import type { QQModelInfo } from "./qq-session";
import type { QQCommandButton } from "./qq-keyboard";

export const QQ_KEYBOARD_MAX_ROWS = 5;
export const QQ_KEYBOARD_BUTTONS_PER_ROW = 2;
const RESERVED_MODEL_KEYBOARD_ROWS = 2;
export const MAX_MODEL_PAGE_SIZE =
	(QQ_KEYBOARD_MAX_ROWS - RESERVED_MODEL_KEYBOARD_ROWS) * QQ_KEYBOARD_BUTTONS_PER_ROW;

export interface ModelPage {
	models: QQModelInfo[];
	page: number;
	total: number;
	totalPages: number;
	offset: number;
	pageSize: number;
	keyboardRows: QQCommandButton[][];
	fallbackCommands: string[];
}

export function normalizeModelPageSize(value: number): number {
	if (!Number.isFinite(value)) return MAX_MODEL_PAGE_SIZE;
	return Math.min(MAX_MODEL_PAGE_SIZE, Math.max(1, Math.trunc(value)));
}

export function buildModelPage(models: QQModelInfo[], page: number, pageSize: number): ModelPage {
	const effectivePageSize = normalizeModelPageSize(pageSize);
	const total = models.length;
	const totalPages = Math.max(1, Math.ceil(total / effectivePageSize));
	if (!Number.isInteger(page) || page < 1 || page > totalPages) {
		throw new RangeError(`模型页码无效；当前共 ${totalPages} 页`);
	}
	const offset = (page - 1) * effectivePageSize;
	const items = models.slice(offset, offset + effectivePageSize);
	const keyboardRows = itemsToKeyboardRows(items, page, totalPages);
	return {
		models: items,
		page,
		total,
		totalPages,
		offset,
		pageSize: effectivePageSize,
		keyboardRows,
		fallbackCommands: fallbackCommands(page, totalPages),
	};
}

export function formatModelPageFallback(page: ModelPage): string {
	if (!page.fallbackCommands.length) return "发送 `/model provider/model` 切换。";
	return `发送 \`${page.fallbackCommands.join("\` 或 \`")}\` 翻页，或发送 \`/model provider/model\` 切换。`;
}

function itemsToKeyboardRows(
	models: QQModelInfo[],
	page: number,
	totalPages: number,
): QQCommandButton[][] {
	const rows: QQCommandButton[][] = [];
	for (let index = 0; index < models.length; index += QQ_KEYBOARD_BUTTONS_PER_ROW) {
		rows.push(models.slice(index, index + QQ_KEYBOARD_BUTTONS_PER_ROW).map((model) => ({
			label: model.name.slice(0, 16),
			command: `/model ${model.provider}/${model.id}`,
			primary: index === 0,
		})));
	}
	if (totalPages > 1) {
		const navigation: QQCommandButton[] = [];
		if (page > 1) navigation.push({ label: `上一页 ${page - 1}/${totalPages}`, command: `/model page ${page - 1}` });
		if (page < totalPages) navigation.push({ label: `下一页 ${page + 1}/${totalPages}`, command: `/model page ${page + 1}` });
		if (navigation.length) rows.push(navigation);
	}
	rows.push([{ label: "返回帮助", command: "/help" }]);
	return rows;
}

function fallbackCommands(page: number, totalPages: number): string[] {
	const commands: string[] = [];
	if (page > 1) commands.push(`/model page ${page - 1}`);
	if (page < totalPages) commands.push(`/model page ${page + 1}`);
	return commands;
}