//! Live controls in an exported program (`primitives_to_rust_app_live`): a program with a
//! step loop reads `n3=0.5` lines on standard input and applies each at the top of its next
//! pass, refusing what the control cannot take.
//!
//! Each program here is compiled with rustc and run. With no line arriving (standard input
//! empty, closed, or open and silent) its stdout is byte for byte the stdout of the program
//! built without live controls: what T1 computes for the baked values does not change. With
//! a line, the control takes the new value at the pass the program says (on stderr), and
//! every pass from then on computes with it.

use flowrs_core::Graph;
use flowrs_core::NodeId;
use flowrs_core::codegen::rust::{
    LiveControl, LiveKind, has_step_loop, live_kind, primitives_to_rust_app,
    primitives_to_rust_app_live,
};
use flowrs_core::graph::dsl::parse_graph;
use std::io::Write;
use std::path::PathBuf;
use std::process::{Command, Stdio};

fn graph(text: &str) -> Graph {
    parse_graph(text).expect("graph text").graph
}

/// A counter: each pass adds the step (n0) to what the last pass summed.
const COUNTER: &str = "let n0 = FloatLiteral { value: 1 };\n\
    let n1 = math.add(a: n1.sum.copy().prev(), b: n0.value);\n\
    let n2 = Indicator(input: n1.sum) { label: \"Count\" };";

/// The counter, paced: each pass waits 40 ms, so a line has time to arrive mid-run.
const PACED: &str = "let n0 = FloatLiteral { value: 1 };\n\
    let n1 = math.add(a: n1.sum.copy().prev(), b: n0.value);\n\
    let n2 = flow.delay { duration_s: 0.04 };\n\
    let n3 = Indicator(input: n1.sum) { label: \"Count\" };";

fn step(min: Option<f64>, max: Option<f64>) -> LiveControl {
    LiveControl {
        node: NodeId(0),
        kind: LiveKind::Number,
        min,
        max,
        options: Vec::new(),
    }
}

/// Build `src` with rustc into a scratch directory; the binary's path.
fn build(src: &str, name: &str) -> PathBuf {
    let dir = std::env::temp_dir().join(format!("flowrs_live_{}_{name}", std::process::id()));
    std::fs::create_dir_all(&dir).unwrap();
    let main = dir.join("main.rs");
    let bin = dir.join("prog");
    std::fs::write(&main, src).unwrap();
    let out = Command::new("rustc")
        .args(["--edition", "2021", "-O", "-o"])
        .arg(&bin)
        .arg(&main)
        .output()
        .expect("rustc runs");
    assert!(
        out.status.success(),
        "{name} does not compile:\n{}\n{src}",
        String::from_utf8_lossy(&out.stderr)
    );
    // The live machinery adds no warning of its own (dead code, an unused binding).
    let warnings = String::from_utf8_lossy(&out.stderr);
    for ours in [
        "flowrs_controls",
        "ctl_n",
        "live_controls",
        "never used",
        "dead_code",
    ] {
        assert!(
            !warnings.contains(ours),
            "{name}: a warning about {ours}:\n{warnings}"
        );
    }
    bin
}

/// How the program's standard input is given.
enum Input<'a> {
    Null,
    Closed,
    Silent,
    Lines(&'a str),
}

/// Run `bin` with `input`; its stdout and stderr.
fn run(bin: &PathBuf, input: Input) -> (String, String) {
    let mut cmd = Command::new(bin);
    cmd.stdout(Stdio::piped()).stderr(Stdio::piped());
    cmd.stdin(match input {
        Input::Null => Stdio::null(),
        _ => Stdio::piped(),
    });
    let mut child = cmd.spawn().expect("it runs");
    // Kept open while the program runs, for `Silent` and `Lines`.
    let mut held = None;
    match input {
        Input::Null => {}
        Input::Closed => drop(child.stdin.take()),
        Input::Silent => held = child.stdin.take(),
        Input::Lines(text) => {
            let mut w = child.stdin.take().unwrap();
            w.write_all(text.as_bytes()).unwrap();
            w.flush().unwrap();
            held = Some(w);
        }
    }
    let out = child.wait_with_output().expect("it ends");
    drop(held);
    assert!(out.status.success(), "{out:?}");
    (
        String::from_utf8(out.stdout).unwrap(),
        String::from_utf8(out.stderr).unwrap(),
    )
}

/// The counts a run printed, in order.
fn counts(stdout: &str) -> Vec<f64> {
    stdout
        .lines()
        .filter_map(|l| l.strip_prefix(">Count:"))
        .map(|v| v.parse().unwrap())
        .collect()
}

#[test]
fn a_control_is_read_from_its_own_binding_set_at_the_top_of_each_pass() {
    let g = graph(COUNTER);
    assert!(has_step_loop(&g));
    let p = primitives_to_rust_app_live(&g, 5, &[], &[step(Some(0.0), Some(5.0))]).unwrap();
    for want in [
        "let mut live_controls = flowrs_controls::listen();",
        "let mut ctl_n0 = 1.0f64;",
        "for (name, value) in live_controls.pending() {",
        "\"n0\" => flowrs_controls::number(&mut ctl_n0, &name, &value, Some(0.0), Some(5.0), false, pass),",
        "_ => flowrs_controls::refuse(&name, &value, \"it is not a control of this program\", pass),",
        "mod flowrs_controls {",
        "pub fn number<T: std::str::FromStr>(",
    ] {
        assert!(p.contains(want), "{want} missing from:\n{p}");
    }
    // The binding is declared before the loop, and set before any node of a pass runs.
    let decl = p.find("let mut ctl_n0").unwrap();
    let lp = p.find("for _step in 0..5 {").unwrap();
    let set = p.find("live_controls.pending()").unwrap();
    let read = p.find("= ctl_n0;").unwrap();
    assert!(decl < lp && lp < set && set < read, "{p}");
    // Only the setters its controls use: no dead code in the program.
    assert!(
        !p.contains("pub fn boolean") && !p.contains("pub fn text("),
        "{p}"
    );
    // No controls: the program is exactly the one built without them.
    assert_eq!(
        primitives_to_rust_app_live(&g, 5, &[], &[]).unwrap(),
        primitives_to_rust_app(&g, 5, &[]).unwrap()
    );
}

#[test]
fn a_program_that_runs_once_takes_no_controls() {
    // One pass of the loop: a change would never apply.
    let g = graph(COUNTER);
    assert!(
        primitives_to_rust_app_live(&g, 1, &[], &[step(None, None)])
            .unwrap_err()
            .contains("one pass")
    );
    // No step loop at all.
    let once = graph(
        "let n0 = FloatLiteral { value: 2 };\nlet n1 = Indicator(input: n0.value) { label: \"Two\" };",
    );
    assert!(!has_step_loop(&once));
    assert!(primitives_to_rust_app_live(&once, 5, &[], &[step(None, None)]).is_err());
}

#[test]
fn what_a_control_holds_while_its_program_runs() {
    let mut g = graph(
        "let n0 = IntLiteral { value: 3 };\n\
         let n1 = FloatLiteral { value: 0.5 };\n\
         let n2 = BoolLiteral { value: true };\n\
         let n3 = StringLiteral { value: \"sine\" };",
    );
    let range = g.add_node("Control", 0.0, 0.0);
    let plain = g.add_node("Control", 0.0, 0.0);
    let add = g.add_node("Add", 0.0, 0.0);
    for (id, k, v) in [
        (range, "value", "1,2"),
        (range, "widget", "range"),
        (plain, "value", "7"),
    ] {
        g.get_node_mut(id)
            .unwrap()
            .properties
            .insert(k.into(), v.into());
    }
    assert_eq!((range, plain, add), (NodeId(4), NodeId(5), NodeId(6)));
    let k = |id| live_kind(&g, NodeId(id));
    assert_eq!(k(0), Ok(LiveKind::Integer));
    assert_eq!(k(1), Ok(LiveKind::Number));
    assert_eq!(k(2), Ok(LiveKind::Bool));
    assert_eq!(k(3), Ok(LiveKind::Text));
    assert!(k(4).unwrap_err().contains("several values"));
    assert!(matches!(k(5), Ok(LiveKind::Integer | LiveKind::Number)));
    assert!(k(6).unwrap_err().contains("not a control"));
    assert!(k(99).is_err());
}

/// The parity proof: with no line arriving, however standard input is given, the live
/// program prints byte for byte what the program built without live controls prints.
#[test]
fn with_no_change_the_program_prints_exactly_what_it_did_before() {
    for (name, text, steps) in [("counter", COUNTER, 8), ("paced", PACED, 6)] {
        let g = graph(text);
        let before = build(
            &primitives_to_rust_app(&g, steps, &[]).unwrap(),
            &format!("{name}_before"),
        );
        let live = build(
            &primitives_to_rust_app_live(&g, steps, &[], &[step(Some(0.0), Some(5.0))]).unwrap(),
            &format!("{name}_live"),
        );
        let (want, _) = run(&before, Input::Null);
        assert!(!want.is_empty(), "{name} printed nothing");
        for (how, input) in [
            ("stdin null", Input::Null),
            ("stdin closed", Input::Closed),
            ("stdin open and silent", Input::Silent),
        ] {
            let (got, err) = run(&live, input);
            assert_eq!(got, want, "{name}, {how}: stdout differs");
            assert!(err.is_empty(), "{name}, {how}: {err}");
        }
    }
}

/// A change applies at the top of the next pass, and from then on; what the control
/// cannot take is refused on stderr, and the control keeps its value.
#[test]
fn a_change_applies_at_the_next_pass_and_a_bad_one_is_refused() {
    let g = graph(PACED);
    let steps = 30;
    let live = build(
        &primitives_to_rust_app_live(&g, steps, &[], &[step(Some(0.0), Some(5.0))]).unwrap(),
        "paced_change",
    );
    let (out, err) = run(
        &live,
        Input::Lines("n0=9\nn7=1\nn0=abc\nnot a line\n$n0=3\n"),
    );
    // The refusals, each saying why, and the change, saying from which pass.
    assert!(err.contains("n0 = 9 refused at pass"), "{err}");
    assert!(err.contains("it is above 5"), "{err}");
    assert!(
        err.contains("n7 = 1 refused at pass") && err.contains("not a control of this program"),
        "{err}"
    );
    assert!(
        err.contains("n0 = abc refused at pass") && err.contains("not a number"),
        "{err}"
    );
    assert!(err.contains("`not a line` is not name=value"), "{err}");
    let from: usize = err
        .lines()
        .find_map(|l| l.strip_prefix("flowrs: n0 = 3 from pass "))
        .expect("the change was taken")
        .trim()
        .parse()
        .unwrap();
    // Every pass before it added 1; it and every pass after, 3.
    let got = counts(&out);
    assert_eq!(got.len(), steps, "{out}");
    let mut sum = 0.0;
    for (i, c) in got.iter().enumerate() {
        let pass = i + 1;
        sum += if pass < from { 1.0 } else { 3.0 };
        assert_eq!(
            *c, sum,
            "pass {pass} (the change from pass {from}): {got:?}"
        );
    }
    assert!(from < steps, "the change came in time: pass {from}");
}

#[test]
fn a_switch_a_whole_number_and_text_each_take_their_own_kind() {
    // Each control feeds an Indicator, so what it holds each pass is printed.
    let g = graph(
        "let n0 = IntLiteral { value: 2 };\n\
         let n1 = BoolLiteral { value: false };\n\
         let n2 = StringLiteral { value: \"sine\" };\n\
         let n8 = FloatLiteral { value: 1 };\n\
         let n3 = math.add(a: n3.sum.copy().prev(), b: n8.value);\n\
         let n4 = flow.delay { duration_s: 0.03 };\n\
         let n5 = Indicator(input: n0.value) { label: \"Whole\" };\n\
         let n6 = Indicator(input: n1.value) { label: \"Switch\" };\n\
         let n7 = Indicator(input: n2.value) { label: \"Shape\" };",
    );
    let c = |id: u64, kind, options: &[&str]| LiveControl {
        node: NodeId(id),
        kind,
        min: Some(0.0),
        max: Some(10.0),
        options: options.iter().map(|s| s.to_string()).collect(),
    };
    let controls = [
        c(0, LiveKind::Integer, &[]),
        c(1, LiveKind::Bool, &[]),
        c(2, LiveKind::Text, &["sine", "square"]),
    ];
    let src = primitives_to_rust_app_live(&g, 20, &[], &controls).unwrap();
    let bin = build(&src, "kinds");
    let (out, err) = run(
        &bin,
        Input::Lines("n0=2.5\nn0=7\nn1=maybe\nn1=true\nn2=saw\nn2=square\n"),
    );
    assert!(
        err.contains("n0 = 2.5 refused") && err.contains("not a whole number"),
        "{err}"
    );
    assert!(err.contains("n1 = maybe refused"), "{err}");
    assert!(
        err.contains("n2 = saw refused") && err.contains("not one of"),
        "{err}"
    );
    for set in [
        "n0 = 7 from pass",
        "n1 = true from pass",
        "n2 = square from pass",
    ] {
        assert!(err.contains(set), "{set}: {err}");
    }
    let last = |name: &str| {
        out.lines()
            .filter_map(|l| l.strip_prefix(&format!(">{name}:")))
            .next_back()
            .unwrap()
            .to_string()
    };
    assert_eq!(last("Whole"), "7");
    assert_eq!(last("Switch"), "1");
    assert_eq!(last("Shape"), "\"square\"|t");
}