"""
Agent runner — resolves provider, parses @-mentions, dispatches messages.

Provider selection (in order):
  1. GROQ_API_KEY   → OpenAI-compat / Groq
  2. OPENAI_API_KEY → OpenAI-compat / OpenAI
  3. (default)      → Claude Code SDK (uses CC subscription)
"""

import json
import logging
import os
import re
from pathlib import Path
from threading import Thread
from typing import Callable

from cht.agent.base import AgentProvider, FrameRef, TranscriptRef, SessionContext

log = logging.getLogger(__name__)

# Predefined actions — label → verb prefix (frame ref appended by UI)
ACTIONS: dict[str, str] = {
    "Describe": "describe",
    "Answer":   "answer",
}


def check_claude_cli() -> str | None:
    """Returns None if OK, or an error string if CLI is missing/unauthenticated."""
    import shutil, subprocess
    if not shutil.which("claude"):
        return "Claude Code CLI not found. Install from https://claude.ai/code"
    try:
        result = subprocess.run(
            ["claude", "--version"],
            capture_output=True, timeout=5
        )
        if result.returncode != 0:
            return "Claude Code CLI error. Run `claude` in a terminal to check."
    except Exception as e:
        return f"Claude Code CLI check failed: {e}"
    return None


def _resolve_provider() -> AgentProvider:
    if os.environ.get("GROQ_API_KEY") or os.environ.get("OPENAI_API_KEY"):
        from cht.agent.openai_compat_provider import OpenAICompatProvider
        return OpenAICompatProvider()
    from cht.agent.claude_sdk_provider import ClaudeSDKProvider
    return ClaudeSDKProvider()


def _parse_mentions(message: str, frames: list[FrameRef]) -> list[FrameRef]:
    """Extract @-references from message. Accepts:
      @F0001  @f1  @1  @001  — all match frame F0001
    """
    mentioned = []
    seen = set()
    for match in re.finditer(r"@([Ff]?\d+)", message):
        raw = match.group(1).lstrip("Ff")
        num = int(raw)
        fid = f"F{num:04d}"
        if fid not in seen:
            frame = next((f for f in frames if f.id == fid), None)
            if frame:
                mentioned.append(frame)
                seen.add(fid)
    return mentioned


def _resolve_frame_path(frames_dir: Path, raw_path: str) -> Path | None:
    """Resolve a frame path from index.json, handling mounted/remote sessions."""
    p = Path(raw_path)
    if p.exists():
        return p
    # Try relative to frames_dir (handles path prefix mismatch from remote)
    local = frames_dir / p.name
    if local.exists():
        return local
    return None


def _load_frames(frames_dir: Path) -> list[FrameRef]:
    index_path = frames_dir / "index.json"
    if not index_path.exists():
        return []
    try:
        entries = json.loads(index_path.read_text())
        frames = []
        for e in entries:
            resolved = _resolve_frame_path(frames_dir, e["path"])
            if resolved:
                frames.append(FrameRef(id=e["id"], path=resolved, timestamp=e["timestamp"]))
        return frames
    except Exception as e:
        log.warning("Could not load frames index: %s", e)
        return []


def _load_transcript(transcript_dir: Path) -> list[TranscriptRef]:
    index_path = transcript_dir / "index.json"
    if not index_path.exists():
        return []
    try:
        entries = json.loads(index_path.read_text())
        return [TranscriptRef(**e) for e in entries]
    except Exception as e:
        log.warning("Could not load transcript index: %s", e)
        return []


def _parse_transcript_mentions(message: str, segments: list[TranscriptRef]) -> list[TranscriptRef]:
    """Extract @T references from message. Accepts @T0001, @t1, @T1."""
    mentioned = []
    seen = set()
    for match in re.finditer(r"@[Tt](\d+)", message):
        num = int(match.group(1))
        tid = f"T{num:04d}"
        if tid not in seen:
            seg = next((s for s in segments if s.id == tid), None)
            if seg:
                mentioned.append(seg)
                seen.add(tid)
    return mentioned


class AgentRunner:
    """Runs agent queries in a background thread, streams chunks to a callback."""

    def __init__(self):
        self._provider: AgentProvider | None = None

    def _get_provider(self) -> AgentProvider:
        if self._provider is None:
            self._provider = _resolve_provider()
            log.info("Agent provider: %s", self._provider.name)
        return self._provider

    @property
    def provider_name(self) -> str:
        try:
            return self._get_provider().name
        except Exception:
            return "unknown"

    @property
    def available_models(self) -> list[str]:
        try:
            return self._get_provider().available_models
        except Exception:
            return []

    @property
    def model(self) -> str:
        try:
            return self._get_provider().model
        except Exception:
            return ""

    @model.setter
    def model(self, value: str):
        self._get_provider().model = value

    def send(
        self,
        message: str,
        stream_mgr,
        tracker,
        on_chunk: Callable[[str], None],
        on_done: Callable[[str | None], None],
    ):
        """Dispatch message in a background thread.

        on_chunk(text) — called for each streamed chunk
        on_done(error_or_None) — called when complete
        """
        def _run():
            try:
                provider = self._get_provider()
                frames = _load_frames(stream_mgr.frames_dir)
                mentioned_frames = _parse_mentions(message, frames)
                transcript = _load_transcript(stream_mgr.transcript_dir)
                mentioned_transcripts = _parse_transcript_mentions(message, transcript)
                context = SessionContext(
                    session_dir=stream_mgr.session_dir,
                    frames=frames,
                    duration=tracker.duration if tracker else 0.0,
                    mentioned_frames=mentioned_frames,
                    transcript_segments=transcript,
                    mentioned_transcripts=mentioned_transcripts,
                )
                for chunk in provider.stream(message, context):
                    on_chunk(chunk)
                on_done(None)
            except Exception as e:
                log.error("Agent error: %s", e)
                on_done(str(e))

        Thread(target=_run, daemon=True, name="agent_runner").start()