"""Read + filter the receiver's ``index.jsonl``.

Usage:

    # All episodes from one host:
    cis490-index --host lab-host-1

    # All episodes for a particular sample:
    cis490-index --sample xmrig-cryptominer

    # Today's episodes, sorted by size:
    cis490-index --since 2026-04-30 --sort size

    # Group/count by host:
    cis490-index --count-by host_id

The index file is the closest thing to a database the receiver has
until we move to Postgres/Timescale. This tool is the temporary CLI
view over it; it's intentionally read-only and never opens episode
tarballs (just the index rows).
"""

from __future__ import annotations

import argparse
import json
import sys
from collections import Counter
from datetime import datetime, timezone
from pathlib import Path


DEFAULT_INDEX = "/var/lib/cis490/index.jsonl"


def _parse_since(s: str) -> datetime:
    # Accept ISO-8601 with or without time.
    for fmt in ("%Y-%m-%dT%H:%M:%S%z", "%Y-%m-%d", "%Y-%m-%dT%H:%M:%S"):
        try:
            dt = datetime.strptime(s, fmt)
            if dt.tzinfo is None:
                dt = dt.replace(tzinfo=timezone.utc)
            return dt
        except ValueError:
            continue
    # Last resort: fromisoformat which handles a wider range in 3.11+.
    dt = datetime.fromisoformat(s)
    if dt.tzinfo is None:
        dt = dt.replace(tzinfo=timezone.utc)
    return dt


def _row_time(row: dict) -> datetime | None:
    s = row.get("received_at_wall")
    if not s:
        return None
    try:
        return datetime.fromisoformat(s.replace("Z", "+00:00"))
    except ValueError:
        return None


def main(argv: list[str] | None = None) -> int:
    p = argparse.ArgumentParser(prog="cis490-index")
    p.add_argument("--index", default=DEFAULT_INDEX,
                   help=f"path to index.jsonl (default {DEFAULT_INDEX})")
    p.add_argument("--host", help="only rows from this host_id")
    p.add_argument("--sample",
                   help="only rows whose meta.sample.name matches "
                        "(requires meta.json from a recent commit)")
    p.add_argument("--since", help="ISO date or datetime; only rows received on/after")
    p.add_argument("--until", help="ISO date or datetime; only rows received before")
    p.add_argument("--sort", choices=("time", "size", "host"), default="time")
    p.add_argument("--count-by",
                   choices=("host_id", "schema_version"),
                   help="instead of printing rows, group + count by this field")
    p.add_argument("--limit", type=int, default=0,
                   help="cap output rows (0 = all)")
    args = p.parse_args(argv)

    path = Path(args.index)
    if not path.exists():
        print(f"no index at {path}", file=sys.stderr)
        return 2

    since = _parse_since(args.since) if args.since else None
    until = _parse_since(args.until) if args.until else None

    rows: list[dict] = []
    with path.open() as f:
        for line in f:
            line = line.strip()
            if not line:
                continue
            try:
                row = json.loads(line)
            except json.JSONDecodeError:
                continue
            if args.host and row.get("host_id") != args.host:
                continue
            if since or until:
                t = _row_time(row)
                if t is None:
                    continue
                if since and t < since:
                    continue
                if until and t >= until:
                    continue
            rows.append(row)

    if args.count_by:
        counts = Counter(r.get(args.count_by, "<missing>") for r in rows)
        for k, n in counts.most_common():
            print(f"{n:>6}  {k}")
        return 0

    sort_keys = {
        "time": lambda r: r.get("received_at_wall", ""),
        "size": lambda r: r.get("size_bytes", 0),
        "host": lambda r: r.get("host_id", ""),
    }
    rows.sort(key=sort_keys[args.sort])
    if args.limit:
        rows = rows[-args.limit:] if args.sort != "size" else rows[:args.limit]

    # Print TSV-ish for quick eyeballing + downstream pipe-friendliness.
    print("received_at_wall\thost_id\tepisode_id\tsize_bytes\tschema_version\tsha256")
    for r in rows:
        print("\t".join(str(r.get(k, "")) for k in
                        ("received_at_wall", "host_id", "episode_id",
                         "size_bytes", "schema_version", "sha256")))
    return 0


if __name__ == "__main__":
    sys.exit(main())