#!/usr/bin/env python3
"""Prove a relayout landed, using the media server's own tables.

A scan answers `204` whether or not it found anything, and a rename that the
scanner has not followed looks exactly like a rename that never happened from
the outside. The only honest proof is the run's journal replayed against the
database the server actually serves from: every `move` row must have a row at
its destination, and NO row may still name its source — a source row is a scan
that has not caught up, and it is the one signature of a library pointing at
files that no longer exist.

Two doors, both read-only, both without a lock while the server runs
(`mode=ro&immutable=1`; there is no `sqlite3` binary on these hosts):

  jellyfin  `BaseItems.Path`. The container binds the share at `/data`, so the
            database holds `/data/<library>/…` where the journal holds
            `/mnt/entropy/<library>/…`. Translate, or every row reads as missing.
  plex      `media_parts.file`, joined up to `metadata_items`. Plex is bound at
            the host path, so its rows match the journal verbatim. Filter
            `deleted_at is null` on BOTH tables — a deleted scan leaves its parts
            behind, and one of those rows is not proof anything landed.

Neither server holds a row for everything the journal renames: a `.log`, `.cue`
or cover image has no row to land in, so its absence is not a fault. The report
therefore breaks the missing rows down by extension, and `--ignore-ext` names
the extensions this server does not index, which are then counted separately and
kept out of the verdict.

Exit codes: 0 every move landed; 1 something is stale or missing (the details are
printed); 2 the journal or the database is not usable at all.
"""

import argparse
import json
import os
import sqlite3
import sys
from collections import Counter

JF_DB = "/home/dank/Containers/jellyfin/config/data/jellyfin.db"
PLEX_DB = ("/var/lib/plexmediaserver/Library/Application Support/Plex Media Server"
           "/Plug-in Support/Databases/com.plexapp.plugins.library.db")

# Per kind: the table whose columns are required, those columns, and the query
# that returns every path the server believes it has.
KINDS = {
    "jellyfin": {
        "table": "BaseItems",
        "columns": {"Path"},
        "sql": "select Path from BaseItems",
        "default_db": JF_DB,
    },
    "plex": {
        "table": "media_parts",
        "columns": {"file", "media_item_id", "deleted_at"},
        "sql": ("select p.file from media_parts p"
                " join media_items m on m.id = p.media_item_id"
                " join metadata_items mi on mi.id = m.metadata_item_id"
                " where p.deleted_at is null and mi.deleted_at is null"),
        "default_db": PLEX_DB,
    },
}

def die(msg):
    print(f"media-verify: {msg}", file=sys.stderr)
    sys.exit(2)


def read_moves(path):
    """The (src, dst) pairs of a journal, in the order the run performed them."""
    moves = []
    try:
        fh = open(path, encoding="utf-8")
    except OSError as e:
        die(f"cannot read the journal {path}: {e.strerror}")
    with fh:
        for n, line in enumerate(fh, 1):
            line = line.strip()
            if not line:
                continue
            try:
                rec = json.loads(line)
            except json.JSONDecodeError:
                die(f"{path} line {n} is not a journal record")
            if rec.get("op") == "move":
                if not rec.get("src") or not rec.get("dst"):
                    die(f"{path} line {n} is a move without both src and dst")
                moves.append((rec["src"], rec["dst"]))
    return moves


def server_paths(db, kind):
    """Every path the server holds, or a refusal that names what is missing."""
    spec = KINDS[kind]
    try:
        con = sqlite3.connect(f"file:{db}?mode=ro&immutable=1", uri=True)
    except sqlite3.Error as e:
        die(f"cannot open {db}: {e}")
    with con:
        have = {r[1] for r in con.execute(f"pragma table_info({spec['table']})")}
        if not spec["columns"] <= have:
            die(f"{db} is not a {kind} library database ({spec['table']} has no "
                f"{','.join(sorted(spec['columns'] - have))})")
        try:
            return {r[0] for r in con.execute(spec["sql"]) if r[0]}
        except sqlite3.Error as e:
            die(f"{db} refused the {kind} query: {e}")


def to_host(path, container, share):
    """The database's path in the journal's terms; identity when it is not a
    container-side path."""
    if not container:
        return path
    prefix = container.rstrip("/") + "/"
    if path.startswith(prefix):
        return share.rstrip("/") + "/" + path[len(prefix):]
    return path


def main():
    ap = argparse.ArgumentParser(description=__doc__.splitlines()[0])
    ap.add_argument("--journal", required=True,
                    help="the run's journal (scripts/media-apply.py writes it)")
    ap.add_argument("--db-kind", choices=sorted(KINDS), required=True)
    ap.add_argument("--db", default=None, help="the server's database on this host")
    ap.add_argument("--share", default="/mnt/entropy",
                    help="the share every journal path lives under")
    ap.add_argument("--container", default=None,
                    help="what the share is called inside the container; empty"
                         " compares verbatim (default /data for jellyfin, nothing"
                         " for plex)")
    ap.add_argument("--show", type=int, default=20,
                    help="how many offenders to name before saying 'and N more'")
    ap.add_argument("--ignore-ext", default="",
                    help="comma-separated extensions this server does not index,"
                         " kept out of the verdict (e.g. log,cue,nfo,srt)")
    args = ap.parse_args()

    db = args.db or KINDS[args.db_kind]["default_db"]
    container = ("/data" if args.db_kind == "jellyfin" else "") \
        if args.container is None else args.container
    ignore = set()
    for ext in args.ignore_ext.split(","):
        ext = ext.strip().lower()
        if ext:
            ignore.add(ext if ext.startswith(".") else "." + ext)

    moves = read_moves(args.journal)
    stored = {to_host(p, container, args.share) for p in server_paths(db, args.db_kind)}

    landed, stale, missing, ignored = 0, [], [], 0
    for src, dst in moves:
        if os.path.splitext(dst)[1].lower() in ignore:
            ignored += 1
            continue
        at_dst, at_src = dst in stored, src in stored
        if at_dst and not at_src:
            landed += 1
            continue
        if at_src:
            stale.append(src)
        if not at_dst:
            missing.append(dst)

    print(f"{args.db_kind}: {len(moves)} moves checked")
    print(f"landed: {landed}")
    print(f"still at src: {len(stale)}")
    print(f"missing from the DB: {len(missing)}")
    if ignored:
        print(f"not indexed (extension ignored): {ignored}")
    if missing:
        exts = Counter(os.path.splitext(d)[1].lower() or "(no extension)"
                       for d in missing)
        print("missing by extension: "
              + ", ".join(f"{e} {n}" for e, n in sorted(exts.items())))
    for label, items in (("stale", stale), ("missing", missing)):
        for path in items[:args.show]:
            print(f"  {label}: {path}")
        if len(items) > args.show:
            print(f"  {label}: … and {len(items) - args.show} more")
    return 1 if (stale or missing) else 0


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