#!/usr/bin/env python3

import argparse
import errno
import os
import platform
import re
import sys
import subprocess
import tempfile
import traceback

# Use the Zulip virtualenv if available
sys.path.append("/home/zulip/deployments/current")
try:
    from scripts.lib.setup_path import setup_path
    setup_path()
except ImportError:
    try:
        import scripts.lib.setup_path_on_import
        scripts.lib.setup_path_on_import  # Suppress unused import warning
    except ImportError:
        pass

import json

sys.path.insert(0, os.path.join(os.path.dirname(__file__), "../../"))
import zulip
from typing import List

temp_dir = "/var/tmp/" if os.name == "posix" else tempfile.gettempdir()

def mkdir_p(path: str) -> None:
    # Python doesn't have an analog to `mkdir -p` < Python 3.2.
    try:
        os.makedirs(path)
    except OSError as e:
        if e.errno == errno.EEXIST and os.path.isdir(path):
            pass
        else:
            raise

def send_log_zulip(file_name: str, count: int, lines: List[str], extra: str = "") -> None:
    content = "%s new errors%s:\n```\n%s\n```" % (count, extra, "\n".join(lines))
    zulip_client.send_message({
        "type": "stream",
        "to": "logs",
        "subject": "%s on %s" % (file_name, platform.node()),
        "content": content,
    })

def process_lines(raw_lines: List[str], file_name: str) -> None:
    lines = []
    for line in raw_lines:
        # Add any filtering or modification code here
        if re.match(r".*upstream timed out.*while reading upstream.*", line):
            continue
        lines.append(line)

    if len(lines) == 0:
        return
    elif len(lines) > 10:
        send_log_zulip(file_name, len(lines), lines[0:3], extra=", examples include")
    else:
        send_log_zulip(file_name, len(lines), lines)

def process_logs() -> None:
    data_file_path = os.path.join(temp_dir, "log2zulip.state")
    mkdir_p(os.path.dirname(data_file_path))
    if not os.path.exists(data_file_path):
        open(data_file_path, "w").write("{}")
    last_data = json.loads(open(data_file_path).read())
    new_data = {}
    for log_file in log_files:
        file_data = last_data.get(log_file, {})
        if not os.path.exists(log_file):
            # If the file doesn't exist, log an error and then move on to the next file
            print("Log file does not exist or could not stat log file: %s" % (log_file,))
            continue
        length = int(subprocess.check_output(["wc", "-l", log_file]).split()[0])
        if file_data.get("last") is None:
            file_data["last"] = 1
        if length + 1 < file_data["last"]:
            # The log file was rotated, restart from empty.  Note that
            # because we don't actually store the log file content, if
            # a log file ends up at the same line length as before
            # immediately after rotation, this tool won't notice.
            file_data["last"] = 1
        output = subprocess.check_output(["tail", "-n+%s" % (file_data["last"],), log_file])
        new_lines = output.decode('utf-8', errors='replace').split('\n')[:-1]
        if len(new_lines) > 0:
            process_lines(new_lines, log_file)
            file_data["last"] += len(new_lines)
        new_data[log_file] = file_data
    open(data_file_path, "w").write(json.dumps(new_data))

if __name__ == "__main__":
    parser = zulip.add_default_arguments(argparse.ArgumentParser())  # type: argparse.ArgumentParser
    parser.add_argument("--control-path", default="/etc/log2zulip.conf")
    args = parser.parse_args()

    lock_path = os.path.join(temp_dir, "log2zulip.lock")
    if os.path.exists(lock_path):
        # This locking code is here to protect against log2zulip,
        # running in a cron job, ending up with multiple copies
        # running at the same time.
        print("Log2zulip lock held; not doing anything")
        sys.exit(0)

    # TODO: Convert this locking code to use a standard context manager.
    try:
        open(lock_path, "w").write("1")
        zulip_client = zulip.init_from_options(args)
        try:
            log_files = json.loads(open(args.control_path).read())
        except (json.JSONDecodeError, OSError):
            print("Could not load control data from %s" % (args.control_path,))
            traceback.print_exc()
            sys.exit(1)
        process_logs()
    finally:
        try:
            os.remove(lock_path)
        except OSError:
            pass