// Copyright (c) Mysten Labs, Inc.
// SPDX-License-Identifier: Apache-2.0

import { CONFIG } from '../config';

export type ApiPagination = {
	take?: number;
	orderBy: {
		id: 'asc' | 'desc';
	};
	cursor?: {
		id: number;
	};
	skip?: number;
};

export enum WhereParamTypes {
	STRING,
	NUMBER,
	BOOLEAN,
}

export type WhereParam = {
	key: string;
	type: WhereParamTypes;
};

/**
 * A helper to prepare pagination based on `req.query`.
 * We are doing only primary key cursor + ordering for this example.
 */
export const parsePaginationForQuery = (body: Record<string, any>) => {
	const pagination: ApiPagination = {
		orderBy: {
			id: Object.hasOwn(body, 'sort') && ['asc', 'desc'].includes(body.sort) ? body.sort : 'desc',
		},
	};

	// Prepare pagination limit (how many items to return)
	if (Object.hasOwn(body, 'limit')) {
		const requestLimit = Number(body.limit);

		if (isNaN(requestLimit)) throw new Error('Invalid limit value');

		pagination.take = requestLimit > CONFIG.DEFAULT_LIMIT ? CONFIG.DEFAULT_LIMIT : requestLimit;
	} else {
		pagination.take = CONFIG.DEFAULT_LIMIT;
	}

	// Prepare cursor pagination (which page to return)
	if (Object.hasOwn(body, 'cursor')) {
		const cursor = Number(body.cursor);
		if (isNaN(cursor)) throw new Error('Invalid cursor');
		pagination.skip = 1;
		pagination.cursor = {
			id: cursor,
		};
	}

	return pagination;
};

/** Parses a where statement based on the query params. */
export const parseWhereStatement = (query: Record<string, any>, acceptedParams: WhereParam[]) => {
	const params: Record<string, any> = {};
	for (const key of Object.keys(query)) {
		const whereParam = acceptedParams.find((x) => x.key === key);
		if (!whereParam) continue;

		const value = query[key];
		if (whereParam.type === WhereParamTypes.STRING) {
			params[key] = value;
		}
		if (whereParam.type === WhereParamTypes.NUMBER) {
			const number = Number(value);
			if (isNaN(number)) throw new Error(`Invalid number for ${key}`);

			params[key] = number;
		}

		// Handle boolean expected values.
		if (whereParam.type === WhereParamTypes.BOOLEAN) {
			let boolValue;
			if (value === 'true') boolValue = true;
			else if (value === 'false') boolValue = false;
			else throw new Error(`Invalid boolean for ${key}`);

			params[key] = boolValue;
		}
	}
	return params;
};

export const getResponseCursor = (results: any[]): number | undefined => {
	return results[results.length - 1]?.id || undefined;
};

/**
 * Helper to format a paginated response.
 *  Assumes `id` as the primary key that we're using the cursor against.
 */
export const formatPaginatedResponse = (data: any[]) => {
	return {
		data,
		cursor: getResponseCursor(data),
	};
};