"""L1: session-coherence smoke -- full walk + rollback, pure logic (no LLM, no DB).

The CI-runnable proxy for 'full session coherence': build a synthetic ledger by
hand (decisions appended directly, not via an LLM) representing a full F1->F8 walk,
then a rollback F6->F4 + re-derive, and assert the invariants the D1-the-L2-version
would check. This is the coherence net for the Phase-A substrate (phase fold,
effective view, teardown).
"""
from pathlib import Path

from tht.decisions import append_decision
from tht.phase import current_phase, effective_decisions
from tht.teardown import teardown_to_phase
from tht.workflow import load_workflow


def _approve(session: Path, phase: int) -> None:
    append_decision(session, type="phase_approved", subject=f"phase:{phase}")


def test_full_walk_reaches_terminal_phase(tmp_path):
    s = tmp_path / "sess"
    s.mkdir()
    wf = load_workflow()
    for n in range(1, wf.max_phase + 1):
        _approve(s, n)
    # terminal: all phases approved -> current_phase == max_phase + 1
    assert current_phase(s) == wf.max_phase + 1


def test_rollback_truncates_effective_view_and_current_phase(tmp_path):
    s = tmp_path / "sess"
    s.mkdir()
    for n in range(1, 7):  # approve F1..F6
        _approve(s, n)
    # a substantive decision at phase 4 (preserved in the ledger)
    append_decision(s, type="table_promoted", subject="phase:4", detail="dim_pazienti")
    assert current_phase(s) == 7
    # rollback to F4
    append_decision(s, type="phase_reopened", subject="phase:4")
    assert current_phase(s) == 4
    # decisions strictly after the reopen target are stale in the effective view.
    # The table_promoted was at phase:4 (<= current 4), so it survives; but a later
    # substantive decision appended AFTER the reopen for a phase > 4 must be excluded.
    append_decision(s, type="sql_approved", subject="phase:7")  # stale: phase 7 > 4
    eff_types = [d.type for d in effective_decisions(s)]
    assert "sql_approved" not in eff_types  # rolled-back decision is stale
    assert "table_promoted" in eff_types   # phase:4 decision is still effective


def test_teardown_deletes_artifacts_beyond_rollback_target(tmp_path):
    s = tmp_path / "sess"
    s.mkdir()
    # artifacts as if F4..F7 had produced them
    (s / "schema_linking.json").write_text("{}")   # F4
    (s / "cte_plan.json").write_text("[]")          # F6
    (s / "sql_final.sql").write_text("SELECT 1")    # F7
    report = teardown_to_phase(s, target_phase=4)
    assert (s / "schema_linking.json").exists()    # F4 preserved (target is 4)
    assert not (s / "cte_plan.json").exists()      # F6 deleted
    assert not (s / "sql_final.sql").exists()      # F7 deleted
    assert "cte_plan.json" in report.deleted_files
    assert "sql_final.sql" in report.deleted_files


def test_re_approve_after_rollback_advances_correctly(tmp_path):
    s = tmp_path / "sess"
    s.mkdir()
    for n in range(1, 4):
        _approve(s, n)
    append_decision(s, type="phase_reopened", subject="phase:2")  # back to F2
    assert current_phase(s) == 2
    _approve(s, 2)
    assert current_phase(s) == 3
    _approve(s, 3)
    assert current_phase(s) == 4


def test_decision_retraction_excluded_from_effective(tmp_path):
    s = tmp_path / "sess"
    s.mkdir()
    # walk to phase 4 in order so current_phase reaches 4 (the fold only advances on
    # an approval for the CURRENT phase, n == cur).
    for n in range(1, 5):
        _approve(s, n)
    append_decision(s, type="table_promoted", subject="phase:4", detail="t1")
    append_decision(s, type="table_excluded", subject="phase:4", detail="t2")
    # retract the table_excluded (seq 6) -- step-level rollback, D15
    append_decision(s, type="decision_retracted", subject="phase:4", retracts=6)
    assert current_phase(s) == 5  # phase 4 approved -> cursor 5
    eff_types = [d.type for d in effective_decisions(s)]
    # the retracted table_excluded and the retraction marker are both gone
    assert eff_types.count("table_excluded") == 0
    assert eff_types.count("decision_retracted") == 0
    assert "table_promoted" in eff_types  # unaffected by the unrelated retraction