import hashlib
import json
import math
import os
from dataclasses import asdict, dataclass, field
from pathlib import Path
from urllib.parse import urlsplit

import tomllib


@dataclass
class Config:
    state_dir: Path = field(
        default_factory=lambda: Path(
            os.environ.get(
                "COORDINATION_STATE_DIR",
                str(
                    Path(os.environ.get("XDG_STATE_HOME", Path.home() / ".local/state"))
                    / "coordination-engine"
                ),
            )
        )
    )
    socket: Path = field(
        default_factory=lambda: Path(
            os.environ.get(
                "COORDINATION_SOCKET",
                str(
                    Path(
                        os.environ.get(
                            "XDG_RUNTIME_DIR", f"/tmp/coordination-{os.getuid()}"
                        )
                    )
                    / "coordination-engine.sock"
                ),
            )
        )
    )
    tamq_socket: Path = field(
        default_factory=lambda: Path(
            os.environ.get(
                "TAMQ_SOCKET",
                str(Path(os.environ.get("XDG_RUNTIME_DIR", "/tmp")) / "tamq.sock"),
            )
        )
    )
    api_base: str = field(
        default_factory=lambda: os.environ.get(
            "STATEHUB_API_BASE", "http://127.0.0.1:8000"
        )
    )
    repos: list[str] = field(default_factory=list)
    endpoints: dict[str, str] = field(default_factory=dict)
    poll_interval: float = 15
    lease_seconds: float = 30
    renew_interval: float = 10
    timeout: float = 5
    busy_timeout: float = 5
    max_attempts: int = 4
    retry_backoff: list[float] = field(default_factory=lambda: [5, 15, 60, 300])
    policy_profile: str = "default"
    # Only these classes may be requested automatically. Unknown classes stop.
    allow: list[str] = field(
        default_factory=lambda: [
            "repo_inspect",
            "repo_edit",
            "local_checks",
            "state_updates",
            "tmux_wake",
        ]
    )

    def validate(self):
        for key in (
            "poll_interval",
            "lease_seconds",
            "renew_interval",
            "timeout",
            "busy_timeout",
        ):
            value = getattr(self, key)
            if (
                isinstance(value, bool)
                or not isinstance(value, (float, int))
                or not math.isfinite(value)
                or value <= 0
            ):
                raise ValueError(f"invalid {key}")
        if self.renew_interval >= self.lease_seconds:
            raise ValueError("renew_interval must be shorter than lease_seconds")
        if type(self.max_attempts) is not int or not 0 <= self.max_attempts <= 9:
            raise ValueError("max_attempts must be 0..9")
        if not self.retry_backoff or any(
            type(v) not in (int, float) or not math.isfinite(v) or v <= 0
            for v in self.retry_backoff
        ):
            raise ValueError("retry_backoff must contain positive finite delays")
        if self.policy_profile != "default" or not set(self.allow) <= {
            "repo_inspect",
            "repo_edit",
            "local_checks",
            "state_updates",
            "tmux_wake",
        }:
            raise ValueError("unsupported policy profile or action grant")
        if not isinstance(self.repos, list) or any(
            not isinstance(r, str)
            or not r
            or any(
                c
                not in "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-._"
                for c in r
            )
            for r in self.repos
        ):
            raise ValueError("repos must contain exact repository slugs")
        if not isinstance(self.endpoints, dict) or any(
            k not in self.repos or not isinstance(v, str) or not v
            for k, v in self.endpoints.items()
        ):
            raise ValueError("endpoints must map configured repos to endpoint IDs")
        url = urlsplit(self.api_base)
        if (
            url.scheme not in {"http", "https"}
            or not url.hostname
            or url.username
            or url.password
            or url.query
            or url.fragment
        ):
            raise ValueError("invalid State Hub URL; credentials are not configuration")
        for name in ("state_dir", "socket", "tamq_socket"):
            setattr(self, name, Path(getattr(self, name)).expanduser().absolute())
        return self

    @property
    def version(self):
        return hashlib.sha256(
            json.dumps(asdict(self), default=str, sort_keys=True).encode()
        ).hexdigest()[:16]

    @classmethod
    def load(cls, path=None):
        path = Path(
            path
            or os.environ.get(
                "COORDINATION_CONFIG",
                str(
                    Path(os.environ.get("XDG_CONFIG_HOME", Path.home() / ".config"))
                    / "coordination-engine/config.toml"
                ),
            )
        )
        data = (
            tomllib.loads(path.read_text()).get("coordination", {})
            if path.exists()
            else {}
        )
        for env, key in [
            ("COORDINATION_STATE_DIR", "state_dir"),
            ("COORDINATION_SOCKET", "socket"),
            ("TAMQ_SOCKET", "tamq_socket"),
            ("STATEHUB_API_BASE", "api_base"),
        ]:
            if env in os.environ:
                data[key] = os.environ[env]
        return cls(**data).validate()