"""Agent run manager.

Drives two agent types:

* **Local directory agent** — sends an ``agent_run`` frame to the connected
  Electron device, waits for the device to stream back file contents via
  ``agent_data`` frames, then calls the LLM to extract structured items from
  each file and pushes inserts to Electron via tool-call round-trips.

* **Cloud connector agent** — fetches data from third-party APIs (Gmail,
  Teams, Outlook) and pushes extracted items to Electron.  **This path is
  a stub** — provider integrations are implemented in Step 3.6.

Usage
-----
Background tasks are spawned with ``asyncio.create_task()``::

    asyncio.create_task(run_local_agent(user_id, config, run_log, device_manager))
    asyncio.create_task(trigger_pending_runs(user_id, device_id, device_manager))

The ``trigger_pending_runs`` function is called by the device WS endpoint
when Electron sends ``device_hello``, so any overdue runs fire immediately
when the device reconnects.
"""

from __future__ import annotations

import asyncio
import json
import logging
import uuid
from datetime import datetime, timedelta, timezone
from typing import Any

from croniter import croniter
from langchain_core.messages import HumanMessage, SystemMessage
from sqlalchemy import select

from app.core.device_manager import DeviceConnectionManager
from app.core.llm import get_llm
from app.db import async_session
from app.models import AgentRunLog, CloudAgentConfig, LocalAgentConfig

logger = logging.getLogger(__name__)

# ── Timeouts ───────────────────────────────────────────────────────────────

# Max seconds to wait for Electron to finish streaming file data.
_FILE_READ_TIMEOUT: int = 120
# Max seconds to wait for Electron to acknowledge a single tool-call insert.
_INSERT_TIMEOUT: int = 30

# ── Allowed tables & extraction schema hints ───────────────────────────────

_ALLOWED_TABLES: frozenset[str] = frozenset(
    {"tasks", "notes", "timelines", "projects", "taskComments"}
)

# Field descriptions fed to the extraction LLM as concise schema references.
_TABLE_SCHEMAS: dict[str, str] = {
    "tasks": (
        "title (str, required), description (str), "
        "status (todo|in_progress|done, default todo), "
        "priority (high|medium|low, default medium), "
        "assignee (JSON array string), dueDate (ms timestamp int), projectId (str)"
    ),
    "notes": "title (str, required), content (str, markdown), projectId (str)",
    "timelines": (
        "title (str, required), projectId (str, required), date (ms timestamp int)"
    ),
    "projects": "name (str, required), clientId (str)",
    "taskComments": "taskId (str, required), author (str), content (str, required)",
}

_EXTRACTION_SYSTEM_PROMPT = """\
You are a data extraction assistant for a freelance project management tool.
Given a document, extract structured records matching the user's instructions.

Output a JSON array (no markdown fences, no explanation) of objects shaped:
  [{{"table": "<table_name>", "data": {{...fields}}}}, ...]

Allowed table names and their fields:
{table_schemas}

Rules:
- Only extract tables listed in the "data_types" instructions.
- Use camelCase field names exactly as shown above.
- Omit optional fields you cannot determine; do not invent data.
- Never include id, createdAt, updatedAt, isAiSuggested, or isApproved.
- If nothing relevant is found, return an empty JSON array: []
- Return ONLY the JSON array.
"""


# ── Cron helper ────────────────────────────────────────────────────────────


def _is_overdue(schedule_cron: str, last_run_at: datetime | None) -> bool:
    """Return ``True`` if the next scheduled run time has already passed.

    Always validates the cron expression first — an invalid expression returns
    ``False`` (fail-safe: never trigger an unparseable schedule).
    """
    try:
        now = datetime.now(timezone.utc)
        if last_run_at is None:
            # Validate the expression before deciding this is overdue.
            croniter(schedule_cron, now)
            return True
        ts = last_run_at
        if ts.tzinfo is None:
            ts = ts.replace(tzinfo=timezone.utc)
        cron = croniter(schedule_cron, ts)
        next_run: datetime = cron.get_next(datetime)
        return now >= next_run
    except Exception as exc:
        logger.warning("agent_runner: cannot parse cron %r: %s", schedule_cron, exc)
        return False  # Fail-safe: don't trigger if expression is invalid.


# ── LLM extraction ─────────────────────────────────────────────────────────


async def _extract_items_from_content(
    prompt_template: str,
    file_content: str,
    data_types: list[str],
) -> list[dict[str, Any]]:
    """Call the LLM to extract structured records from *file_content*.

    Returns a validated list of ``{table: str, data: dict}`` objects.
    Items referencing tables not in *data_types* are discarded.
    """
    allowed = [t for t in data_types if t in _ALLOWED_TABLES]
    if not allowed:
        return []

    schema_text = "\n".join(
        f"  {table}: {_TABLE_SCHEMAS.get(table, '(unknown)')}" for table in allowed
    )
    system_prompt = _EXTRACTION_SYSTEM_PROMPT.format(table_schemas=schema_text)
    user_prompt = (
        f"User instructions: {prompt_template}\n\n"
        f"Extract these record types: {', '.join(allowed)}\n\n"
        f"Document:\n{file_content[:8000]}"
    )

    llm = get_llm()
    raw = ""
    try:
        response = await llm.ainvoke(
            [SystemMessage(content=system_prompt), HumanMessage(content=user_prompt)]
        )
        raw = str(response.content).strip()
        items: list[dict] = json.loads(raw)
        if not isinstance(items, list):
            raise ValueError("LLM response is not a JSON array")
    except json.JSONDecodeError as exc:
        logger.warning(
            "agent_runner: LLM extraction returned invalid JSON: %s — snippet: %.200r",
            exc,
            raw,
        )
        return []
    # Other exceptions (LLM API errors, network errors) propagate to the
    # caller (run_local_agent) which records them per-file in the run log.

    validated: list[dict[str, Any]] = []
    for item in items:
        table = item.get("table")
        data = item.get("data")
        if not isinstance(table, str) or table not in allowed:
            continue
        if not isinstance(data, dict) or not data:
            continue
        # Strip any server-generated or forbidden fields.
        for _field in ("id", "createdAt", "updatedAt", "isAiSuggested", "isApproved"):
            data.pop(_field, None)
        validated.append({"table": table, "data": data})
    return validated


# ── Tool-call insert helper ─────────────────────────────────────────────────


async def _send_insert_to_client(
    user_id: str,
    table: str,
    data: dict[str, Any],
    device_mgr: DeviceConnectionManager,
) -> dict[str, Any]:
    """Send an ``insert`` tool_call frame to Electron and await the tool_result.

    All inserts include ``isAiSuggested=1, isApproved=0`` so the user can
    review AI-produced records before they are treated as confirmed.

    Raises ``asyncio.TimeoutError`` if Electron does not respond within
    ``_INSERT_TIMEOUT`` seconds.  Raises ``RuntimeError`` if the device
    disconnects before the frame can be sent.
    """
    call_id = str(uuid.uuid4())
    payload: dict[str, Any] = {
        "type": "tool_call",
        "id": call_id,
        "action": "insert",
        "table": table,
        "data": {**data, "isAiSuggested": 1, "isApproved": 0},
    }
    fut = device_mgr.create_pending_call(user_id, call_id)
    await device_mgr.send_frame(user_id, payload)
    return await asyncio.wait_for(fut, timeout=_INSERT_TIMEOUT)


# ── Local agent runner ──────────────────────────────────────────────────────


async def run_local_agent(
    user_id: str,
    config: LocalAgentConfig,
    run_log: AgentRunLog,
    device_mgr: DeviceConnectionManager,
) -> None:
    """Execute a local directory agent run end-to-end.

    Steps:

    1. Verify the device identified by ``config.device_id`` is currently online.
    2. Pre-create the agent_data queue so no incoming frames are lost.
    3. Send ``agent_run`` frame to Electron (paths, extensions, prompt, data_types).
    4. Consume ``agent_data`` frames until the ``None`` sentinel from
       ``agent_complete``.
    5. For each received file call the LLM to extract ``{table, data}`` items.
    6. Push each item to Electron as an ``insert`` tool-call; include
       ``isAiSuggested=1, isApproved=0`` so users can review AI suggestions.
    7. Persist the run outcome (status, counts, errors) and update
       ``config.last_run_at``.
    """
    run_id = run_log.id

    # ── 1. Device online check ─────────────────────────────────────────
    if not device_mgr.is_online(user_id, config.device_id):
        logger.info(
            "agent_runner: skip run=%s — device %r offline for user=%s",
            run_id,
            config.device_id,
            user_id,
        )
        await _finalize_run(
            run_log,
            status="error",
            errors=[f"Device {config.device_id!r} is not connected"],
        )
        return

    # ── 2. Pre-create agent_data queue ────────────────────────────────
    try:
        device_mgr.get_agent_data_queue(user_id, run_id)
    except RuntimeError:
        await _finalize_run(
            run_log,
            status="error",
            errors=["Device disconnected before agent run could start"],
        )
        return

    # ── 3. Send agent_run frame ────────────────────────────────────────
    frame: dict[str, Any] = {
        "type": "agent_run",
        "run_id": run_id,
        "agent_id": config.id,
        "config": {
            "paths": config.directory_paths,
            "file_extensions": config.file_extensions,
            "prompt_template": config.prompt_template,
            "data_types": config.data_types,
        },
    }
    try:
        await device_mgr.send_frame(user_id, frame)
    except RuntimeError as exc:
        device_mgr.cleanup_agent_data_queue(user_id, run_id)
        await _finalize_run(
            run_log,
            status="error",
            errors=[f"Failed to send agent_run frame: {exc}"],
        )
        return

    logger.info(
        "agent_runner: sent agent_run run=%s agent=%s user=%s",
        run_id,
        config.id,
        user_id,
    )

    # ── 4. Consume agent_data frames ──────────────────────────────────
    files: list[dict[str, Any]] = []
    errors: list[str] = []

    try:
        queue = device_mgr.get_agent_data_queue(user_id, run_id)
        deadline = asyncio.get_event_loop().time() + _FILE_READ_TIMEOUT
        while True:
            remaining = deadline - asyncio.get_event_loop().time()
            if remaining <= 0:
                errors.append("Timed out waiting for file data from device")
                break
            try:
                frame_data = await asyncio.wait_for(queue.get(), timeout=remaining)
            except asyncio.TimeoutError:
                errors.append("Timed out waiting for file data from device")
                break
            if frame_data is None:
                # Sentinel from agent_complete — stream is done.
                break
            files.extend(frame_data.get("files", []))
    except RuntimeError as exc:
        errors.append(f"Queue error reading agent data: {exc}")

    # ── 5–6. Extract + insert ─────────────────────────────────────────
    items_processed = 0
    items_created = 0

    for file_info in files:
        file_path: str = file_info.get("path", "<unknown>")
        content: str = file_info.get("content", "")
        if not content:
            continue
        items_processed += 1
        try:
            extracted = await _extract_items_from_content(
                config.prompt_template, content, config.data_types
            )
        except Exception as exc:
            errors.append(f"LLM extraction error for {file_path!r}: {exc}")
            continue

        for item in extracted:
            try:
                result = await _send_insert_to_client(
                    user_id, item["table"], item["data"], device_mgr
                )
                if result.get("error"):
                    errors.append(
                        f"Insert failed ({item['table']}, {file_path!r}): {result['error']}"
                    )
                else:
                    items_created += 1
            except asyncio.TimeoutError:
                errors.append(
                    f"Timed out awaiting insert ack ({item['table']}, {file_path!r})"
                )
            except RuntimeError as exc:
                errors.append(f"Insert error ({item['table']}, {file_path!r}): {exc}")

    # ── 7. Finalise ────────────────────────────────────────────────────
    device_mgr.cleanup_agent_data_queue(user_id, run_id)

    if errors and items_created == 0:
        final_status = "error"
    elif errors:
        final_status = "partial"
    else:
        final_status = "success"

    await _finalize_run(
        run_log,
        status=final_status,
        items_processed=items_processed,
        items_created=items_created,
        errors=errors,
        update_config_last_run=True,
        config_id=config.id,
        config_type="local",
    )
    logger.info(
        "agent_runner: run=%s done status=%s processed=%d created=%d errors=%d",
        run_id,
        final_status,
        items_processed,
        items_created,
        len(errors),
    )


# ── Cloud agent runner ─────────────────────────────────────────────────────

# Default lookback window when an agent has never run before.
_CLOUD_DEFAULT_LOOKBACK_DAYS: int = 7


async def run_cloud_agent(
    user_id: str,
    config: CloudAgentConfig,
    run_log: AgentRunLog,
    device_mgr: DeviceConnectionManager,
) -> None:
    """Execute a cloud connector agent run end-to-end.

    Steps:

    1. Verify the user's device is online — results are pushed to Electron
       via WS tool-call frames.  If no device is connected, abort.
    2. Decrypt the stored OAuth token from ``config.oauth_token_encrypted``.
    3. Instantiate the provider client (Gmail or MS Graph).
    4. Fetch messages/emails since ``config.last_run_at`` (or 7 days ago for
       the first run) applying ``config.filter_config`` filters.
    5. For each message/email call ``_extract_items_from_content`` with
       ``config.prompt_template`` to get structured ``{table, data}`` items.
    6. Push each item to Electron as an ``insert`` tool-call.
    7. If the provider refreshed its access token, re-encrypt and write it
       back to ``config.oauth_token_encrypted``.
    8. Persist the run outcome via ``_finalize_run``.
    """
    run_id = run_log.id

    # ── 1. Device online check ─────────────────────────────────────────
    if not device_mgr.is_online(user_id):
        logger.info(
            "agent_runner: skip cloud run=%s — no device online for user=%s",
            run_id,
            user_id,
        )
        await _finalize_run(
            run_log,
            status="error",
            errors=["No connected device — cloud agent results cannot be delivered"],
        )
        return

    # ── 2. Decrypt OAuth token ─────────────────────────────────────────
    from app.integrations import decrypt_token, encrypt_token, get_provider

    if not config.oauth_token_encrypted:
        await _finalize_run(
            run_log,
            status="error",
            errors=[f"No OAuth token stored for cloud agent '{config.name}'"],
        )
        return

    try:
        credentials_info = decrypt_token(config.oauth_token_encrypted)
    except ValueError as exc:
        logger.error("agent_runner: failed to decrypt OAuth token for agent %s: %s", config.id, exc)
        await _finalize_run(
            run_log,
            status="error",
            errors=[f"Failed to decrypt OAuth token: {exc}"],
        )
        return

    # ── 3. Instantiate provider client ────────────────────────────────
    try:
        provider = get_provider(config.provider, credentials_info)
    except ValueError as exc:
        await _finalize_run(
            run_log,
            status="error",
            errors=[str(exc)],
        )
        return

    # ── 4. Fetch messages ─────────────────────────────────────────────
    since: datetime | None = config.last_run_at
    if since is None:
        since = datetime.now(timezone.utc) - timedelta(days=_CLOUD_DEFAULT_LOOKBACK_DAYS)
    if since.tzinfo is None:
        since = since.replace(tzinfo=timezone.utc)

    errors: list[str] = []
    items_processed = 0
    items_created = 0

    try:
        if config.provider == "gmail":
            raw_messages = await provider.fetch_messages(  # type: ignore[union-attr]
                filter_config=config.filter_config,
                since=since,
            )
        elif config.provider == "outlook":
            raw_messages = await provider.fetch_emails(  # type: ignore[union-attr]
                filter_config=config.filter_config,
                since=since,
            )
        elif config.provider == "teams":
            raw_messages = await provider.fetch_messages(  # type: ignore[union-attr]
                filter_config=config.filter_config,
                since=since,
            )
        else:
            raw_messages = []
    except RuntimeError as exc:
        logger.error(
            "agent_runner: provider fetch failed for cloud agent %s: %s",
            config.id,
            exc,
        )
        await _finalize_run(
            run_log,
            status="error",
            errors=[f"Provider fetch failed: {exc}"],
            update_config_last_run=True,
            config_id=config.id,
            config_type="cloud",
        )
        return

    logger.info(
        "agent_runner: cloud agent %s fetched %d item(s) from %s for user=%s",
        config.id,
        len(raw_messages),
        config.provider,
        user_id,
    )

    # ── 5–6. Extract + insert ─────────────────────────────────────────
    for msg in raw_messages:
        content_text = msg.as_text
        if not content_text:
            continue
        items_processed += 1
        try:
            extracted = await _extract_items_from_content(
                config.prompt_template, content_text, config.data_types
            )
        except Exception as exc:
            errors.append(f"LLM extraction error for message {msg.id!r}: {exc}")
            continue

        for item in extracted:
            try:
                result = await _send_insert_to_client(
                    user_id, item["table"], item["data"], device_mgr
                )
                if result.get("error"):
                    errors.append(
                        f"Insert failed ({item['table']}, msg={msg.id!r}): {result['error']}"
                    )
                else:
                    items_created += 1
            except asyncio.TimeoutError:
                errors.append(
                    f"Timed out awaiting insert ack ({item['table']}, msg={msg.id!r})"
                )
            except RuntimeError as exc:
                errors.append(f"Insert error ({item['table']}, msg={msg.id!r}): {exc}")

    # ── 7. Persist refreshed token (if any) ───────────────────────────
    refreshed = getattr(provider, "refreshed_credentials", None)
    if refreshed:
        try:
            new_encrypted = encrypt_token(refreshed)
            async with async_session() as db:
                cfg_result = await db.execute(
                    select(CloudAgentConfig).where(CloudAgentConfig.id == config.id)
                )
                cfg_row = cfg_result.scalar_one_or_none()
                if cfg_row:
                    cfg_row.oauth_token_encrypted = new_encrypted
                    await db.commit()
            logger.debug("agent_runner: refreshed OAuth token persisted for agent %s", config.id)
        except Exception as exc:
            logger.warning("agent_runner: failed to persist refreshed token for agent %s: %s", config.id, exc)

    # ── 8. Finalise ────────────────────────────────────────────────────
    if errors and items_created == 0:
        final_status = "error"
    elif errors:
        final_status = "partial"
    else:
        final_status = "success"

    await _finalize_run(
        run_log,
        status=final_status,
        items_processed=items_processed,
        items_created=items_created,
        errors=errors,
        update_config_last_run=True,
        config_id=config.id,
        config_type="cloud",
    )
    logger.info(
        "agent_runner: cloud run=%s done status=%s processed=%d created=%d errors=%d",
        run_id,
        final_status,
        items_processed,
        items_created,
        len(errors),
    )


# ── Pending-run trigger ─────────────────────────────────────────────────────


async def trigger_pending_runs(
    user_id: str,
    device_id: str,
    device_mgr: DeviceConnectionManager,
) -> None:
    """Dispatch any overdue agent runs after an Electron device connects.

    Called as a background task from the device WS endpoint on ``device_hello``.

    Scheduling rules:

    * **Local agents**: only triggered when ``config.device_id == device_id``.
    * **Cloud agents**: triggered on any connected device (no device binding).
    * Runs execute **sequentially** to avoid flooding the WS connection.
    """
    logger.info(
        "agent_runner: scanning overdue runs for user=%s device=%s", user_id, device_id
    )
    async with async_session() as db:
        local_result = await db.execute(
            select(LocalAgentConfig).where(
                LocalAgentConfig.user_id == user_id,
                LocalAgentConfig.enabled == True,  # noqa: E712
                LocalAgentConfig.device_id == device_id,
            )
        )
        local_configs: list[LocalAgentConfig] = list(local_result.scalars().all())

        cloud_result = await db.execute(
            select(CloudAgentConfig).where(
                CloudAgentConfig.user_id == user_id,
                CloudAgentConfig.enabled == True,  # noqa: E712
            )
        )
        cloud_configs: list[CloudAgentConfig] = list(cloud_result.scalars().all())

    # Build ordered list of overdue (type, config) pairs.
    pending: list[tuple[str, Any]] = []
    for cfg in local_configs:
        if _is_overdue(cfg.schedule_cron, cfg.last_run_at):
            pending.append(("local", cfg))
    for cfg in cloud_configs:
        if _is_overdue(cfg.schedule_cron, cfg.last_run_at):
            pending.append(("cloud", cfg))

    if not pending:
        logger.debug("agent_runner: no overdue runs for user=%s", user_id)
        return

    logger.info(
        "agent_runner: %d overdue run(s) to dispatch for user=%s", len(pending), user_id
    )

    for agent_type, cfg in pending:
        # Create a fresh run log for this scheduled dispatch.
        run_log = AgentRunLog(
            agent_id=cfg.id,
            agent_type=agent_type,
            user_id=user_id,
            status="running",
        )
        async with async_session() as db:
            db.add(run_log)
            await db.commit()
            await db.refresh(run_log)

        if agent_type == "local":
            await run_local_agent(user_id, cfg, run_log, device_mgr)
        else:
            await run_cloud_agent(user_id, cfg, run_log, device_mgr)


# ── Internal helper ─────────────────────────────────────────────────────────


async def _finalize_run(
    run_log: AgentRunLog,
    *,
    status: str,
    items_processed: int = 0,
    items_created: int = 0,
    errors: list[str] | None = None,
    update_config_last_run: bool = False,
    config_id: str | None = None,
    config_type: str | None = None,
) -> None:
    """Persist the run outcome and optionally update ``LocalAgentConfig.last_run_at``.

    Uses a fresh DB session so this is safe to call from background tasks
    after the original request session has closed.
    """
    now = datetime.now(timezone.utc)
    try:
        async with async_session() as db:
            managed = await db.merge(run_log)
            managed.status = status
            managed.items_processed = items_processed
            managed.items_created = items_created
            managed.errors = errors or []
            managed.completed_at = now

            if update_config_last_run and config_id:
                if config_type == "local":
                    cfg_result = await db.execute(
                        select(LocalAgentConfig).where(LocalAgentConfig.id == config_id)
                    )
                    cfg = cfg_result.scalar_one_or_none()
                    if cfg:
                        cfg.last_run_at = now
                elif config_type == "cloud":
                    cfg_result = await db.execute(
                        select(CloudAgentConfig).where(CloudAgentConfig.id == config_id)
                    )
                    cfg = cfg_result.scalar_one_or_none()
                    if cfg:
                        cfg.last_run_at = now

            await db.commit()
    except Exception as exc:
        logger.error(
            "agent_runner: failed to finalize run_log=%s: %s", run_log.id, exc
        )