"""Tests for Task 99 — snapshot UX (manual trigger + list + restore + preview).

Phase 4 surfaces the existing snapshot infrastructure (Phase 1 T20 / T31)
through HTML routes so the user can:

* see what snapshots exist,
* take one on demand,
* restore one with a hard confirm,
* peek at metadata before restoring.

The underlying service API lives in ``chat/services/snapshot.py`` and is
already exercised by ``test_snapshot.py``; here we only verify the web
surface wires the existing functions correctly.
"""

from __future__ import annotations

import json
from pathlib import Path

import pytest
from fastapi.testclient import TestClient

from chat.app import app
from chat.db.connection import open_db
from chat.eventlog.log import append_event
from chat.eventlog.projector import project


def _bot_payload(bot_id: str, name: str) -> dict:
    return {
        "id": bot_id,
        "name": name,
        "persona": "fancy",
        "voice_samples": ["sample"],
        "traits": ["shy"],
        "backstory": "",
        "initial_relationship_to_you": "coworker",
        "kickoff_prose": "",
    }


@pytest.fixture
def client(tmp_path, monkeypatch):
    """A TestClient whose db + data_dir live under ``tmp_path``.

    ``load_settings`` derives ``data_dir`` from ``CHAT_DB_PATH``'s parent
    when ``CHAT_DATA_DIR`` is unset (see ``chat/config.py``), so this also
    isolates the ``data/snapshots/`` tree to ``tmp_path``.
    """
    config_path = tmp_path / "config.toml"
    config_path.write_text('featherless_api_key = "test"\n')
    monkeypatch.setenv("CHAT_CONFIG_PATH", str(config_path))
    monkeypatch.setenv("CHAT_DB_PATH", str(tmp_path / "test.db"))

    with TestClient(app) as c:
        c.tmp_path = tmp_path  # type: ignore[attr-defined]
        yield c


def _seed_bot(db_path: Path, bot_id: str = "bot_a", name: str = "BotA") -> None:
    with open_db(db_path) as conn:
        append_event(conn, kind="bot_authored", payload=_bot_payload(bot_id, name))
        project(conn)


def _take_snapshot_via_service(
    db_path: Path, data_dir: Path, kind: str = "periodic"
) -> Path:
    from chat.services.snapshot import take_snapshot

    with open_db(db_path) as conn:
        return take_snapshot(conn, data_dir=data_dir, kind=kind)


def test_list_snapshots_renders_page(client, tmp_path):
    _seed_bot(tmp_path / "test.db", "bot_a", "BotA")
    # Take two snapshots through the service so the listing has rows.
    p1 = _take_snapshot_via_service(tmp_path / "test.db", tmp_path, kind="periodic")
    p2 = _take_snapshot_via_service(tmp_path / "test.db", tmp_path, kind="rewind")

    response = client.get("/snapshots")
    assert response.status_code == 200
    body = response.text
    # Both filenames should appear in the listing.
    assert p1.stem in body
    assert p2.stem in body
    # Both kinds should be visible.
    assert "periodic" in body
    assert "rewind" in body


def test_take_snapshot_creates_new(client, tmp_path):
    _seed_bot(tmp_path / "test.db", "bot_a", "BotA")
    snapshot_dir = tmp_path / "snapshots" / "periodic"

    before = (
        len(list(snapshot_dir.glob("*.json"))) if snapshot_dir.exists() else 0
    )
    response = client.post("/snapshots/take", follow_redirects=False)
    assert response.status_code == 303
    assert response.headers["location"] == "/snapshots"

    after = len(list(snapshot_dir.glob("*.json")))
    assert after == before + 1


def test_restore_snapshot_with_correct_confirm(client, tmp_path):
    db_path = tmp_path / "test.db"
    _seed_bot(db_path, "bot_a", "BotA")
    snapshot_path = _take_snapshot_via_service(
        db_path, tmp_path, kind="periodic"
    )
    snapshot_id = snapshot_path.stem  # filename without extension

    # Mutate the DB after the snapshot was taken — restoring should erase
    # the new bot.
    with open_db(db_path) as conn:
        append_event(
            conn, kind="bot_authored", payload=_bot_payload("bot_b", "BotB")
        )
        project(conn)
        bots_before = conn.execute(
            "SELECT id FROM bots ORDER BY id"
        ).fetchall()
    assert {r[0] for r in bots_before} == {"bot_a", "bot_b"}

    response = client.post(
        f"/snapshots/restore/{snapshot_id}",
        data={"confirm_id": snapshot_id, "kind": "periodic"},
        follow_redirects=False,
    )
    assert response.status_code == 303

    with open_db(db_path) as conn:
        bots_after = conn.execute(
            "SELECT id FROM bots ORDER BY id"
        ).fetchall()
    # The post-snapshot bot should be gone.
    assert {r[0] for r in bots_after} == {"bot_a"}


def test_restore_snapshot_wrong_confirm_400(client, tmp_path):
    db_path = tmp_path / "test.db"
    _seed_bot(db_path, "bot_a", "BotA")
    snapshot_path = _take_snapshot_via_service(
        db_path, tmp_path, kind="periodic"
    )
    snapshot_id = snapshot_path.stem

    response = client.post(
        f"/snapshots/restore/{snapshot_id}",
        data={"confirm_id": "not_the_right_id", "kind": "periodic"},
        follow_redirects=False,
    )
    assert response.status_code == 400


def test_preview_renders_metadata(client, tmp_path):
    db_path = tmp_path / "test.db"
    _seed_bot(db_path, "bot_a", "BotA")
    snapshot_path = _take_snapshot_via_service(
        db_path, tmp_path, kind="periodic"
    )
    snapshot_id = snapshot_path.stem

    # Append more events post-snapshot so the delta is non-zero.
    with open_db(db_path) as conn:
        append_event(
            conn, kind="bot_authored", payload=_bot_payload("bot_b", "BotB")
        )
        project(conn)

    response = client.get(
        f"/snapshots/{snapshot_id}/preview", params={"kind": "periodic"}
    )
    assert response.status_code == 200
    body = response.text
    assert snapshot_id in body
    # Snapshot's last_event_id and current event_log size should appear.
    dump = json.loads(snapshot_path.read_text())
    assert str(dump["last_event_id"]) in body