"""
Identity management for PostHog analytics tracking.

Handles anonymous/authenticated identity tracking with PostHog aliasing,
supporting pre-login anonymous tracking, post-login identity stitching,
and logout identity rotation.
"""

import fcntl
import json
import os
import tempfile
import uuid
from typing import Any

import httpx
import yaml
from arcade_cli.constants import ARCADE_CONFIG_PATH, CREDENTIALS_FILE_PATH
from arcade_cli.usage.constants import (
    KEY_ANON_ID,
    KEY_LINKED_PRINCIPAL_ID,
    TIMEOUT_ARCADE_API,
    USAGE_FILE_NAME,
)


class UsageIdentity:
    """Manages user identity for PostHog analytics tracking."""

    def __init__(self) -> None:
        self.usage_file_path = os.path.join(ARCADE_CONFIG_PATH, USAGE_FILE_NAME)
        self._data: dict[str, Any] | None = None

    def load_or_create(self) -> dict[str, Any]:
        """Load or create usage.json file with atomic writes and file locking.

        Returns:
            dict: The usage data containing anon_id and optionally linked_email
        """
        if self._data is not None:
            return self._data

        os.makedirs(ARCADE_CONFIG_PATH, exist_ok=True)

        if os.path.exists(self.usage_file_path):
            try:
                with open(self.usage_file_path) as f:
                    # lock file
                    if os.name != "nt":  # Unix-like systems
                        fcntl.flock(f.fileno(), fcntl.LOCK_SH)
                    try:
                        data = json.load(f)
                        if isinstance(data, dict) and KEY_ANON_ID in data:
                            self._data = data
                            return self._data
                    finally:
                        # unlock file
                        if os.name != "nt":
                            fcntl.flock(f.fileno(), fcntl.LOCK_UN)
            except Exception:  # noqa: S110
                pass

        new_data = {KEY_ANON_ID: str(uuid.uuid4()), KEY_LINKED_PRINCIPAL_ID: None}

        self._write_atomic(new_data)
        self._data = new_data
        return self._data

    def _write_atomic(self, data: dict[str, Any]) -> None:
        """Write data atomically to usage.json file

        Args:
            data: The data to write to the usage file
        """
        # Create temp file in same directory for atomic rename
        temp_fd, temp_path = tempfile.mkstemp(
            dir=ARCADE_CONFIG_PATH, prefix=".usage_", suffix=".tmp"
        )

        try:
            with os.fdopen(temp_fd, "w") as f:
                # lock file
                if os.name != "nt":  # Unix-like systems
                    fcntl.flock(f.fileno(), fcntl.LOCK_EX)
                try:
                    json.dump(data, f, indent=2)
                    f.flush()
                    os.fsync(f.fileno())  # ensure data is written to disk
                finally:
                    if os.name != "nt":
                        fcntl.flock(f.fileno(), fcntl.LOCK_UN)

            os.rename(temp_path, self.usage_file_path)
        except Exception:
            # clean up
            import contextlib

            with contextlib.suppress(OSError):
                os.unlink(temp_path)
            raise

    def get_distinct_id(self) -> str:
        """Get distinct_id based on authentication state.

        We use principal_id for authenticated users and anon_id for anonymous users.

        Returns:
            str: Principal ID if authenticated, otherwise anon_id
        """
        data = self.load_or_create()

        # Check if we have a persisted principal_id first
        linked_principal_id = data.get(KEY_LINKED_PRINCIPAL_ID)
        if linked_principal_id:
            return str(linked_principal_id)

        # Try to fetch principal_id from API if not persisted
        principal_id = self.get_principal_id()
        if principal_id:
            return principal_id

        # Fall back to anon_id if not authenticated
        return str(data[KEY_ANON_ID])

    def get_principal_id(self) -> str | None:
        """Fetch principal_id from Arcade Cloud API.

        Returns:
            str | None: Principal ID if authenticated and API call succeeds, None otherwise
        """
        if not os.path.exists(CREDENTIALS_FILE_PATH):
            return None

        try:
            with open(CREDENTIALS_FILE_PATH) as f:
                config = yaml.safe_load(f)

            cloud_config = config.get("cloud", {})
            api_key = cloud_config.get("api", {}).get("key")

            if not api_key:
                return None

            response = httpx.get(
                "https://cloud.arcade.dev/api/v1/auth/validate",
                headers={"accept": "application/json", "Authorization": f"Bearer {api_key}"},
                timeout=TIMEOUT_ARCADE_API,
            )

            if response.status_code == 200:
                data = response.json()
                principal_id = data.get("data", {}).get("principal_id")
                return str(principal_id) if principal_id else None

        except Exception:  # noqa: S110
            # Silent failure - don't disrupt CLI
            pass

        return None

    def should_alias(self) -> bool:
        """Check if PostHog alias is needed.

        Alias is needed when the user is authenticated,
        but the retrieved principal_id doesn't match the persisted linked_principal_id

        Returns:
            bool: True if user is authenticated but not yet aliased
        """
        data = self.load_or_create()
        principal_id = self.get_principal_id()

        return principal_id is not None and principal_id != data.get(KEY_LINKED_PRINCIPAL_ID)

    def reset_to_anonymous(self) -> None:
        """Generate new anonymous ID and clear linked principal_id.

        Used after logout to prevent cross-contamination between multiple
        accounts on the same machine
        """
        # Create fresh data with only anon_id
        new_data = {KEY_ANON_ID: str(uuid.uuid4()), KEY_LINKED_PRINCIPAL_ID: None}

        self._write_atomic(new_data)
        self._data = new_data

    def set_linked_principal_id(self, principal_id: str) -> None:
        """Update linked_principal_id in usage.json.

        Args:
            principal_id: The principal_id to link to the current anon_id
        """
        data = self.load_or_create()
        data[KEY_LINKED_PRINCIPAL_ID] = principal_id

        self._write_atomic(data)
        self._data = data

    @property
    def anon_id(self) -> str:
        """Get the current anonymous ID.

        Returns:
            str: The anonymous ID
        """
        data = self.load_or_create()
        return str(data[KEY_ANON_ID])