//! The flat pattern's DXF keeps ellipses and free-form curves as ELLIPSE and SPLINE entities.

use std::f64::consts::{PI, TAU};

use serde_json::{Value, json};
use solidcraft_geom::{Seg2, Vec2};

use crate::Session;

fn run(s: &mut Session, id: &str, p: Value) -> Value {
    match s.execute(id, &p) {
        Ok(v) => v,
        Err(e) => panic!("{id} {p}: {e}"),
    }
}

/// A 100 × 60 base flange (the default 2.5 mm rule) with `curves` drawn in a sketch and cut through it.
fn plate_with(curves: &[(&str, Value)]) -> Session {
    let mut s = Session::default();
    run(&mut s, "sketch.create", json!({"plane": "XY", "name": "Base"}));
    run(&mut s, "sketch.rectangle.two_point", json!({"p0": [0, 0], "p1": [100, 60]}));
    run(&mut s, "sketch.finish", json!({}));
    run(&mut s, "sheet.flange", json!({"sketch": "Base"}));
    run(&mut s, "sketch.create", json!({"plane": "XY", "name": "Cut"}));
    for (command, params) in curves {
        run(&mut s, command, params.clone());
    }
    run(&mut s, "sketch.finish", json!({}));
    run(&mut s, "solid.extrude", json!({"sketch": "Cut", "through_all": true, "operation": "cut", "direction": "symmetric"}));
    s
}

fn export(s: &mut Session, params: Value) -> String {
    run(s, "sheet.export_dxf", params)["dxf"].as_str().unwrap_or_default().to_string()
}

/// The entities of a DXF text: type and group codes.
type Entity = (String, Vec<(i32, String)>);

fn entities(dxf: &str) -> Vec<Entity> {
    let lines: Vec<&str> = dxf.lines().collect();
    let pairs: Vec<(i32, &str)> = lines.chunks(2).filter_map(|c| Some((c.first()?.trim().parse().ok()?, c.get(1)?.trim()))).collect();
    let start = pairs.iter().position(|p| *p == (2, "ENTITIES")).unwrap_or(0);
    let mut out: Vec<Entity> = Vec::new();
    for (code, value) in pairs.iter().skip(start + 1) {
        match (*code, *value) {
            (0, "ENDSEC") => break,
            (0, kind) => out.push((kind.to_string(), Vec::new())),
            _ => {
                if let Some(last) = out.last_mut() {
                    last.1.push((*code, value.to_string()));
                }
            }
        }
    }
    out
}

fn values(e: &Entity, code: i32) -> Vec<f64> {
    e.1.iter().filter(|(c, _)| *c == code).filter_map(|(_, v)| v.parse().ok()).collect()
}

fn count(es: &[Entity], kind: &str) -> usize {
    es.iter().filter(|e| e.0 == kind).count()
}

fn point(e: &Entity, code: i32) -> Vec2 {
    Vec2::new(values(e, code).first().copied().unwrap_or(f64::NAN), values(e, code + 10).first().copied().unwrap_or(f64::NAN))
}

/// All loops of the flat pattern (outlines, cut-outs, islands).
fn loops(s: &Session) -> Vec<solidcraft_geom::Loop2> {
    let regions = s.model.state().sheets[0].flat_regions().unwrap_or_default();
    regions.iter().flat_map(|r| std::iter::once(r.outer.clone()).chain(r.holes.clone())).collect()
}

/// The profiles of the DXF read into a new sketch: their areas, largest first.
fn reimported_areas(dxf: &str) -> Vec<f64> {
    let mut s = Session::default();
    let id = run(&mut s, "sketch.insert_dxf", json!({"text": dxf, "name": "Back"}))["sketch"].as_u64().unwrap_or(0);
    run(&mut s, "sketch.finish", json!({}));
    let mut areas: Vec<f64> = s.model.state().sketch(id).map(|ss| ss.profiles.iter().map(|p| p.area).collect()).unwrap_or_default();
    areas.sort_by(|a, b| b.total_cmp(a));
    areas
}

#[test]
fn an_elliptic_cut_out_is_one_ellipse() {
    let mut s = plate_with(&[("sketch.ellipse", json!({"center": [40, 30], "major": [55, 30], "minor_radius": 8}))]);
    let dxf = export(&mut s, json!({}));
    let es = entities(&dxf);
    // The four lines of the outline and one ELLIPSE: no other entity.
    assert_eq!((count(&es, "LINE"), count(&es, "ELLIPSE"), es.len()), (4, 1, 5), "{:?}", es.iter().map(|e| &e.0).collect::<Vec<_>>());
    // By hand: centre (40, 30), the major semi-axis 15 along x (to (55, 30) or (25, 30)), the
    // minor one 8, so the ratio is 8/15; the whole turn runs from parameter 0 to 2π.
    let e = es.iter().find(|e| e.0 == "ELLIPSE").unwrap();
    let (c, major) = (point(e, 10), point(e, 11));
    assert!(c.dist(Vec2::new(40.0, 30.0)) < 1e-9 && (major.x.abs() - 15.0).abs() < 1e-9 && major.y.abs() < 1e-9, "{c:?} {major:?}");
    assert!((values(e, 40)[0] - 8.0 / 15.0).abs() < 1e-9 && values(e, 41)[0] == 0.0 && (values(e, 42)[0] - TAU).abs() < 1e-9);
    assert_eq!(values(e, 230), [1.0]);
    // Our reader gets the same ellipse back, and the same plate: 6000 mm² less π·15·8.
    let read = solidcraft_io::read_dxf(&dxf).unwrap();
    assert!(read.iter().any(|g| matches!(g, solidcraft_io::Geom2::Ellipse { c, major, minor }
        if c.dist(Vec2::new(40.0, 30.0)) < 1e-9 && (major.dist(*c) - 15.0).abs() < 1e-9 && (minor - 8.0).abs() < 1e-9)));
    let areas = reimported_areas(&dxf);
    assert!(areas.len() == 2 && (areas[0] - (6000.0 - PI * 120.0)).abs() < 1e-6 && (areas[1] - PI * 120.0).abs() < 1e-6, "{areas:?}");
}

#[test]
fn a_spline_cut_out_is_the_splines_it_was() {
    let points = json!([[20, 15], [40, 45], [65, 40], [85, 20]]);
    let mut s = plate_with(&[("sketch.spline.fit_point", json!({"points": points})), ("sketch.line", json!({"points": [[85, 20], [20, 15]]}))]);
    let dxf = export(&mut s, json!({}));
    let es = entities(&dxf);
    // The cut-out's segments of the flat pattern, one entity each: its cubic pieces are SPLINEs
    // of degree 3 over the same four control points, its line a LINE.
    let hole: Vec<Seg2> = loops(&s).get(1).map(|l| l.segs.clone()).unwrap_or_default();
    let cubics: Vec<[Vec2; 4]> =
        hole.iter().filter_map(|g| if let Seg2::Cubic { p0, p1, p2, p3 } = g { Some([*p0, *p1, *p2, *p3]) } else { None }).collect();
    assert!(!cubics.is_empty() && cubics.len() + 1 == hole.len(), "{hole:?}");
    assert_eq!((count(&es, "LINE"), count(&es, "SPLINE"), es.len()), (5, cubics.len(), 5 + cubics.len()));
    for (spline, want) in es.iter().filter(|e| e.0 == "SPLINE").zip(&cubics) {
        assert_eq!((values(spline, 70), values(spline, 71), values(spline, 72), values(spline, 73)), (vec![8.0], vec![3.0], vec![8.0], vec![4.0]));
        assert_eq!(values(spline, 40), [0.0, 0.0, 0.0, 0.0, 1.0, 1.0, 1.0, 1.0]);
        let (xs, ys) = (values(spline, 10), values(spline, 20));
        assert!(want.iter().enumerate().all(|(i, p)| (xs[i] - p.x).abs() < 1e-9 && (ys[i] - p.y).abs() < 1e-9), "{xs:?} {ys:?} {want:?}");
    }
    // The same plate comes back.
    let areas = reimported_areas(&dxf);
    let plate = s.model.state().sheets[0].flat_regions().unwrap_or_default()[0].area();
    assert!((areas[0] - plate).abs() < 1e-6, "{areas:?} {plate}");
}

#[test]
fn text_is_splines_and_lines_not_chords() {
    let mut s = plate_with(&[("sketch.text", json!({"text": "AB", "at": [30, 20], "height": 12}))]);
    let dxf = export(&mut s, json!({}));
    let es = entities(&dxf);
    // One entity for each segment of the flat pattern: a straight one a LINE, a glyph's
    // quadratic and cubic curves SPLINEs of degree 2 and 3.
    let segs: Vec<Seg2> = loops(&s).iter().flat_map(|l| l.segs.clone()).collect();
    let n = |f: &dyn Fn(&Seg2) -> bool| segs.iter().filter(|g| f(g)).count();
    let (lines, quadratics, cubics) = (
        n(&|g| matches!(g, Seg2::Line { .. })),
        n(&|g| matches!(g, Seg2::Conic { w, .. } if (*w - 1.0).abs() < 1e-12)),
        n(&|g| matches!(g, Seg2::Cubic { .. })),
    );
    assert_eq!(lines + quadratics + cubics, segs.len(), "only lines and Béziers");
    assert_eq!((count(&es, "LINE"), count(&es, "SPLINE"), es.len()), (lines, quadratics + cubics, segs.len()));
    let degree = |d: f64| es.iter().filter(|e| e.0 == "SPLINE" && values(e, 71) == [d]).count();
    assert_eq!((degree(2.0), degree(3.0)), (quadratics, cubics));
    // The plate with the letters cut out comes back from the file with its area (the largest region; the islands inside the
    // letters come in no fixed order).
    let areas = reimported_areas(&dxf);
    let plate = s.model.state().sheets[0].flat_regions().unwrap_or_default().iter().map(|r| r.area()).fold(0.0, f64::max);
    assert!((areas[0] - plate).abs() < 1e-3, "{areas:?} {plate}");
}

#[test]
fn arcs_option_writes_only_lines_and_tangent_arcs_within_a_thousandth() {
    let mut s = plate_with(&[("sketch.ellipse", json!({"center": [40, 30], "major": [55, 30], "minor_radius": 8}))]);
    let dxf = export(&mut s, json!({"curves": "arcs"}));
    let es = entities(&dxf);
    assert!(es.iter().all(|e| e.0 == "LINE" || e.0 == "ARC"), "{:?}", es.iter().map(|e| &e.0).collect::<Vec<_>>());
    let arcs: Vec<(Vec2, f64, [Vec2; 2], Vec<Vec2>)> = es
        .iter()
        .filter(|e| e.0 == "ARC")
        .map(|e| {
            let (c, r, (a0, a1)) = (point(e, 10), values(e, 40)[0], (values(e, 50)[0].to_radians(), values(e, 51)[0].to_radians()));
            let sweep = (a1 - a0).rem_euclid(TAU);
            let samples = (0..=20).map(|k| c + Vec2::from_angle(a0 + sweep * f64::from(k) / 20.0) * r).collect::<Vec<Vec2>>();
            (c, r, [c + Vec2::from_angle(a0) * r, c + Vec2::from_angle(a1) * r], samples)
        })
        .collect();
    // Far fewer than the 336 chords of 0.001 mm.
    assert!(arcs.len() >= 8 && arcs.len() < 100, "{} arcs", arcs.len());
    // Distance to the ellipse ((x − 40)/15)² + ((y − 30)/8)² = 1, to first order |f| / |∇f|.
    let off = |p: Vec2| {
        let (x, y) = (p.x - 40.0, p.y - 30.0);
        let f = (x / 15.0).powi(2) + (y / 8.0).powi(2) - 1.0;
        f.abs() / Vec2::new(2.0 * x / 225.0, 2.0 * y / 64.0).len()
    };
    // (The joint of a biarc's two arcs lies within the tolerance of the curve, not on it.)
    for (_, _, ends, samples) in &arcs {
        let offs: Vec<f64> = samples.iter().map(|p| off(*p)).collect();
        assert!(offs.iter().all(|d| *d <= 1e-3 + 1e-6), "{ends:?}: {offs:?}");
    }
    // Tangent: at each joint the radii of the two arcs lie on one line.
    for (i, (c, r, ends, _)) in arcs.iter().enumerate() {
        for end in ends {
            let others: Vec<_> = arcs.iter().enumerate().filter(|(j, (_, _, e, _))| *j != i && e.iter().any(|q| q.dist(*end) < 1e-6)).collect();
            assert_eq!(others.len(), 1, "joint {end:?}");
            let (_, (c2, r2, _, _)) = others[0];
            assert!((*end - *c).cross(*end - *c2).abs() < 1e-6 * r * r2, "arcs are not tangent at {end:?}");
        }
    }
    // The plate, read back, is the exact one within the perimeter times 0.001 mm.
    let areas = reimported_areas(&dxf);
    assert!((areas[0] - (6000.0 - PI * 120.0)).abs() < 0.1, "{areas:?}");
}

#[test]
fn arcs_option_has_no_splines_for_text_and_the_curves_value_is_checked() {
    let mut s = plate_with(&[("sketch.text", json!({"text": "AB", "at": [30, 20], "height": 12}))]);
    let es = entities(&export(&mut s, json!({"curves": "ARCS"})));
    assert!(es.iter().all(|e| e.0 == "LINE" || e.0 == "ARC") && count(&es, "ARC") > 0);
    let exact = entities(&export(&mut s, json!({"curves": "exact"})));
    assert!(count(&exact, "SPLINE") > 0 && count(&exact, "ARC") == 0);
    assert!(s.execute("sheet.export_dxf", &json!({"curves": "chords"})).is_err());
}

#[test]
fn bend_lines_and_layers_are_still_there() {
    let mut s = plate_with(&[("sketch.ellipse", json!({"center": [40, 30], "major": [55, 30], "minor_radius": 8}))]);
    run(&mut s, "sheet.flange", json!({"edges": [[50, 0, 2.5]], "height": 20}));
    let out = run(&mut s, "sheet.export_dxf", json!({}));
    let es = entities(out["dxf"].as_str().unwrap_or_default());
    let on = |layer: &str| es.iter().filter(|e| e.1.contains(&(8, layer.to_string()))).count();
    assert_eq!(on("BEND_UP") + on("BEND_DOWN"), out["bends"].as_u64().unwrap_or(0) as usize);
    assert!(on("BEND_UP") + on("BEND_DOWN") > 0 && count(&es, "ELLIPSE") == 1 && on("OUTLINE") == es.len() - on("BEND_UP") - on("BEND_DOWN"));
}