from __future__ import annotations

from celery import shared_task
from django.conf import settings
from django.core.files.base import ContentFile
from django.urls import reverse
from django.utils import timezone

from apps.notifications.services import RedisNotificationStore
from apps.reports.models import ReportExportJob
from apps.reports.services import build_table_report, build_user_scoped_table_reports
from apps.reports.services.export_i18n import build_export_locale
from apps.reports.services.exporters import build_excel_report, build_pdf_report


def _build_export_action_url(job: ReportExportJob) -> str:
    path = reverse("report-export-job-download", kwargs={"pk": job.id})
    if settings.BASE_URL:
        return f"{settings.BASE_URL.rstrip('/')}{path}"
    return path


@shared_task(name="reports.generate_export")
def generate_report_export_task(job_id: str):
    job = ReportExportJob.objects.filter(id=job_id).first()
    if not job:
        return None

    job.mark_processing()
    try:
        locale = build_export_locale(job.filters.get("language"))
        report_data = build_table_report(job.requesting_user, job.filters)
        if job.export_type == ReportExportJob.ExportType.EXCEL:
            per_user_reports = build_user_scoped_table_reports(job.requesting_user, job.filters)
            content = build_excel_report(report_data=report_data, locale=locale, per_user_reports=per_user_reports)
            suffix = "xlsx"
            mime_type = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
        else:
            content = build_pdf_report(report_data=report_data, locale=locale)
            suffix = "pdf"
            mime_type = "application/pdf"

        file_name = f"workspace-report-{timezone.now().strftime('%Y%m%d-%H%M%S')}.{suffix}"
        storage_name = f"reports/exports/{job.id}-{file_name}"
        job.file.save(storage_name, ContentFile(content), save=False)
        job.status = ReportExportJob.Status.COMPLETED
        job.file_name = file_name
        job.completed_at = timezone.now()
        job.expires_at = job.completed_at + timezone.timedelta(days=settings.REPORT_EXPORT_RETENTION_DAYS)
        job.error_message = ""
        job.save(
            update_fields=[
                "file",
                "status",
                "file_name",
                "completed_at",
                "expires_at",
                "error_message",
                "updated_at",
            ]
        )

        action_url = _build_export_action_url(job)

        RedisNotificationStore.add(
            str(job.requesting_user_id),
            {
                "type": "report_export_ready",
                "title": "Report export is ready",
                "message": f"Your {job.export_type.upper()} report for {job.workspace.name} is ready to download.",
                "level": "success",
                "action_url": action_url,
                "entity_type": "report_export",
                "entity_id": str(job.id),
                "meta": {
                    "workspace_id": str(job.workspace_id),
                    "workspace_name": job.workspace.name,
                    "export_type": job.export_type,
                    "file_name": file_name,
                    "download_url": action_url,
                    "mime_type": mime_type,
                },
            },
        )
        return str(job.id)
    except Exception as exc:  # noqa: BLE001
        job.mark_failed(str(exc))
        RedisNotificationStore.add(
            str(job.requesting_user_id),
            {
                "type": "report_export_failed",
                "title": "Report export failed",
                "message": f"Your {job.export_type.upper()} report for {job.workspace.name} could not be generated.",
                "level": "error",
                "action_url": "/reports",
                "entity_type": "report_export",
                "entity_id": str(job.id),
                "meta": {
                    "workspace_id": str(job.workspace_id),
                    "workspace_name": job.workspace.name,
                    "export_type": job.export_type,
                },
            },
        )
        raise


@shared_task(name="reports.cleanup_expired_exports")
def cleanup_expired_report_exports_task():
    expired_jobs = ReportExportJob.objects.filter(
        status=ReportExportJob.Status.COMPLETED,
        expires_at__lte=timezone.now(),
    )
    removed = 0
    for job in expired_jobs:
        if job.file:
            job.file.delete(save=False)
        job.mark_expired()
        removed += 1
    return removed