import re

import btrfs
import collectd

PLUGIN = 'btrfs'
TYPE_STATS = "device_stats"
INTERVAL = 600

def read_callback():
    """Read Btrfs device information and dispatch values to collectd."""
    metric = collectd.Values()
    metric.plugin = PLUGIN
    mount_paths = btrfs.utils.mounted_filesystem_paths()
    for path in mount_paths:
        try:
            with btrfs.FileSystem(path) as fs:
                for device in list(fs.devices()):
                    stats = fs.dev_stats(device.devid)
                    dev_info = fs.dev_info(device.devid)
                    metric.plugin_instance = re.sub(
                            r'[^a-zA-Z0-9]',
                            r'-',
                            dev_info.path)[1:]
                    if not metric.plugin_instance:
                        metric.plugin_instance = "missing"
                    for counter, value in stats.counters.items():
                        metric.type_instance = counter
                        metric.dispatch(TYPE_STATS, [value], interval=INTERVAL)
        except Exception as e:
            collectd.error("btrfs: read_callback: {}".format(e))
    collectd.debug("btrfs: read done")

if __name__ != "__main__":
    # Register callbacks
    collectd.register_read(read_callback, INTERVAL)