"""RenderDoc session manager - singleton managing capture file lifecycle."""

import os
from typing import Optional

from .util import rd, make_error


class RenderDocSession:
    """Manages a single RenderDoc capture file's lifecycle."""

    def __init__(self):
        self._initialized: bool = False
        self._cap = None  # CaptureFile
        self._controller = None  # ReplayController
        self._filepath: Optional[str] = None
        self._current_event: Optional[int] = None
        self._action_map = {}
        self._structured_file = None
        self._resource_id_cache = {}  # str(resourceId) → resourceId
        self._texture_desc_cache = {}  # str(resourceId) → TextureDescription

    def _ensure_initialized(self):
        """Initialize the replay system if not already done."""
        if not self._initialized:
            rd.InitialiseReplay(rd.GlobalEnvironment(), [])
            self._initialized = True

    @property
    def is_open(self) -> bool:
        return self._controller is not None

    @property
    def filepath(self) -> Optional[str]:
        return self._filepath

    @property
    def controller(self):
        return self._controller

    @property
    def structured_file(self):
        return self._structured_file

    @property
    def current_event(self) -> Optional[int]:
        return self._current_event

    @property
    def driver_name(self) -> str:
        """Get the API/driver name of the current capture."""
        return self._cap.DriverName() if self._cap else "unknown"

    @property
    def action_map(self):
        """Get the event_id -> ActionDescription mapping."""
        return self._action_map

    def require_open(self) -> Optional[dict]:
        """Return an error dict if no capture is open, else None."""
        if not self.is_open:
            return make_error(
                "No capture file is open. Use open_capture first.", "NO_CAPTURE_OPEN"
            )
        return None

    def open(self, filepath: str) -> dict:
        """Open a .rdc capture file. Closes any previously open capture."""
        self._ensure_initialized()

        if not os.path.isfile(filepath):
            return make_error(f"File not found: {filepath}", "API_ERROR")

        # Close any existing capture
        if self.is_open:
            self.close()

        cap = rd.OpenCaptureFile()
        result = cap.OpenFile(filepath, "", None)
        if result != rd.ResultCode.Succeeded:
            cap.Shutdown()
            return make_error(f"Failed to open file: {result}", "API_ERROR")

        if not cap.LocalReplaySupport():
            cap.Shutdown()
            return make_error("Capture cannot be replayed on this machine", "API_ERROR")

        result, controller = cap.OpenCapture(rd.ReplayOptions(), None)
        if result != rd.ResultCode.Succeeded:
            cap.Shutdown()
            return make_error(f"Failed to initialize replay: {result}", "API_ERROR")

        self._cap = cap
        self._controller = controller
        self._filepath = filepath
        self._current_event = None
        self._structured_file = controller.GetStructuredFile()

        # Build action map
        self._action_map = {}
        self._build_action_map(controller.GetRootActions())

        # Build resource caches
        self._resource_id_cache = {}
        self._texture_desc_cache = {}
        textures = controller.GetTextures()
        buffers = controller.GetBuffers()
        for tex in textures:
            key = str(tex.resourceId)
            self._resource_id_cache[key] = tex.resourceId
            self._texture_desc_cache[key] = tex
        for buf in buffers:
            key = str(buf.resourceId)
            self._resource_id_cache[key] = buf.resourceId
        for res in controller.GetResources():
            key = str(res.resourceId)
            if key not in self._resource_id_cache:
                self._resource_id_cache[key] = res.resourceId

        # Gather summary
        root_actions = controller.GetRootActions()

        return {
            "filepath": filepath,
            "api": cap.DriverName(),
            "total_actions": len(self._action_map),
            "root_actions": len(root_actions),
            "textures": len(textures),
            "buffers": len(buffers),
        }

    def _build_action_map(self, actions):
        """Recursively index all actions by event_id."""
        for a in actions:
            self._action_map[a.eventId] = a
            if len(a.children) > 0:
                self._build_action_map(a.children)

    def resolve_resource_id(self, resource_id_str: str):
        """Resolve a resource ID string to a ResourceId object, or None."""
        return self._resource_id_cache.get(resource_id_str)

    def get_texture_desc(self, resource_id_str: str):
        """Get a TextureDescription by resource ID string, or None."""
        return self._texture_desc_cache.get(resource_id_str)

    def close(self) -> dict:
        """Close the current capture."""
        if not self.is_open:
            return {"status": "no capture was open"}

        filepath = self._filepath
        self._controller.Shutdown()
        self._cap.Shutdown()
        self._controller = None
        self._cap = None
        self._filepath = None
        self._current_event = None
        self._action_map = {}
        self._structured_file = None
        self._resource_id_cache = {}
        self._texture_desc_cache = {}
        return {"status": "closed", "filepath": filepath}

    def set_event(self, event_id: int) -> Optional[dict]:
        """Navigate to a specific event. Returns error dict or None on success."""
        if event_id not in self._action_map:
            return make_error(f"Event ID {event_id} not found", "INVALID_EVENT_ID")
        self._controller.SetFrameEvent(event_id, True)
        self._current_event = event_id
        return None

    def ensure_event(self, event_id: Optional[int]) -> Optional[dict]:
        """If event_id is given, set it. If no event is current, return error.
        Returns error dict or None on success."""
        if event_id is not None:
            return self.set_event(event_id)
        if self._current_event is None:
            return make_error(
                "No event selected. Use set_event or pass event_id.", "INVALID_EVENT_ID"
            )
        return None

    def get_action(self, event_id: int):
        """Get an ActionDescription by event_id, or None."""
        return self._action_map.get(event_id)

    def get_root_actions(self):
        return self._controller.GetRootActions()

    def shutdown(self):
        """Full shutdown - close capture and deinitialize replay."""
        if self.is_open:
            self.close()
        if self._initialized:
            rd.ShutdownReplay()
            self._initialized = False


# Module-level singleton
_session: Optional[RenderDocSession] = None


def get_session() -> RenderDocSession:
    """Get or create the global RenderDocSession singleton."""
    global _session
    if _session is None:
        _session = RenderDocSession()
    return _session