"""v0.5 issue B+C — Pre-flight 0.4: validate the 24h time-bucket choice.

Walk data/processed/cascade_chains/*.json, collect every node's
time_offset_hours, and print three histograms (12h / 24h / 48h bucket
widths). The bucket constant in src/rag/evidence_templating.py
(_TIME_BUCKET_HOURS) defaults to 24h per spec §5.4; if the 24h histogram
shows < 5 edges per (parent_domain × time bucket) on average, switch to
48h and document in the ablation report.

One-shot helper. No CLI, no flags. Run from project root::

    PYTHONPATH=. python scripts/v05_time_offset_histogram.py
"""

from __future__ import annotations

import json
from collections import Counter
from pathlib import Path

CHAINS_DIR = Path("data/processed/cascade_chains")


def _bucket(hours: float, width: int) -> int:
    """Return the lower edge of the bucket containing `hours`."""
    return int(hours // width) * width


def main() -> None:
    offsets: list[tuple[str, float]] = []  # (parent_domain, offset)
    for path in sorted(CHAINS_DIR.glob("*.json")):
        try:
            chain = json.loads(path.read_text())
        except (json.JSONDecodeError, OSError):
            continue
        nodes = chain.get("cascade_events") or []
        # Build id → domain map so we can look up parents
        domain_by_id = {n["id"]: n["domain"] for n in nodes if "id" in n and "domain" in n}
        for node in nodes:
            t = node.get("time_offset_hours")
            if t is None:
                continue
            for pid in node.get("parent_ids") or []:
                pdom = domain_by_id.get(pid, "<root>")
                offsets.append((pdom, float(t)))

    if not offsets:
        print("No node offsets found.")
        return

    print(f"Total parent-edge offsets observed: {len(offsets)}")
    print(f"Range: min={min(t for _, t in offsets):.1f}h  max={max(t for _, t in offsets):.1f}h")
    print()

    for width in (12, 24, 48):
        all_buckets: Counter = Counter(_bucket(t, width) for _, t in offsets)
        domain_bucket: Counter = Counter((pd, _bucket(t, width)) for pd, t in offsets)
        avg_per_dom_bucket = (
            sum(domain_bucket.values()) / len(domain_bucket) if domain_bucket else 0
        )
        print(f"=== Bucket width = {width}h ===")
        print(f"Distinct buckets:               {len(all_buckets)}")
        print(f"Distinct (parent_domain × bucket): {len(domain_bucket)}")
        print(f"Avg edges per (domain × bucket):   {avg_per_dom_bucket:.2f}")
        print("Top buckets (overall):")
        for lo, count in all_buckets.most_common(8):
            hi = lo + width
            print(f"  +{lo:>3}~{hi:<3}h:  {count}")
        print()


if __name__ == "__main__":
    main()