"""
ZFS Command Runner – Wrapper für zpool/zfs CLI Commands
Handles subprocess execution, parsing, caching, error handling
"""

import subprocess
import json
import logging
import glob
import os
from typing import Dict, List, Any, Optional, Tuple
from dataclasses import dataclass
from datetime import datetime, timedelta
import re

logger = logging.getLogger(__name__)

# Cache with TTL
@dataclass
class CacheEntry:
    data: Any
    expires_at: datetime

class ZFSCache:
    def __init__(self):
        self.pool_status = CacheEntry(None, datetime.now())
        self.snapshots = CacheEntry(None, datetime.now())
        self.datasets = CacheEntry(None, datetime.now())

    def get(self, key: str) -> Optional[Any]:
        cache_dict = {
            "pool_status": self.pool_status,
            "snapshots": self.snapshots,
            "datasets": self.datasets,
        }

        if key not in cache_dict:
            return None

        entry = cache_dict[key]
        if not entry or not entry.data:
            return None

        if datetime.now() > entry.expires_at:
            return None

        return entry.data

    def set(self, key: str, data: Any, ttl_seconds: int = 60):
        cache_dict = {
            "pool_status": self.pool_status,
            "snapshots": self.snapshots,
            "datasets": self.datasets,
        }

        if key in cache_dict:
            cache_dict[key].data = data
            cache_dict[key].expires_at = datetime.now() + timedelta(seconds=ttl_seconds)

class ZFSRunner:
    def __init__(self, timeout: int = 5):
        self.timeout = timeout
        self.cache = ZFSCache()

    def run_command(self, cmd: List[str], timeout: Optional[int] = None) -> Tuple[str, str, int]:
        """
        Run subprocess command with timeout
        Returns: (stdout, stderr, returncode)
        """
        if timeout is None:
            timeout = self.timeout

        try:
            result = subprocess.run(
                cmd,
                capture_output=True,
                text=True,
                timeout=timeout,
                check=False
            )
            return result.stdout, result.stderr, result.returncode
        except subprocess.TimeoutExpired:
            logger.error(f"Command timeout after {timeout}s: {' '.join(cmd)}")
            return "", f"Command timeout after {timeout}s", -1
        except FileNotFoundError:
            logger.error(f"Command not found: {' '.join(cmd)}")
            return "", f"Command not found: {cmd[0]}", -1
        except Exception as e:
            logger.error(f"Command execution error: {e}")
            return "", str(e), -1

    # ============== POOL OPERATIONS ==============

    def list_pools(self) -> List[Dict[str, Any]]:
        """
        Get list of ZFS pools with status
        Uses cache (TTL 30s)
        """
        cached = self.cache.get("pool_status")
        if cached:
            return cached

        stdout, stderr, rc = self.run_command(["zpool", "list", "-H", "-p"])

        if rc != 0:
            logger.error(f"zpool list failed: {stderr}")
            return []

        pools = []
        for line in stdout.strip().split("\n"):
            if not line:
                continue

            parts = line.split()
            if len(parts) < 10:
                continue

            pool = {
                "name": parts[0],
                "size": int(parts[1]),
                "alloc": int(parts[2]),
                "free": int(parts[3]),
                "fragmentation": f"{parts[6]}%",
                "capacity": f"{parts[7]}%",
                "health": parts[9]
            }
            pools.append(pool)

        self.cache.set("pool_status", pools, ttl_seconds=30)
        return pools

    def _parse_vdev_tree(self, config_lines: List[str]) -> List[Dict[str, Any]]:
        """
        Parse VDEV tree from zpool status config section.
        Uses indentation levels to reconstruct hierarchy.
        Returns list of vdev dicts with name, state, and error counters (read/write/cksum).
        """
        roots: List[Dict] = []
        stack: List[tuple] = []  # (indent, vdev_dict)

        for line in config_lines:
            if not line.strip():
                continue
            # Skip header line (NAME STATE READ WRITE CKSUM)
            if line.strip().startswith("NAME"):
                continue

            indent = len(line) - len(line.lstrip())
            parts = line.split()
            if not parts:
                continue

            name = parts[0]
            state = parts[1] if len(parts) > 1 else "UNKNOWN"

            # Parse error counters and convert to integers
            read = 0
            write = 0
            cksum = 0

            if len(parts) > 2:
                try:
                    read = int(parts[2])
                except (ValueError, IndexError):
                    read = 0

            if len(parts) > 3:
                try:
                    write = int(parts[3])
                except (ValueError, IndexError):
                    write = 0

            if len(parts) > 4:
                try:
                    cksum = int(parts[4])
                except (ValueError, IndexError):
                    cksum = 0

            vdev: Dict[str, Any] = {
                "name": name,
                "state": state,
                "read": read,
                "write": write,
                "cksum": cksum,
                "children": []
            }

            # Pop stack entries that are at same or deeper indent
            while stack and stack[-1][0] >= indent:
                stack.pop()

            if stack:
                stack[-1][1]["children"].append(vdev)
            else:
                roots.append(vdev)

            stack.append((indent, vdev))

        return roots

    def get_disk_id_map(self) -> Dict[str, str]:
        """
        Build mapping {sda: ata-WDC_WD20EZRZ-..., nvme0n1: nvme-Samsung_...} from /dev/disk/by-id/.
        Prefers ata- prefix, then nvme-, then scsi-, then wwn-.
        """
        mapping: Dict[str, str] = {}
        priority = ["ata-", "nvme-", "scsi-", "wwn-"]

        for pattern in priority:
            for link in glob.glob(f"/dev/disk/by-id/{pattern}*"):
                if "-part" in os.path.basename(link):
                    continue
                try:
                    target = os.path.realpath(link)
                    disk = os.path.basename(target)
                    if disk not in mapping:
                        mapping[disk] = os.path.basename(link)
                except OSError:
                    continue

        return mapping

    def get_smart_info(self, disk: str) -> Dict[str, Any]:
        """
        Run smartctl -A -i --json on /dev/disk and return parsed health data.
        Returns empty dict if smartctl unavailable or disk not SMART-capable.
        """
        stdout, stderr, rc = self.run_command(["smartctl", "-A", "-i", "--json", f"/dev/{disk}"])
        if not stdout:
            return {}
        try:
            data = json.loads(stdout)
        except json.JSONDecodeError:
            return {}

        result: Dict[str, Any] = {}

        # Device info
        device = data.get("device", {})
        model_info = data.get("model_name") or data.get("model_family", "")
        serial = data.get("serial_number", "")
        result["model"] = model_info
        result["serial"] = serial
        result["protocol"] = device.get("protocol", "")

        # Power-on hours
        result["power_on_hours"] = data.get("power_on_time", {}).get("hours")

        # Temperature
        temp = data.get("temperature", {})
        result["temperature"] = temp.get("current")

        # Overall health (from -H flag data embedded in -i)
        smart_status = data.get("smart_status", {})
        result["passed"] = smart_status.get("passed")

        # Key attributes from ata_smart_attributes
        attrs = {a["name"]: a for a in data.get("ata_smart_attributes", {}).get("table", [])}
        result["reallocated_sectors"] = attrs.get("Reallocated_Sector_Ct", {}).get("raw", {}).get("value", 0)
        result["pending_sectors"] = attrs.get("Current_Pending_Sector", {}).get("raw", {}).get("value", 0)
        result["uncorrectable"] = attrs.get("Offline_Uncorrectable", {}).get("raw", {}).get("value", 0)

        return result

    def get_pool_status(self, pool_name: str) -> Dict[str, Any]:
        """
        Get detailed pool status including VDEV tree and error counters
        """
        stdout, stderr, rc = self.run_command(["zpool", "status", pool_name])

        if rc != 0:
            logger.error(f"zpool status failed for {pool_name}: {stderr}")
            return {}

        status: Dict[str, Any] = {
            "name": pool_name,
            "state": None,
            "scan": None,
            "errors": None,
            "vdevs": [],
        }

        lines = stdout.split("\n")
        in_config = False
        config_lines: List[str] = []

        for line in lines:
            stripped = line.strip()
            if stripped.startswith("state:"):
                status["state"] = stripped.split(":", 1)[1].strip()
            elif stripped.startswith("scan:"):
                status["scan"] = stripped.split(":", 1)[1].strip()
            elif stripped.startswith("errors:"):
                status["errors"] = stripped.split(":", 1)[1].strip()
                in_config = False
            elif stripped == "config:":
                in_config = True
            elif in_config:
                # Collect config block lines (skip blank lines at start)
                if stripped or config_lines:
                    config_lines.append(line)

        if config_lines:
            parsed = self._parse_vdev_tree(config_lines)
            if parsed and parsed[0]["name"] == pool_name:
                status["vdevs"] = parsed[0]["children"]
            else:
                status["vdevs"] = parsed

        # Annotate leaf vdevs with disk_id from /dev/disk/by-id/
        disk_id_map = self.get_disk_id_map()
        self._annotate_disk_ids(status["vdevs"], disk_id_map)

        return status

    def _annotate_disk_ids(self, vdevs: List[Dict], disk_id_map: Dict[str, str]) -> None:
        """Recursively annotate leaf vdev nodes with disk_id from by-id map."""
        for vdev in vdevs:
            children = vdev.get("children", [])
            if not children:
                name = vdev.get("name", "")
                # Strip partition suffix (sda1 → sda)
                base = re.sub(r'\d+$', '', name) if name[-1:].isdigit() else name
                vdev["disk_id"] = disk_id_map.get(name) or disk_id_map.get(base)
            else:
                self._annotate_disk_ids(children, disk_id_map)

    def scrub_pool(self, pool_name: str) -> Dict[str, str]:
        """
        Start or resume scrub on pool
        """
        stdout, stderr, rc = self.run_command(["zpool", "scrub", pool_name])

        if rc != 0:
            logger.error(f"zpool scrub failed for {pool_name}: {stderr}")
            return {"status": "error", "message": stderr}

        return {"status": "success", "message": f"Scrub started for {pool_name}"}

    # ============== DATASET/FILESYSTEM OPERATIONS ==============

    def list_datasets(self, pool_name: str, max_depth: int = 2) -> List[Dict[str, Any]]:
        """
        List datasets in pool (with depth limit for performance)
        """
        cached = self.cache.get("datasets")
        if cached and cached.get(pool_name):
            return cached[pool_name]

        stdout, stderr, rc = self.run_command([
            "zfs", "list", "-d", str(max_depth), "-H", "-p",
            "-o", "name,used,avail,refer,mountpoint,type",
            pool_name
        ])

        if rc != 0:
            logger.error(f"zfs list failed for {pool_name}: {stderr}")
            return []

        datasets = []
        for line in stdout.strip().split("\n"):
            if not line:
                continue

            parts = line.split("\t")
            if len(parts) < 6:
                continue

            dataset = {
                "name": parts[0],
                "used": int(parts[1]),
                "avail": int(parts[2]),
                "refer": int(parts[3]),
                "mountpoint": parts[4],
                "type": parts[5]  # filesystem, volume, snapshot
            }
            datasets.append(dataset)

        # Cache per pool
        if not cached:
            cached = {}
        cached[pool_name] = datasets
        self.cache.set("datasets", cached, ttl_seconds=60)

        return datasets

    def create_dataset(self, dataset_name: str, props: Optional[Dict[str, str]] = None) -> Dict[str, str]:
        """
        Create new ZFS dataset/filesystem
        """
        cmd = ["zfs", "create"]

        if props:
            for key, val in props.items():
                cmd.extend(["-o", f"{key}={val}"])

        cmd.append(dataset_name)

        stdout, stderr, rc = self.run_command(cmd)

        if rc != 0:
            logger.error(f"zfs create failed: {stderr}")
            return {"status": "error", "message": stderr}

        return {"status": "success", "message": f"Dataset {dataset_name} created"}

    def set_dataset_properties(self, dataset_name: str, props: Dict[str, str]) -> Dict[str, str]:
        """Set ZFS dataset properties (compression, quota, reservation, etc.)"""
        errors = []
        for key, value in props.items():
            if value is None:
                continue
            stdout, stderr, rc = self.run_command(["zfs", "set", f"{key}={value}", dataset_name])
            if rc != 0:
                errors.append(f"{key}: {stderr.strip()}")

        if errors:
            return {"status": "error", "message": "; ".join(errors)}
        return {"status": "success", "message": f"Properties updated for {dataset_name}"}

    def destroy_dataset(self, dataset_name: str, recursive: bool = False) -> Dict[str, str]:
        """
        Destroy ZFS dataset
        """
        cmd = ["zfs", "destroy"]
        if recursive:
            cmd.append("-r")
        cmd.append(dataset_name)

        stdout, stderr, rc = self.run_command(cmd)

        if rc != 0:
            logger.error(f"zfs destroy failed: {stderr}")
            return {"status": "error", "message": stderr}

        return {"status": "success", "message": f"Dataset {dataset_name} destroyed"}

    # ============== SNAPSHOT OPERATIONS ==============

    def list_snapshots(self, dataset_name: Optional[str] = None, limit: int = 50) -> List[Dict[str, Any]]:
        """
        List snapshots (with limit for performance on many snapshots)
        """
        cache_key = f"snapshots:{dataset_name or '*'}"
        cached = self.cache.get(cache_key)
        if cached:
            return cached

        if dataset_name:
            # No -d limit so sub-datasets (e.g. tank/share) are included
            cmd = ["zfs", "list", "-t", "snapshot", "-r", "-H", "-p",
                   "-o", "name,used,referenced,creation", dataset_name]
        else:
            cmd = ["zfs", "list", "-t", "snapshot", "-H", "-p",
                   "-o", "name,used,referenced,creation"]

        stdout, stderr, rc = self.run_command(cmd)

        if rc != 0:
            logger.error(f"zfs list snapshots failed: {stderr}")
            return []

        snapshots = []
        for line in stdout.strip().split("\n"):
            if not line:
                continue

            parts = line.split("\t")
            if len(parts) < 4:
                continue

            snapshot = {
                "name": parts[0],
                "used": int(parts[1]),
                "referenced": int(parts[2]),
                "creation": int(parts[3]),  # Unix timestamp
            }
            snapshots.append(snapshot)

        # Sort by creation time (newest first) and limit
        snapshots.sort(key=lambda x: x["creation"], reverse=True)
        snapshots = snapshots[:limit]

        self.cache.set(cache_key, snapshots, ttl_seconds=60)
        return snapshots

    def create_snapshot(self, dataset_name: str, snapshot_name: Optional[str] = None) -> Dict[str, str]:
        """
        Create snapshot with auto-generated name if not provided
        """
        if not snapshot_name:
            from datetime import datetime as dt
            snapshot_name = dt.now().strftime("%Y%m%d-%H%M%S")

        full_name = f"{dataset_name}@{snapshot_name}"

        stdout, stderr, rc = self.run_command(["zfs", "snapshot", full_name])

        if rc != 0:
            logger.error(f"zfs snapshot failed: {stderr}")
            return {"status": "error", "message": stderr}

        return {"status": "success", "message": f"Snapshot {full_name} created"}

    def destroy_snapshot(self, snapshot_name: str, recursive: bool = False) -> Dict[str, str]:
        """
        Destroy snapshot
        """
        cmd = ["zfs", "destroy"]
        if recursive:
            cmd.append("-r")
        cmd.append(snapshot_name)

        stdout, stderr, rc = self.run_command(cmd)

        if rc != 0:
            logger.error(f"zfs destroy snapshot failed: {stderr}")
            return {"status": "error", "message": stderr}

        return {"status": "success", "message": f"Snapshot {snapshot_name} destroyed"}

    def rollback_snapshot(self, snapshot_name: str) -> Dict[str, str]:
        """
        Rollback dataset to snapshot
        WARNING: Destroys data after snapshot!
        """
        stdout, stderr, rc = self.run_command(["zfs", "rollback", "-r", snapshot_name])

        if rc != 0:
            logger.error(f"zfs rollback failed: {stderr}")
            return {"status": "error", "message": stderr}

        return {"status": "success", "message": f"Rolled back to {snapshot_name}"}

    # ============== UTILITY ==============

    def clear_cache(self):
        """Clear all caches"""
        self.cache = ZFSCache()
        logger.info("ZFS cache cleared")

# Global instance
zfs_runner = ZFSRunner()