from __future__ import annotations

import asyncio
import logging
from contextlib import asynccontextmanager
from datetime import datetime
from typing import Annotated

from apscheduler.schedulers.asyncio import AsyncIOScheduler
from fastapi import Depends, FastAPI, Header, HTTPException, Query, status
from pydantic import BaseModel, Field

from app.a2a import a2a_router
from app.config import get_settings
from app.core.service import CoreAgentService
from app.security import AuthBackend

settings = get_settings()
logging.basicConfig(level=getattr(logging, settings.log_level.upper(), logging.INFO))
logger = logging.getLogger("personal-agent")
core_service = CoreAgentService(settings=settings, logger=logger)
auth_backend = AuthBackend(settings=settings)

scheduler: AsyncIOScheduler | None = None
scan_lock: asyncio.Lock | None = None
unsubscribe_lock: asyncio.Lock | None = None


class ScanResponse(BaseModel):
    scanned: int
    linkedin: int
    advertising: int
    veille_techno: int
    skipped: int
    failed: int


class AvailabilityRequest(BaseModel):
    start: str
    end: str
    calendar_ids: list[str] | None = None


class BusySlot(BaseModel):
    calendar_id: str
    start: str
    end: str


class AvailabilityResponse(BaseModel):
    start: str
    end: str
    available: bool
    busy_slots: list[BusySlot]
    checked_calendars: list[str]


class UnsubscribeDigestResponse(BaseModel):
    scanned_messages: int
    extracted_unique_links: int
    new_links: int
    sent_to: str | None
    email_sent: bool


class UnsubscribeMethodResponse(BaseModel):
    method_id: str
    method_type: str
    value: str


class MailingListCandidateResponse(BaseModel):
    candidate_id: str
    list_name: str
    sender_domain: str
    message_count: int
    sample_senders: list[str]
    sample_subjects: list[str]
    methods: list[UnsubscribeMethodResponse]
    approved: bool


class UnsubscribeCandidatesResponse(BaseModel):
    scanned_messages: int
    candidates: list[MailingListCandidateResponse]


class ExecuteUnsubscribeRequest(BaseModel):
    selected_candidate_ids: list[str] = Field(default_factory=list)
    max_results: int | None = Field(default=None, ge=1, le=500)
    remember_selection: bool = True


class MethodExecutionResponse(BaseModel):
    candidate_id: str
    list_name: str
    method_id: str
    method_type: str
    value: str
    success: bool
    detail: str


class UnsubscribeExecutionResponse(BaseModel):
    scanned_messages: int
    candidates_considered: int
    selected_candidates: int
    executed_methods: int
    skipped_already_executed: int
    failed_methods: int
    updated_approved_count: int
    results: list[MethodExecutionResponse]


def _is_api_auth_enabled() -> bool:
    return auth_backend.is_enabled()


def require_scope(*required_scopes: str):
    scope_set = {scope.strip() for scope in required_scopes if scope.strip()}

    def _dependency(
        x_api_key: Annotated[str | None, Header(alias="X-API-Key")] = None,
        authorization: Annotated[str | None, Header()] = None,
    ) -> None:
        auth_backend.authenticate(
            x_api_key=x_api_key,
            authorization=authorization,
            required_scopes=scope_set,
        )

    return _dependency


def _run_scan_once(max_results: int) -> ScanResponse:
    result = core_service.scan_mailbox(max_results=max_results)
    return ScanResponse(
        scanned=result.scanned,
        linkedin=result.linkedin,
        advertising=result.advertising,
        veille_techno=result.veille_techno,
        skipped=result.skipped,
        failed=result.failed,
    )


def _run_unsubscribe_digest_once(max_results: int) -> UnsubscribeDigestResponse:
    result = core_service.scan_unsubscribe_digest(max_results=max_results)
    return UnsubscribeDigestResponse(
        scanned_messages=result.scanned_messages,
        extracted_unique_links=result.extracted_unique_links,
        new_links=result.new_links,
        sent_to=result.sent_to,
        email_sent=result.email_sent,
    )


def _run_unsubscribe_candidates_once(max_results: int) -> UnsubscribeCandidatesResponse:
    result = core_service.list_unsubscribe_candidates(max_results=max_results)
    return UnsubscribeCandidatesResponse(
        scanned_messages=result.scanned_messages,
        candidates=[
            MailingListCandidateResponse(
                candidate_id=candidate.candidate_id,
                list_name=candidate.list_name,
                sender_domain=candidate.sender_domain,
                message_count=candidate.message_count,
                sample_senders=candidate.sample_senders,
                sample_subjects=candidate.sample_subjects,
                methods=[
                    UnsubscribeMethodResponse(
                        method_id=method.method_id,
                        method_type=method.method_type,
                        value=method.value,
                    )
                    for method in candidate.methods
                ],
                approved=candidate.approved,
            )
            for candidate in result.candidates
        ],
    )


def _run_unsubscribe_execute_selected(
    selected_candidate_ids: list[str],
    max_results: int,
    remember_selection: bool,
) -> UnsubscribeExecutionResponse:
    result = core_service.execute_unsubscribe_selected(
        selected_candidate_ids=selected_candidate_ids,
        max_results=max_results,
        remember_selection=remember_selection,
    )
    return UnsubscribeExecutionResponse(
        scanned_messages=result.scanned_messages,
        candidates_considered=result.candidates_considered,
        selected_candidates=result.selected_candidates,
        executed_methods=result.executed_methods,
        skipped_already_executed=result.skipped_already_executed,
        failed_methods=result.failed_methods,
        updated_approved_count=result.updated_approved_count,
        results=[
            MethodExecutionResponse(
                candidate_id=item.candidate_id,
                list_name=item.list_name,
                method_id=item.method_id,
                method_type=item.method_type,
                value=item.value,
                success=item.success,
                detail=item.detail,
            )
            for item in result.results
        ],
    )


def _run_unsubscribe_auto_once(max_results: int) -> UnsubscribeExecutionResponse:
    result = core_service.run_unsubscribe_auto(max_results=max_results)
    return UnsubscribeExecutionResponse(
        scanned_messages=result.scanned_messages,
        candidates_considered=result.candidates_considered,
        selected_candidates=result.selected_candidates,
        executed_methods=result.executed_methods,
        skipped_already_executed=result.skipped_already_executed,
        failed_methods=result.failed_methods,
        updated_approved_count=result.updated_approved_count,
        results=[
            MethodExecutionResponse(
                candidate_id=item.candidate_id,
                list_name=item.list_name,
                method_id=item.method_id,
                method_type=item.method_type,
                value=item.value,
                success=item.success,
                detail=item.detail,
            )
            for item in result.results
        ],
    )


def _get_scan_lock() -> asyncio.Lock:
    global scan_lock
    if scan_lock is None:
        scan_lock = asyncio.Lock()
    return scan_lock


def _get_unsubscribe_lock() -> asyncio.Lock:
    global unsubscribe_lock
    if unsubscribe_lock is None:
        unsubscribe_lock = asyncio.Lock()
    return unsubscribe_lock


async def _scheduled_scan() -> None:
    lock = _get_scan_lock()
    if lock.locked():
        logger.info("Previous scan still running, skipping this tick.")
        return

    async with lock:
        try:
            result = await asyncio.to_thread(_run_scan_once, 100)
            logger.info("Scheduled scan complete: %s", result.model_dump())
        except Exception:
            logger.exception("Scheduled scan failed")


async def _scheduled_unsubscribe_digest() -> None:
    lock = _get_unsubscribe_lock()
    if lock.locked():
        logger.info("Previous unsubscribe digest still running, skipping this tick.")
        return

    async with lock:
        try:
            result = await asyncio.to_thread(
                _run_unsubscribe_digest_once, settings.unsubscribe_max_results
            )
            logger.info("Scheduled unsubscribe digest complete: %s", result.model_dump())
        except Exception:
            logger.exception("Scheduled unsubscribe digest failed")


async def _scheduled_unsubscribe_auto() -> None:
    lock = _get_unsubscribe_lock()
    if lock.locked():
        logger.info("Previous unsubscribe auto run still running, skipping this tick.")
        return

    async with lock:
        try:
            result = await asyncio.to_thread(
                _run_unsubscribe_auto_once, settings.unsubscribe_hil_max_results
            )
            logger.info("Scheduled unsubscribe auto run complete: %s", result.model_dump())
        except Exception:
            logger.exception("Scheduled unsubscribe auto run failed")


@asynccontextmanager
async def lifespan(app: FastAPI):
    # Startup
    global scheduler
    _get_scan_lock()
    _get_unsubscribe_lock()
    logger.info(
        "API authentication enabled=%s mode=%s (header: X-API-Key or Bearer token)",
        _is_api_auth_enabled(),
        settings.auth_mode,
    )
    scheduler = AsyncIOScheduler()
    scheduler.add_job( # type: ignore
        _scheduled_scan,
        "interval",
        minutes=settings.gmail_scan_interval_minutes,
        next_run_time=datetime.now(),
    )
    scheduler.add_job( # type: ignore
        _scheduled_unsubscribe_digest,
        "interval",
        minutes=settings.unsubscribe_digest_interval_minutes,
        next_run_time=datetime.now(),
    )
    if settings.unsubscribe_auto_enabled:
        scheduler.add_job( # type: ignore
            _scheduled_unsubscribe_auto,
            "interval",
            minutes=settings.unsubscribe_auto_interval_minutes,
            next_run_time=datetime.now(),
        )
    scheduler.start() # type: ignore
    logger.info(
        "Scheduler started (scan=%s min, digest=%s min, auto_unsub=%s/%s min)",
        settings.gmail_scan_interval_minutes,
        settings.unsubscribe_digest_interval_minutes,
        settings.unsubscribe_auto_enabled,
        settings.unsubscribe_auto_interval_minutes,
    )
    yield
    # Shutdown
    if scheduler:
        scheduler.shutdown(wait=False) # type: ignore


app = FastAPI(title="Personal Agent", version="0.3.0", lifespan=lifespan) # type: ignore
app.include_router(a2a_router)


@app.get("/health")
def health() -> dict[str, object]:
    return {
        "status": "ok",
        "scan_interval_minutes": settings.gmail_scan_interval_minutes,
        "unsubscribe_digest_interval_minutes": settings.unsubscribe_digest_interval_minutes,
        "unsubscribe_auto_enabled": settings.unsubscribe_auto_enabled,
        "unsubscribe_auto_interval_minutes": settings.unsubscribe_auto_interval_minutes,
    }


@app.post(
    "/scan",
    response_model=ScanResponse,
    dependencies=[Depends(require_scope("mail:scan"))],
)
async def scan_now(max_results: int = Query(100, ge=1, le=500)) -> ScanResponse:
    async with _get_scan_lock():
        try:
            return await asyncio.to_thread(_run_scan_once, max_results)
        except FileNotFoundError as exc:
            raise HTTPException(
                status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
                detail=str(exc),
            ) from exc
        except Exception as exc:
            raise HTTPException(
                status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
                detail=f"Gmail scan failed: {exc}",
            ) from exc


@app.post(
    "/availability",
    response_model=AvailabilityResponse,
    dependencies=[Depends(require_scope("availability:read"))],
)
async def availability(request: AvailabilityRequest) -> AvailabilityResponse:
    try:
        result = await asyncio.to_thread(
            core_service.check_availability,
            request.start,
            request.end,
            request.calendar_ids,
        )
        return AvailabilityResponse(
            start=result.start,
            end=result.end,
            available=result.available,
            busy_slots=[
                BusySlot.model_validate(slot, from_attributes=True)
                for slot in result.busy_slots
            ],
            checked_calendars=result.checked_calendars,
        )
    except ValueError as exc:
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail=str(exc)) from exc
    except FileNotFoundError as exc:
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail=str(exc),
        ) from exc
    except Exception as exc:
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail=f"Availability lookup failed: {exc}",
        ) from exc


@app.post(
    "/unsubscribe-digest",
    response_model=UnsubscribeDigestResponse,
    dependencies=[Depends(require_scope("unsubscribe:digest"))],
)
async def unsubscribe_digest_now(
    max_results: int = Query(default=settings.unsubscribe_max_results, ge=1, le=500),
) -> UnsubscribeDigestResponse:
    async with _get_unsubscribe_lock():
        try:
            return await asyncio.to_thread(_run_unsubscribe_digest_once, max_results)
        except FileNotFoundError as exc:
            raise HTTPException(
                status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
                detail=str(exc),
            ) from exc
        except Exception as exc:
            raise HTTPException(
                status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
                detail=f"Unsubscribe digest failed: {exc}",
            ) from exc


@app.post(
    "/unsubscribe/candidates",
    response_model=UnsubscribeCandidatesResponse,
    dependencies=[Depends(require_scope("unsubscribe:read"))],
)
async def unsubscribe_candidates(
    max_results: int = Query(default=settings.unsubscribe_hil_max_results, ge=1, le=500),
) -> UnsubscribeCandidatesResponse:
    async with _get_unsubscribe_lock():
        try:
            return await asyncio.to_thread(_run_unsubscribe_candidates_once, max_results)
        except Exception as exc:
            raise HTTPException(
                status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
                detail=f"Candidate discovery failed: {exc}",
            ) from exc


@app.post(
    "/unsubscribe/execute",
    response_model=UnsubscribeExecutionResponse,
    dependencies=[Depends(require_scope("unsubscribe:execute"))],
)
async def unsubscribe_execute(request: ExecuteUnsubscribeRequest) -> UnsubscribeExecutionResponse:
    max_results = request.max_results or settings.unsubscribe_hil_max_results
    async with _get_unsubscribe_lock():
        try:
            return await asyncio.to_thread(
                _run_unsubscribe_execute_selected,
                request.selected_candidate_ids,
                max_results,
                request.remember_selection,
            )
        except Exception as exc:
            raise HTTPException(
                status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
                detail=f"Unsubscribe execution failed: {exc}",
            ) from exc


@app.post(
    "/unsubscribe/auto-run",
    response_model=UnsubscribeExecutionResponse,
    dependencies=[Depends(require_scope("unsubscribe:execute"))],
)
async def unsubscribe_auto_run(
    max_results: int = Query(default=settings.unsubscribe_hil_max_results, ge=1, le=500),
) -> UnsubscribeExecutionResponse:
    async with _get_unsubscribe_lock():
        try:
            return await asyncio.to_thread(_run_unsubscribe_auto_once, max_results)
        except Exception as exc:
            raise HTTPException(
                status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
                detail=f"Auto unsubscribe run failed: {exc}",
            ) from exc