import { apiClient } from '../shared/api-client.js';
import { buildAcademicCalendarTitle } from '../../admin/js/views/academic-calendar-title.js';

export const GROUP_TABLE_COLUMNS = 10;
export const GROUP_PAGE_SIZES = [25, 50, 100];

export const GROUP_SORT_OPTIONS = Object.freeze([
    { value: 'name,asc', label: 'По названию А–Я' },
    { value: 'name,desc', label: 'По названию Я–А' },
    { value: 'yearStartStudy,desc', label: 'Сначала новые наборы' },
    { value: 'groupSize,desc', label: 'Сначала крупные' },
    { value: 'status,asc', label: 'По статусу' }
]);

export const SUBGROUP_COUNT_OPTIONS = Object.freeze([
    { value: '0', label: 'Без разделения на подгруппы' },
    { value: '2', label: 'Две подгруппы' },
    { value: '3', label: 'Три подгруппы' }
]);

export const FILTER_EF_EMPTY_TEXT = 'Выберите форму обучения';

export function normalizeGroupsState(restored = {}) {
    const size = Number(restored.groupSize);
    return {
        query: restored.groupQuery || '',
        page: Math.max(Number(restored.groupPage) || 0, 0),
        size: GROUP_PAGE_SIZES.includes(size) ? size : 25,
        sort: GROUP_SORT_OPTIONS.some(option => option.value === restored.groupSort)
            ? restored.groupSort
            : 'name,asc',
        educationFormIds: Array.isArray(restored.groupEducationForm)
            ? restored.groupEducationForm.map(String)
            : []
    };
}

export function initialGroupsState(restored = {}) {
    return normalizeGroupsState(restored);
}

export function groupsQueryParams(state) {
    const [sort, direction] = String(state.sort || 'name,asc').split(',');
    const params = new URLSearchParams({
        query: state.query || '',
        page: String(state.page || 0),
        size: String(state.size || 25),
        sort,
        direction,
        includeArchived: 'true'
    });
    (state.educationFormIds || []).forEach(id => params.append('educationFormId', id));
    return `/api/groups/page?${params}`;
}

export function groupsUrlState(state) {
    return {
        groupQuery: state.query || '',
        groupPage: state.page || '',
        groupSize: state.size === 25 ? '' : state.size,
        groupSort: state.sort === 'name,asc' ? '' : state.sort,
        groupEducationForm: state.educationFormIds || []
    };
}

// --- Справочники ---

export function fetchEducationForms(client = apiClient) {
    // legacy молча подставляет пустой список при сбое загрузки форм обучения
    return client.get('/api/education-forms').catch(() => []);
}

export function fetchDepartments(client = apiClient) {
    return client.get('/api/departments', { errorMessage: 'Не удалось загрузить список кафедр' });
}

export function fetchSpecialties(client = apiClient) {
    return client.get('/api/specialties', { errorMessage: 'Не удалось загрузить список специальностей' });
}

export function fetchAcademicYears(client = apiClient) {
    return client.get('/api/admin/calendar/years', { errorMessage: 'Не удалось загрузить учебные годы' });
}

export async function fetchProfilesForSpecialties(specialties, client = apiClient) {
    const pairs = await Promise.all((specialties || []).map(async (speciality) => {
        const profiles = await client.get(
            `/api/specialties/${speciality.id}/profiles`,
            { errorMessage: 'Не удалось загрузить профили обучения' }
        );
        return [String(speciality.id), profiles || []];
    }));
    return new Map(pairs);
}

// --- Реестр групп ---

export function fetchGroupsPage(state, client = apiClient) {
    return client.get(groupsQueryParams(state), { errorMessage: 'Не удалось загрузить группы' });
}

export function groupPayloadFromFields(fields) {
    const checks = [
        ['name', 'Введите название группы'],
        ['groupSize', 'Введите размер группы'],
        ['educationFormId', 'Выберите форму обучения'],
        ['departmentId', 'Выберите кафедру'],
        ['yearStartStudy', 'Введите год начала обучения'],
        ['specialtyId', 'Выберите специальность'],
        ['specialtyProfileId', 'Выберите профиль обучения']
    ];
    for (const [field, message] of checks) {
        if (!fields[field]) return { error: message };
    }
    return {
        payload: {
            name: fields.name,
            groupSize: Number(fields.groupSize),
            educationFormId: Number(fields.educationFormId),
            departmentId: Number(fields.departmentId),
            yearStartStudy: Number(fields.yearStartStudy),
            specialtyId: Number(fields.specialtyId),
            specialtyProfileId: Number(fields.specialtyProfileId)
        }
    };
}

export function createGroup(payload, client = apiClient) {
    return client.post('/api/groups', payload, { errorMessage: 'Ошибка создания' });
}

export function updateGroup(id, payload, client = apiClient) {
    return client.put(`/api/groups/${id}`, payload, { errorMessage: 'Ошибка обновления' });
}

export function archiveGroup(id, client = apiClient) {
    return client.delete(`/api/groups/${id}`, { errorMessage: 'Ошибка архивирования' });
}

export function restoreGroup(id, client = apiClient) {
    return client.post(`/api/groups/${id}/restore`, {}, { errorMessage: 'Ошибка восстановления' });
}

// --- Подгруппы ---

export function fetchSubgroups(groupId, client = apiClient) {
    return client.get(`/api/groups/${groupId}/subgroups`, { errorMessage: 'Не удалось загрузить подгруппы' });
}

export function createSubgroup(groupId, payload, client = apiClient) {
    return client.post(`/api/groups/${groupId}/subgroups`, payload, { errorMessage: 'Ошибка сохранения подгруппы' });
}

export function updateSubgroup(groupId, id, payload, client = apiClient) {
    return client.put(`/api/groups/${groupId}/subgroups/${id}`, payload, { errorMessage: 'Ошибка сохранения подгруппы' });
}

export function deleteSubgroup(groupId, id, client = apiClient) {
    return client.delete(`/api/groups/${groupId}/subgroups/${id}`, { errorMessage: 'Ошибка удаления подгруппы' });
}

export function naturalSubgroupOrder(name) {
    const number = String(name || '').match(/\d+/)?.[0];
    return number ? String(number).padStart(3, '0') : String(name || '');
}

export function sortSubgroups(subgroups) {
    return [...(subgroups || [])].sort((left, right) =>
        naturalSubgroupOrder(left.name).localeCompare(naturalSubgroupOrder(right.name), 'ru'));
}

export function suggestedSubgroupCapacities(groupSize, count) {
    if (!groupSize || !count) return [];
    const base = Math.floor(groupSize / count);
    const remainder = groupSize % count;
    return Array.from({ length: count }, (_, index) => base + (index < remainder ? 1 : 0));
}

export function validateSubgroupCapacities(capacities, groupSize, count) {
    if (capacities.length !== count || capacities.some(value => !Number.isInteger(value) || value <= 0)) {
        return 'Укажите положительную численность для каждой подгруппы';
    }

    const total = capacities.reduce((sum, value) => sum + value, 0);
    if (total !== groupSize) {
        return `Сумма численностей подгрупп должна быть равна численности группы (${groupSize} чел.)`;
    }

    return null;
}

// Синхронизация подгрупп воспроизводит legacy-порядок: сначала удаляем лишние,
// затем обновляем существующие (сначала уменьшающие вместимость), затем создаём новые.
export async function syncSubgroups(groupId, existingSubgroups, capacities, client = apiClient) {
    const targetCount = capacities.length;
    const extraSubgroups = existingSubgroups.slice(targetCount);
    for (const subgroup of extraSubgroups) {
        await deleteSubgroup(groupId, subgroup.id, client);
    }

    const updates = [];
    const creates = [];
    for (let index = 0; index < targetCount; index += 1) {
        const payload = {
            name: `Подгруппа ${index + 1}`,
            studentCapacity: capacities[index]
        };
        const existing = existingSubgroups[index];
        if (existing) {
            updates.push({ existing, payload });
        } else {
            creates.push(payload);
        }
    }

    updates.sort((left, right) => {
        const leftIncreases = left.payload.studentCapacity > Number(left.existing.studentCapacity || 0);
        const rightIncreases = right.payload.studentCapacity > Number(right.existing.studentCapacity || 0);
        return Number(leftIncreases) - Number(rightIncreases);
    });

    for (const update of updates) {
        await updateSubgroup(groupId, update.existing.id, update.payload, client);
    }

    for (const payload of creates) {
        await createSubgroup(groupId, payload, client);
    }
}

// --- Календарные графики ---

export function calendarsOptionsEndpoint({ query, academicYearId, specialtyId, profileId, studyFormId, selectedId }) {
    const params = new URLSearchParams({
        query,
        academicYearId,
        specialtyId,
        profileId,
        studyFormId,
        limit: '30'
    });
    if (selectedId) params.set('selectedId', selectedId);
    return `/api/admin/academic-calendars/options?${params}`;
}

export function fetchCalendarsOptions(params, client = apiClient) {
    return client.get(calendarsOptionsEndpoint(params), { errorMessage: 'Не удалось загрузить календарные графики' });
}

export function fetchCalendarAssignments(groupId, client = apiClient) {
    return client.get(`/api/groups/${groupId}/calendar-assignments`, { errorMessage: 'Не удалось загрузить назначения графиков' });
}

export function saveCalendarAssignment(groupId, { academicYearId, calendarId }, client = apiClient) {
    return client.put(
        `/api/groups/${groupId}/calendar-assignments`,
        { academicYearId: Number(academicYearId), calendarId: Number(calendarId) },
        { errorMessage: 'Ошибка назначения графика' }
    );
}

export function deleteCalendarAssignment(groupId, id, client = apiClient) {
    return client.delete(`/api/groups/${groupId}/calendar-assignments/${id}`, { errorMessage: 'Ошибка удаления назначения' });
}

// --- Фильтр форм обучения ---

export function efFilterLabel(educationForms, selectedIds) {
    const ids = selectedIds || [];
    if (!ids.length) return 'Все';
    if (ids.length === 1) {
        const form = (educationForms || []).find(item => String(item.id) === ids[0]);
        return form?.name || FILTER_EF_EMPTY_TEXT;
    }
    return `Выбрано: ${ids.length}`;
}

// --- Метки ---

export function departmentLabel(departments, departmentId) {
    const department = (departments || []).find(item => String(item.id) === String(departmentId));
    if (!department) return departmentId || '-';
    return department.departmentName || department.name || departmentId;
}

export function departmentOptionLabel(department) {
    const name = department.departmentName || department.name || 'Без названия';
    const code = department.departmentCode || department.code || department.id;
    return `${name} (${code})`;
}

export function specialityLabel(specialties, specialityId) {
    const speciality = (specialties || []).find(item => String(item.id) === String(specialityId));
    if (!speciality) return specialityId || '-';
    const code = speciality.specialityCode || speciality.specialtyCode || speciality.specialty_code || speciality.id;
    const name = speciality.specialityName || speciality.name || '';
    return name ? `${code} — ${name}` : code;
}

export function specialityOptionLabel(speciality) {
    const code = speciality.specialityCode || speciality.specialtyCode || speciality.specialty_code;
    const name = speciality.specialityName || speciality.name;
    return `${code} · ${name}`;
}

export function subjectLabel(subject) {
    const code = subject.subjectCode ? `${subject.subjectCode} · ` : '';
    return `${code}${subject.subjectName || subject.subjectId || 'Без названия'}`;
}

export function statusLabel(group) {
    if (group.status === 'ARCHIVED') return 'Архив';
    return group.studyStateName || (group.active ? 'Активна' : 'Неактивна');
}

export function statusBadgeClass(group) {
    if (group.status === 'ARCHIVED' || group.studyState === 'GRADUATED' || group.studyState === 'INACTIVE') {
        return 'badge-unavailable';
    }
    if (group.studyState === 'NOT_STARTED') {
        return 'badge-ef';
    }
    return 'badge-available';
}

export function calendarOptionLabel(calendar) {
    return buildAcademicCalendarTitle(calendar) || calendar.title || `График ${calendar.id}`;
}

export function calendarOptionDescription(calendar) {
    return `${calendar.academicYearTitle || ''} · ${calendar.studyFormName || ''}`;
}

export function assignmentCalendarTitle(assignment) {
    return assignment.calendarTitle || '-';
}

export function assignmentSubjectsGroups(subjects) {
    const grouped = new Map();
    (subjects || []).forEach(subject => {
        const key = String(subject.semesterNumber || '-');
        if (!grouped.has(key)) grouped.set(key, []);
        grouped.get(key).push(subject);
    });
    return Array.from(grouped.entries())
        .sort(([a], [b]) => Number(a) - Number(b))
        .map(([semesterNumber, items]) => ({ semesterNumber, items }));
}

export function groupsEmptyMessage(state) {
    return state.query || (state.educationFormIds || []).length
        ? 'По заданным условиям группы не найдены'
        : 'Групп пока нет';
}