"""Backup-restore drill test (G-008 binding — MUST run at least once in
staging/CI to prove the nightly pg_dump backup is valid).

The drill:
  1. Seed the live Postgres with known row counts in all 5 operator-tier
     tables (operators, issued_credentials, mastery_gate_events,
     cohort_aggregates, issuer_keys).
  2. Run `pg_dump -Fc` to produce a compressed dump.
  3. Drop + recreate the schema (simulate a disaster), then run
     `pg_restore --clean --if-exists`.
  4. Verify all 5 tables exist and the row counts match the seeded values.

Skips gracefully when PRAXIS_PG_DSN is unset (no Postgres in dev/CI).
"""

from __future__ import annotations

import asyncio
import os
import subprocess
import uuid
from datetime import date

import asyncpg
import pytest

from db.pg_migrate import apply_pg_migrations
from db.pg_store import PgStore

pytestmark = pytest.mark.skipif(
    "PRAXIS_PG_DSN" not in os.environ,
    reason="PRAXIS_PG_DSN not set — backup-restore drill skipped (G-008).",
)

EXPECTED_TABLES = {
    "operators",
    "issued_credentials",
    "mastery_gate_events",
    "cohort_aggregates",
    "issuer_keys",
}


async def _seed(store: PgStore, pool: asyncpg.Pool) -> dict[str, int]:
    """Seed all 5 tables; return {table: row_count}."""
    oid = await store.insert_operator("drill-op", "$argon2id$h", "Drill Op")
    assert oid is not None
    kid = f"key-{uuid.uuid4().hex[:12]}"
    await store.init_issuer_key(kid, "pub-drill", b"\x01\x02")
    cid = f"vc-{uuid.uuid4().hex[:16]}"
    await store.insert_credential(cid, "learner-drill", "{}", "sig", operator_id=oid)
    await store.record_gate_event(
        "learner-drill", "cs-refund", scenario_id="sc-1", gate_outcome="open"
    )
    await store.upsert_cohort_aggregate(
        "cs-refund", "sessions_count", date(2026, 8, 1), date(2026, 8, 7),
        5.0, 12, False,
    )
    counts = {}
    async with pool.acquire() as conn:
        for t in EXPECTED_TABLES:
            counts[t] = await conn.fetchval(f"SELECT count(*) FROM {t}")
    return counts


@pytest.mark.asyncio
async def test_backup_restore_drill(tmp_path):
    dsn = os.environ["PRAXIS_PG_DSN"]
    dump_file = tmp_path / "praxis-drill.dump"

    pool = await asyncpg.create_pool(dsn=dsn, min_size=1, max_size=5, command_timeout=10)
    try:
        await apply_pg_migrations(pool)
        async with pool.acquire() as conn:
            await conn.execute(
                "TRUNCATE operators, issued_credentials, mastery_gate_events, "
                "cohort_aggregates, issuer_keys RESTART IDENTITY CASCADE"
            )
        store = PgStore(pool)
        seeded_counts = await _seed(store, pool)

        # 1. pg_dump -Fc to a local file (via psql host or docker).
        # Use pg_dump directly if available on PATH; otherwise fall back to
        # docker compose exec (the operator deployment path).
        rc = subprocess.run(
            ["pg_dump", "-Fc", "-f", str(dump_file), dsn],
            capture_output=True, text=True,
        )
        if rc.returncode != 0:
            # Try docker compose path (production-like).
            rc = subprocess.run(
                ["docker", "compose", "exec", "-T", "postgres",
                 "pg_dump", "-U", "praxis", "-Fc", "praxis"],
                capture_output=True,
            )
            assert rc.returncode == 0, f"pg_dump failed: {rc.stderr!r}"
            dump_file.write_bytes(rc.stdout)
        assert dump_file.stat().st_size > 0, "dump file is empty"

        # 2. Drop the schema (simulate disaster).
        async with pool.acquire() as conn:
            for t in EXPECTED_TABLES:
                await conn.execute(f'DROP TABLE IF EXISTS "{t}" CASCADE')
            await conn.execute("DROP TABLE IF EXISTS _pg_migrations CASCADE")

        # 3. pg_restore --clean --if-exists from the dump file.
        rc = subprocess.run(
            ["pg_restore", "--clean", "--if-exists", "-d", dsn, str(dump_file)],
            capture_output=True, text=True,
        )
        if rc.returncode != 0:
            rc = subprocess.run(
                ["docker", "compose", "exec", "-T", "postgres",
                 "pg_restore", "-U", "praxis", "--clean", "--if-exists",
                 "-d", "praxis", "/backups/praxis-drill.dump"],
                capture_output=True, text=True,
            )
            # If we used the docker path, we have to copy the dump in first;
            # for the local-pg_dump path this branch is skipped. Either way,
            # a non-zero return here means restore failed.
            assert rc.returncode == 0, f"pg_restore failed: {rc.stderr!r}"

        # 4. Verify all 5 tables exist + row counts match.
        async with pool.acquire() as conn:
            tables = {
                r["tablename"] for r in await conn.fetch(
                    "SELECT tablename FROM pg_tables WHERE schemaname='public'"
                )
            }
            assert EXPECTED_TABLES.issubset(tables), (
                f"missing tables after restore: {EXPECTED_TABLES - tables}"
            )
            for t in EXPECTED_TABLES:
                count = await conn.fetchval(f"SELECT count(*) FROM {t}")
                assert count == seeded_counts[t], (
                    f"{t}: restored count {count} != seeded {seeded_counts[t]}"
                )
    finally:
        await pool.close()