import { apiClient } from '../shared/api-client.js';

// Срез «Просмотр расписаний» (этап 5, волна 5): чистая логика и контракты API,
// перенесённые из legacy admin/js/views/schedule-view.js без изменения поведения.

export const ROLE_DEPARTMENT = 'DEPARTMENT';
export const TARGET_GROUPS = 'groups';
export const TARGET_TEACHERS = 'teachers';
export const TARGET_CLASSROOMS = 'classrooms';
export const TARGET_DEPARTMENTS = 'departments';

export const PARITY_LABELS = Object.freeze({
    BOTH: 'каждая',
    ODD: 'нечётная',
    EVEN: 'чётная'
});

export const DAY_SHORT_LABELS = Object.freeze({
    1: 'Пн',
    2: 'Вт',
    3: 'Ср',
    4: 'Чт',
    5: 'Пт',
    6: 'Сб',
    7: 'Вс'
});

export const DAY_FULL_LABELS = Object.freeze({
    1: 'Понедельник',
    2: 'Вторник',
    3: 'Среда',
    4: 'Четверг',
    5: 'Пятница',
    6: 'Суббота',
    7: 'Воскресенье'
});

export const DAY_ORDER = Object.freeze([1, 2, 3, 4, 5, 6, 7]);

export const CELL_PARITY_LAYOUT = Object.freeze([
    Object.freeze({ parity: 'ODD', label: 'Нечётная' }),
    Object.freeze({ parity: 'EVEN', label: 'Чётная' })
]);

export const MOBILE_QUERY = '(max-width: 760px)';
export const DEFAULT_SEMESTER_WEEKS = 22;
export const SCHEDULE_REFRESH_PROMPT = 'Нажмите «Показать», чтобы обновить расписание';

// --- Дата и время ---

export function parseIsoDate(value) {
    const [year, month, day] = String(value).split('-').map(Number);
    return new Date(year, month - 1, day);
}

export function toIsoDate(date) {
    return [
        date.getFullYear(),
        String(date.getMonth() + 1).padStart(2, '0'),
        String(date.getDate()).padStart(2, '0')
    ].join('-');
}

export function addDays(date, days) {
    const next = new Date(date);
    next.setDate(next.getDate() + days);
    return next;
}

export function isoDay(value) {
    const day = parseIsoDate(value).getDay();
    return day === 0 ? 7 : day;
}

export function datesBetween(startDate, endDate) {
    const dates = [];
    for (let date = parseIsoDate(startDate); date <= parseIsoDate(endDate); date.setDate(date.getDate() + 1)) {
        dates.push(toIsoDate(date));
    }
    return dates;
}

export function weekStart(value) {
    const date = parseIsoDate(value);
    const day = date.getDay() || 7;
    date.setDate(date.getDate() + 1 - day);
    return toIsoDate(date);
}

export function twoWeekRange(value) {
    const selected = parseIsoDate(value);
    const start = addDays(selected, 1 - isoDay(value));
    const end = addDays(start, 13);
    return {
        startDate: toIsoDate(start),
        endDate: toIsoDate(end)
    };
}

export function formatDate(value) {
    if (!value) return '-';
    const [year, month, day] = String(value).split('-');
    return `${day}.${month}.${year}`;
}

export function formatDateShort(value) {
    const [, month, day] = String(value).split('-');
    return `${day}.${month}`;
}

export function trimTime(value) {
    return String(value || '').slice(0, 5);
}

export function dayShort(dayOfWeek) {
    return DAY_SHORT_LABELS[Number(dayOfWeek)] || '-';
}

// --- Семестры и периоды ---

export function semesterOptionLabel(semester) {
    const type = String(semester?.semesterType || '').toLowerCase();
    const typeLabel = type === 'autumn'
        ? 'Осенний семестр'
        : (type === 'spring' ? 'Весенний семестр' : 'Семестр');
    const academicYear = semester?.academicYearTitle || 'Учебный год';
    const dates = semester?.startDate && semester?.endDate
        ? ` · ${formatDate(semester.startDate)} — ${formatDate(semester.endDate)}`
        : '';
    return `${academicYear} · ${typeLabel}${dates}`;
}

export function findSemesterForDate(semesters, date) {
    return (semesters || []).find(semester => dateWithinSemester(date, semester)) || null;
}

export function scheduleRangeForSemester(selectedDate, semester) {
    if (semester?.startDate && semester?.endDate) {
        return {
            startDate: semester.startDate,
            endDate: semester.endDate
        };
    }
    return twoWeekRange(selectedDate);
}

export function dateWithinSemester(date, semester) {
    return Boolean(
        date
        && semester?.startDate
        && semester?.endDate
        && date >= semester.startDate
        && date <= semester.endDate
    );
}

export function semesterWeekCount(semester) {
    if (!semester?.startDate || !semester?.endDate) return DEFAULT_SEMESTER_WEEKS;
    const start = parseIsoDate(semester.startDate);
    const end = parseIsoDate(semester.endDate);
    const days = Math.max(1, Math.round((end - start) / 86400000) + 1);
    return Math.max(1, Math.ceil(days / 7));
}

export function semesterScheduleCaption(semester) {
    const weeks = semesterWeekCount(semester);
    const weekLabel = weeks === 1 ? '1 неделя' : `недели 1–${weeks}`;
    return `Весь семестр · ${weekLabel}`;
}

export function periodCaption(range, semester = null) {
    if (!range) return 'Учебное расписание';
    const rangeLabel = `${formatDate(range.startDate)} — ${formatDate(range.endDate)}`;
    return semester ? `${semesterOptionLabel(semester)} · ${rangeLabel}` : rangeLabel;
}

export function formatLessonWeeksText(startWeek, endWeek) {
    const start = Number(startWeek);
    const end = Number(endWeek);
    if (!Number.isFinite(start) || !Number.isFinite(end)) return '';
    return start === end
        ? `(${start} нед.)`
        : `(с ${start} по ${end} нед.)`;
}

// Диапазон недель занятия: явные границы из матрицы либо расчёт по часам.
export function getLessonWeeksText(lesson) {
    if (lesson?.displayStartWeek != null && lesson?.displayEndWeek != null) {
        return formatLessonWeeksText(lesson.displayStartWeek, lesson.displayEndWeek);
    }
    if (!lesson || lesson.weekNumber == null || lesson.lessonTypeAcademicHours == null) {
        return '';
    }
    const totalHours = lesson.lessonTypeAcademicHours;
    const consumedBefore = lesson.consumedLessonTypeAcademicHoursBeforeLesson || 0;

    // Каждое занятие - это 2 часа
    const totalLessons = Math.ceil(totalHours / 2);
    if (totalLessons <= 0) return '';

    const parity = lesson.ruleParity || lesson.parity;
    let startWeek;
    let endWeek;

    if (parity === 'EVEN' || parity === 'ODD') {
        // Раз в две недели
        startWeek = lesson.weekNumber - consumedBefore;
        endWeek = startWeek + (totalLessons - 1) * 2;
    } else {
        // Каждую неделю
        const steps = Math.floor(consumedBefore / 2);
        startWeek = lesson.weekNumber - steps;
        endWeek = startWeek + totalLessons - 1;
    }

    if (startWeek <= 0) startWeek = 1;
    if (endWeek < startWeek) endWeek = startWeek;

    return formatLessonWeeksText(startWeek, endWeek);
}

// --- Разделы расписания ---

export function allowedGroupIdsForScheduleTarget(target, selectedGroupId) {
    return target === TARGET_GROUPS && selectedGroupId
        ? new Set([String(selectedGroupId)])
        : new Set();
}

export function splitTypeForTarget(target) {
    if (target === TARGET_TEACHERS) return TARGET_TEACHERS;
    if (target === TARGET_CLASSROOMS) return TARGET_CLASSROOMS;
    return TARGET_GROUPS;
}

export function buildSectionContext({ target, selectedGroupId, groups }) {
    const allowedGroupIds = allowedGroupIdsForScheduleTarget(target, selectedGroupId);
    const groupNamesById = new Map((groups || []).map(group => [String(group.id), group.name]));
    return {
        selectedGroupId,
        selectedGroupName: selectedGroupId
            ? (groupNamesById.get(String(selectedGroupId)) || `Группа ${selectedGroupId}`)
            : '',
        allowedGroupIds,
        groupNamesById
    };
}

export function buildScheduleSections(lessons, splitType, context) {
    const sections = new Map();

    lessons.forEach(lesson => {
        splitEntitiesForLesson(lesson, splitType, context).forEach(entity => {
            if (!sections.has(entity.key)) {
                sections.set(entity.key, {
                    key: entity.key,
                    title: entity.title,
                    lessons: []
                });
            }
            sections.get(entity.key).lessons.push(lesson);
        });
    });

    return Array.from(sections.values())
        .map(section => ({
            ...section,
            lessons: sortLessons(section.lessons)
        }))
        .sort((a, b) => naturalCompare(a.title, b.title));
}

function splitEntitiesForLesson(lesson, splitType, context) {
    if (splitType === TARGET_TEACHERS) {
        return [singleEntity('teacher', lesson.teacherId, lesson.teacherName, 'Преподаватель не указан')];
    }
    if (splitType === TARGET_CLASSROOMS) {
        return [singleEntity('classroom', lesson.classroomId, lesson.classroomName, 'Аудитория не указана')];
    }
    if (context.selectedGroupId) {
        return [singleEntity('group', context.selectedGroupId, context.selectedGroupName, 'Группа не указана')];
    }
    return listEntities('group', lesson.groupIds, lesson.groupNames, 'Группа не указана', context.allowedGroupIds, context.groupNamesById);
}

function singleEntity(prefix, id, name, fallback) {
    const title = name || fallback;
    return {
        id,
        key: `${prefix}:${id ?? title}`,
        title
    };
}

function listEntities(prefix, ids = [], names = [], fallback, allowedIds = new Set(), namesById = new Map()) {
    const safeIds = Array.isArray(ids) ? ids : [];
    const safeNames = Array.isArray(names) ? names : [];
    if (!safeIds.length && !safeNames.length) {
        return allowedIds.size ? [] : [singleEntity(prefix, null, fallback, fallback)];
    }
    const maxLength = Math.max(safeIds.length, safeNames.length);
    const entities = [];
    for (let index = 0; index < maxLength; index += 1) {
        const id = safeIds[index] ?? null;
        if (allowedIds.size && (id == null || !allowedIds.has(String(id)))) {
            continue;
        }
        const name = namesById.get(String(id)) || safeNames[index] || (id == null ? fallback : `Группа ${id}`);
        entities.push(singleEntity(prefix, id, name, fallback));
    }
    return entities;
}

export function sortLessons(lessons) {
    return [...lessons].sort((a, b) =>
        naturalCompare(a.date, b.date)
        || compareSlots(lessonSlotDescriptor(a), lessonSlotDescriptor(b))
        || naturalCompare(a.subjectName, b.subjectName)
        || naturalCompare(a.teacherName, b.teacherName)
        || naturalCompare(a.classroomName, b.classroomName)
    );
}

function lessonSlotDescriptor(lesson) {
    return {
        key: lessonSlotKey(lesson),
        orderNumber: lesson.timeSlotOrder,
        startTime: lesson.startTime
    };
}

// --- Слоты и сетки ---

export function lessonSlotKey(lesson) {
    const value = lesson.timeSlotOrder ?? lesson.timeSlotId ?? `${lesson.startTime || ''}-${lesson.endTime || ''}`;
    return value ? String(value) : 'unknown';
}

export function dateSlotKey(date, slotKey) {
    return `${date}:${slotKey}`;
}

export function collectSlots(lessons) {
    const slots = new Map();
    lessons.forEach(lesson => {
        const key = lessonSlotKey(lesson);
        const existing = slots.get(key);
        const next = {
            key,
            id: lesson.timeSlotId,
            orderNumber: lesson.timeSlotOrder,
            startTime: lesson.startTime,
            endTime: lesson.endTime,
            orderLabel: lesson.timeSlotOrder ? `${lesson.timeSlotOrder} пара` : 'Пара',
            timeLabel: lesson.startTime || lesson.endTime
                ? `${trimTime(lesson.startTime)}-${trimTime(lesson.endTime)}`
                : 'Время не указано'
        };
        if (!existing || existing.timeLabel === 'Время не указано') {
            slots.set(key, next);
        }
    });
    return Array.from(slots.values()).sort(compareSlots);
}

export function groupLessonsByDateSlot(lessons) {
    const grouped = new Map();
    lessons.forEach(lesson => {
        if (!lesson.date) return;
        const key = dateSlotKey(lesson.date, lessonSlotKey(lesson));
        if (!grouped.has(key)) grouped.set(key, []);
        grouped.get(key).push(lesson);
    });
    grouped.forEach(items => {
        items.sort((a, b) => naturalCompare(a.subjectName, b.subjectName)
            || naturalCompare(a.teacherName, b.teacherName)
            || naturalCompare((a.groupNames || []).join(','), (b.groupNames || []).join(',')));
    });
    return grouped;
}

export function buildCombinedWeekBlocks(startDate, endDate, lessons) {
    const dates = datesBetween(startDate, endDate);
    const weekGroups = new Map();
    dates.forEach(date => {
        const key = weekStart(date);
        if (!weekGroups.has(key)) weekGroups.set(key, []);
        weekGroups.get(key).push(date);
    });

    const weekStarts = Array.from(weekGroups.keys()).sort((a, b) => naturalCompare(a, b));
    const blocks = [];
    for (let index = 0; index < weekStarts.length; index += 2) {
        const firstWeek = weekGroups.get(weekStarts[index]) || [];
        const secondWeek = weekGroups.get(weekStarts[index + 1]) || [];
        const blockDates = [...firstWeek, ...secondWeek];
        const firstParity = weekParity(firstWeek, lessons) || 'ODD';
        const secondParity = weekParity(secondWeek, lessons) || (firstParity === 'ODD' ? 'EVEN' : 'ODD');
        const datesWithFallback = [
            ...firstWeek.map(date => ({ date, fallbackParity: firstParity })),
            ...secondWeek.map(date => ({ date, fallbackParity: secondParity }))
        ];
        blocks.push({
            startDate: blockDates[0],
            endDate: blockDates[blockDates.length - 1],
            datesByDay: buildDatesByDay(datesWithFallback, lessons),
            label: `Период ${formatDate(blockDates[0])} - ${formatDate(blockDates[blockDates.length - 1])}`
        });
    }
    return blocks;
}

function weekParity(dates, lessons) {
    for (const date of dates) {
        const parity = parityForDate(date, lessons);
        if (parity) return parity;
    }
    return null;
}

export function buildDatesByDay(datesWithFallback, lessons) {
    const datesByDay = {};
    datesWithFallback.forEach(({ date, fallbackParity }) => {
        const day = isoDay(date);
        const parity = parityForDate(date, lessons) || fallbackParity;
        if (!datesByDay[day]) datesByDay[day] = {};
        datesByDay[day][parity] = date;
    });
    return datesByDay;
}

export function parityForDate(date, lessons) {
    const lesson = lessons.find(item => item.date === date && ['ODD', 'EVEN'].includes(item.parity));
    if (lesson?.parity) return lesson.parity;
    const withWeek = lessons.find(item => item.date === date && item.weekNumber != null);
    if (withWeek?.weekNumber != null) return Number(withWeek.weekNumber) % 2 === 0 ? 'EVEN' : 'ODD';
    return null;
}

export function combinedWeekCaption() {
    return 'Нечётная и чётная недели';
}

export function mobileDayCaption() {
    return 'Нечётная / Чётная';
}

// --- Матрица семестра ---

export function buildSemesterLessonMatrix(lessons) {
    const weekRanges = new Map();
    lessons.forEach(lesson => {
        const signature = lessonContentSignature(lesson);
        const weekNumber = Number(lesson.weekNumber);
        if (!Number.isFinite(weekNumber)) return;
        const range = weekRanges.get(signature) || { startWeek: weekNumber, endWeek: weekNumber };
        range.startWeek = Math.min(range.startWeek, weekNumber);
        range.endWeek = Math.max(range.endWeek, weekNumber);
        weekRanges.set(signature, range);
    });

    const matrix = new Map();
    lessons.forEach(lesson => {
        const day = Number(lesson.dayOfWeek) || isoDay(lesson.date);
        const parity = ['ODD', 'EVEN'].includes(lesson.parity)
            ? lesson.parity
            : (Number(lesson.weekNumber) % 2 === 0 ? 'EVEN' : 'ODD');
        const signature = lessonContentSignature(lesson);
        const key = `${day}:${lessonSlotKey(lesson)}:${parity}`;
        if (!matrix.has(key)) matrix.set(key, new Map());
        if (!matrix.get(key).has(signature)) {
            const range = weekRanges.get(signature);
            matrix.get(key).set(signature, {
                ...lesson,
                displayStartWeek: range?.startWeek,
                displayEndWeek: range?.endWeek
            });
        }
    });

    return new Map(Array.from(matrix.entries()).map(([key, values]) => [
        key,
        Array.from(values.values()).sort((a, b) => naturalCompare(a.subjectName, b.subjectName))
    ]));
}

export function slotStatesForDates(datesByParity, slot, lessonsByDateSlot) {
    return CELL_PARITY_LAYOUT.map(({ parity, label }) => ({
        parity,
        label,
        state: scheduleSlotState(datesByParity[parity], slot, lessonsByDateSlot)
    }));
}

export function slotStatesForSemester(day, slot, lessonMatrix) {
    return CELL_PARITY_LAYOUT.map(({ parity, label }) => {
        const lessons = lessonMatrix.get(`${day}:${slot.key}:${parity}`) || [];
        return {
            parity,
            label,
            state: lessons.length ? { kind: 'busy', lessons } : { kind: 'free', lessons: [] }
        };
    });
}

export function scheduleSlotState(date, slot, lessonsByDateSlot) {
    if (!date) {
        return { kind: 'empty', lessons: [] };
    }
    const lessons = lessonsByDateSlot.get(dateSlotKey(date, slot.key)) || [];
    if (lessons.length) {
        return { kind: 'busy', lessons };
    }
    return { kind: 'free', lessons: [] };
}

export function slotStatesEqual(first, second) {
    if (first.kind !== second.kind) return false;
    if (first.kind !== 'busy') return true;
    return lessonSetSignature(first.lessons) === lessonSetSignature(second.lessons);
}

function lessonSetSignature(lessons) {
    return lessons
        .map(lessonContentSignature)
        .sort((a, b) => naturalCompare(a, b))
        .join('|');
}

export function lessonContentSignature(lesson) {
    return [
        lesson.scheduleRuleSlotId || lesson.scheduleRuleId || '',
        lesson.subjectId || lesson.subjectName || '',
        lesson.teacherId || lesson.teacherName || '',
        lesson.classroomId || lesson.classroomName || '',
        lesson.lessonTypeId || lesson.lessonTypeName || '',
        lesson.lessonFormat || '',
        lesson.scheduleOverrideId || '',
        lesson.overrideAction || '',
        lesson.originalLessonDate || '',
        valueListSignature(lesson.groupIds, lesson.groupNames),
        valueListSignature(lesson.subgroupIds, lesson.subgroupNames)
    ].join(':');
}

function valueListSignature(primary = [], fallback = []) {
    const primaryList = Array.isArray(primary) ? primary : [];
    const fallbackList = Array.isArray(fallback) ? fallback : [];
    const source = primaryList.length ? primaryList : fallbackList;
    return [...source]
        .map(value => String(value))
        .sort((a, b) => naturalCompare(a, b))
        .join(',');
}

// --- Подписи ---

export function lessonCountLabel(count) {
    const tail = count % 100;
    if (tail >= 11 && tail <= 14) return `${count} занятий`;
    if (count % 10 === 1) return `${count} занятие`;
    if ([2, 3, 4].includes(count % 10)) return `${count} занятия`;
    return `${count} занятий`;
}

export function sectionCountLabel(count) {
    const tail = count % 100;
    if (tail >= 11 && tail <= 14) return `${count} расписаний`;
    if (count % 10 === 1) return `${count} расписание`;
    if ([2, 3, 4].includes(count % 10)) return `${count} расписания`;
    return `${count} расписаний`;
}

// --- Справочники ---

export function roomLabel(room) {
    return [room?.name, room?.building, room?.floor ? `${room.floor} этаж` : null].filter(Boolean).join(' · ');
}

export function groupOptionLabel(group) {
    return group?.name || '';
}

export function teacherOptionLabel(teacher) {
    return teacher?.fullName || teacher?.username || '';
}

export function mergeDictionaryItems(dictionaries, key, items) {
    const merged = new Map((dictionaries[key] || []).map(item => [String(item.id), item]));
    (items || []).forEach(item => merged.set(String(item.id), item));
    dictionaries[key] = [...merged.values()];
}

// --- Контракты API ---

export async function fetchScheduleViewDictionaries(client = apiClient) {
    const [departments, subjects, lessonTypes, semesters] = await Promise.all([
        client.get('/api/departments', { errorMessage: 'Ошибка загрузки кафедр' }),
        client.get('/api/subjects', { errorMessage: 'Ошибка загрузки дисциплин' }),
        client.get('/api/lesson-types', { errorMessage: 'Ошибка загрузки типов занятий' }),
        client.get('/api/schedule/semesters', { errorMessage: 'Ошибка загрузки семестров' })
    ]);
    return {
        groups: [],
        teachers: [],
        classrooms: [],
        departments: departments || [],
        subjects: subjects || [],
        lessonTypes: lessonTypes || [],
        semesters: semesters || []
    };
}

export function scheduleSearchEndpoint(filters) {
    const params = new URLSearchParams({
        startDate: filters.startDate,
        endDate: filters.endDate
    });
    applyTargetFilter(params, filters);
    addOptional(params, 'subjectId', filters.subjectId);
    addOptional(params, 'lessonTypeId', filters.lessonTypeId);
    addOptional(params, 'parity', filters.parity);
    return `/api/schedule/search?${params}`;
}

// Backend отвергает поиск сразу по всем активным группам («Уточните группу
// или кафедру»), поэтому запрос без выбранной цели заведомо вернёт 400.
// Используется, чтобы не показывать ошибку там, где достаточно подсказки.
export function hasScheduleSearchTarget(filters) {
    if (filters.role === ROLE_DEPARTMENT) {
        return Boolean(filters.userDepartmentId);
    }
    if (filters.target === TARGET_GROUPS) {
        return Boolean(filters.groupId);
    }
    if (filters.target === TARGET_TEACHERS) {
        return Boolean(filters.teacherId);
    }
    if (filters.target === TARGET_CLASSROOMS) {
        return Boolean(filters.classroomId);
    }
    if (filters.target === TARGET_DEPARTMENTS) {
        return Boolean(filters.departmentId);
    }
    return false;
}

function applyTargetFilter(params, filters) {
    if (filters.role === ROLE_DEPARTMENT) {
        params.set('departmentId', filters.userDepartmentId);
        return;
    }
    if (filters.target === TARGET_GROUPS) {
        addOptional(params, 'groupId', filters.groupId);
        return;
    }
    if (filters.target === TARGET_TEACHERS) {
        addOptional(params, 'teacherId', filters.teacherId);
        return;
    }
    if (filters.target === TARGET_CLASSROOMS) {
        addOptional(params, 'classroomId', filters.classroomId);
        return;
    }
    if (filters.target === TARGET_DEPARTMENTS) {
        addOptional(params, 'departmentId', filters.departmentId);
    }
}

function addOptional(params, key, value) {
    if (value) params.set(key, value);
}

export async function fetchScheduleLessons(filters, client = apiClient) {
    return client.get(scheduleSearchEndpoint(filters), { errorMessage: 'Ошибка загрузки расписания' });
}

export function scheduleOverridesEndpoint(range) {
    return `/api/edu-office/schedule/overrides?startDate=${range.startDate}&endDate=${range.endDate}`;
}

export async function fetchScheduleOverrides(range, client = apiClient) {
    return client.get(scheduleOverridesEndpoint(range), { errorMessage: 'Ошибка загрузки разовых изменений' });
}

export function groupsOptionsEndpoint(query, selectedId, departmentId = '') {
    const params = new URLSearchParams({ query, limit: '30' });
    if (selectedId) params.set('selectedId', selectedId);
    if (departmentId) params.set('departmentId', departmentId);
    return `/api/groups/options?${params}`;
}

export function teachersOptionsEndpoint(query, selectedId) {
    const params = new URLSearchParams({ query, limit: '30' });
    if (selectedId) params.set('selectedId', selectedId);
    return `/api/users/teachers/options?${params}`;
}

export function classroomsOptionsEndpoint(query, selectedId) {
    const params = new URLSearchParams({ query, limit: '30' });
    if (selectedId) params.set('selectedId', selectedId);
    return `/api/classrooms/options?${params}`;
}

export async function fetchGroupOptions(query, selectedId, departmentId, client = apiClient) {
    return client.get(groupsOptionsEndpoint(query, selectedId, departmentId), { errorMessage: 'Ошибка поиска групп' });
}

export async function fetchTeacherOptions(query, selectedId, client = apiClient) {
    return client.get(teachersOptionsEndpoint(query, selectedId), { errorMessage: 'Ошибка поиска преподавателей' });
}

export async function fetchClassroomOptions(query, selectedId, client = apiClient) {
    return client.get(classroomsOptionsEndpoint(query, selectedId), { errorMessage: 'Ошибка поиска аудиторий' });
}

// --- Состояние фильтров в URL ---

export function initialScheduleViewState(values = {}) {
    return {
        target: values.scheduleTarget || TARGET_GROUPS,
        entity: values.scheduleEntity || '',
        date: values.scheduleDate || '',
        yearId: values.scheduleYear || '',
        semesterId: values.scheduleSemester || '',
        subjectId: values.scheduleSubject || '',
        lessonTypeId: values.scheduleLessonType || '',
        parity: values.scheduleParity || ''
    };
}

export function entityValueForTarget(target, entityIds = {}) {
    if (target === TARGET_GROUPS) return entityIds.groupId || '';
    if (target === TARGET_TEACHERS) return entityIds.teacherId || '';
    if (target === TARGET_CLASSROOMS) return entityIds.classroomId || '';
    if (target === TARGET_DEPARTMENTS) return entityIds.departmentId || '';
    return '';
}

export function scheduleViewUrlState(filters) {
    return {
        scheduleTarget: filters.role === ROLE_DEPARTMENT ? '' : filters.target,
        scheduleEntity: filters.entityValue || '',
        scheduleDate: filters.date || '',
        scheduleYear: filters.yearId || '',
        scheduleSemester: filters.semesterId || '',
        scheduleSubject: filters.subjectId || '',
        scheduleLessonType: filters.lessonTypeId || '',
        scheduleParity: filters.parity || ''
    };
}

// --- Служебные сравнения ---

function compareSlots(a, b) {
    const first = Number(a.orderNumber || a.key);
    const second = Number(b.orderNumber || b.key);
    if (!Number.isNaN(first) && !Number.isNaN(second) && first !== second) {
        return first - second;
    }
    return naturalCompare(a.startTime, b.startTime)
        || naturalCompare(a.key, b.key);
}

function naturalCompare(a, b) {
    return String(a || '').localeCompare(String(b || ''), 'ru', { numeric: true, sensitivity: 'base' });
}