//! Which keyless primitives have their paint position FORCED by occlusion?
//!
//! An opaque full-screen quad must sort below every element visible at any
//! instant it is opaque. Where that set is *every* other element, its position is
//! forced to first — derived from the file, not analogised from a neighbour.
//!
//! Controls, both measured in the running game and both reproduced here:
//!   * `palogo_eff0.prm` is measured painting FIRST — and comes out forced first.
//!   * `pteff00.prm` is measured painting LAST — and is forced below only a
//!     handful, so the constraint permits it on top.
//!
//! ⚠️ Assumes straight alpha-over blending. Blend mode is ❔ in
//! `ui-prm-primitives.md`; an additive quad at alpha 255 would not occlude.
use sylpheed_formats::{pak, ratc, ui_layout};

fn main() {
    let root =
        std::env::var("SYLPHEED_DISC").expect("set SYLPHEED_DISC to the extracted disc root");
    let mut paks: Vec<_> = std::fs::read_dir(format!("{root}/dat"))
        .expect("dat/")
        .flatten()
        .map(|e| e.path())
        .filter(|p| p.extension().and_then(|s| s.to_str()) == Some("pak"))
        .collect();
    paks.sort();
    let (mut forced, mut partial, mut free) = (0usize, 0usize, 0usize);
    let mut names: std::collections::BTreeMap<String, (usize, usize)> = Default::default();
    for p in &paks {
        let Ok(ar) = pak::PakArchive::open(p) else {
            continue;
        };
        for e in ar.entries() {
            let Ok(by) = ar.read(e) else { continue };
            if !ratc::is_ratc(&by) {
                continue;
            }
            let Some(b) = ui_layout::parse_build(&by) else {
                continue;
            };
            let tmax = b
                .elements
                .iter()
                .flat_map(|el| el.keyframes.iter().filter_map(|k| k.time))
                .max()
                .unwrap_or(0);
            if tmax == 0 {
                continue;
            }
            for el in &b.elements {
                if ui_layout::sprite_layer_key(&b, &by, el).is_some() {
                    continue;
                }
                // full-screen only: a quad that does not cover cannot occlude
                if el.pivot_x * 2 < 1280 || el.pivot_y * 2 < 720 {
                    continue;
                }
                let op: Vec<u32> = (0..=tmax)
                    .filter(|&t| el.pose_at(t).map(|k| k.fade >> 24) == Some(255))
                    .collect();
                if op.is_empty() {
                    continue;
                }
                let others: Vec<&ui_layout::Element> =
                    b.elements.iter().filter(|o| o.index != el.index).collect();
                if others.is_empty() {
                    continue;
                }
                let below = others
                    .iter()
                    .filter(|o| {
                        op.iter()
                            .any(|&t| o.pose_at(t).map(|k| k.fade >> 24).unwrap_or(0) > 0)
                    })
                    .count();
                let ent = names.entry(el.name.clone()).or_default();
                ent.1 += 1;
                if below == others.len() {
                    forced += 1;
                    ent.0 += 1
                } else if below > 0 {
                    partial += 1
                } else {
                    free += 1
                }
            }
        }
    }
    println!("keyless FULL-SCREEN primitives with an opaque interval:");
    println!("  position FORCED FIRST (below every other element) : {forced}");
    println!("  forced below SOME but not all                     : {partial}");
    println!("  occludes nothing                                  : {free}");
    println!("\nby name — instances forced first / total:");
    for (n, (f, t)) in &names {
        println!("  {n:>24}  {f:>4} / {t}");
    }
}