#!/usr/local/bin/python3

# FreeNAS 11.1 not support #!/usr/bin/env python3

import json
import subprocess

SYSCTL = "/sbin/sysctl"
ZPOOL = "/usr/local/sbin/zpool"


def percent(numerator, denominator, default=0):
    try:
        return numerator / denominator * 100
    except ZeroDivisionError:
        return default


def main(args):
    p = subprocess.run(
        [SYSCTL, "-q", "kstat.zfs", "vfs.zfs"],
        stdout=subprocess.PIPE,
        universal_newlines=True,
    )

    if p.returncode != 0:
        return p.returncode

    def chomp(line):
        bits = [b.strip() for b in line.split(":")]
        try:
            return bits[0], int(bits[1])
        except ValueError:
            return bits[0], bits[1]

    stats = dict(chomp(line) for line in p.stdout.splitlines() if line)
    if "kstat.zfs.misc.arcstats.recycle_miss" not in stats:
        stats["kstat.zfs.misc.arcstats.recycle_miss"] = 0

    output = dict()

    # ARC misc
    output["deleted"] = stats["kstat.zfs.misc.arcstats.deleted"]
    output["evict_skip"] = stats["kstat.zfs.misc.arcstats.evict_skip"]
    output["mutex_skip"] = stats["kstat.zfs.misc.arcstats.mutex_miss"]
    output["recycle_miss"] = stats["kstat.zfs.misc.arcstats.recycle_miss"]

    # ARC size
    output["target_size_per"] = (
        stats["kstat.zfs.misc.arcstats.c"]
        / stats["kstat.zfs.misc.arcstats.c_max"]
        * 100
    )
    output["arc_size_per"] = (
        stats["kstat.zfs.misc.arcstats.size"]
        / stats["kstat.zfs.misc.arcstats.c_max"]
        * 100
    )
    output["target_size_arat"] = (
        stats["kstat.zfs.misc.arcstats.c"] / stats["kstat.zfs.misc.arcstats.c_max"]
    )
    output["min_size_per"] = (
        stats["kstat.zfs.misc.arcstats.c_min"]
        / stats["kstat.zfs.misc.arcstats.c_max"]
        * 100
    )

    output["arc_size"] = stats["kstat.zfs.misc.arcstats.size"]
    output["target_size_max"] = stats["kstat.zfs.misc.arcstats.c_max"]
    output["target_size_min"] = stats["kstat.zfs.misc.arcstats.c_min"]
    output["target_size"] = stats["kstat.zfs.misc.arcstats.c"]

    # ARC size breakdown
    output["mfu_size"] = (
        stats["kstat.zfs.misc.arcstats.size"] - stats["kstat.zfs.misc.arcstats.p"]
    )
    output["p"] = stats["kstat.zfs.misc.arcstats.p"]
    output["rec_used_per"] = (
        stats["kstat.zfs.misc.arcstats.p"] / stats["kstat.zfs.misc.arcstats.size"] * 100
    )
    output["freq_used_per"] = (
        output["mfu_size"] / stats["kstat.zfs.misc.arcstats.size"] * 100
    )

    # ARC misc efficiency stats
    output["arc_hits"] = stats["kstat.zfs.misc.arcstats.hits"]
    output["arc_misses"] = stats["kstat.zfs.misc.arcstats.misses"]
    output["demand_data_hits"] = stats["kstat.zfs.misc.arcstats.demand_data_hits"]
    output["demand_data_misses"] = stats["kstat.zfs.misc.arcstats.demand_data_misses"]
    output["demand_meta_hits"] = stats["kstat.zfs.misc.arcstats.demand_metadata_hits"]
    output["demand_meta_misses"] = stats[
        "kstat.zfs.misc.arcstats.demand_metadata_misses"
    ]
    output["mfu_ghost_hits"] = stats["kstat.zfs.misc.arcstats.mfu_ghost_hits"]
    output["mfu_hits"] = stats["kstat.zfs.misc.arcstats.mfu_hits"]
    output["mru_ghost_hits"] = stats["kstat.zfs.misc.arcstats.mru_ghost_hits"]
    output["mru_hits"] = stats["kstat.zfs.misc.arcstats.mru_hits"]
    output["pre_data_hits"] = stats["kstat.zfs.misc.arcstats.prefetch_data_hits"]
    output["pre_data_misses"] = stats["kstat.zfs.misc.arcstats.prefetch_data_misses"]
    output["pre_meta_hits"] = stats["kstat.zfs.misc.arcstats.prefetch_metadata_hits"]
    output["pre_meta_misses"] = stats[
        "kstat.zfs.misc.arcstats.prefetch_metadata_misses"
    ]

    output["anon_hits"] = output["arc_hits"] - (
        output["mfu_hits"]
        + output["mru_hits"]
        + output["mfu_ghost_hits"]
        + output["mru_ghost_hits"]
    )
    output["arc_accesses_total"] = output["arc_hits"] + output["arc_misses"]
    output["demand_data_total"] = (
        output["demand_data_hits"] + output["demand_data_misses"]
    )
    output["pre_data_total"] = output["pre_data_hits"] + output["pre_data_misses"]
    output["real_hits"] = output["mfu_hits"] + output["mru_hits"]

    # ARC efficiency percents
    output["cache_hits_per"] = percent(output["arc_hits"], output["arc_accesses_total"])
    output["cache_miss_per"] = percent(
        output["arc_misses"], output["arc_accesses_total"]
    )
    output["actual_hit_per"] = percent(
        output["real_hits"], output["arc_accesses_total"]
    )
    output["data_demand_per"] = percent(
        output["demand_data_hits"], output["demand_data_total"]
    )
    output["data_pre_per"] = percent(output["pre_data_hits"], output["pre_data_total"])
    output["anon_hits_per"] = percent(output["anon_hits"], output["arc_hits"])
    output["mru_per"] = percent(output["mru_hits"], output["arc_hits"])
    output["mfu_per"] = percent(output["mfu_hits"], output["arc_hits"])
    output["mru_ghost_per"] = percent(output["mru_ghost_hits"], output["arc_hits"])
    output["mfu_ghost_per"] = percent(output["mfu_ghost_hits"], output["arc_hits"])
    output["demand_hits_per"] = percent(output["demand_data_hits"], output["arc_hits"])
    output["pre_hits_per"] = percent(output["pre_data_hits"], output["arc_hits"])
    output["meta_hits_per"] = percent(output["demand_meta_hits"], output["arc_hits"])
    output["pre_meta_hits_per"] = percent(output["pre_meta_hits"], output["arc_hits"])
    output["demand_misses_per"] = percent(
        output["demand_data_misses"], output["arc_misses"]
    )
    output["pre_misses_per"] = percent(output["pre_data_misses"], output["arc_misses"])
    output["meta_misses_per"] = percent(
        output["demand_meta_misses"], output["arc_misses"]
    )
    output["pre_meta_misses_per"] = percent(
        output["pre_meta_misses"], output["arc_misses"]
    )

    # pools
    p = subprocess.run(
        [ZPOOL, "list", "-pH"], stdout=subprocess.PIPE, universal_newlines=True
    )
    if p.returncode != 0:
        return p.returncode
    output["pools"] = []
    fields = [
        "name",
        "size",
        "alloc",
        "free",
        "ckpoint",
        "expandsz",
        "frag",
        "cap",
        "dedup",
    ]
    for l in p.stdout.splitlines():
        p = dict(zip(fields, l.split("\t")))
        if p["ckpoint"] == "-":
            p["ckpoint"] = 0
        if p["expandsz"] == "-":
            p["expandsz"] = 0
        p["frag"] = p["frag"].rstrip("%")
        if p["frag"] == "-":
            p["frag"] = 0
        p["cap"] = p["cap"].rstrip("%")
        if p["cap"] == "-":
            p["cap"] = 0
        p["dedup"] = p["dedup"].rstrip("x")
        output["pools"].append(p)

    print(json.dumps(output))

    return 0


if __name__ == "__main__":
    import sys

    sys.exit(main(sys.argv[1:]))