from __future__ import annotations

from dataclasses import dataclass
from datetime import datetime

from django.core.paginator import Page, Paginator
from django.urls import reverse

from apps.notifications.models import DigestOutbox, ReminderOutbox
from apps.profiles.models import ProfileRevision
from apps.sources.models import Source, SourceRun

from ..models import ApplicationTimelineEvent, Feedback, JobVersion


@dataclass(frozen=True)
class ActivityEvent:
    occurred_at: datetime
    event_type: str
    title: str
    detail: str
    tone: str
    url: str
    object_label: str


ACTIVITY_FILTERS = (
    ("all", "Alle activiteit"),
    ("source", "Bronruns"),
    ("job", "Vacatures"),
    ("application", "Sollicitaties"),
    ("feedback", "Feedback"),
    ("notification", "Notificaties"),
    ("profile", "Profiel"),
)


def _source_events() -> list[ActivityEvent]:
    events = []
    runs = SourceRun.objects.exclude(source__source_type=Source.Type.EMAIL)
    for run in runs.select_related("source").order_by("-started_at")[:100]:
        detail = (
            f"{run.extracted_count} geëxtraheerd · {run.created_count} nieuw · "
            f"{run.duplicate_count} duplicaat"
        )
        if run.error_category:
            detail = f"{run.error_category}: {run.error_message or 'geen foutdetail'}"
        events.append(
            ActivityEvent(
                run.started_at,
                "source",
                f"Bronrun {run.get_status_display().lower()}",
                detail,
                "positive" if run.status == SourceRun.Status.SUCCESS else "attention",
                reverse("sources:list") + f"#source-details-{run.source_id}",
                run.source.name,
            )
        )
    return events


def _job_events() -> list[ActivityEvent]:
    return [
        ActivityEvent(
            version.created_at,
            "job",
            "Vacature-inhoud gewijzigd" if version.changed_fields else "Vacatureversie opgeslagen",
            ", ".join(version.changed_fields)
            if version.changed_fields
            else "Bronmoment vastgelegd",
            "neutral",
            reverse("jobs:detail", kwargs={"pk": version.job_id}),
            version.job.original_title,
        )
        for version in JobVersion.objects.select_related("job").order_by("-created_at")[:100]
    ]


def build_activity_page(
    *, user, event_type: str = "all", query: str = "", page: int | str = 1, per_page: int = 20
) -> Page:
    """Combine bounded trustworthy events into a user-safe read-only timeline."""

    events: list[ActivityEvent] = []
    if event_type in {"all", "source"}:
        events.extend(_source_events())
    if event_type in {"all", "job"}:
        events.extend(_job_events())
    if event_type in {"all", "feedback"}:
        for item in (
            Feedback.objects.filter(user=user).select_related("job").order_by("-created_at")[:100]
        ):
            events.append(
                ActivityEvent(
                    item.created_at,
                    "feedback",
                    item.get_action_display(),
                    item.reason or "Gebruikersactie opgeslagen",
                    "neutral",
                    reverse("jobs:detail", kwargs={"pk": item.job_id}),
                    item.job.original_title,
                )
            )
    if event_type in {"all", "application"}:
        for item in (
            ApplicationTimelineEvent.objects.filter(user=user)
            .select_related("application__job")
            .order_by("-created_at")[:100]
        ):
            events.append(
                ActivityEvent(
                    item.created_at,
                    "application",
                    item.get_event_type_display(),
                    "Sollicitatiedossier bijgewerkt",
                    "positive" if item.event_type == item.EventType.STATUS_CHANGED else "neutral",
                    reverse("jobs:application-edit", kwargs={"pk": item.application_id}),
                    item.application.job.original_title,
                )
            )
    if event_type in {"all", "notification"}:
        for model, label in ((DigestOutbox, "Samenvatting"), (ReminderOutbox, "Herinnering")):
            for item in model.objects.filter(profile__user=user).order_by("-created_at")[:60]:
                events.append(
                    ActivityEvent(
                        item.created_at,
                        "notification",
                        f"{label} {item.get_status_display().lower()}",
                        item.subject,
                        "positive" if item.status == item.Status.SENT else "attention",
                        reverse("dashboard:system"),
                        label,
                    )
                )
    if event_type in {"all", "profile"}:
        for item in (
            ProfileRevision.objects.filter(profile__user=user)
            .select_related("profile")
            .order_by("-created_at")[:60]
        ):
            events.append(
                ActivityEvent(
                    item.created_at,
                    "profile",
                    f"Zoekprofiel versie {item.version}",
                    item.reason or "Profielconfiguratie opgeslagen",
                    "neutral",
                    reverse("profiles:edit", kwargs={"pk": item.profile_id}),
                    item.profile.name,
                )
            )
    normalized_query = query.strip().casefold()
    if normalized_query:
        events = [
            item
            for item in events
            if normalized_query in f"{item.title} {item.detail} {item.object_label}".casefold()
        ]
    events.sort(key=lambda item: item.occurred_at, reverse=True)
    return Paginator(events, per_page).get_page(page)