//! Undo/redo, the timeline, deletion and selection.

use serde_json::{Value, json};
use solvecraft_doc::{Feature, FeatureKind};

use super::CommandSpec;
use crate::params::{bad, bool_, num, str_, string_list};
use crate::{EngineError, Result, Sel, Session, Snapshot};

pub static COMMANDS: &[CommandSpec] = &[
    CommandSpec::new("edit.undo", "Undo", undo).icon("undo").key("Ctrl+Z").noundo(),
    CommandSpec::new("edit.redo", "Redo", redo).icon("redo").key("Ctrl+Y").noundo(),
    CommandSpec::new("timeline.compute_all", "Compute All", compute_all).at("SOLID", "MODIFY").icon("compute").noundo(),
    CommandSpec::new("timeline.delete", "Delete", delete)
        .at("SOLID", "MODIFY")
        .icon("delete")
        .key("Delete")
        .params("features: [id or name] (a sketch takes its dependent features with it)"),
    CommandSpec::new("timeline.rename", "Rename", rename).params("feature: id|name, name"),
    CommandSpec::new("timeline.rollback", "Move Timeline Marker", rollback).params("position: number of features to keep active (omit = end)"),
    CommandSpec::new("timeline.roll_to", "Roll History Marker", rollback)
        .params("position: number of features to keep active (omit = end) | feature: id|name (the marker goes right after it)"),
    CommandSpec::new("timeline.reorder", "Reorder Feature", reorder)
        .params("feature: id|name, position: its new index; refused when a feature that worked would fail"),
    CommandSpec::new("timeline.redefine", "Edit Feature", redefine)
        .params("feature: id|name, command: the feature's command id, params: its parameters (the feature is rebuilt in place)"),
    CommandSpec::new("timeline.dependents", "Feature Dependents", dependents)
        .noundo()
        .params("feature: id|name → features deleted with it, and features that would fail without it"),
    CommandSpec::new("timeline.suppress", "Suppress Feature", suppress).params("feature: id|name, suppressed?: bool (default toggles)"),
    CommandSpec::new("timeline.edit", "Edit Feature", edit_feature)
        .params("feature: id|name, set: {fields to change, e.g. {\"extent\": {\"distance\": \"30\"}}}"),
    CommandSpec::new("select.set", "Select", select_set)
        .noundo()
        .params("items: [{type: body|edge|face|feature|sketch_curve|sketch_point|profile, …}], add?: bool"),
    CommandSpec::new("select.clear", "Clear Selection", select_clear).noundo(),
];

fn undo(s: &mut Session, _p: &Value) -> Result<Value> {
    let Some(prev) = s.undo.pop() else { return Err(EngineError::Other("nothing to undo".into())) };
    let label = prev.label.clone();
    s.redo.push(Snapshot { label: label.clone(), doc: s.doc.clone(), active_sketch: s.active_sketch });
    s.doc = prev.doc;
    s.active_sketch = prev.active_sketch;
    s.selection.clear();
    s.refresh();
    Ok(json!({"undone": label}))
}

fn redo(s: &mut Session, _p: &Value) -> Result<Value> {
    let Some(next) = s.redo.pop() else { return Err(EngineError::Other("nothing to redo".into())) };
    let label = next.label.clone();
    s.undo.push(Snapshot { label: label.clone(), doc: s.doc.clone(), active_sketch: s.active_sketch });
    s.doc = next.doc;
    s.active_sketch = next.active_sketch;
    s.selection.clear();
    s.refresh();
    Ok(json!({"redone": label}))
}

fn compute_all(s: &mut Session, _p: &Value) -> Result<Value> {
    s.model = solvecraft_doc::Model::new();
    s.refresh();
    let errors = s.model.results.iter().filter(|r| r.error.is_some()).count();
    Ok(json!({"features": s.model.results.len(), "errors": errors}))
}

fn feature_id(s: &Session, v: Option<&Value>, cmd: &str) -> Result<u64> {
    let key = match v {
        Some(Value::Number(n)) => n.to_string(),
        Some(Value::String(x)) => x.clone(),
        _ => return Err(bad(cmd, "`feature` must be an id or name")),
    };
    s.doc.find_feature(&key).map(|f| f.id).ok_or_else(|| bad(cmd, format!("no feature `{key}`")))
}

fn delete(s: &mut Session, p: &Value) -> Result<Value> {
    let cmd = "timeline.delete";
    let mut keys = string_list(p, "features");
    if let Some(Value::Array(a)) = p.get("features") {
        keys.extend(a.iter().filter_map(Value::as_u64).map(|n| n.to_string()));
    }
    if let Some(f) = p.get("feature") {
        keys.push(match f {
            Value::Number(n) => n.to_string(),
            Value::String(x) => x.clone(),
            _ => String::new(),
        });
    }
    if keys.is_empty() {
        return Err(bad(cmd, "`features` must list features"));
    }
    let mut gone = Vec::new();
    for k in keys {
        let Some(id) = s.doc.find_feature(&k).map(|f| f.id) else {
            if gone.is_empty() {
                return Err(bad(cmd, format!("no feature `{k}`")));
            }
            continue;
        };
        gone.extend(s.doc_mut().delete_feature(id)?);
    }
    if s.active_sketch.is_some_and(|a| gone.contains(&a)) {
        s.active_sketch = None;
    }
    s.selection.clear();
    Ok(json!({"deleted": gone}))
}

fn rename(s: &mut Session, p: &Value) -> Result<Value> {
    let cmd = "timeline.rename";
    let id = feature_id(s, p.get("feature"), cmd)?;
    let name =
        str_(p, "name").map(str::trim).filter(|n| !n.is_empty() && n.len() <= 128).ok_or_else(|| bad(cmd, "`name` must be 1…128 characters"))?;
    if s.doc.features.iter().any(|f| f.name == name && f.id != id) {
        return Err(bad(cmd, format!("another feature is called `{name}`")));
    }
    if let Some(f) = s.doc_mut().feature_mut(id) {
        f.name = name.to_string();
    }
    Ok(json!({"feature": id, "name": name}))
}

fn rollback(s: &mut Session, p: &Value) -> Result<Value> {
    let n = s.doc.features.len();
    let pos = match p.get("feature") {
        Some(f) => {
            let id = feature_id(s, Some(f), "timeline.roll_to")?;
            s.doc.feature_index(id).map(|i| i + 1)
        }
        None => num(p, "position").map(|x| x.max(0.0) as usize),
    };
    s.doc_mut().marker = match pos {
        Some(k) if k < n => Some(k),
        _ => None,
    };
    s.selection.clear();
    Ok(json!({"marker": s.doc.marker.unwrap_or(n), "features": n}))
}

fn suppress(s: &mut Session, p: &Value) -> Result<Value> {
    let id = feature_id(s, p.get("feature"), "timeline.suppress")?;
    let want = bool_(p, "suppressed");
    let f = s.doc_mut().feature_mut(id).ok_or_else(|| EngineError::Other("feature".into()))?;
    f.suppressed = want.unwrap_or(!f.suppressed);
    Ok(json!({"feature": id, "suppressed": f.suppressed}))
}

fn merge(dst: &mut Value, src: &Value, depth: usize) {
    if depth > 16 {
        return;
    }
    match (dst, src) {
        (Value::Object(d), Value::Object(s)) => {
            for (k, v) in s {
                match d.get_mut(k) {
                    Some(slot) if slot.is_object() && v.is_object() => merge(slot, v, depth + 1),
                    _ => {
                        d.insert(k.clone(), v.clone());
                    }
                }
            }
        }
        (d, s) => *d = s.clone(),
    }
}

fn edit_feature(s: &mut Session, p: &Value) -> Result<Value> {
    let cmd = "timeline.edit";
    let id = feature_id(s, p.get("feature"), cmd)?;
    let set = p.get("set").filter(|v| v.is_object()).ok_or_else(|| bad(cmd, "`set` must be an object of fields"))?;
    let f = s.doc.feature(id).cloned().ok_or_else(|| bad(cmd, "feature"))?;
    let mut v = serde_json::to_value(&f).map_err(|e| EngineError::Other(e.to_string()))?;
    merge(&mut v, set, 0);
    let mut nf: Feature = serde_json::from_value(v).map_err(|e| bad(cmd, format!("invalid feature: {e}")))?;
    nf.id = f.id;
    if std::mem::discriminant(&nf.kind) != std::mem::discriminant(&f.kind) {
        return Err(bad(cmd, "the feature type cannot change"));
    }
    if let (FeatureKind::Sketch { sketch: a, .. }, FeatureKind::Sketch { sketch: b, .. }) = (&nf.kind, &f.kind)
        && a != b
    {
        return Err(bad(cmd, "edit sketch geometry with the sketch commands"));
    }
    // New edges for a blend: remember where they sit now (in the model before the feature).
    if let (
        FeatureKind::Fillet { edges: a, body, .. } | FeatureKind::Chamfer { edges: a, body, .. },
        FeatureKind::Fillet { edges: b, .. } | FeatureKind::Chamfer { edges: b, .. },
    ) = (&nf.kind, &f.kind)
        && a != b
    {
        let before = s.model.state_before(id);
        nf.edge_refs = solvecraft_doc::edge_refs(&before, body, a);
        nf.edge_names = solvecraft_doc::edge_names_for(&before, body, a);
    }
    // New face points: their faces' names now.
    if nf.kind.face_points() != f.kind.face_points() {
        nf.face_names = solvecraft_doc::naming::face_names_at(&s.model.state_before(id), &nf.kind.face_points());
    }
    if let Some(slot) = s.doc_mut().feature_mut(id) {
        *slot = nf;
    }
    s.refresh();
    if let Some(e) = s.model.result(id).and_then(|r| r.error.clone()) {
        return Err(EngineError::Other(e));
    }
    Ok(json!({"feature": id, "recomputed": s.model.last_recomputed}))
}

fn select_set(s: &mut Session, p: &Value) -> Result<Value> {
    let items = p.get("items").and_then(Value::as_array).cloned().unwrap_or_default();
    if items.len() > 10_000 {
        return Err(bad("select.set", "too many items"));
    }
    let mut sel: Vec<Sel> = Vec::new();
    for it in items {
        let one: Sel = serde_json::from_value(it).map_err(|e| bad("select.set", e.to_string()))?;
        sel.push(one);
    }
    if !bool_(p, "add").unwrap_or(false) {
        s.selection.clear();
    }
    for x in sel {
        if !s.selection.contains(&x) {
            s.selection.push(x);
        }
    }
    s.revision += 1;
    Ok(json!({"selected": s.selection.len()}))
}

fn select_clear(s: &mut Session, _p: &Value) -> Result<Value> {
    s.selection.clear();
    s.revision += 1;
    Ok(json!({"selected": 0}))
}

/// Features that worked in `before` and fail in `after`: (name, error).
fn newly_broken(before: &solvecraft_doc::Model, after: &solvecraft_doc::Model) -> Vec<(String, String)> {
    after
        .results
        .iter()
        .filter_map(|r| {
            let e = r.error.clone()?;
            let was_ok = before.result(r.id).is_some_and(|b| b.error.is_none() && !b.skipped);
            was_ok.then(|| (r.name.clone(), e))
        })
        .collect()
}

fn reorder(s: &mut Session, p: &Value) -> Result<Value> {
    let cmd = "timeline.reorder";
    let id = feature_id(s, p.get("feature"), cmd)?;
    let n = s.doc.features.len();
    let to = num(p, "position").map(|x| x.max(0.0) as usize).ok_or_else(|| bad(cmd, "`position` must be a number"))?.min(n.saturating_sub(1));
    let from = s.doc.feature_index(id).ok_or_else(|| bad(cmd, "feature"))?;
    if from == to {
        return Ok(json!({"feature": id, "position": to}));
    }
    let mut next = (*s.doc).clone();
    let f = next.features.remove(from);
    let name = f.name.clone();
    next.features.insert(to, f);
    // Everything that evaluated before must still evaluate.
    let mut after = solvecraft_doc::Model::new();
    after.evaluate(&next);
    let broken = newly_broken(&s.model, &after);
    if !broken.is_empty() {
        let list: Vec<String> = broken.iter().map(|(n, e)| format!("{n} ({e})")).collect();
        return Err(bad(cmd, format!("moving {name} there breaks {}", list.join("; "))));
    }
    *s.doc_mut() = next;
    Ok(json!({"feature": id, "position": to}))
}

fn redefine(s: &mut Session, p: &Value) -> Result<Value> {
    let cmd = "timeline.redefine";
    let id = feature_id(s, p.get("feature"), cmd)?;
    let cid = str_(p, "command").ok_or_else(|| bad(cmd, "`command` must name the feature's command"))?;
    let spec = super::find_command(cid).ok_or_else(|| bad(cmd, format!("no command `{cid}`")))?;
    if spec.id.starts_with("timeline.") || spec.id.starts_with("select.") || spec.id.starts_with("sketch.") {
        return Err(bad(cmd, format!("`{cid}` does not make a feature")));
    }
    let params = p.get("params").cloned().unwrap_or_else(|| json!({}));
    let idx = s.doc.feature_index(id).ok_or_else(|| bad(cmd, "feature"))?;
    let old = s.doc.feature(id).cloned().ok_or_else(|| bad(cmd, "feature"))?;
    let marker = s.doc.marker;
    // Build the new definition where the feature sits, against the model before it.
    s.doc_mut().marker = Some(idx);
    s.refresh();
    let r = (spec.run)(s, &params);
    let made = r.as_ref().ok().and_then(|v| v.get("feature")).and_then(Value::as_u64);
    let new = made.and_then(|nid| s.doc.feature(nid).cloned());
    if let Some(nid) = made {
        s.doc_mut().features.retain(|f| f.id != nid);
    }
    s.doc_mut().marker = marker;
    r?;
    let new = new.ok_or_else(|| bad(cmd, format!("`{cid}` did not make a feature")))?;
    if std::mem::discriminant(&new.kind) != std::mem::discriminant(&old.kind) {
        return Err(bad(cmd, format!("{} is not a {} feature", old.name, cid)));
    }
    if let Some(slot) = s.doc_mut().feature_mut(id) {
        slot.kind = new.kind;
    }
    s.refresh();
    if let Some(e) = s.model.result(id).and_then(|r| r.error.clone()) {
        return Err(EngineError::Other(e));
    }
    Ok(json!({"feature": id, "recomputed": s.model.last_recomputed}))
}

fn dependents(s: &mut Session, p: &Value) -> Result<Value> {
    let cmd = "timeline.dependents";
    let id = feature_id(s, p.get("feature"), cmd)?;
    let mut next = (*s.doc).clone();
    let gone = next.delete_feature(id)?;
    let mut after = solvecraft_doc::Model::new();
    after.evaluate(&next);
    let names = |ids: &[u64]| -> Vec<String> { ids.iter().filter(|x| **x != id).filter_map(|x| s.doc.feature(*x).map(|f| f.name.clone())).collect() };
    let broken: Vec<String> = newly_broken(&s.model, &after).into_iter().map(|(n, _)| n).collect();
    Ok(json!({"deleted_with_it": names(&gone), "would_fail": broken}))
}