"""Tests for toposort.topo_sort.

Runs two ways, both from this directory only:
    python3 test_toposort.py
    python3 -m unittest discover -p 'test_*.py'

Assertions execute at import (the convention this file already used), so a
failure surfaces under `unittest discover` as an import error rather than a
silent pass.

Q61 / 2026-10-24: the module is resolved from THIS file's directory and from
nowhere else. The previous `sys.path.insert(0, '/root/.hermes/wizard-outputs/beam')`
measured a host copy rather than the committed bytes, so the gate could pass
while the repository's blob was broken. `MODULE_PATH` is asserted below.
"""
import pathlib
import sys

HERE = pathlib.Path(__file__).resolve().parent
sys.path.insert(0, str(HERE))

import toposort as toposort_module
from toposort import topo_sort

# The module under test must be the committed file next to this test.
MODULE_PATH = pathlib.Path(toposort_module.__file__).resolve()
assert MODULE_PATH == (HERE / "toposort.py"), (MODULE_PATH, HERE)

_checks = 0


def eq(got, expected, what):
    global _checks
    _checks += 1
    assert got == expected, f"{what}: got {got!r}, expected {expected!r}"


def ok(cond, what):
    global _checks
    _checks += 1
    assert cond, what


def order_of(spec, take):
    """Build a graph from `spec`, passing every dependency sequence through `take`."""
    return {n: (() if ds is None else take(ds)) for n, ds in spec.items()}


def check_valid(result, spec, what):
    """result must be a valid topological order of `spec` (deps before dependents)."""
    global _checks
    _checks += 1
    assert result.cycle is None, f"{what}: unexpected cycle {result.cycle!r}"
    order = result.sorted
    assert order is not None, f"{what}: sorted is None with no cycle"
    nodes = set(spec)
    for ds in spec.values():
        nodes.update(ds or ())
    assert sorted(order) == sorted(nodes), f"{what}: not a permutation: {order!r}"
    pos = {n: i for i, n in enumerate(order)}
    for node, ds in spec.items():
        for dep in (ds or ()):
            assert pos[dep] < pos[node], f"{what}: {dep!r} after {node!r} in {order!r}"


def check_cycle(result, spec, what):
    """result.cycle must be a real cycle: consecutive edges exist, last -> first."""
    global _checks
    _checks += 1
    assert result.sorted is None, f"{what}: expected no order, got {result.sorted!r}"
    cyc = result.cycle
    assert cyc, f"{what}: empty cycle"
    for i, u in enumerate(cyc):
        v = cyc[(i + 1) % len(cyc)]
        assert v in (spec.get(u) or ()), f"{what}: no edge {u!r}->{v!r} in {cyc!r}"


# ---------------------------------------------------------------- baseline cases
r = topo_sort({'a': ['b'], 'b': []})
eq(r.sorted, ['b', 'a'], "simple")
eq(r.cycle, None, "simple cycle")

eq(topo_sort({'a': [], 'b': []}).sorted, ['a', 'b'], "disconnected")
eq(topo_sort({}).sorted, [], "empty")

DIAMOND = {'a': ['b', 'c'], 'b': ['d'], 'c': ['d'], 'd': []}
d = topo_sort(DIAMOND)
eq(d.cycle, None, "diamond cycle")
check_valid(d, DIAMOND, "diamond")

two = topo_sort({'a': ['b'], 'b': ['a']})
eq(two.sorted, None, "2-cycle sorted")
check_cycle(two, {'a': ['b'], 'b': ['a']}, "2-cycle")

eq(topo_sort({'a': ['a']}).cycle, ['a'], "self loop")
eq(topo_sort({'a': ['b']}).sorted, ['b', 'a'], "successor only")

# ------------------------------------------------- Q61(a): iterator dependencies
# Specs are written with plain tuples; `take` decides how each dependency
# sequence is delivered. Every delivery form must produce the SAME order, and
# that order must be valid -- not merely equal to a wrong reference.
SPECS = {
    "single":     {'a': ('b',), 'b': ()},
    "chain3":     {'c': ('b',), 'b': ('d',), 'd': ()},
    "chain6":     {'f': ('e',), 'e': ('d',), 'd': ('c',), 'c': ('b',), 'b': ('a',), 'a': ()},
    "diamond":    DIAMOND,
    "fork":       {'root': ('l', 'r'), 'l': (), 'r': ()},
    "join":       {'a': ('x',), 'b': ('x',), 'c': ('a', 'b'), 'x': ()},
    "multi":      {'a': ('b',), 'b': (), 'c': ('d',), 'd': (), 'e': ()},
    "missingdep": {'a': ('z',)},
    "empty":      {},
}

TAKERS = {
    "tuple":         tuple,
    "list":          list,
    "generator":     lambda ds: (d for d in ds),
    "map_object":    lambda ds: map(str, ds),
    "filter":        lambda ds: filter(lambda d: True, ds),
    "reversed_iter": lambda ds: reversed(list(ds)),
    "set":           set,
}

for name, spec in SPECS.items():
    reference = topo_sort(order_of(spec, tuple))
    check_valid(reference, spec, f"{name}/tuple")
    for tname, take in TAKERS.items():
        result = topo_sort(order_of(spec, take))
        eq(result.cycle, None, f"{name}/{tname} cycle")
        eq(result.sorted, reference.sorted, f"{name}/{tname} order")
        check_valid(result, spec, f"{name}/{tname}")

# The exact repro from Q61: a two-node graph where the generator was exhausted
# by the first pass and the result was a silent, wrong 'success'.
gen = topo_sort({'a': iter(['b']), 'b': []})
eq(gen.sorted, ['b', 'a'], "Q61 repro: generator dependency")

# Cycles must survive iterator delivery too -- and still be reported as cycles.
CYCLES = {
    "self":  {'a': ('a',)},
    "two":   {'a': ('b',), 'b': ('a',)},
    "three": {'a': ('b',), 'b': ('c',), 'c': ('a',)},
    "tail":  {'head': ('a',), 'a': ('b',), 'b': ('a',)},
}
for name, spec in CYCLES.items():
    for tname, take in TAKERS.items():
        check_cycle(topo_sort(order_of(spec, take)), spec, f"{name}/{tname}")

eq(topo_sort({'a': iter(['a'])}).cycle, ['a'], "self loop as iterator")

# ------------------------------------------------------- determinism / stability
for _ in range(3):
    eq(topo_sort(order_of(SPECS["join"], list)).sorted,
       topo_sort(order_of(SPECS["join"], tuple)).sorted, "repeat determinism")

# ------------------------------------------- Q61(b) sibling copy drift guard
# wizard-work/beam carries a second, historically byte-identical copy at
# toposort/toposort.py. Two copies of a fixed bug is how it comes back; assert
# they agree rather than trusting that they do.
SIBLING = HERE / "toposort" / "toposort.py"
if SIBLING.exists():
    ok(SIBLING.read_bytes() == (HERE / "toposort.py").read_bytes(),
       f"sibling copy differs from toposort.py: {SIBLING}")


def test_all():
    """Kept so pytest/unittest see a callable; module-level asserts already ran."""
    return _checks


print(f"ALL PASS ({_checks} checks)")