"""Settings and state persistence in the data volume (atomic JSON writes)."""

from __future__ import annotations

import json
import os
import re
import secrets
import tempfile
import threading
from dataclasses import asdict, dataclass, field, fields
from pathlib import Path

V1_LOCATION_SLOT = "CC2 Slot {n}"


def atomic_write(path: Path, data: bytes, mode: int = 0o644) -> None:
    path.parent.mkdir(parents=True, exist_ok=True)
    fd, tmp = tempfile.mkstemp(dir=path.parent, prefix=f".{path.name}.")
    try:
        os.fchmod(fd, mode)
        with os.fdopen(fd, "wb") as f:
            f.write(data)
            f.flush()
            os.fsync(f.fileno())
        os.replace(tmp, path)
    except BaseException:
        try:
            os.unlink(tmp)
        except FileNotFoundError:
            pass
        raise
    try:
        dfd = os.open(path.parent, os.O_DIRECTORY)
        try:
            os.fsync(dfd)
        finally:
            os.close(dfd)
    except OSError:
        pass


def atomic_write_json(path: Path, obj, mode: int = 0o644) -> None:
    atomic_write(path, json.dumps(obj, indent=2, sort_keys=True, ensure_ascii=False).encode(), mode)


def read_json(path: Path, default):
    try:
        return json.loads(path.read_text())
    except FileNotFoundError:
        return default


def _coerce(typ, value, name):
    typ = typ if isinstance(typ, str) else typ.__name__
    try:
        if typ == "bool":
            if isinstance(value, str):
                return value.strip().lower() in ("1", "true", "yes", "on", "ja")
            return bool(value)
        if typ == "int":
            return int(value)
        if typ == "float":
            return float(value)
        return str(value).strip()
    except (TypeError, ValueError):
        raise ValueError(f"Ungültiger Wert für {name}") from None


def new_printer_id() -> str:
    return "p" + secrets.token_hex(3)


@dataclass
class PrinterConfig:
    id: str = ""
    name: str = "CC2"
    host: str = "10.10.2.202"
    ssh_port: int = 22
    ssh_user: str = "root"
    cc2_url: str = "http://10.10.2.202:8081"
    enabled: bool = True

    @classmethod
    def from_dict(cls, d: dict) -> "PrinterConfig":
        p = cls()
        for f in fields(p):
            if f.name in d and d[f.name] is not None:
                setattr(p, f.name, _coerce(f.type, d[f.name], f.name))
        if not p.id:
            p.id = new_printer_id()
        p.validate()
        return p

    def validate(self) -> None:
        if not re.fullmatch(r"[a-z0-9_-]{1,32}", self.id):
            raise ValueError("Ungültige Drucker-ID")
        if not self.name.strip():
            raise ValueError("Druckername fehlt")
        if len(self.name) > 60:
            raise ValueError("Druckername ist zu lang (max. 60 Zeichen)")
        if not self.host.strip():
            raise ValueError(f"{self.name}: Drucker-IP fehlt")
        if not 1 <= self.ssh_port <= 65535:
            raise ValueError(f"{self.name}: SSH-Port ungültig")
        if not self.cc2_url.startswith(("http://", "https://")):
            raise ValueError(f"{self.name}: CC2-Control-URL muss mit http:// beginnen")
        self.cc2_url = self.cc2_url.rstrip("/")

    def to_dict(self) -> dict:
        return asdict(self)


@dataclass
class Settings:
    spoolman_url: str = "http://10.10.6.10:7912"
    id_offset: int = 10000
    poll_interval: float = 5.0
    location_slot: str = "{printer} Slot {n}"
    location_storage: str = "Lager"
    spoolman_fields: bool = True  # also write the extra fields "drucker" and "slot"
    empty_grace: float = 20.0  # seconds with tray status 0 before a slot counts as empty
    settle_seconds: float = 60.0  # `remaining` must be unchanged this long before booking
    archive_empty: bool = True  # archive a Spoolman spool whose roll ran out
    public_url: str = ""  # the bridge as phones reach it (links on NFC tags); empty: the address in the browser
    dry_run: bool = True
    printers: list[PrinterConfig] = field(default_factory=list)

    # environment variable -> field (only used as defaults before settings.json exists)
    ENV = {
        "SPOOLMAN_URL": "spoolman_url", "ID_OFFSET": "id_offset", "POLL_INTERVAL": "poll_interval",
        "DRY_RUN": "dry_run",
    }
    PRINTER_ENV = {
        "PRINTER_NAME": "name", "PRINTER_HOST": "host", "SSH_PORT": "ssh_port", "SSH_USER": "ssh_user",
        "CC2_URL": "cc2_url",
    }

    @classmethod
    def from_dict(cls, d: dict) -> "Settings":
        s = cls()
        s.update(migrate_settings(d))
        return s

    def update(self, d: dict) -> None:
        for f in fields(self):
            if f.name == "printers" or f.name not in d or d[f.name] is None:
                continue
            setattr(self, f.name, _coerce(f.type, d[f.name], f.name))
        if d.get("printers") is not None:
            self.printers = [p if isinstance(p, PrinterConfig) else PrinterConfig.from_dict(p) for p in d["printers"]]
        self.validate()

    def validate(self) -> None:
        if not 0 <= self.id_offset <= 65000:
            raise ValueError("ID-Offset muss zwischen 0 und 65000 liegen")
        if not 1 <= self.poll_interval <= 300:
            raise ValueError("Abfrage-Intervall muss zwischen 1 und 300 s liegen")
        if "{n}" not in self.location_slot:
            raise ValueError("Ortsname für Slots muss {n} enthalten")
        if len(self.printers) > 1 and "{printer}" not in self.location_slot:
            raise ValueError("Bei mehreren Druckern muss der Ortsname {printer} enthalten")
        if not self.spoolman_url.startswith(("http://", "https://")):
            raise ValueError("Spoolman-URL muss mit http:// oder https:// beginnen")
        self.spoolman_url = self.spoolman_url.rstrip("/")
        self.public_url = self.public_url.strip().rstrip("/")
        if self.public_url and not re.fullmatch(r"https?://[^\s/?#]+(/[^\s?#]*)?", self.public_url):
            raise ValueError("Adresse der Bridge muss mit http:// oder https:// beginnen, ohne ? oder #")
        if not self.location_storage.strip():
            raise ValueError("Ortsname für das Lager fehlt")
        ids = [p.id for p in self.printers]
        names = [p.name.strip().lower() for p in self.printers]
        if len(set(ids)) != len(ids) or len(set(names)) != len(names):
            raise ValueError("Druckernamen müssen eindeutig sein")
        if len(self.printers) > 8:
            raise ValueError("Höchstens 8 Drucker")

    def to_dict(self) -> dict:
        d = asdict(self)
        d["printers"] = [p.to_dict() for p in self.printers]
        return d

    def printer(self, pid: str) -> PrinterConfig | None:
        return next((p for p in self.printers if p.id == pid), None)

    def slot_location(self, printer: PrinterConfig | str, slot: int) -> str:
        name = printer.name if isinstance(printer, PrinterConfig) else printer
        return self.location_slot.replace("{printer}", name).replace("{n}", str(slot + 1))


def migrate_settings(d: dict) -> dict:
    """v1 had one printer at the top level; v2 keeps a list of printers."""
    d = dict(d)
    if "printers" not in d and "printer_host" in d:
        d["printers"] = [{
            "id": "p1", "name": d.get("printer_name") or "CC2", "host": d.get("printer_host"),
            "ssh_port": d.get("ssh_port", 22), "ssh_user": d.get("ssh_user", "root"),
            "cc2_url": d.get("cc2_url"), "enabled": True,
        }]
        if d.get("location_slot") == V1_LOCATION_SLOT:
            d["location_slot"] = Settings.location_slot
    for key in ("printer_host", "printer_name", "ssh_port", "ssh_user", "cc2_url"):
        d.pop(key, None)
    return d


class SettingsStore:
    def __init__(self, data_dir: Path, env: dict | None = None):
        self.path = data_dir / "settings.json"
        self._lock = threading.Lock()
        stored = read_json(self.path, None)
        if stored is None:
            env = os.environ if env is None else env
            defaults = {f: env[k] for k, f in Settings.ENV.items() if env.get(k)}
            printer = {f: env[k] for k, f in Settings.PRINTER_ENV.items() if env.get(k)}
            defaults["printers"] = [{"id": "p1", **printer}]
            self.settings = Settings.from_dict(defaults)
        else:
            self.settings = Settings.from_dict(stored)
            if "printer_host" in stored:  # write the migrated form once
                atomic_write_json(self.path, self.settings.to_dict())

    def get(self) -> Settings:
        with self._lock:
            return Settings.from_dict(self.settings.to_dict())

    def save(self, changes: dict) -> Settings:
        with self._lock:
            new = Settings.from_dict({**self.settings.to_dict(), **changes})
            atomic_write_json(self.path, new.to_dict())
            self.settings = new
            return Settings.from_dict(new.to_dict())


class StateStore:
    """Bridge state: per printer slot mappings, booked consumption and last record; Spoolman locations."""

    def __init__(self, data_dir: Path, first_printer: str = "p1"):
        self.path = data_dir / "state.json"
        self.data = migrate_state(read_json(self.path, {}), first_printer)

    def printer(self, pid: str) -> dict:
        p = self.data["printers"].setdefault(pid, {})
        p.setdefault("slots", {})
        p.setdefault("booked", {})
        p.setdefault("last_record", None)
        p.setdefault("scans", [])
        p.setdefault("last", {})  # slot -> roll that last left it (for putting it back)
        p.setdefault("takeout", [])  # windows in which a tray prints for a roll taken out in CC2 Control
        p.setdefault("log_seen", None)  # CC2 Control log entries already looked at
        p.setdefault("extra", [])  # bookings from CC2 Control's log still to make
        return p

    def save(self) -> None:
        atomic_write_json(self.path, self.data)


def migrate_state(data: dict, first_printer: str) -> dict:
    data.setdefault("printers", {})
    if data.get("version", 1) < 2:
        if any(k in data for k in ("slots", "booked", "last_record", "scans")):
            data["printers"][first_printer] = {
                "slots": data.pop("slots", {}), "booked": data.pop("booked", {}),
                "last_record": data.pop("last_record", None), "scans": data.pop("scans", []),
            }
        applied = {}
        for sid, loc in (data.pop("locations", None) or {}).items():
            if loc.get("done"):
                applied[sid] = {"location": loc["done"], "printer": None, "slot": None}
        data["applied"] = applied
        data["written_locations"] = sorted({a["location"] for a in applied.values()})
        data["version"] = 2
    data.setdefault("applied", {})
    data.setdefault("written_locations", [])
    if "written_printers" not in data:
        data["written_printers"] = sorted({a["printer"] for a in data["applied"].values() if a.get("printer")})
    return data