import os
import pathlib
import signal
import subprocess
import threading
from contextlib import closing, contextmanager
from typing import Any, Dict, Optional, Tuple
from uuid import UUID

import pytest
from fixtures.log_helper import log
from fixtures.neon_fixtures import (
    Etcd,
    NeonEnv,
    NeonEnvBuilder,
    NeonPageserverHttpClient,
    PageserverPort,
    PortDistributor,
    Postgres,
    assert_no_in_progress_downloads_for_tenant,
    assert_timeline_local,
    base_dir,
    neon_binpath,
    pg_distrib_dir,
    wait_for_last_record_lsn,
    wait_for_upload,
    wait_until,
)
from fixtures.utils import lsn_from_hex, lsn_to_hex, subprocess_capture


def assert_abs_margin_ratio(a: float, b: float, margin_ratio: float):
    assert abs(a - b) / a < margin_ratio, abs(a - b) / a


@contextmanager
def new_pageserver_helper(new_pageserver_dir: pathlib.Path,
                          pageserver_bin: pathlib.Path,
                          remote_storage_mock_path: pathlib.Path,
                          pg_port: int,
                          http_port: int,
                          broker: Optional[Etcd]):
    """
    cannot use NeonPageserver yet because it depends on neon cli
    which currently lacks support for multiple pageservers
    """
    # actually run new pageserver
    cmd = [
        str(pageserver_bin),
        '--workdir',
        str(new_pageserver_dir),
        '--daemonize',
        '--update-config',
        f"-c listen_pg_addr='localhost:{pg_port}'",
        f"-c listen_http_addr='localhost:{http_port}'",
        f"-c pg_distrib_dir='{pg_distrib_dir}'",
        f"-c id=2",
        f"-c remote_storage={{local_path='{remote_storage_mock_path}'}}",
    ]
    if broker is not None:
        cmd.append(f"-c broker_endpoints=['{broker.client_url()}']", )

    log.info("starting new pageserver %s", cmd)
    out = subprocess.check_output(cmd, text=True)
    log.info("started new pageserver %s", out)
    try:
        yield
    finally:
        log.info("stopping new pageserver")
        pid = int((new_pageserver_dir / 'pageserver.pid').read_text())
        os.kill(pid, signal.SIGQUIT)


@contextmanager
def pg_cur(pg):
    with closing(pg.connect()) as conn:
        with conn.cursor() as cur:
            yield cur


def load(pg: Postgres, stop_event: threading.Event, load_ok_event: threading.Event):
    log.info("load started")

    inserted_ctr = 0
    failed = False
    while not stop_event.is_set():
        try:
            with pg_cur(pg) as cur:
                cur.execute("INSERT INTO load VALUES ('some payload')")
                inserted_ctr += 1
        except:
            if not failed:
                log.info("load failed")
            failed = True
            load_ok_event.clear()
        else:
            if failed:
                with pg_cur(pg) as cur:
                    # if we recovered after failure verify that we have correct number of rows
                    log.info("recovering at %s", inserted_ctr)
                    cur.execute("SELECT count(*) FROM load")
                    # it seems that sometimes transaction gets committed before we can acknowledge
                    # the result, so sometimes selected value is larger by one than we expect
                    assert cur.fetchone()[0] - inserted_ctr <= 1
                    log.info("successfully recovered %s", inserted_ctr)
                    failed = False
                    load_ok_event.set()
    log.info('load thread stopped')


def populate_branch(
    pg: Postgres,
    tenant_id: UUID,
    ps_http: NeonPageserverHttpClient,
    create_table: bool,
    expected_sum: Optional[int],
) -> Tuple[UUID, int]:
    # insert some data
    with pg_cur(pg) as cur:
        cur.execute("SHOW neon.timeline_id")
        timeline_id = UUID(cur.fetchone()[0])
        log.info("timeline to relocate %s", timeline_id.hex)

        cur.execute("SELECT pg_current_wal_flush_lsn()")
        log.info("pg_current_wal_flush_lsn() %s", lsn_from_hex(cur.fetchone()[0]))
        log.info("timeline detail %s",
                 ps_http.timeline_detail(tenant_id=tenant_id, timeline_id=timeline_id))

        # we rely upon autocommit after each statement
        # as waiting for acceptors happens there
        if create_table:
            cur.execute("CREATE TABLE t(key int, value text)")
        cur.execute("INSERT INTO t SELECT generate_series(1,1000), 'some payload'")
        if expected_sum is not None:
            cur.execute("SELECT sum(key) FROM t")
            assert cur.fetchone() == (expected_sum, )
        cur.execute("SELECT pg_current_wal_flush_lsn()")

        current_lsn = lsn_from_hex(cur.fetchone()[0])
        return timeline_id, current_lsn


def ensure_checkpoint(
    pageserver_cur,
    pageserver_http: NeonPageserverHttpClient,
    tenant_id: UUID,
    timeline_id: UUID,
    current_lsn: int,
):
    # run checkpoint manually to be sure that data landed in remote storage
    pageserver_cur.execute(f"checkpoint {tenant_id.hex} {timeline_id.hex}")

    # wait until pageserver successfully uploaded a checkpoint to remote storage
    wait_for_upload(pageserver_http, tenant_id, timeline_id, current_lsn)


def check_timeline_attached(
    new_pageserver_http_client: NeonPageserverHttpClient,
    tenant_id: UUID,
    timeline_id: UUID,
    old_timeline_detail: Dict[str, Any],
    old_current_lsn: int,
):
    # new pageserver should be in sync (modulo wal tail or vacuum activity) with the old one because there was no new writes since checkpoint
    new_timeline_detail = assert_timeline_local(new_pageserver_http_client, tenant_id, timeline_id)

    # when load is active these checks can break because lsns are not static
    # so lets check with some margin
    assert_abs_margin_ratio(lsn_from_hex(new_timeline_detail['local']['disk_consistent_lsn']),
                            lsn_from_hex(old_timeline_detail['local']['disk_consistent_lsn']),
                            0.03)

    assert_abs_margin_ratio(lsn_from_hex(new_timeline_detail['local']['disk_consistent_lsn']),
                            old_current_lsn,
                            0.03)


def switch_pg_to_new_pageserver(env: NeonEnv,
                                pg: Postgres,
                                new_pageserver_port: int,
                                tenant_id: UUID,
                                timeline_id: UUID) -> pathlib.Path:
    pg.stop()

    pg_config_file_path = pathlib.Path(pg.config_file_path())
    pg_config_file_path.open('a').write(
        f"\nneon.pageserver_connstring = 'postgresql://no_user:@localhost:{new_pageserver_port}'")

    pg.start()

    timeline_to_detach_local_path = env.repo_dir / 'tenants' / tenant_id.hex / 'timelines' / timeline_id.hex
    files_before_detach = os.listdir(timeline_to_detach_local_path)
    assert 'metadata' in files_before_detach, f'Regular timeline {timeline_to_detach_local_path} should have the metadata file,\
            but got: {files_before_detach}'
    assert len(files_before_detach) >= 2, f'Regular timeline {timeline_to_detach_local_path} should have at least one layer file,\
            but got {files_before_detach}'

    return timeline_to_detach_local_path


def post_migration_check(pg: Postgres, sum_before_migration: int, old_local_path: pathlib.Path):
    with pg_cur(pg) as cur:
        # check that data is still there
        cur.execute("SELECT sum(key) FROM t")
        assert cur.fetchone() == (sum_before_migration, )
        # check that we can write new data
        cur.execute("INSERT INTO t SELECT generate_series(1001,2000), 'some payload'")
        cur.execute("SELECT sum(key) FROM t")
        assert cur.fetchone() == (sum_before_migration + 1500500, )

    assert not os.path.exists(old_local_path), f'After detach, local timeline dir {old_local_path} should be removed'


@pytest.mark.parametrize(
    'method',
    [
        # A minor migration involves no storage breaking changes.
        # It is done by attaching the tenant to a new pageserver.
        'minor',
        # A major migration involves exporting a postgres datadir
        # basebackup and importing it into the new pageserver.
        # This kind of migration can tolerate breaking changes
        # to storage format
        'major',
    ])
@pytest.mark.parametrize('with_load', ['with_load', 'without_load'])
def test_tenant_relocation(neon_env_builder: NeonEnvBuilder,
                           port_distributor: PortDistributor,
                           test_output_dir,
                           method: str,
                           with_load: str):
    neon_env_builder.enable_local_fs_remote_storage()

    env = neon_env_builder.init_start()

    # create folder for remote storage mock
    remote_storage_mock_path = env.repo_dir / 'local_fs_remote_storage'

    # we use two branches to check that they are both relocated
    # first branch is used for load, compute for second one is used to
    # check that data is not lost

    pageserver_http = env.pageserver.http_client()

    tenant_id, initial_timeline_id = env.neon_cli.create_tenant(UUID("74ee8b079a0e437eb0afea7d26a07209"))
    log.info("tenant to relocate %s initial_timeline_id %s", tenant_id, initial_timeline_id)

    env.neon_cli.create_branch("test_tenant_relocation_main", tenant_id=tenant_id)
    pg_main = env.postgres.create_start(branch_name='test_tenant_relocation_main',
                                        tenant_id=tenant_id)

    timeline_id_main, current_lsn_main = populate_branch(
        pg_main,
        tenant_id=tenant_id,
        ps_http=pageserver_http,
        create_table=True,
        expected_sum=500500,
    )

    env.neon_cli.create_branch(
        new_branch_name="test_tenant_relocation_second",
        ancestor_branch_name="test_tenant_relocation_main",
        ancestor_start_lsn=lsn_to_hex(current_lsn_main),
        tenant_id=tenant_id,
    )
    pg_second = env.postgres.create_start(branch_name='test_tenant_relocation_second',
                                          tenant_id=tenant_id)

    timeline_id_second, current_lsn_second = populate_branch(
        pg_second,
        tenant_id=tenant_id,
        ps_http=pageserver_http,
        create_table=False,
        expected_sum=1001000,
    )

    # wait until pageserver receives that data
    wait_for_last_record_lsn(pageserver_http, tenant_id, timeline_id_main, current_lsn_main)
    timeline_detail_main = assert_timeline_local(pageserver_http, tenant_id, timeline_id_main)

    wait_for_last_record_lsn(pageserver_http, tenant_id, timeline_id_second, current_lsn_second)
    timeline_detail_second = assert_timeline_local(pageserver_http, tenant_id, timeline_id_second)

    if with_load == 'with_load':
        # create load table
        with pg_cur(pg_main) as cur:
            cur.execute("CREATE TABLE load(value text)")

        load_stop_event = threading.Event()
        load_ok_event = threading.Event()
        load_thread = threading.Thread(
            target=load,
            args=(pg_main, load_stop_event, load_ok_event),
            daemon=True,  # To make sure the child dies when the parent errors
        )
        load_thread.start()

    # this requirement introduces a problem
    # if user creates a branch during migration
    # it wont appear on the new pageserver
    with pg_cur(env.pageserver) as cur:
        ensure_checkpoint(
            cur,
            pageserver_http=pageserver_http,
            tenant_id=tenant_id,
            timeline_id=timeline_id_main,
            current_lsn=current_lsn_main,
        )

        ensure_checkpoint(
            cur,
            pageserver_http=pageserver_http,
            tenant_id=tenant_id,
            timeline_id=timeline_id_second,
            current_lsn=current_lsn_second,
        )

    log.info("inititalizing new pageserver")
    # bootstrap second pageserver
    new_pageserver_dir = env.repo_dir / 'new_pageserver'
    new_pageserver_dir.mkdir()

    new_pageserver_pg_port = port_distributor.get_port()
    new_pageserver_http_port = port_distributor.get_port()
    log.info("new pageserver ports pg %s http %s", new_pageserver_pg_port, new_pageserver_http_port)
    pageserver_bin = pathlib.Path(neon_binpath) / 'pageserver'

    new_pageserver_http = NeonPageserverHttpClient(port=new_pageserver_http_port, auth_token=None)

    with new_pageserver_helper(new_pageserver_dir,
                               pageserver_bin,
                               remote_storage_mock_path,
                               new_pageserver_pg_port,
                               new_pageserver_http_port,
                               neon_env_builder.broker):

        # Migrate either by attaching from s3 or import/export basebackup
        if method == "major":
            cmd = [
                "poetry",
                "run",
                "python",
                os.path.join(base_dir, "scripts/export_import_between_pageservers.py"),
                "--tenant-id",
                tenant_id.hex,
                "--from-host",
                "localhost",
                "--from-http-port",
                str(pageserver_http.port),
                "--from-pg-port",
                str(env.pageserver.service_port.pg),
                "--to-host",
                "localhost",
                "--to-http-port",
                str(new_pageserver_http_port),
                "--to-pg-port",
                str(new_pageserver_pg_port),
                "--pg-distrib-dir",
                pg_distrib_dir,
                "--work-dir",
                os.path.join(test_output_dir),
            ]
            subprocess_capture(test_output_dir, cmd, check=True)
        elif method == "minor":
            # call to attach timeline to new pageserver
            new_pageserver_http.tenant_attach(tenant_id)

            # check that it shows that download is in progress
            tenant_status = new_pageserver_http.tenant_status(tenant_id=tenant_id)
            assert tenant_status.get('has_in_progress_downloads'), tenant_status

            # wait until tenant is downloaded
            wait_until(number_of_iterations=10,
                       interval=1,
                       func=lambda: assert_no_in_progress_downloads_for_tenant(
                           new_pageserver_http, tenant_id))

            check_timeline_attached(
                new_pageserver_http,
                tenant_id,
                timeline_id_main,
                timeline_detail_main,
                current_lsn_main,
            )

            check_timeline_attached(
                new_pageserver_http,
                tenant_id,
                timeline_id_second,
                timeline_detail_second,
                current_lsn_second,
            )

        # rewrite neon cli config to use new pageserver for basebackup to start new compute
        cli_config_lines = (env.repo_dir / 'config').read_text().splitlines()
        cli_config_lines[-2] = f"listen_http_addr = 'localhost:{new_pageserver_http_port}'"
        cli_config_lines[-1] = f"listen_pg_addr = 'localhost:{new_pageserver_pg_port}'"
        (env.repo_dir / 'config').write_text('\n'.join(cli_config_lines))

        old_local_path_main = switch_pg_to_new_pageserver(
            env,
            pg_main,
            new_pageserver_pg_port,
            tenant_id,
            timeline_id_main,
        )

        old_local_path_second = switch_pg_to_new_pageserver(
            env,
            pg_second,
            new_pageserver_pg_port,
            tenant_id,
            timeline_id_second,
        )

        # detach tenant from old pageserver before we check
        # that all the data is there to be sure that old pageserver
        # is no longer involved, and if it is, we will see the errors
        pageserver_http.tenant_detach(tenant_id)

        post_migration_check(pg_main, 500500, old_local_path_main)
        post_migration_check(pg_second, 1001000, old_local_path_second)

        # ensure that we can successfully read all relations on the new pageserver
        with pg_cur(pg_second) as cur:
            cur.execute('''
                DO $$
                DECLARE
                r RECORD;
                BEGIN
                FOR r IN
                SELECT relname FROM pg_class WHERE relkind='r'
                LOOP
                    RAISE NOTICE '%', r.relname;
                    EXECUTE 'SELECT count(*) FROM quote_ident($1)' USING r.relname;
                END LOOP;
                END$$;
                ''')

        if with_load == 'with_load':
            assert load_ok_event.wait(3)
            log.info('stopping load thread')
            load_stop_event.set()
            load_thread.join(timeout=10)
            log.info('load thread stopped')

        # bring old pageserver back for clean shutdown via neon cli
        # new pageserver will be shut down by the context manager
        cli_config_lines = (env.repo_dir / 'config').read_text().splitlines()
        cli_config_lines[-2] = f"listen_http_addr = 'localhost:{env.pageserver.service_port.http}'"
        cli_config_lines[-1] = f"listen_pg_addr = 'localhost:{env.pageserver.service_port.pg}'"
        (env.repo_dir / 'config').write_text('\n'.join(cli_config_lines))