"""Per-task persistence: project-memory (HTTP) and Obsidian vault (git)."""
from __future__ import annotations

import asyncio
import json
import logging
import os
import time
from datetime import date

import httpx
from slugify import slugify

from app.config import settings

logger = logging.getLogger(__name__)

MCP_ACCEPT = "application/json, text/event-stream"


def _parse_mcp_response(resp: httpx.Response) -> dict:
    """Parse JSON or SSE body from streamable HTTP MCP responses."""
    content_type = resp.headers.get("content-type", "")
    text = resp.text.strip()
    if "text/event-stream" in content_type or text.startswith("event:") or text.startswith("data:"):
        for line in text.splitlines():
            if line.startswith("data:"):
                payload = line[5:].strip()
                if payload and payload != "[DONE]":
                    return json.loads(payload)
        return {}
    if text:
        return resp.json()
    return {}


class _MemoryMcpSession:
    """Reusable streamable-HTTP session for the project-memory MCP server.

    Performs the initialize handshake once and reuses the HTTP client +
    Mcp-Session-Id across calls, re-initializing only when the session is
    rejected (e.g. server restart / expired session).
    """

    def __init__(self) -> None:
        self._client: httpx.AsyncClient | None = None
        self._session_id: str | None = None
        self._lock = asyncio.Lock()
        self._req_id = 0

    def _headers(self) -> dict[str, str]:
        headers = {"Content-Type": "application/json", "Accept": MCP_ACCEPT}
        if settings.memory_mcp_token:
            headers["Authorization"] = f"Bearer {settings.memory_mcp_token}"
        if self._session_id:
            headers["Mcp-Session-Id"] = self._session_id
        return headers

    async def _ensure_client(self) -> httpx.AsyncClient:
        if self._client is None:
            self._client = httpx.AsyncClient(timeout=30)
        return self._client

    async def _handshake(self) -> None:
        client = await self._ensure_client()
        self._session_id = None
        init_body = {
            "jsonrpc": "2.0",
            "id": 1,
            "method": "initialize",
            "params": {
                "protocolVersion": "2024-11-05",
                "capabilities": {},
                "clientInfo": {"name": "agentic-os", "version": "0.1.0"},
            },
        }
        resp = await client.post(settings.memory_mcp_url, headers=self._headers(), json=init_body)
        resp.raise_for_status()
        self._session_id = resp.headers.get("mcp-session-id") or resp.headers.get("Mcp-Session-Id")
        await client.post(
            settings.memory_mcp_url,
            headers=self._headers(),
            json={"jsonrpc": "2.0", "method": "notifications/initialized"},
        )

    async def _call_once(self, tool_name: str, arguments: dict) -> dict | None:
        client = await self._ensure_client()
        self._req_id += 1
        body = {
            "jsonrpc": "2.0",
            "id": self._req_id,
            "method": "tools/call",
            "params": {"name": tool_name, "arguments": arguments},
        }
        resp = await client.post(settings.memory_mcp_url, headers=self._headers(), json=body)
        resp.raise_for_status()
        data = _parse_mcp_response(resp)
        if data.get("error"):
            raise RuntimeError(data["error"].get("message", str(data["error"])))
        return data.get("result")

    async def call(self, tool_name: str, arguments: dict) -> dict | None:
        async with self._lock:
            if self._session_id is None:
                await self._handshake()
            try:
                return await self._call_once(tool_name, arguments)
            except (httpx.HTTPStatusError, RuntimeError) as exc:
                # Session may have expired; re-handshake once and retry.
                logger.info("memory MCP retry after error: %s", exc)
                await self._handshake()
                return await self._call_once(tool_name, arguments)


_memory_session = _MemoryMcpSession()


async def memory_mcp_call(tool_name: str, arguments: dict) -> dict | None:
    """Run one MCP tool call against project-memory over a reused HTTP session."""
    if not settings.memory_mcp_url:
        return None
    return await _memory_session.call(tool_name, arguments)


async def create_task_memory(
    title: str,
    content: str,
    memory_type: str = "fix",
    tags: list[str] | None = None,
    importance: int = 3,
    *,
    vessel_name: str | None = None,
    task_id: int | None = None,
) -> str | None:
    """Call memory_upsert on the project-memory MCP over HTTP JSON-RPC."""
    tag_list = list(tags or ["agentic-os"])
    if vessel_name:
        from slugify import slugify

        tag_list.append(f"vessel:{slugify(vessel_name, lowercase=True)}")
    if task_id is not None:
        tag_list.append(f"task:{task_id}")

    body_parts = []
    if vessel_name:
        body_parts.append(f"Vessel: {vessel_name}")
    if task_id is not None:
        body_parts.append(f"Task ID: {task_id}")
    body_parts.append(content)
    full_content = "\n\n".join(body_parts)

    args = {
        "project_id": settings.memory_task_project_id,
        "memory_type": memory_type,
        "title": title,
        "content": full_content,
        "tags": tag_list,
        "importance": importance,
    }

    try:
        result = await memory_mcp_call("memory_upsert", args)
        if not isinstance(result, dict):
            return None
        structured = result.get("structuredContent")
        if isinstance(structured, dict):
            mid = structured.get("id") or structured.get("memory_id")
            if mid:
                return str(mid)
        for block in result.get("content", []):
            text = block.get("text") if isinstance(block, dict) else None
            if text and "id" in text:
                return text[:128]
    except Exception as exc:  # noqa: BLE001
        logger.warning("create_task_memory failed: %s", exc)
    return None


def _vault_dir() -> str:
    return os.path.join(settings.runtime_dir, "obsidian-vault")


async def _run(cmd: list[str], cwd: str | None = None) -> tuple[int, str]:
    proc = await asyncio.create_subprocess_exec(
        *cmd,
        cwd=cwd,
        stdout=asyncio.subprocess.PIPE,
        stderr=asyncio.subprocess.STDOUT,
    )
    out, _ = await proc.communicate()
    return proc.returncode or 0, out.decode(errors="replace")


async def _repair_vault_git(vault: str) -> None:
    """Recover from stuck rebase/merge so commits can be pushed to origin/main."""
    git_dir = os.path.join(vault, ".git")
    if not os.path.isdir(git_dir):
        return

    if os.path.isdir(os.path.join(git_dir, "rebase-merge")) or os.path.isdir(
        os.path.join(git_dir, "rebase-apply")
    ):
        logger.warning("Obsidian vault stuck in git rebase; attempting continue/abort")
        code, _ = await _run(["git", "rebase", "--continue"], cwd=vault)
        if code != 0:
            await _run(["git", "rebase", "--abort"], cwd=vault)

    if os.path.isfile(os.path.join(git_dir, "MERGE_HEAD")):
        logger.warning("Obsidian vault stuck in git merge; aborting")
        await _run(["git", "merge", "--abort"], cwd=vault)

    code, _ = await _run(["git", "checkout", "main"], cwd=vault)
    if code != 0:
        await _run(["git", "checkout", "-B", "main"], cwd=vault)


async def _vault_pull(vault: str) -> None:
    await _repair_vault_git(vault)
    code, out = await _run(["git", "pull", "--ff-only", "origin", "main"], cwd=vault)
    if code != 0:
        logger.warning("vault ff-only pull failed: %s", out[:300])
        await _repair_vault_git(vault)
        await _run(["git", "pull", "--no-rebase", "origin", "main"], cwd=vault)


async def _vault_commit_and_push(vault: str, rel_path: str, title: str) -> tuple[bool, str | None]:
    """Stage, commit, and push one note. Returns (pushed, error_message)."""
    if not settings.obsidian_auto_push or not settings.gitea_token:
        return False, None

    await _repair_vault_git(vault)
    await _run(["git", "add", rel_path], cwd=vault)
    code, out = await _run(
        [
            "git",
            "-c",
            "user.email=agentic-os@paraskeva.net",
            "-c",
            "user.name=Agentic OS",
            "commit",
            "-m",
            f"agentic-os task: {title}",
        ],
        cwd=vault,
    )
    if code != 0 and "nothing to commit" not in out.lower():
        return False, out.strip()[:500]

    await _repair_vault_git(vault)
    code, out = await _run(["git", "push", "origin", "main"], cwd=vault)
    if code != 0:
        logger.warning("vault push failed: %s", out)
        return False, out.strip()[:500]
    return True, None


_VAULT_PULL_TTL = 300.0  # seconds between background `git pull` of the vault
_vault_pull_lock = asyncio.Lock()
_vault_last_pull = 0.0


async def ensure_vault(*, force_pull: bool = False) -> str | None:
    global _vault_last_pull
    vault = _vault_dir()
    clone_url = settings.gitea_clone_url(settings.obsidian_vault_repo)
    if os.path.isdir(os.path.join(vault, ".git")):
        # Throttle pulls: skip if pulled recently (deduped across concurrent tasks).
        now = time.monotonic()
        if force_pull or now - _vault_last_pull >= _VAULT_PULL_TTL:
            async with _vault_pull_lock:
                if force_pull or time.monotonic() - _vault_last_pull >= _VAULT_PULL_TTL:
                    await _vault_pull(vault)
                    _vault_last_pull = time.monotonic()
        return vault
    os.makedirs(settings.runtime_dir, exist_ok=True)
    code, out = await _run(["git", "clone", clone_url, vault])
    if code != 0:
        logger.warning("vault clone failed: %s", out)
        return None
    _vault_last_pull = time.monotonic()
    return vault


async def write_obsidian_note(
    title: str,
    issue: str,
    steps: list[str] | str,
    cause: str | None,
    resolution: str | None,
    resolved: bool,
    *,
    vessel_name: str | None = None,
    task_id: int | None = None,
    diagnostics_md: str | None = None,
) -> tuple[str | None, str | None]:
    """Write task note to vault. Returns (relative_path, push_error)."""
    vault = await ensure_vault()
    if not vault:
        return None, "Obsidian vault unavailable (clone failed)"

    folder = settings.obsidian_tasks_folder
    os.makedirs(os.path.join(vault, folder), exist_ok=True)
    slug = slugify(title)[:60] or "task"
    filename = f"{date.today().isoformat()}-{slug}.md"
    rel_path = f"{folder}/{filename}"
    abs_path = os.path.join(vault, rel_path)

    steps_md = (
        "\n".join(f"- {s}" for s in steps) if isinstance(steps, list) else str(steps or "")
    )
    status_label = "Resolved" if resolved else "Unresolved"
    vessel_line = f"vessel: {vessel_name}\n" if vessel_name else ""
    task_line = f"task_id: {task_id}\n" if task_id is not None else ""
    diag_section = ""
    if diagnostics_md:
        diag_section = f"\n## Diagnostic findings\n{diagnostics_md}\n"

    body = f"""---
tags: [agentic-os, troubleshooting]
{vessel_line}{task_line}status: {status_label.lower()}
created: {date.today().isoformat()}
---

# {title}

## Vessel
{vessel_name or "_Not specified._"}

## Issue
{issue}

## Troubleshooting steps
{steps_md}

## Root cause
{cause or "_Not determined._"}

## Resolution ({status_label})
{resolution or "_No resolution recorded._"}
{diag_section}"""
    def _write() -> None:
        with open(abs_path, "w", encoding="utf-8") as fh:
            fh.write(body)

    await asyncio.to_thread(_write)

    pushed, push_error = await _vault_commit_and_push(vault, rel_path, title)
    if push_error:
        logger.warning("Obsidian note written locally at %s but git push failed: %s", rel_path, push_error)
    elif not pushed and settings.obsidian_auto_push:
        push_error = "Note saved in vault clone only (auto-push disabled or no Gitea token)"

    return rel_path, push_error