//! When an element has MORE THAN ONE plateau, does `rest_plateau()` pick the
//! wrong one — and is that the 21.9 % residual?
//!
//! `rest_vs_settle` found that among elements holding a pose ACROSS the screen's
//! settle instant, `pose_at(settle)` and `rest()` still disagree 21.9 % of the
//! time. I hypothesised that `rest_plateau()` picks the **longest** run (it does —
//! `len >= any_len`), which need not be the run covering the settle instant.
//!
//! ⚠️ **Control**: on elements with exactly ONE plateau that covers the settle
//! instant, the two MUST agree. If they do not, the hypothesis is not the
//! explanation and something else is wrong.
//!
//!     cargo run -p sylpheed-formats --example plateau_choice
use std::path::PathBuf;
use sylpheed_formats::{pak::PakArchive, ui_layout};

fn main() {
    let root = PathBuf::from(std::env::var("SYLPHEED_DISC").expect("SYLPHEED_DISC"));
    let mut paks: Vec<PathBuf> = std::fs::read_dir(root.join("dat"))
        .expect("dat/")
        .filter_map(|e| e.ok().map(|e| e.path()))
        .filter(|p| p.extension().is_some_and(|x| x == "pak"))
        .collect();
    paks.sort();
    let (mut one_cov, mut one_agree) = (0usize, 0usize); // control
    let (mut multi_cov, mut multi_agree, mut multi_wrongrun) = (0usize, 0usize, 0usize);
    for pak in &paks {
        let Ok(ar) = PakArchive::open(pak) else {
            continue;
        };
        for e in ar.entries() {
            let Ok(by) = ar.read(e) else { continue };
            let Some(b) = ui_layout::parse_build(&by) else {
                continue;
            };
            let Some((lo, hi)) = b.settle_window() else {
                continue;
            };
            if hi - lo < 10 {
                continue;
            }
            let st = lo + (hi - lo) / 2;
            for el in &b.elements {
                let k = &el.keyframes;
                if k.len() < 2 {
                    continue;
                }
                let same = |a: &ui_layout::Keyframe, c: &ui_layout::Keyframe| {
                    a.fade == c.fade
                        && a.scale_x == c.scale_x
                        && a.scale_y == c.scale_y
                        && a.tint == c.tint
                        && a.x == c.x
                        && a.y == c.y
                };
                // enumerate maximal runs of length >= 2, with their time spans
                let mut runs: Vec<(usize, usize)> = Vec::new();
                let mut i = 0usize;
                while i < k.len() {
                    let mut j = i;
                    while j + 1 < k.len() && same(&k[j], &k[j + 1]) {
                        j += 1
                    }
                    if j - i + 1 >= 2 {
                        runs.push((i, j))
                    }
                    i = j + 1;
                }
                if runs.is_empty() {
                    continue;
                }
                let covers = |&(a, c): &(usize, usize)| match (k[a].time, k[c].time) {
                    (Some(t0), Some(t1)) => t0 <= st && st <= t1,
                    _ => false,
                };
                let covering: Vec<_> = runs.iter().filter(|r| covers(r)).collect();
                if covering.is_empty() {
                    continue;
                }
                let (Some(r), Some(s)) = (el.rest(), el.pose_at(st)) else {
                    continue;
                };
                let agree = r.fade == s.fade
                    && r.x == s.x
                    && r.y == s.y
                    && r.scale_x == s.scale_x
                    && r.scale_y == s.scale_y;
                if runs.len() == 1 {
                    one_cov += 1;
                    if agree {
                        one_agree += 1
                    }
                } else {
                    multi_cov += 1;
                    if agree {
                        multi_agree += 1
                    } else {
                        // did rest() land on a run that does NOT cover settle?
                        let on_covering = covering.iter().any(|&&(a, c)| {
                            (a..=c).any(|idx| {
                                let kk = &k[idx];
                                kk.fade == r.fade
                                    && kk.x == r.x
                                    && kk.y == r.y
                                    && kk.scale_x == r.scale_x
                                    && kk.scale_y == r.scale_y
                            })
                        });
                        if !on_covering {
                            multi_wrongrun += 1
                        }
                    }
                }
            }
        }
    }
    println!("CONTROL — exactly ONE plateau, and it covers the settle instant:");
    println!(
        "  {one_cov} elements, rest() and pose_at(settle) agree on {one_agree} ({:.1} %)",
        100.0 * one_agree as f64 / one_cov.max(1) as f64
    );
    println!("\nTEST — MORE THAN ONE plateau, at least one covering the settle instant:");
    println!(
        "  {multi_cov} elements, agree on {multi_agree} ({:.1} %)",
        100.0 * multi_agree as f64 / multi_cov.max(1) as f64
    );
    println!(
        "  of the {} disagreements, rest() landed on a run that does NOT cover",
        multi_cov - multi_agree
    );
    println!("  the settle instant: {multi_wrongrun}");
    println!("\n--- END (if this line is missing, the run did not finish) ---");
}