#!/usr/bin/env python3
"""
variants-report.py - inventory of resource/Variants/*.mw4 (saved mechlab loadouts).

    python3 variants-report.py <variantsDir> <v4hManifest.tsv> <oursManifest.tsv>

A variant package holds 4 records:
    [0] 'Resource\\Variants\\<name>'   4 B   (raw id)
    [1] '{Mech}'                       ~350 B
    [2] '<chassis>{Subsystem}'         ~4 KB  <- names the chassis it needs
    [3] '<8-char token>'               16 B

So the chassis a variant depends on is readable straight from the manifest,
with no decompression: the record whose name ends in '{Subsystem}'.

The report groups variants by chassis and flags any whose chassis is absent
from the target build's core.mw4 (those will not load).
"""
import sys, os, collections


def chassis_in_core(manifest):
    """Set of chassis names that core.mw4 defines (one *.subsystems per chassis)."""
    out = set()
    with open(manifest, encoding="latin-1") as fh:
        for line in fh:
            pkg, _rid, name, *_ = line.rstrip("\n").split("\t")
            if pkg.lower() != "core.mw4":
                continue
            n = name.lower().replace("\\", "/")
            if n.endswith(".subsystems"):
                out.add(n.rsplit("/", 1)[-1][:-len(".subsystems")])
    return out


def variant_chassis(manifest):
    """variantPkgRelPath -> chassis name it requires."""
    out = {}
    with open(manifest, encoding="latin-1") as fh:
        for line in fh:
            pkg, _rid, name, *_ = line.rstrip("\n").split("\t")
            if not pkg.lower().startswith("variants/"):
                continue
            if name.endswith("{Subsystem}"):
                out[pkg] = name[:-len("{Subsystem}")].lower()
    return out


def main():
    if len(sys.argv) != 4:
        sys.exit(__doc__)
    vdir, v4h_manifest, ours_manifest = sys.argv[1:4]
    have_v4h = chassis_in_core(v4h_manifest)
    have_ours = chassis_in_core(ours_manifest)
    vc = variant_chassis(v4h_manifest)

    print(f"# variant packages: {len(vc)}   (files on disk: "
          f"{len([f for f in os.listdir(vdir) if f.lower().endswith('.mw4')])})")
    print(f"# chassis defined in V4H core.mw4 : {len(have_v4h)}")
    print(f"# chassis defined in OUR core.mw4 : {len(have_ours)}")
    print(f"# chassis only V4H defines        : {sorted(have_v4h - have_ours)}")
    print()

    by = collections.defaultdict(list)
    for pkg, ch in vc.items():
        by[ch].append(pkg)

    loadable_now = broken = needs_new_mech = 0
    print(f"{'chassis':22s} {'count':>5s}  status")
    for ch in sorted(by, key=lambda c: (-len(by[c]), c)):
        n = len(by[ch])
        if ch in have_ours:
            status = "loadable in OUR build today"
            loadable_now += n
        elif ch in have_v4h:
            status = "needs the new chassis ported"
            needs_new_mech += n
        else:
            status = "BROKEN - chassis missing from V4H too"
            broken += n
        print(f"{ch:22s} {n:5d}  {status}")

    print()
    print(f"loadable in our build today : {loadable_now}")
    print(f"blocked on new chassis      : {needs_new_mech}")
    print(f"broken / orphaned           : {broken}")
    for ch in sorted(by):
        if ch not in have_v4h:
            print(f"  orphan chassis '{ch}': " + ", ".join(sorted(by[ch])))


if __name__ == "__main__":
    main()