from __future__ import annotations

from typing import Any

from django.db.models import Avg, Count, Max, Q, QuerySet

from apps.profiles.models import SearchProfile
from apps.sources.models import Source

from ..models import Application, Employer, JobPosting, ScoreRun
from .cockpit import annotate_latest_profile_score
from .relevance import it_relevance_query


def employer_index_queryset(*, user, profile: SearchProfile | None) -> QuerySet[Employer]:
    score_filter = Q(jobs__scores__profile=profile) if profile else Q(pk__isnull=True)
    return Employer.objects.annotate(
        active_vacancies=Count(
            "jobs", filter=Q(jobs__status=JobPosting.Status.ACTIVE), distinct=True
        ),
        relevant_vacancies=Count(
            "jobs",
            filter=Q(jobs__status=JobPosting.Status.ACTIVE) & it_relevance_query("jobs__"),
            distinct=True,
        ),
        previous_applications=Count(
            "jobs__applications",
            filter=Q(jobs__applications__user=user),
            distinct=True,
        ),
        source_count=Count("jobs__source_aliases__source", distinct=True),
        latest_job_at=Max("jobs__first_seen"),
        average_match=Avg("jobs__scores__score", filter=score_filter),
    )


def filter_employers(
    queryset: QuerySet[Employer], *, query: str = "", channel: str = "", active_only: bool = False
) -> QuerySet[Employer]:
    if query.strip():
        queryset = queryset.filter(
            Q(name__icontains=query.strip())
            | Q(domain__icontains=query.strip())
            | Q(jobs__raw_location__icontains=query.strip())
        )
    if channel == "direct":
        queryset = queryset.filter(is_direct_employer=True, is_recruiter=False)
    elif channel == "recruiter":
        queryset = queryset.filter(is_recruiter=True)
    if active_only:
        queryset = queryset.filter(active_vacancies__gt=0)
    return queryset.order_by("-relevant_vacancies", "-active_vacancies", "name").distinct()


def build_employer_detail(
    *, employer: Employer, user, profile: SearchProfile | None
) -> dict[str, Any]:
    jobs = annotate_latest_profile_score(
        employer.jobs.select_related("employer").all(), profile
    ).order_by("-first_seen")
    sources = Source.objects.filter(job_aliases__job__employer=employer).distinct().order_by("name")
    locations = list(
        employer.jobs.exclude(raw_location="")
        .order_by("raw_location")
        .values_list("raw_location", flat=True)
        .distinct()[:8]
    )
    return {
        "employer": employer,
        "recent_jobs": list(jobs[:12]),
        "active_jobs": list(jobs.filter(status=JobPosting.Status.ACTIVE)[:8]),
        "applications": list(
            Application.objects.filter(user=user, job__employer=employer)
            .select_related("job")
            .order_by("-updated_at")[:8]
        ),
        "sources": list(sources[:10]),
        "locations": locations,
        "match_history": list(
            ScoreRun.objects.filter(profile=profile, job__employer=employer)
            .select_related("job")
            .order_by("-created_at")[:20]
        )
        if profile
        else [],
    }