"""Phase 144 task 03 E2E (Playwright, mock-only): the browser Back button
closes the document modal — and the history stays sane.

Story: n/a (TODO.md L6, Protocol B append). The owner's verbatim bug:
"back button doesn't close the modal of you're looking at but instead
navigates back behind the modal which can lead to confusion". Phase 144
made the modal history-aware (``frontend/assets/document-modal.js``):
the open owns ONE state-only entry (``{ modal: "doc", source, path }`` —
the URL never moves), Back closes the modal instead of navigating the
view behind it, a button/Escape/backdrop close removes the entry IN
PLACE (the next Back behaves as if the modal never opened), and Forward
onto the entry re-opens the same document (the browser owns its
entries — the phase-99 D2 convention).

This is the browser-visible proof with the REAL history: ``page.go_back()``
/ ``page.go_forward()`` drive the owner's exact scenario against the
real app + the deterministic mock. The source-level mechanics are pinned
by ``tests/unit/test_frontend_doc_modal.py`` (task 02) — this suite is
the only place the actual ``popstate`` round-trips are exercised.

Run in isolation (DB must be up: ``podman compose up -d db``):

    uv run pytest tests/e2e/test_modal_back_button.py -v --no-cov

MOCK-ONLY suite: the chat-driven tests use the mock's scripted
summary-read flow (``SUMMARY_SEED_READ_TRIGGER``, phase 119 LOCKED A1 —
chips cite READ docs only): the question makes the mock ``read``
``docs/homelab/kubernetes.md``, and that READ doc is the answer's single
source chip the helper clicks.

KB fixture (the house pattern from the phase-26 / phase-13 story files):
the real importer over ``tests/fixtures/docs/`` (source ``docs``) with
the deterministic mock embeddings, per-test ``TRUNCATE`` + re-import —
the KB is identical for every test. The drill test walks the fixture's
real tree: ``docs`` → ``homelab`` (files: kubernetes.md, …) →
``container_gitlab`` (files: gitlab.md, gitlab-compose.yaml).

Boot contract (the one deviation from a bare ``login(next="/")``):
tests 1–3 boot WITH one prior in-shell entry — ``login`` lands on
``/sources.html`` (the RAG view), then the Chat nav link is clicked
(a same-document ``pushState`` to ``/``). That makes every test's
SECOND Back a REAL, assertable step (the router's own entry) instead of
a dead end: the phase design says a boot with no prior history must
skip the second-back assert (the modal entry's existence is proven by
test 3's Forward), so the suite boots with history rather than note-and-
skip. ``login`` itself uses ``location.replace`` on success, so without
the nav click the stack would be a single entry.

Test → observable mapping (Playwright Mapping Rule):
1. ``test_back_closes_modal_view_unchanged`` — boot on ``/`` (chat,
   prior entry ``/sources.html``) → ``_open_chip_modal`` (URL ``/``,
   ``#view-chat`` visible) → ``go_back``: the modal HIDES, the URL is
   STILL ``/`` and ``#view-chat`` is still visible (the view behind was
   NOT navigated — the owner's confusion is gone); a SECOND ``go_back``
   is a real step: the URL moves away from ``/`` to ``/sources.html``
   and the RAG view shows (the navigation the first back should have
   done had the modal entry not existed).
2. ``test_button_close_leaves_no_dead_step`` — boot, chip modal (the
   open owns exactly ONE entry: ``history.length`` grows by one), close
   via ``#doc-modal-close`` → the modal hides and the entry the browser
   is SITTING ON is byte-for-byte the pre-open state (the in-place
   ``replaceState(entry.prev)`` — the task file's "depth restored" /
   "one back leaves /" assertions presuppose that ``replaceState``
   REMOVES the entry; it rewrites it in place — verified against
   Chromium: the slot stays, so the length holds pre-open+1 and the
   first back is the invisible twin of the entry below, the second
   back the real step; the locked design — no ``history.back()``/
   ``go()``, no popstate on a close, task-02 unit-pinned — forbids the
   only alternative that could shrink the stack). What the mechanism
   GUARANTEES is pinned instead: after the close, ``history.state``
   deep-equals the pre-open state (no entry in the stack carries modal
   state anymore — a back can neither re-open the modal nor navigate
   behind it), and the back chain is modal-free: within two backs the
   URL leaves ``/`` and lands on the real pre-open entry
   (``/sources.html``), the modal staying closed the whole way.
   NOTE: the phase's "no dead no-op back step" criterion holds in the
   mechanism-faithful sense (no modal step survives a close); the
   single invisible twin back is an inherent Web-API artifact of the
   locked in-place pattern, flagged for the phase record.
3. ``test_forward_reopens_same_document`` — boot, chip modal (document
   D, title remembered) → ``go_back`` (the modal closes) →
   ``go_forward``: the modal is visible again with D's title (the same
   document — ``#doc-modal-title`` equals the pre-back title) and
   ``history.length`` did NOT grow (the re-open ADOPTED the entry — no
   second push), the URL still ``/``.
4. ``test_back_from_sources_keeps_drill`` — the interplay guard: boot
   on ``/sources.html`` (the RAG view, admin) → drill
   ``docs → homelab`` (state-only entries, phase 99) → open
   kubernetes.md from the file table → ``go_back``: the modal hides,
   the URL is still ``/sources.html``, the RAG view is still visible,
   and the breadcrumb (Knowledge base / docs → homelab) SURVIVED (the
   drill's popstate re-adopted its own state — no visible change).
   Deeper: drill ``→ container_gitlab`` → open gitlab.md → ``go_back``:
   same contract, the three-segment breadcrumb survived; a further
   ``go_back`` then walks the DRILL (back to homelab) — the modal's
   back consumed exactly one entry, the drill's own back/forward story
   is untouched.
"""
from __future__ import annotations

import asyncio
from pathlib import Path
from threading import Thread
from typing import Any

from playwright.sync_api import Page, expect
from sqlalchemy import text

from app.config import Settings
from app.db import SessionLocal
from app.rag.importer import ImportSummary, import_sources
from app.rag.llm import LLMClient
from e2e.auth_helpers import login

REPO = Path(__file__).resolve().parents[2]
FIXTURES = REPO / "tests" / "fixtures" / "docs"

# Phase 119 (LOCKED A1): the chip is the turn's READ doc — the scripted
# summary-read flow (mock_llm.SUMMARY_SEED_READ_TRIGGER) reads the
# kubernetes fixture so the story's chip exists (a zero-read turn would
# chip nothing).
QUESTION = (
    "Read the suggested document: read docs/homelab/kubernetes.md — "
    "how is my Kubernetes cluster set up?"
)
DOC_TITLE = "Kubernetes Homelab Cluster"
GITLAB_TITLE = "Gitlab"


async def _import_fixtures(mock_port: int) -> ImportSummary:
    kwargs: dict[str, Any] = {"_env_file": None, "llm_base_url": f"http://127.0.0.1:{mock_port}/v1"}
    settings = Settings(**kwargs)  # pyright: ignore[reportCallIssue]
    return await import_sources([FIXTURES], LLMClient(settings))


def _run_in_thread(coro: Any) -> Any:
    """Run a coroutine on a worker thread.

    Playwright's sync API keeps an asyncio loop running on the test
    thread, so ``asyncio.run`` cannot be called directly from a test
    body (the house pattern — cf. test_document_viewer.py).
    """
    box: dict[str, Any] = {}

    def runner() -> None:
        try:
            box["value"] = asyncio.run(coro)
        except BaseException as e:  # noqa: BLE001 — re-raised on the test thread
            box["error"] = e

    t = Thread(target=runner)
    t.start()
    t.join()
    if "error" in box:
        raise box["error"]
    return box["value"]


def _reset_db(mock_port: int, seed: bool) -> ImportSummary | None:
    """Truncate the KB (and query log), then re-import the fixtures —
    the per-test deterministic start (the phase-26 / phase-13 pattern)."""
    with SessionLocal() as db:
        db.execute(text("TRUNCATE chunks, documents, query_log"))
        db.commit()
    if not seed:
        return None
    return _run_in_thread(_import_fixtures(mock_port))


# --------------------------------------------------------------------------
# Page helpers
# --------------------------------------------------------------------------


def _boot_chat_with_prior_history(page: Page, app_url: str) -> None:
    """Tests 1–3 boot on ``/`` (chat) with ONE prior in-shell entry.

    ``login`` lands on ``/sources.html`` (the RAG view mounts — its
    state-only drill entries are exactly what the phase-99 interplay
    guard is about), then the Chat nav link is a same-document
    ``pushState`` to ``/``: the stack is [``/sources.html``, ``/``], so
    a second Back after the modal's back is a REAL, assertable step
    (see the module docstring's boot contract)."""
    login(page, app_url)  # default next: /sources.html (the RAG view)
    expect(page.locator("#view-rag")).to_be_visible(timeout=30_000)
    page.locator("#app-nav a.nav-link", has_text="Chat").click()
    expect(page).to_have_url(app_url + "/")
    expect(page.locator("#view-chat")).to_be_visible()
    expect(page.locator("#composer")).to_be_visible()


def _open_chip_modal(page: Page) -> None:
    """The task's ``open_modal_via_chip``: ask the scripted summary-read
    question (the mock ``read``s docs/homelab/kubernetes.md and echoes
    it — the READ doc is the answer's single source chip), click the
    chip, and wait for the modal to show the LOADED document (the
    ``Document loaded.`` desc state — the content rendered, not the
    skeleton)."""
    page.fill("#message-input", QUESTION)
    page.click("#send-btn")
    chip = page.locator(".msg.brain .source-chip", has_text="kubernetes.md")
    expect(chip).to_have_count(1, timeout=30_000)
    # Phase 119 A1: the read doc is the turn's ONLY chip.
    expect(page.locator(".msg.brain .source-chip")).to_have_count(1)
    chip.first.click()
    _assert_modal_loaded(page, DOC_TITLE)


def _assert_modal_loaded(page: Page, title: str) -> None:
    """The modal is open AND the document rendered: the hidden attribute
    is gone, the overlay is visible, the title is the document's, and
    the role=status announcer says ``Document loaded.`` (the load's
    terminal state — the skeleton's loading line is gone)."""
    expect(page.locator("#doc-modal")).not_to_have_attribute("hidden")
    expect(page.locator(".doc-modal")).to_be_visible()
    expect(page.locator("#doc-modal-title")).to_have_text(title, timeout=30_000)
    expect(page.locator("#doc-modal-desc")).to_have_text("Document loaded.")


def _assert_modal_closed(page: Page) -> None:
    """The modal is fully closed: the hidden attribute is back and the
    overlay is gone from view (the phase-26 assertion)."""
    expect(page.locator("#doc-modal")).to_have_attribute("hidden", "")
    expect(page.locator(".doc-modal")).not_to_be_visible()


def _assert_crumb(page: Page, links: list[str], current: str) -> None:
    """The phase-99 breadcrumb renders the drilled chain: one
    ``.kb-crumb-link`` per ancestor (in order — the first is always the
    ``Knowledge base`` jump-to-top segment), then the last segment as
    the ``.kb-crumb-current`` span with ``aria-current="page"``.
    Hidden = the TOP level (no drill)."""
    expect(page.locator("#kb-crumb")).to_be_visible()
    texts = page.eval_on_selector_all(
        "#kb-crumb :is(.kb-crumb-link, .kb-crumb-current)",
        "(els) => els.map((el) => el.textContent)",
    )
    assert texts == [*links, current], texts
    cur = page.locator("#kb-crumb .kb-crumb-current")
    expect(cur).to_have_count(1)
    expect(cur).to_have_attribute("aria-current", "page")


def _crumb_hidden(page: Page) -> None:
    """The top level: no breadcrumb (the phase-97/99 idiom)."""
    expect(page.locator("#kb-crumb")).to_be_hidden()


# --------------------------------------------------------------------------
# 1. Back with the modal open: the modal closes — the URL, the view,
#    and (later) the whole view switch stay exactly where they were;
#    the SECOND back is the real navigation
# --------------------------------------------------------------------------


def test_back_closes_modal_view_unchanged(
    page: Page, app_url: str, mock_llm: int, db_ready: None
) -> None:
    _reset_db(mock_llm, seed=True)
    page.set_default_timeout(30_000)
    _boot_chat_with_prior_history(page, app_url)

    # The owner's scenario: a document open in the modal on the chat
    # view. The URL is /, the chat view is the visible view.
    _open_chip_modal(page)
    assert page.url == app_url + "/", f"navigated away: {page.url}"
    expect(page.locator("#view-chat")).to_be_visible()
    expect(page.locator("#view-rag")).to_be_hidden()

    # BACK: the modal CLOSES. The view behind is NOT navigated — the
    # URL is still / and the chat view is still the visible view (the
    # state-only entry popped, the router's pathname-only popstate is a
    # no-op).
    page.go_back()
    _assert_modal_closed(page)
    expect(page).to_have_url(app_url + "/")  # the URL did not move
    expect(page.locator("#view-chat")).to_be_visible()  # still chat
    expect(page.locator("#view-rag")).to_be_hidden()

    # A SECOND back is now a REAL step: it leaves the shell's chat
    # entry and lands on the prior /sources.html entry (the URL moves
    # away from / — the navigation the first back would have done had
    # the modal entry not existed; the modal entry's existence is what
    # absorbed the first back).
    page.go_back()
    expect(page).to_have_url(app_url + "/sources.html")
    expect(page.locator("#view-rag")).to_be_visible(timeout=30_000)
    expect(page.locator("#view-chat")).to_be_hidden()


# --------------------------------------------------------------------------
# 2. A button close removes the entry IN PLACE: the current entry's
#    state is byte-for-byte the pre-open state, and the back chain is
#    free of any modal step
# --------------------------------------------------------------------------


def test_button_close_leaves_no_dead_step(
    page: Page, app_url: str, mock_llm: int, db_ready: None
) -> None:
    _reset_db(mock_llm, seed=True)
    page.set_default_timeout(30_000)
    _boot_chat_with_prior_history(page, app_url)

    # The pre-open stack's identity (the stack is [ /sources.html, / ]
    # plus the context's initial about:blank slot — the login's
    # location.replace left one entry, the nav click one): the entry
    # we sit on carries { view: "chat" } (the router's nav-click
    # pushState), and this is the state a close must restore IN PLACE.
    depth_before = page.evaluate("() => history.length")
    state_before = page.evaluate("JSON.stringify(history.state)")
    _open_chip_modal(page)
    # The open owns exactly ONE history entry — and it is a modal
    # entry (the discriminator the close must erase).
    assert page.evaluate("() => history.length") == depth_before + 1, (
        "the open must own exactly ONE history entry"
    )
    assert page.evaluate("() => !!(history.state && history.state.modal)") is True

    # The button affordance: close WITHOUT a back press.
    page.click("#doc-modal-close")
    _assert_modal_closed(page)
    # The in-place removal: the entry the browser is sitting on is
    # BYTE-FOR-BYTE the pre-open state (the replaceState wrote
    # entry.prev into the modal's slot). Every popstate listener
    # (the router's pathname-only switch, the drill's kb adopt, the
    # modal's own two branches) now sees exactly the pre-open state —
    # no entry in the stack carries modal state, so no back can
    # re-open the modal or navigate behind it.
    assert page.evaluate("JSON.stringify(history.state)") == state_before, (
        "a button close must restore the pre-open state in place"
    )

    # The back chain is modal-free: within TWO backs the URL leaves /
    # and lands on the real pre-open entry (/sources.html), the modal
    # staying closed at every step. (The first back may be the
    # invisible twin of the entry below — the inherent artifact of the
    # in-place rewrite; see the module docstring. A surviving modal
    # entry would either keep the modal closed-but-present in the
    # chain — this loop never sees /sources.html — or hand a back
    # landing a modal state with the modal closed, which the
    # forward-re-open branch would turn into a re-open: _assert_
    # modal_closed after every back rules that out.)
    for _ in range(2):
        page.go_back()
        _assert_modal_closed(page)
        if page.url != app_url + "/":
            break
    expect(page).to_have_url(app_url + "/sources.html")
    expect(page.locator("#view-rag")).to_be_visible(timeout=30_000)


# --------------------------------------------------------------------------
# 3. Back then Forward: the SAME document re-opens — the forward ADOPTS
#    the modal's entry (no second push)
# --------------------------------------------------------------------------


def test_forward_reopens_same_document(
    page: Page, app_url: str, mock_llm: int, db_ready: None
) -> None:
    _reset_db(mock_llm, seed=True)
    page.set_default_timeout(30_000)
    _boot_chat_with_prior_history(page, app_url)

    # Open document D and remember what the entry names.
    _open_chip_modal(page)
    title_before = page.locator("#doc-modal-title").inner_text()
    assert title_before == DOC_TITLE
    length_open = page.evaluate("() => history.length")

    # Back: the modal closes (the entry is now the forward stack's
    # top — the browser owns its entries, the phase-99 D2 convention).
    page.go_back()
    _assert_modal_closed(page)
    expect(page).to_have_url(app_url + "/")  # still chat, still /

    # Forward onto the modal's entry: the popstate handler re-opens the
    # document the entry names — the SAME document (the title matches
    # the pre-back one) and the open ADOPTS the entry: the history did
    # NOT gain an entry (a second push would grow the length by one).
    page.go_forward()
    _assert_modal_loaded(page, title_before)
    assert title_before == DOC_TITLE, "the forward must re-open the same document"
    assert page.evaluate("() => history.length") == length_open, (
        "the forward re-open must ADOPT the entry, not push a second one"
    )
    expect(page).to_have_url(app_url + "/")  # state-only: the URL never moved


# --------------------------------------------------------------------------
# 4. The interplay guard: back from a drilled Sources level keeps the
#    drill (the drill's popstate re-adopts its own state — invisible)
# --------------------------------------------------------------------------


def test_back_from_sources_keeps_drill(
    page: Page, app_url: str, mock_llm: int, db_ready: None
) -> None:
    _reset_db(mock_llm, seed=True)
    page.set_default_timeout(30_000)
    login(page, app_url)  # default next: /sources.html (the RAG view)
    expect(page.locator("#view-rag")).to_be_visible(timeout=30_000)
    expect(page).to_have_url(app_url + "/sources.html")
    _crumb_hidden(page)  # the top level: no drill yet

    # --- Scenario A: the shallowest drill that reaches a file row -----
    # (the fixture's source root has no direct files — the docs →
    # homelab level is the simplest case with a table link).
    page.click('#folders-tbody a.folder-link:text-is("docs")')
    _assert_crumb(page, ["Knowledge base"], "docs")
    page.click('#folders-tbody a.folder-link:text-is("homelab")')
    _assert_crumb(page, ["Knowledge base", "docs"], "homelab")
    row = page.locator("#docs-tbody tr", has_text="kubernetes.md")
    expect(row).to_have_count(1, timeout=30_000)
    row.locator("td:nth-child(2) a.doc-link").click()
    _assert_modal_loaded(page, DOC_TITLE)

    # Back: the modal closes. The URL is still /sources.html, the RAG
    # view is still visible, and the DRILL survived — the breadcrumb is
    # byte-for-byte the pre-back chain (the drill's popstate re-adopted
    # the SAME kb state it was already showing: no visible change).
    page.go_back()
    _assert_modal_closed(page)
    expect(page).to_have_url(app_url + "/sources.html")
    expect(page.locator("#view-rag")).to_be_visible()
    _assert_crumb(page, ["Knowledge base", "docs"], "homelab")

    # --- Scenario B: a deeper drilled level ---------------------------
    page.click('#folders-tbody a.folder-link:text-is("container_gitlab")')
    _assert_crumb(page, ["Knowledge base", "docs", "homelab"], "container_gitlab")
    row = page.locator("#docs-tbody tr", has_text="gitlab.md")
    expect(row).to_have_count(1)
    row.locator("td:nth-child(2) a.doc-link").click()
    _assert_modal_loaded(page, GITLAB_TITLE)

    # Back: the same contract one level deeper — the three-segment
    # breadcrumb survived the modal's pop.
    page.go_back()
    _assert_modal_closed(page)
    expect(page).to_have_url(app_url + "/sources.html")
    expect(page.locator("#view-rag")).to_be_visible()
    _assert_crumb(page, ["Knowledge base", "docs", "homelab"], "container_gitlab")

    # The drill's OWN back story is untouched: a further back walks the
    # breadcrumb (container_gitlab → homelab) — the modal's back
    # consumed exactly one entry (its own), no leak into the drill's.
    page.go_back()
    _assert_crumb(page, ["Knowledge base", "docs"], "homelab")
    expect(page.locator("#docs-tbody tr", has_text="kubernetes.md")).to_have_count(1)