#!/usr/bin/env python3
"""
PI wrapper for HF Spaces.

Tries to use native pi-mono RPC if available; otherwise falls back to a
Python-based re-implementation that mimics PI's event stream and tool set
(read, bash) using the OpenAI function-calling API.
"""

from __future__ import annotations

import json
import os
import re
import shlex
import subprocess
import sys
import threading
import time
from datetime import datetime, timezone
from pathlib import Path
from typing import Any, Dict, Generator, Iterator, List, Optional

import openai
try:
    from charset_normalizer import from_bytes
except ImportError:
    from_bytes = None
try:
    from pypdf import PdfReader
except ImportError:
    PdfReader = None

# ---------------------------------------------------------------------------
# Config
# ---------------------------------------------------------------------------
APP_DIR = Path(__file__).resolve().parent
if (APP_DIR / "pi-mono").exists():
    REPO_ROOT = APP_DIR
else:
    REPO_ROOT = APP_DIR.parent
DEFAULT_PI_REPO = REPO_ROOT / "pi-mono"
DEFAULT_PACKAGE_DIR = DEFAULT_PI_REPO / "packages" / "coding-agent"
DEFAULT_AGENT_DIR = DEFAULT_PI_REPO / ".pi" / "agent"


def _node_bin() -> str:
    """Find node >= 20."""
    nvm_dir = Path(os.environ.get("NVM_DIR", Path.home() / ".nvm"))
    versions_dir = nvm_dir / "versions" / "node"
    if versions_dir.is_dir():
        candidates = sorted(
            (d for d in versions_dir.iterdir() if d.name.startswith("v")),
            key=lambda d: tuple(int(x) for x in d.name.lstrip("v").split(".")),
            reverse=True,
        )
        for candidate in candidates:
            major = int(candidate.name.lstrip("v").split(".")[0])
            node = candidate / "bin" / "node"
            if major >= 20 and node.exists():
                return str(node)
    # Try system node
    for candidate in ("node", "nodejs"):
        try:
            result = subprocess.run(
                [candidate, "--version"],
                capture_output=True,
                text=True,
                timeout=5,
            )
            if result.returncode == 0:
                version = result.stdout.strip().lstrip("v")
                major = int(version.split(".")[0])
                if major >= 20:
                    return candidate
        except Exception:
            pass
    return "node"


def pi_mono_available() -> bool:
    """Check whether a built pi-mono package exists."""
    dist_cli = DEFAULT_PACKAGE_DIR / "dist" / "cli.js"
    return dist_cli.exists()


# ---------------------------------------------------------------------------
# Native PI RPC client (adapted from pi_rpc_runner.py)
# ---------------------------------------------------------------------------
class NativePiClient:
    def __init__(
        self,
        *,
        package_dir: Path,
        cwd: Path,
        agent_dir: Path,
        provider: str,
        model: str,
        tools: str,
        session_dir: Optional[Path] = None,
        session_path: Optional[Path] = None,
        continue_session: bool = False,
        api_key: str = "",
    ) -> None:
        self.package_dir = package_dir
        self.cwd = cwd
        self.agent_dir = agent_dir
        self.provider = provider
        self.model = model
        self.tools = tools
        self.session_dir = session_dir
        self.session_path = session_path
        self.continue_session = continue_session
        self.api_key = api_key
        self.proc: Optional[subprocess.Popen[bytes]] = None
        self.stderr_chunks: List[str] = []
        self._stderr_thread: Optional[threading.Thread] = None
        self._request_id = 0

    def _ensure_built_cli(self) -> Path:
        dist_cli = self.package_dir / "dist" / "cli.js"
        if dist_cli.exists():
            return dist_cli
        pi_repo_root = self.package_dir.parents[1]
        sys.stderr.write("[setup] dist/cli.js not found, running `npm run build`\n")
        sys.stderr.flush()
        subprocess.run(
            ["npm", "run", "build"],
            cwd=str(pi_repo_root),
            check=True,
        )
        if not dist_cli.exists():
            raise RuntimeError(f"Build completed but CLI not found at {dist_cli}")
        return dist_cli

    def _build_command(self) -> List[str]:
        dist_cli = self._ensure_built_cli()
        cmd = [_node_bin(), str(dist_cli), "--mode", "rpc"]
        if self.provider:
            cmd.extend(["--provider", self.provider])
        if self.model:
            cmd.extend(["--model", self.model])
        if self.tools:
            cmd.extend(["--tools", self.tools])
        if self.session_dir:
            cmd.extend(["--session-dir", str(self.session_dir)])
        if self.session_path:
            cmd.extend(["--session", str(self.session_path)])
        elif self.continue_session:
            cmd.append("--continue")
        return cmd

    def start(self) -> None:
        if self.proc is not None:
            raise RuntimeError("RPC client already started")
        env = os.environ.copy()
        env["PI_CODING_AGENT_DIR"] = str(self.agent_dir)
        if self.api_key:
            env["OPENAI_API_KEY"] = self.api_key
        self.command = self._build_command()
        self.proc = subprocess.Popen(
            self.command,
            cwd=str(self.cwd),
            env=env,
            stdin=subprocess.PIPE,
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE,
        )
        assert self.proc.stderr is not None
        self._stderr_thread = threading.Thread(target=self._drain_stderr, daemon=True)
        self._stderr_thread.start()

    def _drain_stderr(self) -> None:
        assert self.proc is not None
        assert self.proc.stderr is not None
        for raw in self.proc.stderr:
            self.stderr_chunks.append(raw.decode("utf-8", errors="replace"))

    def stop(self) -> None:
        if self.proc is None:
            return
        try:
            if self.proc.poll() is None:
                self.proc.terminate()
                self.proc.wait(timeout=2)
        except subprocess.TimeoutExpired:
            self.proc.kill()
            self.proc.wait(timeout=2)
        finally:
            self.proc = None

    def _next_id(self) -> str:
        self._request_id += 1
        return f"py-{self._request_id}"

    def _send(self, payload: Dict[str, Any]) -> None:
        if self.proc is None or self.proc.stdin is None:
            raise RuntimeError("RPC client is not running")
        line = json.dumps(payload, ensure_ascii=False, separators=(",", ":")) + "\n"
        self.proc.stdin.write(line.encode("utf-8"))
        self.proc.stdin.flush()

    def call(self, command_type: str, **payload: Any) -> Dict[str, Any]:
        request_id = self._next_id()
        message = {"id": request_id, "type": command_type, **payload}
        self._send(message)
        while True:
            event = self._read_json_line()
            if event.get("type") == "response" and event.get("id") == request_id:
                if not event.get("success", False):
                    raise RuntimeError(f"RPC {command_type} failed: {event.get('error', 'unknown error')}")
                return event

    def _read_json_line(self) -> Dict[str, Any]:
        if self.proc is None or self.proc.stdout is None:
            raise RuntimeError("RPC client is not running")
        raw = self.proc.stdout.readline()
        if not raw:
            stderr_text = "".join(self.stderr_chunks).strip()
            raise RuntimeError(f"RPC process exited unexpectedly. stderr:\n{stderr_text}")
        if raw.endswith(b"\n"):
            raw = raw[:-1]
        if raw.endswith(b"\r"):
            raw = raw[:-1]
        return json.loads(raw.decode("utf-8"))

    def stream_events(
        self,
        message: str,
        *,
        max_turns: Optional[int] = None,
    ) -> Generator[Dict[str, Any], None, str]:
        """Yield raw PI events and finally return the assistant's full text."""
        request_id = self._next_id()
        self._send({"id": request_id, "type": "prompt", "message": message})

        auxiliary_ids: set[str] = set()
        text_parts: List[str] = []
        prompt_ack = False
        seen_turns = 0
        sent_turn_limit_abort = False

        while True:
            event = self._read_json_line()
            yield event

            event_type = event.get("type")

            if event_type == "response":
                response_id = event.get("id")
                if response_id == request_id:
                    if not event.get("success", False):
                        raise RuntimeError(f"RPC prompt failed: {event.get('error', 'unknown error')}")
                    prompt_ack = True
                continue

            if event_type == "turn_start":
                seen_turns += 1
                if max_turns is not None and seen_turns > max_turns and not sent_turn_limit_abort:
                    abort_id = self._next_id()
                    auxiliary_ids.add(abort_id)
                    self._send({"id": abort_id, "type": "abort"})
                    sent_turn_limit_abort = True
                continue

            if event_type == "message_update":
                assistant_event = event.get("assistantMessageEvent", {})
                if assistant_event.get("type") == "text_delta":
                    text_parts.append(assistant_event.get("delta", ""))
                continue

            if event_type == "agent_end":
                if not prompt_ack:
                    raise RuntimeError("Received agent_end before prompt acknowledgement")
                break

        return "".join(text_parts)


# ---------------------------------------------------------------------------
# Fallback Python PI agent (OpenAI function calling)
# ---------------------------------------------------------------------------

SYSTEM_PROMPT_TEMPLATE = """You are Pi, an autonomous research assistant. Your goal is to answer the user's question by exploring documents in the working directory.

You have access to the following tools:
- read: Read the contents of a file.
- bash: Execute a shell command. Useful for listing files, searching with rg/grep/find, etc.

Guidelines:
1. Start by exploring the directory structure to understand what files are available.
2. Use targeted searches (rg, grep) to find relevant content.
3. Read files that seem relevant to the question.
4. Provide a clear, concise final answer based on the evidence found.
5. If the answer cannot be found, state that clearly.

Working directory: {cwd}
"""


def _read_tool(cwd: Path, file_path: str) -> str:
    """Read a file relative to cwd."""
    try:
        target = cwd / file_path
        # Security: prevent reading outside cwd
        target = target.resolve()
        cwd_resolved = cwd.resolve()
        if not str(target).startswith(str(cwd_resolved)):
            return f"Error: Access denied – path '{file_path}' is outside the working directory."
        if not target.exists():
            return f"Error: File '{file_path}' does not exist."
        if target.is_dir():
            items = sorted(target.iterdir())
            lines = [f"Directory: {file_path}/"]
            for item in items[:50]:
                suffix = "/" if item.is_dir() else ""
                lines.append(f"  {item.name}{suffix}")
            if len(items) > 50:
                lines.append(f"  ... and {len(items) - 50} more items")
            return "\n".join(lines)
        if target.suffix.lower() == ".pdf":
            if PdfReader is None:
                return "Error: PDF parsing support is unavailable because pypdf is not installed."
            reader = PdfReader(str(target))
            page_texts: List[str] = []
            for idx, page in enumerate(reader.pages, start=1):
                text = (page.extract_text() or "").strip()
                if text:
                    page_texts.append(f"[Page {idx}]\n{text}")
            content = "\n\n".join(page_texts).strip()
        else:
            raw = target.read_bytes()
            if from_bytes is not None:
                best = from_bytes(raw).best()
                if best is not None:
                    content = str(best)
                else:
                    for encoding in ("utf-8", "utf-8-sig", "utf-16", "utf-16-le", "utf-16-be", "gb18030", "big5", "shift_jis"):
                        try:
                            content = raw.decode(encoding)
                            break
                        except UnicodeDecodeError:
                            continue
                    else:
                        content = raw.decode("utf-8", errors="replace")
            else:
                for encoding in ("utf-8", "utf-8-sig", "utf-16", "utf-16-le", "utf-16-be", "gb18030", "big5", "shift_jis"):
                    try:
                        content = raw.decode(encoding)
                        break
                    except UnicodeDecodeError:
                        continue
                else:
                    content = raw.decode("utf-8", errors="replace")
        max_len = 12000
        if len(content) > max_len:
            content = content[:max_len] + f"\n\n...[truncated, total {len(content)} chars]"
        return content
    except Exception as e:
        return f"Error reading '{file_path}': {e}"


def _bash_tool(cwd: Path, command: str) -> str:
    """Run a shell command inside cwd."""
    try:
        # Basic security: block dangerous commands
        dangerous = {"rm", "mv", "cp", "chmod", "chown", "sudo", "su", "ssh", "curl", "wget", "python", "python3", "node", "npm", "pip", "pip3", "docker", "kubectl"}
        tokens = shlex.split(command)
        if tokens and tokens[0] in dangerous:
            return f"Error: Command '{tokens[0]}' is not allowed for security reasons."

        result = subprocess.run(
            command,
            shell=True,
            cwd=str(cwd),
            capture_output=True,
            text=True,
            timeout=30,
        )
        output = result.stdout
        if result.stderr:
            output += "\n" + result.stderr
        max_len = 8000
        if len(output) > max_len:
            output = output[:max_len] + f"\n\n...[truncated, total {len(output)} chars]"
        return output
    except subprocess.TimeoutExpired:
        return "Error: Command timed out after 30 seconds."
    except Exception as e:
        return f"Error: {e}"


def _utc_now() -> str:
    return datetime.now(timezone.utc).isoformat()


def _chunk_text(text: str, *, size: int = 48) -> Iterator[str]:
    if not text:
        return
    for i in range(0, len(text), size):
        yield text[i : i + size]


class FallbackPiAgent:
    """A lightweight Python agent that mimics PI's behavior using OpenAI tool use."""

    def __init__(
        self,
        *,
        cwd: Path,
        api_key: str,
        model: str = "gpt-4o",
        max_turns: int = 6,
    ):
        self.cwd = cwd
        self.api_key = api_key
        self.model = model
        self.max_turns = max_turns
        self.client = openai.OpenAI(api_key=api_key)

    def _mk_event(self, typ: str, **kwargs) -> Dict[str, Any]:
        return {"type": typ, "timestamp": _utc_now(), **kwargs}

    def stream_events(
        self,
        message: str,
    ) -> Generator[Dict[str, Any], None, str]:
        system_prompt = SYSTEM_PROMPT_TEMPLATE.format(cwd=str(self.cwd.resolve()))

        messages: List[Dict[str, Any]] = [
            {"role": "system", "content": system_prompt},
            {"role": "user", "content": message},
        ]

        tools = [
            {
                "type": "function",
                "function": {
                    "name": "read",
                    "description": "Read a file or list a directory. Provide a relative path from the working directory.",
                    "parameters": {
                        "type": "object",
                        "properties": {
                            "file_path": {
                                "type": "string",
                                "description": "Relative path to the file or directory to read.",
                            },
                        },
                        "required": ["file_path"],
                    },
                },
            },
            {
                "type": "function",
                "function": {
                    "name": "bash",
                    "description": "Execute a shell command in the working directory. Useful for searching with rg/grep/find, listing files, etc.",
                    "parameters": {
                        "type": "object",
                        "properties": {
                            "command": {
                                "type": "string",
                                "description": "Shell command to execute. Keep it simple and focused.",
                            },
                        },
                        "required": ["command"],
                    },
                },
            },
        ]

        final_text = ""

        for turn in range(1, self.max_turns + 1):
            yield self._mk_event("turn_start", turn=turn)
            yield self._mk_event("message_start", message={"role": "assistant", "content": []})

            response = self.client.chat.completions.create(
                model=self.model,
                messages=messages,  # type: ignore[arg-type]
                tools=tools,  # type: ignore[arg-type]
                tool_choice="auto",
                temperature=0.2,
            )

            choice = response.choices[0]
            msg = choice.message

            # Stream assistant text if present
            if msg.content:
                final_text = msg.content
                yield self._mk_event(
                    "message_update",
                    assistantMessageEvent={"type": "text_start", "contentIndex": 0},
                )
                for chunk in _chunk_text(msg.content):
                    yield self._mk_event(
                        "message_update",
                        assistantMessageEvent={"type": "text_delta", "contentIndex": 0, "delta": chunk},
                    )
                yield self._mk_event(
                    "message_update",
                    assistantMessageEvent={"type": "text_end", "contentIndex": 0, "content": msg.content},
                )

            # Handle tool calls
            if msg.tool_calls:
                # Build single assistant message with all tool calls
                assistant_msg: Dict[str, Any] = {
                    "role": "assistant",
                    "content": msg.content or None,
                    "tool_calls": [
                        {
                            "id": tc.id,
                            "type": "function",
                            "function": {
                                "name": tc.function.name,
                                "arguments": tc.function.arguments,
                            },
                        }
                        for tc in msg.tool_calls
                    ],
                }

                # Assistant message with tool_calls MUST come before tool results
                messages.append(assistant_msg)

                for tc in msg.tool_calls:
                    fn_name = tc.function.name
                    yield self._mk_event(
                        "message_update",
                        assistantMessageEvent={"type": "toolcall_start", "contentIndex": 0},
                    )
                    for chunk in _chunk_text(tc.function.arguments or ""):
                        yield self._mk_event(
                            "message_update",
                            assistantMessageEvent={
                                "type": "toolcall_delta",
                                "contentIndex": 0,
                                "delta": chunk,
                            },
                        )
                    yield self._mk_event(
                        "message_update",
                        assistantMessageEvent={
                            "type": "toolcall_end",
                            "contentIndex": 0,
                            "toolCall": {
                                "id": tc.id,
                                "name": fn_name,
                                "arguments": tc.function.arguments,
                            },
                        },
                    )
                    try:
                        fn_args = json.loads(tc.function.arguments)
                    except json.JSONDecodeError:
                        fn_args = {}

                    yield self._mk_event(
                        "tool_execution_start",
                        toolName=fn_name,
                        args=fn_args,
                        toolCallId=tc.id,
                    )

                    if fn_name == "read":
                        result = _read_tool(self.cwd, fn_args.get("file_path", ""))
                    elif fn_name == "bash":
                        result = _bash_tool(self.cwd, fn_args.get("command", ""))
                    else:
                        result = f"Error: Unknown tool '{fn_name}'"

                    is_error = result.startswith("Error:")
                    for chunk in _chunk_text(result):
                        yield self._mk_event(
                            "tool_execution_update",
                            toolName=fn_name,
                            toolCallId=tc.id,
                            output=chunk,
                        )
                    yield self._mk_event(
                        "tool_execution_end",
                        toolName=fn_name,
                        toolCallId=tc.id,
                        isError=is_error,
                        result=result,
                    )

                    messages.append({
                        "role": "tool",
                        "tool_call_id": tc.id,
                        "content": result,
                    })

                yield self._mk_event("message_end", message={"role": "assistant", "content": []})
                continue  # next turn

            # No tool calls → agent is done
            yield self._mk_event("message_end", message={"role": "assistant", "content": msg.content or ""})
            yield self._mk_event("agent_end")
            return final_text or "(no answer provided)"

        # Max turns reached — ask model to summarise with all gathered context
        messages.append({
            "role": "user",
            "content": (
                "You have used all available research turns. "
                "Based on every file you have read and every search you have run, "
                "please give your best final answer to the original question. "
                "Be as complete and accurate as the evidence allows."
            ),
        })
        try:
            summary = self.client.chat.completions.create(
                model=self.model,
                messages=messages,  # type: ignore[arg-type]
                temperature=0.2,
            )
            final_text = summary.choices[0].message.content or final_text
            if final_text:
                yield self._mk_event(
                    "message_update",
                    assistantMessageEvent={"type": "text_start", "contentIndex": 0},
                )
                for chunk in _chunk_text(final_text):
                    yield self._mk_event(
                        "message_update",
                        assistantMessageEvent={"type": "text_delta", "contentIndex": 0, "delta": chunk},
                    )
                yield self._mk_event(
                    "message_update",
                    assistantMessageEvent={"type": "text_end", "contentIndex": 0, "content": final_text},
                )
        except Exception:
            pass
        yield self._mk_event("agent_end", note=f"Reached max_turns={self.max_turns}")
        return final_text or "(max turns reached without final answer)"


# ---------------------------------------------------------------------------
# Unified runner
# ---------------------------------------------------------------------------

def run_pi(
    question: str,
    *,
    cwd: Path,
    api_key: str,
    provider: str = "openai",
    model: str = "gpt-4o",
    max_turns: int = 6,
    session_dir: Optional[Path] = None,
    session_path: Optional[Path] = None,
    continue_session: bool = False,
) -> Generator[Dict[str, Any], None, str]:
    """
    Run PI (native if available, else fallback) and yield events.
    Returns the final answer text via StopIteration.value.
    """
    if pi_mono_available() and provider != "fallback":
        client = NativePiClient(
            package_dir=DEFAULT_PACKAGE_DIR,
            cwd=cwd,
            agent_dir=DEFAULT_AGENT_DIR,
            provider=provider,
            model=model,
            tools="read,bash",
            session_dir=session_dir,
            session_path=session_path,
            continue_session=continue_session,
            api_key=api_key,
        )
        try:
            client.start()
            yield from client.stream_events(question, max_turns=max_turns)
        finally:
            client.stop()
        # stream_events returns via StopIteration; we need to handle this
        # Actually generator yield + return doesn't work well with yield from
        # Let me refactor
    else:
        agent = FallbackPiAgent(
            cwd=cwd,
            api_key=api_key,
            model=model,
            max_turns=max_turns,
        )
        return (yield from agent.stream_events(question))


# Refactored to return (events_gen, final_answer_promise)
def run_pi_stream(
    question: str,
    *,
    cwd: Path,
    api_key: str,
    provider: str = "openai",
    model: str = "gpt-4o",
    max_turns: int = 6,
    session_dir: Optional[Path] = None,
    session_path: Optional[Path] = None,
    continue_session: bool = False,
) -> Iterator[Dict[str, Any]]:
    """
    Iterator that yields PI events.  The *last* item is a sentinel dict
    ``{"type": "__final__", "text": "..."}`` containing the answer.
    """
    if pi_mono_available() and provider != "fallback":
        client = NativePiClient(
            package_dir=DEFAULT_PACKAGE_DIR,
            cwd=cwd,
            agent_dir=DEFAULT_AGENT_DIR,
            provider=provider,
            model=model,
            tools="read,bash",
            session_dir=session_dir,
            session_path=session_path,
            continue_session=continue_session,
            api_key=api_key,
        )
        text_parts: List[str] = []
        try:
            client.start()
            state_response = client.call("get_state")
            state_data = state_response.get("data", {}) or {}
            if state_data.get("thinkingLevel") == "off":
                client.call("set_thinking_level", level="high")
                state_response = client.call("get_state")
                state_data = state_response.get("data", {}) or {}
            yield {
                "type": "__session__",
                "runner": "Native PI",
                "provider": provider,
                "model": model,
                "sessionFile": state_data.get("sessionFile"),
                "sessionId": state_data.get("sessionId"),
                "thinkingLevel": state_data.get("thinkingLevel"),
            }
            request_id = client._next_id()
            client._send({"id": request_id, "type": "prompt", "message": question})

            prompt_ack = False
            seen_turns = 0
            sent_abort = False

            while True:
                event = client._read_json_line()
                yield event
                et = event.get("type")

                if et == "response" and event.get("id") == request_id:
                    if not event.get("success", True):
                        yield {"type": "error", "error": event.get("error", "RPC prompt failed")}
                        break
                    prompt_ack = True
                    continue

                if et == "turn_start":
                    seen_turns += 1
                    if max_turns and seen_turns > max_turns and not sent_abort:
                        client._send({"id": client._next_id(), "type": "abort"})
                        sent_abort = True
                    continue

                if et == "message_update":
                    ame = event.get("assistantMessageEvent", {})
                    if ame.get("type") == "text_delta":
                        text_parts.append(ame.get("delta", ""))
                    continue

                if et == "agent_end":
                    break

            final_state_response = client.call("get_state")
            final_state_data = final_state_response.get("data", {}) or {}
            yield {
                "type": "__session__",
                "runner": "Native PI",
                "provider": provider,
                "model": model,
                "sessionFile": final_state_data.get("sessionFile"),
                "sessionId": final_state_data.get("sessionId"),
                "thinkingLevel": final_state_data.get("thinkingLevel"),
            }

        except Exception as exc:
            yield {"type": "error", "error": str(exc)}
        finally:
            client.stop()

        final_text = "".join(text_parts)
        yield {"type": "__final__", "text": final_text}

    else:
        yield {
            "type": "__session__",
            "runner": "Fallback Agent",
            "provider": provider,
            "model": model,
            "thinkingLevel": "unsupported",
        }
        agent = FallbackPiAgent(
            cwd=cwd,
            api_key=api_key,
            model=model,
            max_turns=max_turns,
        )
        text_parts: List[str] = []
        try:
            for event in agent.stream_events(question):
                yield event
                if event.get("type") == "message_update":
                    ame = event.get("assistantMessageEvent", {})
                    if ame.get("type") == "text_delta":
                        text_parts.append(ame.get("delta", ""))
        except Exception as exc:
            yield {"type": "error", "error": str(exc)}
        yield {"type": "__final__", "text": "".join(text_parts)}