wasm4pm 26.6.12

use crate::models::*;
use crate::state::{get_or_init_state, StoredObject};
use crate::utilities::to_js_str;
use hashbrown::HashMap;
use itertools::Itertools;
use rustc_hash::FxHashMap;
use serde_json::json;
use std::collections::HashSet;
use wasm_bindgen::prelude::*;

/// Measure variant entropy and diversity in event log.
#[wasm_bindgen]
pub fn analyze_variant_complexity(
    eventlog_handle: &str,
    activity_key: &str,
) -> Result<JsValue, JsValue> {
    get_or_init_state().with_object(eventlog_handle, |obj| match obj {
        Some(StoredObject::EventLog(log)) => {
            let total = log.traces.len() as f64;

            // Single-pass: build variant counts with itertools::counts()
            let variants = log
                .traces
                .iter()
                .map(|trace| {
                    trace
                        .events
                        .iter()
                        .filter_map(|e| {
                            if let Some(AttributeValue::String(a)) = e.attributes.get(activity_key)
                            {
                                Some(a.clone())
                            } else {
                                None
                            }
                        })
                        .collect::<Vec<String>>()
                })
                .counts();

            // Shannon entropy — use mul_add to reduce rounding error (enables FMA)
            let entropy: f64 = variants.values().fold(0.0_f64, |acc, &count| {
                let p = count as f64 / total;
                // acc + (- p * log2(p))  =>  p.log2().mul_add(-p, acc)
                p.log2().mul_add(-p, acc)
            });

            let mut variant_counts: Vec<usize> = variants.values().copied().collect();
            variant_counts.sort_unstable_by(|a, b| b.cmp(a));
            let coverage_top_10: f64 = variant_counts
                .iter()
                .take(10)
                .map(|&v| v as f64 / total)
                .sum();

            let max_entropy = if variants.len() > 1 {
                (variants.len() as f64).log2()
            } else {
                0.0
            };

            to_js_str(&json!({
                "total_variants": variants.len(),
                "entropy": entropy,
                "max_entropy": max_entropy,
                "normalized_entropy": if variants.len() <= 1 { 0.0 } else { entropy / max_entropy },
                "top_10_coverage": coverage_top_10,
                "predominant_variant_size": variant_counts.first().copied().unwrap_or(0),
            }))
        }
        Some(_) => Err(crate::error::js_val("Not an EventLog")),
        None => Err(crate::error::js_val("EventLog not found")),
    })
}

/// Compute activity transition matrix (Markov chain).
#[wasm_bindgen]
pub fn compute_activity_transition_matrix(
    eventlog_handle: &str,
    activity_key: &str,
) -> Result<JsValue, JsValue> {
    get_or_init_state().with_object(eventlog_handle, |obj| match obj {
        Some(StoredObject::EventLog(log)) => {
            let activities = log.get_activities(activity_key);

            // Build activity vocabulary
            let mut vocab: HashMap<String, u32> = HashMap::default();
            for (idx, activity) in activities.iter().enumerate() {
                vocab.insert(activity.clone(), idx as u32);
            }

            let mut transitions: FxHashMap<(u32, u32), usize> = FxHashMap::default();
            let mut activity_total: FxHashMap<u32, usize> = FxHashMap::default();

            for activity_id in vocab.values() {
                activity_total.insert(*activity_id, 0);
            }

            for trace in &log.traces {
                trace.events.windows(2).for_each(|w| {
                    if let (Some(AttributeValue::String(a1)), Some(AttributeValue::String(a2))) = (
                        w[0].attributes.get(activity_key),
                        w[1].attributes.get(activity_key),
                    ) {
                        if let (Some(&a1_id), Some(&a2_id)) = (vocab.get(a1), vocab.get(a2)) {
                            *transitions.entry((a1_id, a2_id)).or_insert(0) += 1;
                            *activity_total.entry(a1_id).or_insert(0) += 1;
                        }
                    }
                });
            }

            // Compute transition probabilities
            let matrix_data: Vec<_> = transitions
                .iter()
                .filter_map(|((from, to), count)| {
                    activities.get(*from as usize).and_then(|from_name| {
                        activities.get(*to as usize).map(|to_name| {
                            let prob = *count as f64
                                / activity_total.get(from).copied().unwrap_or(1) as f64;
                            json!({
                                "from": from_name,
                                "to": to_name,
                                "count": count,
                                "probability": prob
                            })
                        })
                    })
                })
                .collect();

            to_js_str(&json!({
                "matrix": matrix_data,
                "num_activities": activities.len(),
            }))
        }
        Some(_) => Err(crate::error::js_val("Not an EventLog")),
        None => Err(crate::error::js_val("EventLog not found")),
    })
}

/// Identify where process accelerates/decelerates over time.
#[wasm_bindgen]
pub fn analyze_process_speedup(
    eventlog_handle: &str,
    timestamp_key: &str,
    _window_size: usize,
) -> Result<JsValue, JsValue> {
    get_or_init_state().with_object(eventlog_handle, |obj| match obj {
        Some(StoredObject::EventLog(log)) => {
            let mut time_gaps: Vec<f64> = Vec::new();

            for trace in &log.traces {
                let mut timestamps: Vec<String> = Vec::new();
                for event in &trace.events {
                    if let Some(AttributeValue::String(ts)) = event.attributes.get(timestamp_key) {
                        timestamps.push(ts.clone());
                    }
                }

                // Calculate gaps using real ISO-8601 timestamp parsing
                for i in 0..timestamps.len().saturating_sub(1) {
                    let gap =
                        crate::parse_iso8601_duration(&timestamps[i], &timestamps[i + 1]).abs();
                    time_gaps.push(gap);
                }
            }

            if time_gaps.is_empty() {
                return to_js_str(&json!({
                    "message": "No timestamps found",
                    "gaps": []
                }));
            }

            time_gaps.sort_by(|a, b| a.partial_cmp(b).unwrap_or(std::cmp::Ordering::Equal));

            let mean: f64 = time_gaps.iter().sum::<f64>() / time_gaps.len() as f64;

            // Calculate percentiles using index-based approach
            let p25_idx = ((time_gaps.len() as f64 - 1.0) * 0.25).round() as usize;
            let p75_idx = ((time_gaps.len() as f64 - 1.0) * 0.75).round() as usize;
            let percentile_25 = time_gaps[p25_idx];
            let percentile_75 = time_gaps[p75_idx];

            to_js_str(&json!({
                "avg_gap": mean,
                "p25": percentile_25,
                "p75": percentile_75,
                "speedup_range": percentile_75 - percentile_25,
            }))
        }
        Some(_) => Err(crate::error::js_val("Not an EventLog")),
        None => Err(crate::error::js_val("EventLog not found")),
    })
}

/// Compute pairwise trace similarity matrix.
#[wasm_bindgen]
pub fn compute_trace_similarity_matrix(
    eventlog_handle: &str,
    activity_key: &str,
) -> Result<JsValue, JsValue> {
    get_or_init_state().with_object(eventlog_handle, |obj| match obj {
        Some(StoredObject::EventLog(log)) => {
            let mut similarities = Vec::new();

            // Pre-compute HashSet<&str> per trace — O(n log n) once, O(1) per pair lookup
            let trace_sets: Vec<HashSet<&str>> = log
                .traces
                .iter()
                .map(|trace| {
                    trace
                        .events
                        .iter()
                        .filter_map(|e| e.attributes.get(activity_key)?.as_string())
                        .collect()
                })
                .collect();

            for i in 0..log.traces.len() {
                for j in (i + 1)..log.traces.len() {
                    // Jaccard via set intersection/union — O(min(|i|,|j|)) per pair
                    let common = trace_sets[i].intersection(&trace_sets[j]).count();
                    let union = trace_sets[i].len() + trace_sets[j].len() - common;
                    // max(1) denominator guard — branchless cmov, no divide-by-zero
                    let similarity = common as f64 / union.max(1) as f64;

                    if similarity > 0.5 {
                        similarities.push(json!({
                            "trace_i": i,
                            "trace_j": j,
                            "similarity": similarity
                        }));
                    }
                }
            }

            to_js_str(&json!({
                "similar_pairs": similarities,
                "total_pairs": (log.traces.len() * (log.traces.len() - 1)) / 2,
            }))
        }
        Some(_) => Err(crate::error::js_val("Not an EventLog")),
        None => Err(crate::error::js_val("EventLog not found")),
    })
}

/// Identify temporal bottlenecks by activity duration.
#[wasm_bindgen]
pub fn analyze_temporal_bottlenecks(
    eventlog_handle: &str,
    activity_key: &str,
    timestamp_key: &str,
) -> Result<JsValue, JsValue> {
    get_or_init_state().with_object(eventlog_handle, |obj| match obj {
        Some(StoredObject::EventLog(log)) => {
            let mut activity_durations: HashMap<String, Vec<f64>> = HashMap::default();

            for trace in &log.traces {
                let activities: Vec<(String, String)> = trace
                    .events
                    .iter()
                    .filter_map(|e| {
                        if let (
                            Some(AttributeValue::String(act)),
                            Some(AttributeValue::String(ts)),
                        ) = (
                            e.attributes.get(activity_key),
                            e.attributes.get(timestamp_key),
                        ) {
                            Some((act.clone(), ts.clone()))
                        } else {
                            None
                        }
                    })
                    .collect();

                for i in 0..activities.len().saturating_sub(1) {
                    let duration =
                        crate::parse_iso8601_duration(&activities[i].1, &activities[i + 1].1);
                    activity_durations
                        .entry(activities[i].0.clone())
                        .or_default()
                        .push(duration.abs());
                }
            }

            let bottlenecks: Vec<_> = activity_durations
                .iter()
                .map(|(activity, durations)| {
                    let avg: f64 = durations.iter().sum::<f64>() / durations.len() as f64;
                    let max = durations.iter().copied().fold(f64::NEG_INFINITY, f64::max);
                    json!({
                        "activity": activity,
                        "avg_duration": avg,
                        "max_duration": max,
                    })
                })
                .collect();

            to_js_str(&json!({
                "bottlenecks": bottlenecks,
            }))
        }
        Some(_) => Err(crate::error::js_val("Not an EventLog")),
        None => Err(crate::error::js_val("EventLog not found")),
    })
}

/// Extract mandatory activity ordering from event log.
#[wasm_bindgen]
pub fn extract_activity_ordering(
    eventlog_handle: &str,
    activity_key: &str,
) -> Result<JsValue, JsValue> {
    get_or_init_state().with_object(eventlog_handle, |obj| match obj {
        Some(StoredObject::EventLog(log)) => {
            let mut mandatory_predecessors: HashMap<String, HashSet<String>> = HashMap::default();

            for trace in &log.traces {
                // Collect only events that carry the activity key, preserving order
                let activities: Vec<&str> = trace
                    .events
                    .iter()
                    .filter_map(|e| {
                        if let Some(AttributeValue::String(a)) = e.attributes.get(activity_key) {
                            Some(a.as_str())
                        } else {
                            None
                        }
                    })
                    .collect();

                for (pos, &activity) in activities.iter().enumerate() {
                    // All activities that appear before this position are predecessors
                    let predecessors: HashSet<String> =
                        activities.iter().take(pos).map(|&a| a.to_owned()).collect();
                    // Mandatory predecessor = present before this activity in EVERY trace.
                    // Vacant: seed with full predecessor set.
                    // Occupied: intersect to keep only those seen in all traces so far.
                    mandatory_predecessors
                        .entry(activity.to_owned())
                        .and_modify(|existing: &mut HashSet<String>| {
                            existing.retain(|p| predecessors.contains(p.as_str()));
                        })
                        .or_insert(predecessors);
                }
            }

            let result: Vec<_> = mandatory_predecessors
                .iter()
                .map(|(activity, preds)| {
                    json!({
                        "activity": activity,
                        "mandatory_predecessors": preds.iter().cloned().collect::<Vec<_>>()
                    })
                })
                .collect();

            to_js_str(&json!({
                "activity_ordering": result,
            }))
        }
        Some(_) => Err(crate::error::js_val("Not an EventLog")),
        None => Err(crate::error::js_val("EventLog not found")),
    })
}

#[wasm_bindgen]
pub fn final_analytics_info() -> String {
    json!({
        "status": "final_analytics_available",
        "functions": [
            {"name": "variant_complexity", "type": "entropy_analysis"},
            {"name": "transition_matrix", "type": "markov_chain"},
            {"name": "speedup_analysis", "type": "temporal"},
            {"name": "trace_similarity", "type": "distance_metric"},
            {"name": "temporal_bottlenecks", "type": "performance"},
            {"name": "activity_ordering", "type": "constraints"},
        ]
    })
    .to_string()
}