# Copyright (C) 2009-2010 Canonical Ltd.
# Copyright (C) 2012 Hewlett-Packard Development Company, L.P.
#
# Author: Scott Moser <scott.moser@canonical.com>
# Author: Juerg Haefliger <juerg.haefliger@hp.com>
#
# This file is part of cloud-init. See LICENSE file for license information.

"""Rsyslog: Configure system logging via rsyslog"""

import os
import re
from textwrap import dedent

from cloudinit import log as logging
from cloudinit import subp, util
from cloudinit.config.schema import MetaSchema, get_meta_doc
from cloudinit.distros import ALL_DISTROS
from cloudinit.settings import PER_INSTANCE

MODULE_DESCRIPTION = """\
This module configures remote system logging using rsyslog.

Configuration for remote servers can be specified in ``configs``, but for
convenience it can be specified as key value pairs in ``remotes``.
"""

meta: MetaSchema = {
    "id": "cc_rsyslog",
    "name": "Rsyslog",
    "title": "Configure system logging via rsyslog",
    "description": MODULE_DESCRIPTION,
    "distros": [ALL_DISTROS],
    "frequency": PER_INSTANCE,
    "examples": [
        dedent(
            """\
            rsyslog:
                remotes:
                    maas: 192.168.1.1
                    juju: 10.0.4.1
                service_reload_command: auto
            """
        ),
        dedent(
            """\
            rsyslog:
                config_dir: /opt/etc/rsyslog.d
                config_filename: 99-late-cloud-config.conf
                configs:
                    - "*.* @@192.158.1.1"
                    - content: "*.*   @@192.0.2.1:10514"
                      filename: 01-example.conf
                    - content: |
                        *.*   @@syslogd.example.com
                remotes:
                    maas: 192.168.1.1
                    juju: 10.0.4.1
                service_reload_command: [your, syslog, restart, command]
            """
        ),
    ],
}

__doc__ = get_meta_doc(meta)

DEF_FILENAME = "20-cloud-config.conf"
DEF_DIR = "/etc/rsyslog.d"
DEF_RELOAD = "auto"
DEF_REMOTES = {}

KEYNAME_CONFIGS = "configs"
KEYNAME_FILENAME = "config_filename"
KEYNAME_DIR = "config_dir"
KEYNAME_RELOAD = "service_reload_command"
KEYNAME_LEGACY_FILENAME = "rsyslog_filename"
KEYNAME_LEGACY_DIR = "rsyslog_dir"
KEYNAME_REMOTES = "remotes"

LOG = logging.getLogger(__name__)

COMMENT_RE = re.compile(r"[ ]*[#]+[ ]*")
HOST_PORT_RE = re.compile(
    r"^(?P<proto>[@]{0,2})"
    r"(([\[](?P<bracket_addr>[^\]]*)[\]])|(?P<addr>[^:]*))"
    r"([:](?P<port>[0-9]+))?$"
)


def reload_syslog(distro, command=DEF_RELOAD):
    if command == DEF_RELOAD:
        service = distro.get_option("rsyslog_svcname", "rsyslog")
        return distro.manage_service("try-reload", service)
    return subp.subp(command, capture=True)


def load_config(cfg: dict) -> dict:
    """Return an updated config.

    Support converting the old top level format into new format.
    Raise a `ValueError` if some top level entry has an incorrect type.
    """
    mycfg = cfg.get("rsyslog", {})

    if isinstance(cfg.get("rsyslog"), list):
        LOG.warning(
            "DEPRECATION: This rsyslog list format is deprecated and will be "
            "removed in a future version of cloud-init. Use documented keys."
        )
        mycfg = {KEYNAME_CONFIGS: cfg.get("rsyslog")}
        if KEYNAME_LEGACY_FILENAME in cfg:
            mycfg[KEYNAME_FILENAME] = cfg[KEYNAME_LEGACY_FILENAME]
        if KEYNAME_LEGACY_DIR in cfg:
            mycfg[KEYNAME_DIR] = cfg[KEYNAME_LEGACY_DIR]

    fillup = (
        (KEYNAME_CONFIGS, [], list),
        (KEYNAME_DIR, DEF_DIR, str),
        (KEYNAME_FILENAME, DEF_FILENAME, str),
        (KEYNAME_RELOAD, DEF_RELOAD, (str, list)),
        (KEYNAME_REMOTES, DEF_REMOTES, dict),
    )

    for key, default, vtypes in fillup:
        if key not in mycfg:
            mycfg[key] = default
        elif not isinstance(mycfg[key], vtypes):
            raise ValueError(
                f"Invalid type for key `{key}`. Expected type(s): {vtypes}. "
                f"Current type: {type(mycfg[key])}"
            )

    return mycfg


def apply_rsyslog_changes(configs, def_fname, cfg_dir):
    # apply the changes in 'configs' to the paths in def_fname and cfg_dir
    # return a list of the files changed
    files = []
    for cur_pos, ent in enumerate(configs):
        if isinstance(ent, dict):
            if "content" not in ent:
                LOG.warning(
                    "No 'content' entry in config entry %s", cur_pos + 1
                )
                continue
            content = ent["content"]
            filename = ent.get("filename", def_fname)
        else:
            content = ent
            filename = def_fname

        filename = filename.strip()
        if not filename:
            LOG.warning("Entry %s has an empty filename", cur_pos + 1)
            continue

        filename = os.path.join(cfg_dir, filename)

        # Truncate filename first time you see it
        omode = "ab"
        if filename not in files:
            omode = "wb"
            files.append(filename)

        try:
            endl = ""
            if not content.endswith("\n"):
                endl = "\n"
            util.write_file(filename, content + endl, omode=omode)
        except Exception:
            util.logexc(LOG, "Failed to write to %s", filename)

    return files


def parse_remotes_line(line, name=None):
    try:
        data, comment = COMMENT_RE.split(line)
        comment = comment.strip()
    except ValueError:
        data, comment = (line, None)

    toks = data.strip().split()
    match = None
    if len(toks) == 1:
        host_port = data
    elif len(toks) == 2:
        match, host_port = toks
    else:
        raise ValueError("line had multiple spaces: %s" % data)

    toks = HOST_PORT_RE.match(host_port)

    if not toks:
        raise ValueError("Invalid host specification '%s'" % host_port)

    proto = toks.group("proto")
    addr = toks.group("addr") or toks.group("bracket_addr")
    port = toks.group("port")

    if addr.startswith("[") and not addr.endswith("]"):
        raise ValueError("host spec had invalid brackets: %s" % addr)

    if comment and not name:
        name = comment

    t = SyslogRemotesLine(
        name=name, match=match, proto=proto, addr=addr, port=port
    )
    t.validate()
    return t


class SyslogRemotesLine(object):
    def __init__(
        self, name=None, match=None, proto=None, addr=None, port=None
    ):
        if not match:
            match = "*.*"
        self.name = name
        self.match = match
        if not proto:
            proto = "udp"
        if proto == "@":
            proto = "udp"
        elif proto == "@@":
            proto = "tcp"
        self.proto = proto

        self.addr = addr
        if port:
            self.port = int(port)
        else:
            self.port = None

    def validate(self):
        if self.port:
            try:
                int(self.port)
            except ValueError as e:
                raise ValueError(
                    "port '%s' is not an integer" % self.port
                ) from e

        if not self.addr:
            raise ValueError("address is required")

    def __repr__(self):
        return "[name=%s match=%s proto=%s address=%s port=%s]" % (
            self.name,
            self.match,
            self.proto,
            self.addr,
            self.port,
        )

    def __str__(self):
        buf = self.match + " "
        if self.proto == "udp":
            buf += "@"
        elif self.proto == "tcp":
            buf += "@@"

        if ":" in self.addr:
            buf += "[" + self.addr + "]"
        else:
            buf += self.addr

        if self.port:
            buf += ":%s" % self.port

        if self.name:
            buf += " # %s" % self.name
        return buf


def remotes_to_rsyslog_cfg(remotes, header=None, footer=None):
    if not remotes:
        return None
    lines = []
    if header is not None:
        lines.append(header)
    for name, line in remotes.items():
        if not line:
            continue
        try:
            lines.append(str(parse_remotes_line(line, name=name)))
        except ValueError as e:
            LOG.warning("failed loading remote %s: %s [%s]", name, line, e)
    if footer is not None:
        lines.append(footer)
    return "\n".join(lines) + "\n"


def handle(name, cfg, cloud, log, _args):
    if "rsyslog" not in cfg:
        log.debug(
            "Skipping module named %s, no 'rsyslog' key in configuration", name
        )
        return

    mycfg = load_config(cfg)
    configs = mycfg[KEYNAME_CONFIGS]

    if mycfg[KEYNAME_REMOTES]:
        configs.append(
            remotes_to_rsyslog_cfg(
                mycfg[KEYNAME_REMOTES],
                header="# begin remotes",
                footer="# end remotes",
            )
        )

    if not mycfg["configs"]:
        log.debug("Empty config rsyslog['configs'], nothing to do")
        return

    changes = apply_rsyslog_changes(
        configs=mycfg[KEYNAME_CONFIGS],
        def_fname=mycfg[KEYNAME_FILENAME],
        cfg_dir=mycfg[KEYNAME_DIR],
    )

    if not changes:
        log.debug("restart of syslog not necessary, no changes made")
        return

    try:
        restarted = reload_syslog(cloud.distro, command=mycfg[KEYNAME_RELOAD])
    except subp.ProcessExecutionError as e:
        restarted = False
        log.warning("Failed to reload syslog", e)

    if restarted:
        # This only needs to run if we *actually* restarted
        # syslog above.
        cloud.cycle_logging()
        # This should now use rsyslog if
        # the logging was setup to use it...
        log.debug("%s configured %s files", name, changes)


# vi: ts=4 expandtab syntax=python