"""
Tests für die job_preview-View.

Hängt nicht am echten LibreOffice – build_preview wird auf Service-Ebene
gepatcht, sodass die Tests in <1 s laufen.
"""
from __future__ import annotations

from pathlib import Path

import pytest
from django.core.files.uploadedfile import SimpleUploadedFile
from django.urls import reverse

from mailmerge.services.preview import PreviewError, PreviewResult


PREVIEW_URL_NAME = "job-preview"
FAKE_PDF = b"%PDF-1.4 fake preview\n"


# ---------------------------------------------------------------------------
# HTTP-Method / Auth
# ---------------------------------------------------------------------------

class TestPreviewAccess:
    def test_login_required(self, client, db):
        url = reverse(PREVIEW_URL_NAME)
        response = client.post(url, {})
        # Django leitet auf Login um (302)
        assert response.status_code == 302
        assert "/login" in response["Location"].lower() or "login" in response["Location"].lower()

    def test_get_not_allowed(self, auth_client):
        url = reverse(PREVIEW_URL_NAME)
        response = auth_client.get(url)
        assert response.status_code == 405


# ---------------------------------------------------------------------------
# Form-Validierung
# ---------------------------------------------------------------------------

class TestPreviewFormValidation:
    def test_missing_files_returns_form(self, auth_client):
        url = reverse(PREVIEW_URL_NAME)
        response = auth_client.post(url, {})
        # Kein PDF, sondern Form-Template zurück
        assert response.status_code == 200
        assert response["Content-Type"].startswith("text/html")

    def test_rejects_non_csv_extension(
        self, auth_client, letter_template, docx_bytes
    ):
        url = reverse(PREVIEW_URL_NAME)
        bogus = SimpleUploadedFile("file.txt", b"foo", content_type="text/plain")
        response = auth_client.post(url, {
            "template": str(letter_template.pk),
            "recipients_csv": bogus,
        })
        assert response.status_code == 200
        assert b"Nur .csv-Dateien" in response.content


# ---------------------------------------------------------------------------
# Happy Path
# ---------------------------------------------------------------------------

@pytest.fixture
def patched_build_preview(monkeypatch):
    """Ersetzt build_preview in der Views-Importebene durch einen Stub."""
    def fake_build_preview(template_path: Path, csv_file):
        return PreviewResult(
            pdf_bytes=FAKE_PDF,
            used_row={"nachname": "Huber"},
            placeholders=["anrede_brief", "nachname", "vorname", "ort"],
            csv_columns=["anrede_brief", "nachname", "vorname", "ort"],
            missing_columns=[],
            extra_columns=[],
        )
    monkeypatch.setattr(
        "mailmerge.views.build_preview", fake_build_preview
    )
    return fake_build_preview


class TestPreviewHappyPath:
    def test_returns_pdf_content_type(
        self, auth_client, letter_template, csv_uploaded_valid, patched_build_preview
    ):
        url = reverse(PREVIEW_URL_NAME)
        response = auth_client.post(url, {
            "template": str(letter_template.pk),
            "recipients_csv": csv_uploaded_valid,
        })
        assert response.status_code == 200
        assert response["Content-Type"] == "application/pdf"

    def test_returns_pdf_body(
        self, auth_client, letter_template, csv_uploaded_valid, patched_build_preview
    ):
        url = reverse(PREVIEW_URL_NAME)
        response = auth_client.post(url, {
            "template": str(letter_template.pk),
            "recipients_csv": csv_uploaded_valid,
        })
        assert response.content == FAKE_PDF

    def test_content_disposition_inline(
        self, auth_client, letter_template, csv_uploaded_valid, patched_build_preview
    ):
        url = reverse(PREVIEW_URL_NAME)
        response = auth_client.post(url, {
            "template": str(letter_template.pk),
            "recipients_csv": csv_uploaded_valid,
        })
        assert response["Content-Disposition"].startswith("inline")

    def test_placeholders_header_set(
        self, auth_client, letter_template, csv_uploaded_valid, patched_build_preview
    ):
        url = reverse(PREVIEW_URL_NAME)
        response = auth_client.post(url, {
            "template": str(letter_template.pk),
            "recipients_csv": csv_uploaded_valid,
        })
        assert "X-Preview-Placeholders" in response
        assert "nachname" in response["X-Preview-Placeholders"]


# ---------------------------------------------------------------------------
# Extra-Spalten als Hinweis-Header
# ---------------------------------------------------------------------------

class TestPreviewExtraColumnsHeader:
    @pytest.fixture
    def patched_with_extras(self, monkeypatch):
        def fake_build_preview(template_path, csv_file):
            return PreviewResult(
                pdf_bytes=FAKE_PDF,
                used_row={"nachname": "Huber"},
                placeholders=["nachname"],
                csv_columns=["nachname", "personalnr"],
                missing_columns=[],
                extra_columns=["personalnr"],
            )
        monkeypatch.setattr(
            "mailmerge.views.build_preview", fake_build_preview
        )

    def test_extra_columns_header_contains_value(
        self, auth_client, letter_template, csv_uploaded_valid, patched_with_extras
    ):
        url = reverse(PREVIEW_URL_NAME)
        response = auth_client.post(url, {
            "template": str(letter_template.pk),
            "recipients_csv": csv_uploaded_valid,
        })
        assert response["X-Preview-Extra-Columns"] == "personalnr"


# ---------------------------------------------------------------------------
# Fehlerpfade: PreviewError und unerwartete Exceptions
# ---------------------------------------------------------------------------

class TestPreviewErrorHandling:
    def test_preview_error_renders_form_with_message(
        self, auth_client, letter_template, csv_uploaded_valid, monkeypatch
    ):
        def fake_build_preview(template_path, csv_file):
            raise PreviewError("Spalte 'ort' fehlt")

        monkeypatch.setattr(
            "mailmerge.views.build_preview", fake_build_preview
        )

        url = reverse(PREVIEW_URL_NAME)
        response = auth_client.post(url, {
            "template": str(letter_template.pk),
            "recipients_csv": csv_uploaded_valid,
        })
        assert response.status_code == 200
        assert response["Content-Type"].startswith("text/html")
        # Django escaped Apostrophe in Templates ("'" -> "&#x27;")
        body = response.content.decode("utf-8")
        assert "Spalte" in body and "ort" in body and "fehlt" in body

    def test_unexpected_exception_renders_form(
        self, auth_client, letter_template, csv_uploaded_valid, monkeypatch
    ):
        def fake_build_preview(template_path, csv_file):
            raise RuntimeError("LibreOffice timeout")

        monkeypatch.setattr(
            "mailmerge.views.build_preview", fake_build_preview
        )

        url = reverse(PREVIEW_URL_NAME)
        response = auth_client.post(url, {
            "template": str(letter_template.pk),
            "recipients_csv": csv_uploaded_valid,
        })
        assert response.status_code == 200
        assert response["Content-Type"].startswith("text/html")
        assert b"Vorschau konnte nicht erstellt werden" in response.content
        assert b"LibreOffice timeout" in response.content