//! 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!("improvise-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}"
    );
}