type FontSizeValue = [string, Record<'lineHeight', string>]

export function isRelativeValue(value: string) {
	let isPercentValue = value.endsWith('%')
	let isUnitlessValue = /\d$/.test(value)

	return isPercentValue || isUnitlessValue
}

export function getRelativeValue(value: string) {
	let isPercentValue = value.endsWith('%')

	return isPercentValue
		? Number.parseInt(value.replace('%', ''), 10) / 100
		: Number.parseFloat(value)
}

export function normalizeValue(value: string | FontSizeValue, root: number, fs?: number): number {
	value = Array.isArray(value) ? value[0] : value

	if (value.endsWith('px')) return Number.parseFloat(value.replace('px', ''))
	if (value.endsWith('rem')) return root * Number.parseFloat(value.replace('rem', ''))

	if (isRelativeValue(value) && fs !== undefined) {
		return fs * getRelativeValue(value)
	}

	return Number.parseInt(value, 10)
}

const cssRegex = /^([+-]?(?:\d+|\d*\.\d+))([a-z]*|%)$/

export function getValueAndUnit(value: string): [number, string | undefined] {
	if (typeof value !== 'string') return [value, '']
	let matchedValue = cssRegex.exec(value)
	if (matchedValue !== null) return [Number.parseFloat(value), matchedValue[2]]
	return [Number.parseInt(value, 10), undefined]
}

export function isPlainObject(value: unknown) {
	if (Object.prototype.toString.call(value) !== '[object Object]') {
		return false
	}

	let prototype = Object.getPrototypeOf(value) as unknown
	return prototype === null || prototype === Object.prototype
}

type ThemeValue = string | string[] | ((p?: any) => string)

/**
 * Returns a value based on the core theme section.  Adapted from Tailwind
 * internals.
 * @see https://github.com/tailwindlabs/tailwindcss/blob/30ea5b14a631b6f68e56740c3d09bb54fcbad08a/src/util/transformThemeValue.js
 */
export function normalizeThemeValue(key: string, value: ThemeValue) {
	switch (key) {
		case 'fontSize':
		case 'lineHeight':
			if (typeof value === 'function') value = value({})
			if (Array.isArray(value)) value = value[0]

			return value

		case 'fontFamily':
			if (typeof value === 'function') value = value({})
			if (Array.isArray(value)) value = value.join(', ')

			return value

		default:
			if (typeof value === 'function') value = value({})

			return value
	}
}

export function round(value: number) {
	return Number.parseFloat(value.toFixed(4)).toString()
}

/**
 * Takes a theme value for lineHeight and returns the `--line-height-offset`
 * custom property.
 */
export function lineHeightProperties(lineHeight?: string, rootSize = 16) {
	if (lineHeight === undefined) return {}

	let lineHeightActual = isRelativeValue(lineHeight)
		? `calc(${getRelativeValue(lineHeight)} * var(--font-size-px))`
		: normalizeValue(lineHeight, rootSize)

	return {
		'--line-height-offset': `calc((((var(--line-height-scale) * var(--font-size-px)) - ${lineHeightActual}) / 2) / var(--font-size-px))`,
	}
}