"""Phase 14 SP6: the export bundle carries the tree.

A bundle is the only part of this phase a migration can never reach: the
file already exists on somebody's disk. So there are two formats, and the
two halves of this file check different properties.

v2 must be lossless for a story that forked. v1 could not be, because it
stored one list for two stories, interleaved by `index`, which read back
as a mangled story. Losslessness here means the tree: every branch, the
fork point it left on its parent, which attempt at each turn is the
story, and what each node left behind. That last item is what a branch
switch restores, and a tree nobody can switch inside is not the tree
that was exported.

v1 must still import, because a backup that stops importing is not a
backup.

Both formats follow one rule: a bundle carries what was chosen and never
what is derived. The lineage, the head depth, the legacy `index`, and the
variant ordinals are all rebuilt on the way in, so a hand-edited file
cannot disagree with itself. The tests that matter most here hand the
importer a file that does disagree with itself.

    python -m pytest tests/test_bundle_v2.py -v
"""
import pytest
from fastapi import Depends
from fastapi.testclient import TestClient

from app import auth, bundle, limits, models
from app.context import lineage
from app.database import Base, SessionLocal, engine, get_db
from app.main import app
from app.routers import adventures

from fakes import ScriptedProvider

SCHEMA = {"player": {"hp": {"min": 0, "max": 100, "initial": 100}}}

# Ten gold a turn, so the stored gold total tells how many turns the
# story behind it played. This makes an after-snapshot visible from outside.
GOLD_SCRIPT = """
const modifier = (text) => {
  state.gold = (state.gold || 0) + 10;
  return { text };
};
modifier(text);
"""

OPENING = "You enter a cave."


@pytest.fixture()
def client(monkeypatch):
    Base.metadata.create_all(bind=engine)
    setup = SessionLocal()
    user = models.User(is_guest=False, email="bundle@example.com")
    setup.add(user)
    setup.flush()
    setup.add(models.Settings(user_id=user.id, api_key="enc:dummy", model="test-model"))
    scenario = models.Scenario(user_id=user.id, title="S", stat_schema=SCHEMA)
    setup.add(scenario)
    setup.flush()
    adv = models.Adventure(
        user_id=user.id, title="Cave", scenario_id=scenario.id,
        script_state={}, world_state={"player": {"hp": 100}},
    )
    setup.add(adv)
    setup.flush()
    setup.add(models.Action(adventure_id=adv.id, type="start", text=OPENING))
    setup.add(models.AdventureScript(
        adventure_id=adv.id, position=0, enabled=True, name="Gold", output_js=GOLD_SCRIPT,
    ))
    setup.commit()
    adv_id, user_id = adv.id, user.id
    setup.close()

    ScriptedProvider.replies = ["A reply."]
    ScriptedProvider.calls = 0
    monkeypatch.setattr(adventures.turns, "OpenAICompatibleProvider", ScriptedProvider)
    monkeypatch.setattr(auth, "resolve_provider_config", lambda s: auth.ProviderConfig(
        "http://fake", "k", "test-model", False))
    monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)
    monkeypatch.setattr(limits, "check_row_cap", lambda *a, **k: None)

    def _current_user(db=Depends(get_db)):
        return db.get(models.User, user_id)

    app.dependency_overrides[auth.get_current_user] = _current_user
    c = TestClient(app)
    c.adv_id = adv_id
    try:
        yield c
    finally:
        app.dependency_overrides.clear()
        adventures.turns._active_turns.clear()
        Base.metadata.drop_all(bind=engine)


# ------------------------------------------------------------------ helpers

def _play(client, adv_id, text="look around", type="do"):
    r = client.post(f"/api/adventures/{adv_id}/actions", json={"type": type, "text": text})
    assert r.status_code == 200, r.text


def _retry(client, adv_id):
    assert client.post(f"/api/adventures/{adv_id}/retry").status_code == 200


def _export(client, adv_id) -> dict:
    r = client.get(f"/api/adventures/{adv_id}/export")
    assert r.status_code == 200, r.text
    return r.json()


def _import(client, payload):
    return client.post("/api/adventures/import", json=payload)


def _imported(client, payload) -> int:
    r = _import(client, payload)
    assert r.status_code == 201, r.text
    return r.json()["id"]


def _branches(client, adv_id) -> list[dict]:
    r = client.get(f"/api/adventures/{adv_id}/branches")
    assert r.status_code == 200, r.text
    return r.json()


def _switch(client, adv_id, branch_id):
    r = client.post(f"/api/adventures/{adv_id}/branches/{branch_id}/switch")
    assert r.status_code == 200, r.text


def _texts(client, adv_id) -> list[str]:
    return [a["text"] for a in client.get(f"/api/adventures/{adv_id}").json()["actions"]]


def _every_branch_story(client, adv_id) -> list[list[str]]:
    """What each branch tells, in branch order. This is the whole tree as text."""
    stories = []
    for branch in _branches(client, adv_id):
        _switch(client, adv_id, branch["id"])
        stories.append(_texts(client, adv_id))
    return stories


def _adventure_count() -> int:
    db = SessionLocal()
    try:
        return db.query(models.Adventure).count()
    finally:
        db.close()


def _rows(adv_id) -> list[models.Action]:
    db = SessionLocal()
    try:
        return (
            db.query(models.Action)
            .filter(models.Action.adventure_id == adv_id)
            .order_by(models.Action.branch_id, models.Action.depth,
                      models.Action.id)
            .all()
        )
    finally:
        db.close()


def _branch_rows(adv_id) -> list[models.Branch]:
    db = SessionLocal()
    try:
        return (
            db.query(models.Branch)
            .filter(models.Branch.adventure_id == adv_id)
            .order_by(models.Branch.id)
            .all()
        )
    finally:
        db.close()


def _script_state(adv_id) -> dict:
    db = SessionLocal()
    try:
        return db.get(models.Adventure, adv_id).script_state
    finally:
        db.close()


def _forked_story(client) -> int:
    """A story that went two ways and stayed both.

        root: start > do > [attempt two] > do > next turn
        fork:              [ATTEMPT ONE] > do > elsewhere

    The discarded attempt is the one this function promotes, because a
    fork moves the attempt being left for and leaves the line it came
    from untouched.

    Returns the adventure id, with the head on the fork.
    """
    adv_id = client.adv_id
    ScriptedProvider.replies = ["Attempt one.", "Attempt two.", "Next turn.", "Elsewhere."]
    _play(client, adv_id)
    _retry(client, adv_id)
    _play(client, adv_id, "go deeper")
    discarded = [a.id for a in _rows(adv_id) if a.type == "ai" and not a.live][0]
    assert client.post(f"/api/adventures/{adv_id}/actions/{discarded}/fork").status_code == 200
    _play(client, adv_id, "go sideways")
    return adv_id


# ------------------------------------------------------- the round trip (v2)

def test_a_forked_story_survives_the_round_trip(client):
    """The main claim: both futures come back, and both are still readable.

    This is the thing v1 could not do. The check is not "the same rows",
    since the ids are new, but "the same stories", read the way a player
    reads them: by switching to a branch and looking at what it says.
    """
    original = _forked_story(client)
    before = _every_branch_story(client, original)
    assert len(before) == 2, "the fixture forked"
    assert before[0] != before[1], "and the two branches tell different stories"

    copy = _imported(client, _export(client, original))
    assert copy != original
    assert _every_branch_story(client, copy) == before


def test_the_fork_point_comes_back_where_it_was_put(client):
    """`fork_depth` is stored, never inferred, including through a file.

    Inferring it from where two branches' nodes first differ would guess
    at how the story was played, and that guess fails as soon as an
    attempt happens to repeat its parent's text.
    """
    original = _forked_story(client)
    before = [(b["parent_branch_id"] is None, b["fork_depth"]) for b in _branches(client, original)]

    copy = _imported(client, _export(client, original))
    assert [(b["parent_branch_id"] is None, b["fork_depth"])
            for b in _branches(client, copy)] == before


def test_the_head_comes_back_on_the_branch_it_was_left_on(client):
    original = _forked_story(client)
    head_before = [b["is_head"] for b in _branches(client, original)]
    assert head_before == [False, True], "the fixture left the head on the fork"

    copy = _imported(client, _export(client, original))
    assert [b["is_head"] for b in _branches(client, copy)] == head_before
    # The tip it sits at is derived from the nodes that arrived, not
    # read from the file. The bundle never states how deep a branch goes.
    assert _texts(client, copy) == _texts(client, original)


def test_a_switch_in_the_copy_restores_what_that_branch_left_behind(client):
    """This test justifies why the bundle carries after-snapshots.

    The gold script adds ten a turn, so the stored gold total counts the
    turns behind it. A bundle that carried the actions but not the
    outcomes would import a tree that reads correctly but switches to the
    wrong state.
    """
    original = _forked_story(client)
    # Play one more turn on the fork, so the two tips end up at
    # genuinely different totals. Turn for turn, both branches earn the
    # same gold, so a switch that restored nothing would still look right.
    ScriptedProvider.replies = ["Further still."]
    _play(client, original, "press on")

    per_branch = []
    for branch in _branches(client, original):
        _switch(client, original, branch["id"])
        per_branch.append(_script_state(original).get("gold"))
    assert len(set(per_branch)) == len(per_branch), "the tips are at different totals"

    copy = _imported(client, _export(client, original))
    restored = []
    for branch in _branches(client, copy):
        _switch(client, copy, branch["id"])
        restored.append(_script_state(copy).get("gold"))
    assert restored == per_branch


def test_a_memory_comes_back_on_the_node_it_hangs_off(client):
    """Derived work is addressed by coordinate, so the coordinate is carried."""
    original = _forked_story(client)
    tip = [a for a in _rows(original) if a.live][-1]
    db = SessionLocal()
    try:
        db.add(models.Memory(
            adventure_id=original, text="They met a goblin.",
            source_start=0, source_end=tip.depth,
            branch_id=tip.branch_id, depth=tip.depth,
        ))
        db.commit()
    finally:
        db.close()

    exported = _export(client, original)
    assert [(m["branch"], m["depth"]) for m in exported["memories"]] == [(1, tip.depth)]

    copy = _imported(client, exported)
    db = SessionLocal()
    try:
        memories = db.query(models.Memory).filter(
            models.Memory.adventure_id == copy).all()
        branches = [b.id for b in _branch_rows(copy)]
        assert [(branches.index(m.branch_id), m.depth) for m in memories] == [(1, tip.depth)]
    finally:
        db.close()


# --------------------------------------------------- what is not in the file

def test_the_lineage_is_rebuilt_rather_than_carried(client):
    """A cache of `parent` plus `fork_depth` is not a second thing to ship.

    The file states where each branch forked. The ancestry that makes the
    fork readable is computed from that value on the way in, capped at
    the fork exactly as `tree.fork` caps it. Shipping the cache too would
    put two sources of truth for one fact in a file anybody can hand-edit.
    """
    original = _forked_story(client)
    exported = _export(client, original)
    assert all("lineage" not in b for b in exported["branches"])

    root, forked = _branch_rows(_imported(client, exported))
    assert root.lineage == [[root.id, None]]
    assert forked.lineage == [[forked.id, None], [root.id, forked.fork_depth]]
    # This is the arithmetic the reader depends on. The parent is capped
    # one depth short of the attempt that was promoted, so the fork
    # cannot see it.
    assert lineage.entries_of(forked) == [(forked.id, None), (root.id, forked.fork_depth)]


def test_two_branches_each_keep_their_own_node_at_one_depth(client):
    """A depth describes a path, not the adventure.

    The fork and the branch it left both hold a turn at depth 2, and they are
    not the same turn. The import used to issue a global `index` per turn as
    well, so that every coordinate had a number nothing else held. SP8 dropped
    that column, so the coordinate is all there is, and it has to survive the
    round trip on its own.
    """
    copy = _imported(client, _export(client, _forked_story(client)))
    rows = _rows(copy)

    at_depth_2 = [r for r in rows if r.depth == 2]
    assert len({r.branch_id for r in at_depth_2}) == 2


# ------------------------------------------------------- a file that is wrong

def test_a_node_naming_a_branch_the_file_does_not_list_is_refused(client):
    """The import must refuse this file rather than half-apply it. A tree
    missing a branch is a story that silently stops, which is the failure
    this whole phase exists to prevent."""
    payload = _export(client, _forked_story(client))
    payload["branches"] = payload["branches"][:1]
    before = _adventure_count()

    r = _import(client, payload)
    assert r.status_code == 400, r.text
    assert "branch" in r.json()["detail"].lower()
    assert _adventure_count() == before, "nothing was created"


def test_a_branch_forking_from_one_listed_after_it_is_refused(client):
    """The ordering rule guarantees no cycles at the cost of one
    comparison. Without it, a cycle would produce an import that never
    returns instead of one that fails cleanly."""
    payload = _export(client, _forked_story(client))
    payload["branches"] = [{"parent": 1, "forkDepth": 0}, {"parent": None, "forkDepth": None}]
    before = _adventure_count()

    r = _import(client, payload)
    assert r.status_code == 400, r.text
    assert _adventure_count() == before


def test_a_fork_with_no_depth_is_refused(client):
    payload = _export(client, _forked_story(client))
    payload["branches"][1].pop("forkDepth")
    before = _adventure_count()

    r = _import(client, payload)
    assert r.status_code == 400, r.text
    assert "depth" in r.json()["detail"].lower()
    assert _adventure_count() == before


def test_more_branches_than_the_cap_is_refused(client, monkeypatch):
    monkeypatch.setattr(auth, "MULTI_USER", True)
    payload = {
        "format": bundle.FORMAT, "title": "Too many",
        "branches": [{"parent": None, "forkDepth": None}]
                    * (limits.MAX_BRANCHES_PER_ADVENTURE + 1),
        "actions": [],
    }
    before = _adventure_count()

    r = _import(client, payload)
    assert r.status_code == 409, r.text
    assert _adventure_count() == before


def test_a_turn_the_file_gives_no_live_attempt_still_tells_one(client):
    """A coordinate with nothing live is a turn no read can see.

    The file is allowed to be wrong about this, since it is a text file
    someone can edit. The import picks the first attempt instead of
    importing a story with a gap.
    """
    payload = _export(client, _forked_story(client))
    for node in payload["actions"]:
        node["live"] = False
    copy = _imported(client, payload)

    assert _texts(client, copy), "the story is readable"
    live = [(r.branch_id, r.depth) for r in _rows(copy) if r.live]
    assert len(live) == len(set(live)), "exactly one live attempt per coordinate"
    assert len(live) == len({(r.branch_id, r.depth) for r in _rows(copy)})


# ------------------------------------------------------------- the v1 reader

def test_a_v1_bundle_still_imports(client):
    """The v1 reader must remain even after the v1 writer is gone, because
    those files already exist and are saved."""
    payload = {
        "format": bundle.LEGACY_FORMAT,
        "title": "Old backup",
        "memoryCursor": 0, "summaryCursor": 0,
        "actions": [
            {"index": 0, "type": "start", "text": OPENING},
            {"index": 1, "type": "do", "text": "> You go north."},
            {
                "index": 2, "type": "ai", "text": "Two.",
                "variants": [{"text": "One."}, {"text": "Two."}],
                "variantIndex": 1,
            },
        ],
    }
    copy = _imported(client, payload)

    assert _texts(client, copy) == [OPENING, "> You go north.", "Two."]
    # The import produces one branch, and the `variants` array splits
    # back into the sibling group it always described.
    assert len(_branches(client, copy)) == 1
    ai = [r for r in _rows(copy) if r.type == "ai"]
    assert [(r.text, r.live) for r in ai] == [("One.", False), ("Two.", True)]
    assert len({(r.branch_id, r.depth) for r in ai}) == 1


def test_a_v1_bundle_with_a_cursor_lands_it_on_a_node(client):
    """v1 counts covered actions. The tree anchors them to a node instead.
    The translation needs the nodes to exist first, so it runs after they
    are written."""
    payload = {
        "format": bundle.LEGACY_FORMAT, "title": "Old backup",
        "memoryCursor": 2, "summaryCursor": 2,
        "actions": [
            {"index": 0, "type": "start", "text": OPENING},
            {"index": 1, "type": "story", "text": "A corridor."},
            {"index": 2, "type": "story", "text": "A door."},
        ],
    }
    copy = _imported(client, payload)

    db = SessionLocal()
    try:
        adventure = db.get(models.Adventure, copy)
        assert adventure.memory_cursor_branch_id is not None
        assert adventure.memory_cursor_depth == 1, "the second story action"
    finally:
        db.close()


def test_a_v2_bundle_brings_its_anchors_back(client):
    """The other direction: v2 carries the anchor directly."""
    original = _forked_story(client)
    tip = [a for a in _rows(original) if a.live][-1]
    db = SessionLocal()
    try:
        adventure = db.get(models.Adventure, original)
        adventure.memory_cursor_branch_id = tip.branch_id
        adventure.memory_cursor_depth = tip.depth
        db.commit()
    finally:
        db.close()

    exported = _export(client, original)
    assert exported["memoryCursor"] == {"branch": 1, "depth": tip.depth}

    copy = _imported(client, exported)
    db = SessionLocal()
    try:
        adventure = db.get(models.Adventure, copy)
        branches = [b.id for b in _branch_rows(copy)]
        assert branches.index(adventure.memory_cursor_branch_id) == 1
        assert adventure.memory_cursor_depth == tip.depth
    finally:
        db.close()


def test_a_v1_memory_that_summarises_nothing_lands_on_the_root(client):
    """The import must answer the question migration 62 already answered.

    A v1 file has no depths, and a memory the player typed has no
    `sourceEnd` to derive one from. It used to come back with a NULL
    depth, the exact state SP7 removed from the schema.
    `Path._entry_clause` compares `depth <= max_depth`, and a NULL fails
    that comparison. The memory would read fine until the imported
    adventure forked, then vanish from the new branch.
    """
    payload = {
        "format": bundle.LEGACY_FORMAT, "title": "Old backup",
        "memoryCursor": 0, "summaryCursor": 0,
        "actions": [
            {"index": 0, "type": "start", "text": OPENING},
            {"index": 1, "type": "story", "text": "A corridor."},
        ],
        "memories": [
            {"text": "Kira is the innkeeper's daughter"},          # typed
            {"text": "The corridor, summarised", "sourceStart": 1, "sourceEnd": 1},
        ],
    }
    copy = _imported(client, payload)

    db = SessionLocal()
    try:
        rows = {m.text: m for m in db.query(models.Memory)
                .filter(models.Memory.adventure_id == copy).all()}
        assert rows["Kira is the innkeeper's daughter"].depth == 0, (
            "a typed memory anchors at the root, which every branch can see"
        )
        assert rows["The corridor, summarised"].depth == 1, "derived from its range"
        assert all(m.depth is not None for m in rows.values())
        assert all(m.branch_id is not None for m in rows.values())
    finally:
        db.close()


def test_the_action_cap_counts_the_rows_a_v1_file_expands_into(client, monkeypatch):
    """The cap must count what gets written, not what the file lists.

    A v1 turn carries its retries in a `variants` array, and SP4 made
    every attempt a row, so one entry can expand into ten. Counting
    entries instead of rows would let a file inside the cap write a
    multiple of it. The body-size limit does not help here: the text is
    tiny, and the row count is the actual cost.
    """
    monkeypatch.setattr(auth, "MULTI_USER", True)
    monkeypatch.setattr(limits, "MAX_ACTIONS_PER_ADVENTURE", 6)
    monkeypatch.setattr(limits, "_BUNDLE_LIST_CAPS",
                        {**limits._BUNDLE_LIST_CAPS, "actions": 6})
    payload = {
        "format": bundle.LEGACY_FORMAT, "title": "Small file, many rows",
        "memoryCursor": 0, "summaryCursor": 0,
        "actions": [{"index": 0, "type": "start", "text": OPENING}] + [
            {
                "index": i, "type": "ai", "text": "Take four.",
                "variants": [{"text": f"Take {n}."} for n in range(4)],
                "variantIndex": 3,
            }
            for i in range(1, 4)
        ],
    }
    assert len(payload["actions"]) <= 6, "the file itself is inside the cap"
    before = _adventure_count()

    r = _import(client, payload)
    assert r.status_code == 409, r.text
    assert _adventure_count() == before, "and nothing was written"


def test_an_unknown_format_is_refused(client):
    r = _import(client, {"format": "ai-dnd-adventure-v3", "title": "From the future"})
    assert r.status_code == 400, r.text
    assert bundle.FORMAT in r.json()["detail"]