import { collapseWhiteSpace } from 'collapse-white-space';
import { isSnowflake, type Snowflake } from 'discord-snowflake';

const VALID_URL_PATTERN = new URLPattern({
	protocol: '(http(?:s)?|mailto)'
});

export function typeOf(data: unknown): string {
	if (data === null) {
		return 'null'
	}
	if (Array.isArray(data)) {
		return 'array'
	}
	return typeof data
}

export function string(data: string|undefined, trim?: boolean): string {
	if (typeof data !== 'string') {
		throw Error(`expected string, but was ${typeOf(data)}`)
	}
	return collapseWhiteSpace(data, {
		style: 'js',
		trim: trim ?? true,
		preserveLineEndings: false
	})
}

export function discordSnowflake(data: string|Snowflake|undefined): Snowflake {
	const text = string(data)
	if (!isSnowflake(text)) {
		throw Error(`expected Discord snowflake, but was ${typeOf(data)}`)
	}
	return text
}

export function substring(data: string|undefined): string {
	const text = string(data, false)
	if (text.length === 0) {
		return '%';
	}
	return '%' + text.replaceAll('\\', '\\\\')
		.replaceAll('_', '\\_')
		.replaceAll('%', '\\%') + '%';
}

export function tableIdentifierOrId(data: string|undefined): string
export function tableIdentifierOrId(data: string|number|undefined): string|number
export function tableIdentifierOrId(data: string|number|undefined): string|number {
	if (typeof data === 'number') {
		return integer(data)
	} else {
		return string(data).toLowerCase()
	}
}

export function tableIdentifierSubstring(data: string|undefined): string {
	return substring(tableIdentifierOrId(data))
}

export function URL(data: string|undefined): string {
	const url = string(data)
	if (!VALID_URL_PATTERN.test(url)) {
		throw Error('url must be a valid HTTP, HTTPS, or MAILTO URL');
	}
	return url
}

export function boolean(data: boolean|undefined): number {
	if (typeof data !== 'boolean') {
		throw Error(`expected boolean but was ${typeof(data)}`)
	}
	return data ? 1 : 0
}

export function integer(data: number|undefined): number {
	const num = number(data)
	if (!Number.isInteger(num)) {
		throw Error(`expected integer but was ${data}`)
	}
	return num
}

export function number(data: number|undefined): number {
	if (typeof data !== 'number') {
		throw Error(`expected number but was ${typeof(data)}`)
	}
	return data
}

export function timestamp(data: number|undefined): number {
	return integer(data)
}

export function jsonObject(data: object|undefined): string {
	if (typeof data !== 'object' || typeOf(data) !== 'object') {
		throw Error(`expected object but was ${typeof(data)}`)
	}
	return JSON.stringify(data)
}

export function jsonArray(data: (readonly unknown[])|undefined): string {
	if (!Array.isArray(data)) {
		throw Error(`expected object but was ${typeof(data)}`)
	}
	return JSON.stringify(data)
}

export function nullable<T extends (value: undefined) => string|number>(transformer: T): (value: Parameters<T>[0]|null) => ReturnType<T>|null {
	return (value: Parameters<T>[0]|null): ReturnType<T>|null => value === null ? null : transformer(value) as ReturnType<T>
}