"""Incremental requests retain business rows and survive query changes/errors."""

import os

os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
import pytest
from PySide6.QtCore import Qt
from PySide6.QtTest import QTest
from PySide6.QtWidgets import QApplication, QTableWidget, QTableWidgetItem, QVBoxLayout, QWidget

from doctor_workstation.ui.infinite_list import InfiniteList
from doctor_workstation.ui.widgets import get_value, page_items


@pytest.fixture(scope="module")
def app():
    return QApplication.instance() or QApplication([])


class Requests:
    def __init__(self):
        self.pending = []

    def __call__(self, function, **callbacks):
        self.pending.append((function, callbacks))

    def finish(self, index=0, error=None):
        fn, cb = self.pending.pop(index)
        if error:
            cb["on_error"](error)
        else:
            cb["on_success"](fn())
        cb["on_finished"]()


def setup(app, size=2):
    host = QWidget()
    layout = QVBoxLayout(host)
    table = QTableWidget(0, 2)
    footer = InfiniteList(size)
    footer.bind(table)
    layout.addWidget(table)
    layout.addWidget(footer)
    host.resize(420, 220)
    seen = []
    errors = []
    jobs = Requests()

    def apply(result):
        rows = page_items(result)
        seen.append(result)
        table.setRowCount(len(rows))
        for i, row in enumerate(rows):
            for col in range(2):
                item = QTableWidgetItem(str(row["id"]))
                item.setData(Qt.ItemDataRole.UserRole, row)
                if col == 1:
                    item.setFlags(item.flags() | Qt.ItemFlag.ItemIsUserCheckable)
                    item.setCheckState(Qt.CheckState.Unchecked)
                table.setItem(i, col, item)

    return host, table, footer, seen, errors, jobs, apply


def test_append_deduplicates_and_preserves_selection_checks_metadata(app):
    host, table, f, seen, errors, jobs, apply = setup(app)
    pages = {
        1: {"items": [{"id": 1}, {"id": 2}], "total": 4, "extend": {"scope": "mine"}},
        2: {"items": [{"id": 2}, {"id": 3}], "total": 4},
        3: {"items": [{"id": 4}], "total": 4},
    }
    f.reload(lambda p: pages[p], apply, errors.append, runner=jobs, query_key="a")
    jobs.finish()
    table.selectRow(1)
    table.item(1, 1).setCheckState(Qt.CheckState.Checked)
    f.load_more()
    f.load_more()
    assert len(jobs.pending) == 1
    jobs.finish()
    assert [r["id"] for r in f.rows] == [1, 2, 3]
    assert table.currentRow() == 1 and table.item(1, 1).checkState() == Qt.CheckState.Checked
    assert get_value(seen[-1], "extend.scope") == "mine"
    f.load_more()
    jobs.finish()
    assert not f.has_more
    assert table.rowCount() == 4 and not errors
    host.close()


def test_changed_query_discards_old_success_and_error(app):
    host, t, f, seen, errors, jobs, apply = setup(app)
    f.reload(
        lambda p: {"items": [{"id": 1}], "total": 1},
        apply,
        errors.append,
        runner=jobs,
        query_key="a",
    )
    f.reload(
        lambda p: {"items": [{"id": 2}], "total": 1},
        apply,
        errors.append,
        runner=jobs,
        query_key="b",
    )
    jobs.finish(1)
    jobs.finish(0, error=RuntimeError("stale"))
    assert f.rows == [{"id": 2}] and not errors and not f.loading
    f.invalidate()
    assert not f.has_more
    host.close()


def test_append_failure_retry_and_empty_end_are_bounded(app):
    host, t, f, seen, errors, jobs, apply = setup(app)
    calls = []

    def fetch(p):
        calls.append(p)
        return {"items": [{"id": 1}, {"id": 2}] if p == 1 else [], "total": 8}

    f.reload(fetch, apply, errors.append, runner=jobs, query_key="a")
    jobs.finish()
    f.load_more()
    jobs.finish(error=RuntimeError("offline"))
    assert t.rowCount() == 2 and f.page == 1 and not f.retry_button.isHidden()
    f.load_more()
    assert not jobs.pending
    f.retry()
    jobs.finish()
    assert f.page == 2 and not f.has_more
    assert calls == [1, 2] and len(errors) == 1
    host.close()


def test_refresh_retains_loaded_prefix_until_complete(app):
    host, t, f, seen, errors, jobs, apply = setup(app)
    calls = []

    def fetch(p):
        calls.append(p)
        return {"items": [{"id": p * 2 - 1}, {"id": p * 2}], "total": 6}

    f.reload(fetch, apply, errors.append, runner=jobs, query_key="a")
    jobs.finish()
    f.load_more()
    jobs.finish()
    assert t.rowCount() == 4
    f.reload(fetch, apply, errors.append, runner=jobs, query_key="a")
    jobs.finish()
    assert t.rowCount() == 4 and f.loading
    jobs.finish()
    assert t.rowCount() == 4 and f.page == 2
    assert calls == [1, 2, 1, 2]
    host.close()


def test_scroll_autofill_then_load_at_bottom(app):
    host, t, f, seen, errors, jobs, apply = setup(app, size=12)

    def fetch(p):
        return {"items": [{"id": i} for i in range((p - 1) * 12, p * 12)], "total": 36}

    host.show()
    app.processEvents()
    f.reload(fetch, apply, errors.append, runner=jobs, query_key="a")
    jobs.finish()
    app.processEvents()
    QTest.qWait(60)
    assert not jobs.pending
    t.verticalScrollBar().setValue(t.verticalScrollBar().maximum())
    QTest.qWait(60)
    assert len(jobs.pending) == 1
    old = t.verticalScrollBar().value()
    jobs.finish()
    assert t.verticalScrollBar().value() == old and t.rowCount() == 24
    host.close()


def test_poll_during_slow_request_keeps_work_and_updates_consumer_callbacks(app):
    host, table, footer, seen, errors, jobs, apply = setup(app)
    completed = []

    def fetch(page):
        return {"items": [{"id": page * 2 - 1}, {"id": page * 2}], "total": 6}

    footer.reload(fetch, apply, errors.append, runner=jobs, query_key="a")
    footer.reload(
        fetch,
        apply,
        errors.append,
        runner=jobs,
        query_key="a",
        on_finished=lambda: completed.append("latest"),
    )
    assert len(jobs.pending) == 1
    jobs.finish()
    assert completed == ["latest"] and table.rowCount() == 2
    footer.load_more()
    footer.reload(fetch, apply, errors.append, runner=jobs, query_key="a")
    assert len(jobs.pending) == 1
    jobs.finish()
    assert table.rowCount() == 4 and footer.page == 2
    footer.reload(fetch, apply, errors.append, runner=jobs, query_key="a")
    jobs.finish()  # Prefix page 2 now pending.
    footer.reload(fetch, apply, errors.append, runner=jobs, query_key="a")
    assert len(jobs.pending) == 1
    jobs.finish()
    assert footer.page == 2 and not footer.loading and table.rowCount() == 4
    host.close()