import {Guid} from 'guid-typescript';
import {NachklangTicketsDB} from '../Tickets.db.js';
import {generateUniqueCode} from '../tickets.codes.js';
import {VoucherCode, VoucherStatus} from '../tickets.interface.js';
import {isValidEmail} from '../tickets.validation.js';

export interface WildcardGenerateInput {
	eventIds: number[];
	maxGuests: number;
	quantity: number;
}

export interface PersonalizedRowInput {
	name: string;
	email: string;
	eventIds: number[];
	maxGuests: number;
}

const mapVoucherRow = (row: any): VoucherCode => ({
	code: row.code,
	status: row.status,
	maxGuests: row.max_guests,
	prefillName: row.prefill_name,
	prefillEmail: row.prefill_email,
	batchId: row.batch_id,
	createdByEmail: row.created_by_email,
	createdAt: row.created_at,
	eligibleEventIds: []
});

/**
 * Guards the event allow-list (event_ticket_settings) at the one place
 * codes actually get minted - the admin event picker already filters to
 * allow-listed events, but that's cosmetic unless generation enforces the
 * same rule server-side. Without this, any event_id could be passed
 * directly (bypassing the picker) and get a fully-uncapped, no-deadline
 * redeemable code minted for a non-concert Calendar event.
 */
const assertEventsAllowListed = async (conn: any, eventIds: number[]): Promise<void> => {
	const uniqueIds = [...new Set(eventIds)];
	const rows = await conn.query('SELECT event_id FROM event_ticket_settings WHERE event_id IN (?)', [uniqueIds]);
	const allowListed = new Set<number>(rows.map((r: any) => r.event_id));
	const missing = uniqueIds.filter(id => !allowListed.has(id));
	if (missing.length > 0) {
		throw new Error(`event(s) not added to the ticket shop yet: ${missing.join(', ')}`);
	}
};

/**
 * Attaches eligibleEventIds to a list of voucher rows in one extra query,
 * rather than N+1 per code.
 */
const attachEligibleEvents = async (conn: any, vouchers: VoucherCode[]): Promise<VoucherCode[]> => {
	if (vouchers.length === 0) return vouchers;
	const codes = vouchers.map(v => v.code);
	const rows = await conn.query('SELECT code, event_id FROM voucher_code_events WHERE code IN (?)', [codes]);
	const byCode = new Map<string, number[]>();
	for (const row of rows) {
		const list = byCode.get(row.code) || [];
		list.push(row.event_id);
		byCode.set(row.code, list);
	}
	for (const voucher of vouchers) {
		voucher.eligibleEventIds = byCode.get(voucher.code) || [];
	}
	return vouchers;
};

/**
 * Batch-generates N wildcard codes sharing the same eligible events and
 * max-guest count. All codes get the same batchId so the admin UI can group
 * "codes generated together" (e.g. for printing a sheet for the conductor).
 */
export const generateWildcardBatch = async (input: WildcardGenerateInput, createdByEmail: string): Promise<string[]> => {
	if (input.quantity < 1 || input.quantity > 500) {
		throw new Error('quantity must be between 1 and 500');
	}
	if (input.eventIds.length === 0) {
		throw new Error('at least one eligible event is required');
	}

	let conn = await NachklangTicketsDB.getConnection();
	try {
		await conn.beginTransaction();

		await assertEventsAllowListed(conn, input.eventIds);

		const existingRows = await conn.query('SELECT code FROM voucher_codes');
		const existingCodes = new Set<string>(existingRows.map((r: any) => r.code));

		const batchId = Guid.create().toString();
		const codes: string[] = [];
		for (let i = 0; i < input.quantity; i++) {
			const code = generateUniqueCode(existingCodes);
			codes.push(code);
			await conn.query(
				'INSERT INTO voucher_codes (code, status, max_guests, batch_id, created_by_email) VALUES (?,?,?,?,?)',
				[code, 'UNUSED', input.maxGuests, batchId, createdByEmail]
			);
			for (const eventId of input.eventIds) {
				await conn.query('INSERT INTO voucher_code_events (code, event_id) VALUES (?,?)', [code, eventId]);
			}
		}

		await conn.commit();
		return codes;
	} catch (err) {
		await conn.rollback();
		throw err;
	} finally {
		await conn.end();
	}
};

/**
 * Bulk-creates personalized codes from a list of rows (repeating-row admin
 * UI - see docs/plan-ticket-shop.md). One code per row, all sharing a
 * batchId for the submission.
 */
export const generatePersonalizedBatch = async (rows: PersonalizedRowInput[], createdByEmail: string): Promise<string[]> => {
	if (rows.length === 0) {
		throw new Error('at least one row is required');
	}
	for (const row of rows) {
		if (!row.name || !row.email || row.eventIds.length === 0) {
			throw new Error('each row requires a name, email, and at least one eligible event');
		}
		if (!isValidEmail(row.email)) {
			throw new Error(`"${row.email}" does not look like a valid email address`);
		}
	}

	let conn = await NachklangTicketsDB.getConnection();
	try {
		await conn.beginTransaction();

		await assertEventsAllowListed(conn, rows.flatMap(r => r.eventIds));

		const existingRows = await conn.query('SELECT code FROM voucher_codes');
		const existingCodes = new Set<string>(existingRows.map((r: any) => r.code));

		const batchId = Guid.create().toString();
		const codes: string[] = [];
		for (const row of rows) {
			const code = generateUniqueCode(existingCodes);
			codes.push(code);
			await conn.query(
				'INSERT INTO voucher_codes (code, status, max_guests, prefill_name, prefill_email, batch_id, created_by_email) VALUES (?,?,?,?,?,?,?)',
				[code, 'UNUSED', row.maxGuests, row.name, row.email, batchId, createdByEmail]
			);
			for (const eventId of row.eventIds) {
				await conn.query('INSERT INTO voucher_code_events (code, event_id) VALUES (?,?)', [code, eventId]);
			}
		}

		await conn.commit();
		return codes;
	} catch (err) {
		await conn.rollback();
		throw err;
	} finally {
		await conn.end();
	}
};

export interface ListVouchersFilter {
	eventId?: number;
	status?: VoucherStatus;
}

export const listVouchers = async (filter: ListVouchersFilter): Promise<VoucherCode[]> => {
	let conn = await NachklangTicketsDB.getConnection();
	try {
		let query = 'SELECT vc.* FROM voucher_codes vc';
		const params: any[] = [];
		const where: string[] = [];

		if (filter.eventId !== undefined) {
			query += ' INNER JOIN voucher_code_events vce ON vce.code = vc.code';
			where.push('vce.event_id = ?');
			params.push(filter.eventId);
		}
		if (filter.status) {
			where.push('vc.status = ?');
			params.push(filter.status);
		}
		if (where.length > 0) {
			query += ' WHERE ' + where.join(' AND ');
		}
		query += ' GROUP BY vc.code ORDER BY vc.created_at DESC';

		const rows = await conn.query(query, params);
		const vouchers = rows.map(mapVoucherRow);
		return await attachEligibleEvents(conn, vouchers);
	} finally {
		await conn.end();
	}
};

export const getVoucher = async (code: string): Promise<VoucherCode | null> => {
	let conn = await NachklangTicketsDB.getConnection();
	try {
		const rows = await conn.query('SELECT * FROM voucher_codes WHERE code = ?', [code]);
		if (rows.length === 0) return null;
		const [voucher] = await attachEligibleEvents(conn, [mapVoucherRow(rows[0])]);
		return voucher;
	} finally {
		await conn.end();
	}
};

export type VoidCodeResult = 'VOIDED' | 'NOT_FOUND' | 'NOT_UNUSED';

export const voidCode = async (code: string, adminEmail: string, reason: string | null): Promise<VoidCodeResult> => {
	let conn = await NachklangTicketsDB.getConnection();
	try {
		await conn.beginTransaction();

		const rows = await conn.query('SELECT status FROM voucher_codes WHERE code = ?', [code]);
		if (rows.length === 0) {
			await conn.rollback();
			return 'NOT_FOUND';
		}
		if (rows[0].status !== 'UNUSED') {
			await conn.rollback();
			return 'NOT_UNUSED';
		}

		await conn.query('UPDATE voucher_codes SET status = ? WHERE code = ?', ['VOID', code]);
		await conn.query(
			'INSERT INTO voucher_audit_log (code, redemption_id, admin_email, action, reason) VALUES (?,NULL,?,?,?)',
			[code, adminEmail, 'VOID', reason]
		);

		await conn.commit();
		return 'VOIDED';
	} catch (err) {
		await conn.rollback();
		throw err;
	} finally {
		await conn.end();
	}
};