::new(bin())
            .args([sub, "--help"])
            .output()
            .expect("the improvise binary runs");
        let text = format!("{}{}", stdout_of(&out), stderr_of(&out));
        assert!(
            !text.contains("JSON") && !text.contains("json"),
            "`{sub} --help` still advertises JSON, which it refuses: {text}"
        );
    }
}

/// The language it does accept, demonstrated end to end so the help above has
/// something true to point at.
#[test]
fn the_language_the_help_names_is_the_one_it_accepts() {
    let scratch = Scratch::new("lang");
    let doc = seeded(&scratch, "m.improv");
    let out = run_cmd(&["add-item Region East"], &doc);
    assert!(out.status.success(), "the command line form was refused");
    let text = std::fs::read_to_string(&doc).expect("the document");
    assert!(text.contains("East"), "the item was not added: {text}");

    let json = run_cmd(&[r#"{"cmd":"add-item","args":["Region","West"]}"#], &doc);
    assert!(
        !json.status.success(),
        "the JSON form the help used to advertise was accepted after all"
    );
}

/// The rival this separates from: making any emitted status a non-zero exit.
/// `fit-measure` reports its reproducing seed the same way — `context/code/cli.md`.
#[test]
fn a_command_that_succeeds_while_reporting_still_exits_zero() {
    let scratch = Scratch::new("reports");
    let doc = seeded(&scratch, "m.improv");
    let save = format!("w {}", doc.display());
    let out = run_cmd(&["add-item Region East", &save], &doc);
    assert!(
        !stderr_of(&out).trim().is_empty(),
        "a successful save reported nothing, so this test proves nothing"
    );
    assert!(
        out.status.success(),
        "a successful command that reported was treated as a failure: {:?}",
        stderr_of(&out)
    );
}

/// A run that did change the document still writes it, even when the last thing
/// it did was save somewhere else and clear the dirty flag.
#[test]
fn a_run_that_changed_the_document_still_writes_it() {
    let scratch = Scratch::new("elsewhere");
    let doc = seeded(&scratch, "m.improv");
    let other = scratch.path("other.improv");
    let save = format!("w {}", other.display());
    run_cmd(&["add-item Region East", &save], &doc);
    let text = std::fs::read_to_string(&doc).expect("the -f document");
    assert!(
        text.contains("East"),
        "the -f document lost an edit because `:w` elsewhere cleared the flag: {text}"
    );
}

/// A document whose row axis carries three items, so a cursor move has
/// somewhere to go and the three landing places are distinguishable.
fn three_rows(scratch: &Scratch, name: &str) -> PathBuf {
    let doc = scratch.path(name);
    run_cmd(&["add-category Region"], &doc);
    run_cmd(&["add-items Region North South East"], &doc);
    doc
}

fn hidden_line(doc: &Path) -> String {
    std::fs::read_to_string(doc)
        .expect("the document")
        .lines()
        .find(|l| l.starts_with("hidden:"))
        .unwrap_or("(nothing hidden)")
        .to_string()
}

/// Evidence: `context/test-evidence/cli.md`.
#[test]
fn a_script_can_move_the_cursor_and_the_next_command_sees_it() {
    let scratch = Scratch::new("cursor");
    let moved = three_rows(&scratch, "moved.improv");
    let still = three_rows(&scratch, "still.improv");

    run_cmd(&["move-selection 2 0 . hide-selected-row-item"], &moved);
    run_cmd(&["hide-selected-row-item"], &still);

    assert_eq!(
        hidden_line(&still),
        "hidden: Region/North",
        "without a move the cursor is at the origin; if this changes, the other \
         half of this test stops meaning anything"
    );
    assert_eq!(
        hidden_line(&moved),
        "hidden: Region/East",
        "`move-selection 2 0` must move the cursor two rows down before the \
         next command reads it (improvise-6uva)"
    );
}

/// Evidence: `context/test-evidence/cli.md`.
#[test]
fn a_script_cursor_move_survives_the_line_that_made_it() {
    let scratch = Scratch::new("cursor-lines");
    let doc = three_rows(&scratch, "lines.improv");
    run_cmd(&["move-selection 1 0", "hide-selected-row-item"], &doc);
    assert_eq!(hidden_line(&doc), "hidden: Region/South");
}

fn cell_lines(doc: &Path) -> Vec<String> {
    std::fs::read_to_string(doc)
        .expect("the document")
        .lines()
        .filter(|l| l.contains(" = "))
        .map(|l| l.trim().to_string())
        .collect()
}

/// Evidence: `context/test-evidence/cli.md`.
#[test]
fn an_explicit_coordinate_still_beats_the_cursor() {
    let scratch = Scratch::new("explicit");
    let doc = scratch.path("cells.improv");
    run_cmd(&["add-category Region"], &doc);
    run_cmd(&["add-items Region North South East"], &doc);
    run_cmd(
        &[
            "set-cell 1 Region/North",
            "set-cell 2 Region/South",
            "set-cell 3 Region/East",
        ],
        &doc,
    );
    assert_eq!(cell_lines(&doc).len(), 3, "the fixture wrote three cells");

    // The cursor is at the origin, which is North. Clearing East by name must
    // clear East, not whatever the cursor happens to be sitting on.
    run_cmd(&["clear-cell Region/East"], &doc);
    let left = cell_lines(&doc);
    assert!(
        left.iter().any(|l| l.contains("North")),
        "the cursor cell was cleared instead of the named one: {left:?}"
    );
    assert!(
        !left.iter().any(|l| l.contains("East")),
        "the named cell survived: {left:?}"
    );
}

/// North=1, South=2, East=3 on the row axis; the cursor starts on North.
fn three_cells(scratch: &Scratch, name: &str) -> PathBuf {
    let doc = three_rows(scratch, name);
    run_cmd(
        &[
            "set-cell 1 Region/North",
            "set-cell 2 Region/South",
            "set-cell 3 Region/East",
        ],
        &doc,
    );
    assert_eq!(cell_lines(&doc).len(), 3, "the fixture wrote three cells");
    doc
}

fn value_of(doc: &Path, item: &str) -> Option<String> {
    cell_lines(doc)
        .into_iter()
        .find(|l| l.contains(&format!("Region={item}")))
        .and_then(|l| l.rsplit(" = ").next().map(str::to_string))
}

/// Evidence: `context/test-evidence/cli.md`.
#[test]
fn commit_cell_edit_writes_the_named_cell_and_spares_the_cursors() {
    let scratch = Scratch::new("commit-explicit");
    let doc = three_cells(&scratch, "commit.improv");

    let out = run_cmd(
        &["move-selection 1 0 . commit-cell-edit editing 5 Region/East"],
        &doc,
    );
    assert!(out.status.success(), "the line failed: {}", stderr_of(&out));
    let cells = cell_lines(&doc);
    assert_eq!(value_of(&doc, "East").as_deref(), Some("5"), "{cells:?}");
    assert_eq!(
        value_of(&doc, "South").as_deref(),
        Some("2"),
        "the cell under the cursor was touched: {cells:?}"
    );
    assert_eq!(
        value_of(&doc, "North").as_deref(),
        Some("1"),
        "the origin cell was touched: {cells:?}"
    );
}

/// Evidence: `context/test-evidence/cli.md`.
#[test]
fn a_line_whose_gate_passes_runs_whole() {
    let scratch = Scratch::new("commit-atomic");
    let doc = scratch.path("atomic.improv");
    let out = run_cmd(
        &["add-category Foo . commit-cell-edit editing 5 Foo/x"],
        &doc,
    );
    assert!(
        !stderr_of(&out).contains("Parse error"),
        "a line the gate accepted was refused part-way: {}",
        stderr_of(&out)
    );
    let text = std::fs::read_to_string(&doc).expect("the document");
    assert!(
        text.lines()
            .any(|l| l.contains("Foo=x") && l.ends_with("= 5")),
        "the commit did not land: {text}"
    );
}

/// Evidence: `context/test-evidence/cli.md`.
#[test]
fn a_malformed_commit_line_is_refused_whole() {
    let scratch = Scratch::new("commit-malformed");
    let doc = seeded(&scratch, "malformed.improv");
    let out = run_cmd(&["add-category Foo . commit-cell-edit editing 5"], &doc);
    assert!(!out.status.success(), "a malformed line exited 0");
    let text = std::fs::read_to_string(&doc).expect("the document");
    assert!(
        !text.contains("Foo"),
        "the first half of a refused line landed: {text}"
    );
}

/// Runs `improvise cmd` with no controlling terminal and the given `LINES`,
/// so the only size the process can discover is the one handed to it here.
#[cfg(unix)]
fn run_cmd_in_a_terminal_of(rows: u16, cols: u16, args: &[&str], file: &Path) -> Output {
    use std::os::unix::process::CommandExt;
    let mut cmd = Command::new(bin());
    cmd.arg("cmd")
        .args(args)
        .arg("-f")
        .arg(file)
        .env("TERM", "xterm")
        .env("LINES", rows.to_string())
        .env("COLUMNS", cols.to_string())
        .stdin(std::process::Stdio::null());
    // SAFETY: `setsid` is async-signal-safe, and leaving the runner's terminal
    // is what makes `LINES` the only size the child can find.
    unsafe {
        cmd.pre_exec(|| {
            libc::setsid();
            Ok(())
        });
    }
    cmd.output().expect("the improvise binary runs")
}

/// Evidence: `context/test-evidence/cli.md`.
#[cfg(unix)]
#[test]
fn a_script_writes_the_same_record_whatever_terminal_ran_it() {
    let scratch = Scratch::new("extent");
    let items: Vec<String> = (1..=60).map(|i| format!("R{i:02}")).collect();
    let seed = scratch.path("seed.improv");
    run_cmd(&["add-category Region"], &seed);
    run_cmd(&[&format!("add-items Region {}", items.join(" "))], &seed);
    let script = ["page-scroll 1 . hide-selected-row-item"];

    let mut hidden = Vec::new();
    for (rows, cols) in [(24, 80), (60, 200)] {
        let doc = scratch.path(&format!("{rows}x{cols}.improv"));
        std::fs::copy(&seed, &doc).expect("a copy of the seed");
        let out = run_cmd_in_a_terminal_of(rows, cols, &script, &doc);
        assert!(out.status.success(), "{}", stderr_of(&out));
        hidden.push(hidden_line(&doc));
    }
    assert_ne!(
        hidden[0], "hidden: Region/R01",
        "the cursor never moved, so the page size was never read"
    );
    assert!(
        hidden[0].starts_with("hidden: Region/R"),
        "the script hid nothing, so agreement proves nothing: {hidden:?}"
    );
    assert_eq!(
        hidden[0], hidden[1],
        "the same script hid a different record at a different terminal size"
    );
}

/// Evidence: `context/test-evidence/cli.md`.
#[test]
fn a_commit_whose_advance_has_nowhere_to_go_still_exits_zero() {
    let scratch = Scratch::new("commit-tail");
    let doc = three_cells(&scratch, "tail.improv");
    let out = run_cmd(
        &["move-selection 2 0 . commit-cell-edit editing 9 Region/South"],
        &doc,
    );
    assert_eq!(
        value_of(&doc, "South").as_deref(),
        Some("9"),
        "the write did not land"
    );
    assert!(
        out.status.success(),
        "the write landed and was saved, yet the run exited non-zero: {:?}",
        stderr_of(&out)
    );

    let empty = scratch.path("empty.improv");
    let out = run_cmd(
        &["add-category Foo . commit-cell-edit editing 5 Foo/x"],
        &empty,
    );
    assert!(
        out.status.success(),
        "a commit on an empty grid landed and exited non-zero: {:?}",
        stderr_of(&out)
    );
}

/// Evidence: `context/test-evidence/cli.md`.
#[test]
fn a_refusal_that_only_writes_a_status_exits_non_zero() {
    let scratch = Scratch::new("refusal-exit");
    let doc = seeded(&scratch, "m.improv");
    let out = run_cmd(&["add-item Nonexistent Thing"], &doc);
    assert!(
        stderr_of(&out).contains("Nonexistent"),
        "the refusal was not reported, so its exit code proves nothing: {:?}",
        stderr_of(&out)
    );
    assert!(
        !out.status.success(),
        "a refused command exited 0: {:?}",
        stderr_of(&out)
    );
}

/// Two regions, East repeated: records #1 and #3 share every coordinate.
fn colliding_csv(scratch: &Scratch) -> PathBuf {
    let csv = scratch.path("dups.csv");
    std::fs::write(&csv, "Region,Revenue\nEast,10\nWest,5\nEast,20\n").unwrap();
    csv
}

fn run_import(csv: &Path, out: &Path, extra: &[&str]) -> Output {
    Command::new(bin())
        .arg("import")
        .arg(csv)
        .arg("--no-wizard")
        .args(extra)
        .arg("-o")
        .arg(out)
        .output()
        .expect("the improvise binary runs")
}

/// improvise-cgqt: nobody is there to ask, so an unanswered collision stops
/// the import and names the records. `context/test-evidence/cli.md`.
#[test]
fn a_headless_import_with_duplicates_refuses_by_default_and_names_them() {
    let scratch = Scratch::new("dup_refuse");
    let out_path = scratch.path("out.improv");
    let out = run_import(&colliding_csv(&scratch), &out_path, &[]);
    let err = stderr_of(&out);
    assert!(!out.status.success(), "{err}");
    assert!(err.contains("2 records (#1, #3): Region=East"), "{err}");
    assert!(err.contains("--on-duplicate"), "names the way out: {err}");
    assert!(!out_path.exists(), "nothing half-imported is written");
}

#[test]
fn a_headless_import_sums_duplicates_when_told_to() {
    let scratch = Scratch::new("dup_sum");
    let out_path = scratch.path("out.improv");
    let out = run_import(
        &colliding_csv(&scratch),
        &out_path,
        &["--on-duplicate", "sum"],
    );
    assert!(out.status.success(), "{}", stderr_of(&out));
    let doc = std::fs::read_to_string(&out_path).unwrap();
    assert!(doc.contains("= 30"), "{doc}");
    assert!(!doc.contains("Occurrence"), "{doc}");
}

#[test]
fn a_headless_import_keeps_duplicates_separate_when_told_to() {
    let scratch = Scratch::new("dup_separate");
    let out_path = scratch.path("out.improv");
    let out = run_import(
        &colliding_csv(&scratch),
        &out_path,
        &["--on-duplicate", "separate"],
    );
    assert!(out.status.success(), "{}", stderr_of(&out));
    let doc = std::fs::read_to_string(&out_path).unwrap();
    assert!(doc.contains("## Category: Occurrence"), "{doc}");
    assert!(doc.contains("= 10") && doc.contains("= 20"), "{doc}");
    assert!(!doc.contains("= 30"), "{doc}");
}

/// Dates across two years, one per month, so nothing collides.
fn dated_csv(scratch: &Scratch) -> PathBuf {
    let csv = scratch.path("dated.csv");
    std::fs::write(
        &csv,
        "Date,Revenue\n2024-01-15,1\n2024-04-02,10\n2025-01-03,100\n",
    )
    .unwrap();
    csv
}

/// improvise-8jk6.3, headless: `--extract` builds ONE hierarchical category by
/// default, as the wizard does, and it is written with its `>` lines.
#[test]
fn a_headless_date_import_is_one_hierarchical_category() {
    let scratch = Scratch::new("date_hierarchy");
    let out_path = scratch.path("out.improv");
    let out = run_import(
        &dated_csv(&scratch),
        &out_path,
        &[
            "--extract",
            "Date:Year",
            "--extract",
            "Date:Quarter",
            "--extract",
            "Date:Month",
        ],
    );
    assert!(out.status.success(), "{}", stderr_of(&out));
    let doc = std::fs::read_to_string(&out_path).unwrap();
    assert!(!doc.contains("Date_Month"), "{doc}");
    assert!(doc.contains("- |2024-01|[|2024-Q1|]"), "{doc}");
    assert!(doc.contains("> |2024-Q1|[|2024|]"), "{doc}");
    assert!(!doc.contains("expanded"), "it opens folded: {doc}");
}

/// The flat split stays available headless, as `s` makes it in the wizard.
#[test]
fn a_headless_date_import_splits_when_told_to() {
    let scratch = Scratch::new("date_split");
    let out_path = scratch.path("out.improv");
    let out = run_import(
        &dated_csv(&scratch),
        &out_path,
        &["--extract", "Date:Month", "--split-date", "Date"],
    );
    assert!(out.status.success(), "{}", stderr_of(&out));
    let doc = std::fs::read_to_string(&out_path).unwrap();
    assert!(doc.contains("## Category: Date_Month"), "{doc}");
    assert!(doc.contains("2024-01-15"), "the raw dates stay: {doc}");
}

/// improvise-8jk6.3 review: a `--split-date` that names nothing splittable
/// said nothing and exited 0.
#[test]
fn split_date_naming_an_unknown_or_non_date_field_is_refused() {
    let scratch = Scratch::new("split_date_unknown");
    for field in ["Nope", "Revenue"] {
        let out_path = scratch.path("out.improv");
        let out = run_import(
            &dated_csv(&scratch),
            &out_path,
            &["--extract", "Date:Month", "--split-date", field],
        );
        assert!(!out.status.success(), "{field}: {}", stderr_of(&out));
        let err = stderr_of(&out);
        assert!(err.contains("--split-date") && err.contains(field), "{err}");
    }
}

/// improvise-8jk6.3 review: `--axis Date_Month:column` names a category the
/// hierarchical import no longer builds, and was dropped without a word.
#[test]
fn an_axis_naming_a_category_the_import_did_not_build_is_refused() {
    let scratch = Scratch::new("axis_unknown");
    let out_path = scratch.path("out.improv");
    let out = run_import(
        &dated_csv(&scratch),
        &out_path,
        &["--extract", "Date:Month", "--axis", "Date_Month:column"],
    );
    assert!(!out.status.success(), "{}", stderr_of(&out));
    let err = stderr_of(&out);
    assert!(err.contains("Date_Month") && err.contains("--split-date"), "{err}");
}

/// code-maat's reports: three schemas, a stray note, and room for the output.
fn code_maat_folder(scratch: &Scratch) -> PathBuf {
    let dir = scratch.path("maat");
    std::fs::create_dir_all(&dir).unwrap();
    for (name, body) in [
        (
            "coupling.csv",
            "entity,coupled,degree,average-revs\nsrc/a.rs,src/b.rs,80,5\n",
        ),
        ("age.csv", "entity,age-months\nsrc/a.rs,2\nsrc/b.rs,9\n"),
        (
            "abs-churn.csv",
            "date,added,deleted,commits\n2026-01-02,10,3,2\n",
        ),
        ("README.txt", "not a report\n"),
    ] {
        std::fs::write(dir.join(name), body).unwrap();
    }
    dir
}

/// improvise-lpzu: a folder argument is its `*.csv` files, merged sparsely and
/// in name order. Evidence: `context/test-evidence/cli.md`.
#[test]
fn a_headless_import_of_a_folder_merges_its_csv_files_and_repeats_byte_for_byte() {
    let scratch = Scratch::new("folder_import");
    let dir = code_maat_folder(&scratch);
    let out_path = dir.join("maat.improv");

    let first = run_import(&dir, &out_path, &[]);
    assert!(first.status.success(), "{}", stderr_of(&first));
    let doc = std::fs::read_to_string(&out_path).unwrap();
    for line in [
        "File=coupling, _Measure=degree, coupled=|src/b.rs|, entity=|src/a.rs| = 80",
        "File=age, _Measure=age-months, entity=|src/b.rs| = 9",
        "File=abs-churn, _Measure=added, date=|2026-01-02| = 10",
    ] {
        assert!(doc.lines().any(|l| l == line), "{line} missing from\n{doc}");
    }
    assert!(!doc.contains("README"), "{doc}");
    let views: Vec<&str> = doc.lines().filter(|l| l.starts_with("## View: ")).collect();
    assert_eq!(
        views,
        [
            "## View: Default",
            "## View: abs-churn",
            "## View: age",
            "## View: coupling"
        ]
    );
    assert!(doc.lines().any(|l| l == "File: filter, coupling"), "{doc}");
    assert!(doc.contains("Initial View: Default"), "{doc}");

    // The output now sits in the folder; a second run must not read it.
    let second = run_import(&dir, &out_path, &[]);
    assert!(second.status.success(), "{}", stderr_of(&second));
    assert_eq!(std::fs::read_to_string(&out_path).unwrap(), doc);
}

/// improvise-lpzu: a file and a folder together are one merge, and a folder
/// with nothing to import is named. Evidence: `context/test-evidence/cli.md`.
#[test]
fn a_headless_import_takes_files_and_folders_together_and_refuses_an_empty_folder() {
    let scratch = Scratch::new("folder_mixed");
    let dir = code_maat_folder(&scratch);
    let extra = scratch.path("extra.csv");
    std::fs::write(&extra, "entity,age-months\nsrc/z.rs,4\n").unwrap();
    let out_path = scratch.path("out.improv");

    let out = Command::new(bin())
        .args(["import", "--no-wizard", "-o"])
        .arg(&out_path)
        .arg(&extra)
        .arg(&dir)
        .output()
        .unwrap();
    assert!(out.status.success(), "{}", stderr_of(&out));
    let doc = std::fs::read_to_string(&out_path).unwrap();
    assert!(
        doc.contains("File=extra, _Measure=age-months, entity=|src/z.rs| = 4"),
        "{doc}"
    );
    assert!(doc.contains("File=coupling"), "{doc}");

    let empty = scratch.path("empty");
    std::fs::create_dir_all(&empty).unwrap();
    let refused = run_import(&empty, &scratch.path("never.improv"), &[]);
    assert!(!refused.status.success());
    let err = stderr_of(&refused);
    assert!(
        err.contains(&format!("no CSV files in folder {}", empty.display())),
        "{err}"
    );
    assert!(!scratch.path("never.improv").exists());
}

/// improvise-lpzu, the user's ruling: a folder always merges, so even one CSV
/// keeps its file identity. Evidence: `context/test-evidence/cli.md`.
#[test]
fn a_folder_of_one_csv_still_gets_a_file_category_and_its_view_but_a_lone_file_does_not() {
    let scratch = Scratch::new("folder_single");
    let dir = scratch.path("one");
    std::fs::create_dir_all(&dir).unwrap();
    let csv = dir.join("age.csv");
    std::fs::write(&csv, "entity,age-months\nsrc/a.rs,2\n").unwrap();

    let from_folder = scratch.path("folder.improv");
    let out = run_import(&dir, &from_folder, &[]);
    assert!(out.status.success(), "{}", stderr_of(&out));
    let doc = std::fs::read_to_string(&from_folder).unwrap();
    assert!(doc.contains("## Category: File\n- age\n"), "{doc}");
    assert!(doc.lines().any(|l| l == "File: filter, age"), "{doc}");
    assert!(
        doc.contains("File=age, _Measure=age-months, entity=|src/a.rs| = 2"),
        "{doc}"
    );

    let from_file = scratch.path("file.improv");
    let out = run_import(&csv, &from_file, &[]);
    assert!(out.status.success(), "{}", stderr_of(&out));
    let doc = std::fs::read_to_string(&from_file).unwrap();
    assert!(
        !doc.contains("File"),
        "a lone file keeps today's shape: {doc}"
    );
}