import { t } from '@/i18n'
import type {
	ImageVariant,
	NewVariantRequest,
	VariantDefinition,
	VariantFit,
	VariantFormat,
} from '@/composables/useImageVariants'

export const NAME_MAX_LENGTH = 32
const DIMENSION_MIN = 1
const DIMENSION_MAX = 8000
export const QUALITY_MIN = 1
export const QUALITY_MAX = 100
const DEFAULT_QUALITY = 80

const NAME_PATTERN = /^[a-z0-9-]{2,32}$/
const WHOLE_NUMBER = /^\d+$/

export type FieldName = 'name' | 'width' | 'height' | 'quality'

export interface VariantFormValues {
	name: string
	width: string
	height: string
	fit: VariantFit
	format: VariantFormat
	quality: string
	generateOnUpload: boolean
	enabled: boolean
}

export type FieldErrors = Partial<Record<FieldName, string>> & { dimension?: string }

export const FIELD_ORDER: FieldName[] = ['name', 'width', 'height', 'quality']

export const VARIANT_TEMPLATES = [
	{ name: 'thumb', width: 400, height: 300, quality: 80 },
	{ name: 'hero', width: 1200, height: 630, quality: 82 },
] as const

export function blankValues(): VariantFormValues {
	return {
		name: '',
		width: '',
		height: '',
		fit: 'cover',
		format: 'original',
		quality: String(DEFAULT_QUALITY),
		generateOnUpload: false,
		enabled: true,
	}
}

export function valuesFromTemplate(
	template: (typeof VARIANT_TEMPLATES)[number],
): VariantFormValues {
	return {
		...blankValues(),
		name: template.name,
		width: String(template.width),
		height: String(template.height),
		format: 'webp',
		quality: String(template.quality),
	}
}

export function valuesFromVariant(variant: ImageVariant): VariantFormValues {
	return {
		name: variant.name,
		width: variant.width === null ? '' : String(variant.width),
		height: variant.height === null ? '' : String(variant.height),
		fit: variant.fit,
		format: variant.format,
		quality: String(variant.quality ?? DEFAULT_QUALITY),
		generateOnUpload: variant.generate_on_upload,
		enabled: variant.enabled,
	}
}

export function hasChanged(current: VariantFormValues, initial: VariantFormValues) {
	return (Object.keys(initial) as (keyof VariantFormValues)[]).some(
		(key) => current[key] !== initial[key],
	)
}

export function usesQuality(format: VariantFormat) {
	return format !== 'png'
}

function wholeNumberInRange(text: string, min: number, max: number) {
	const trimmed = text.trim()
	if (!WHOLE_NUMBER.test(trimmed)) {
		return null
	}
	const value = Number(trimmed)
	return value >= min && value <= max ? value : null
}

export function parseDimension(text: string) {
	return wholeNumberInRange(text, DIMENSION_MIN, DIMENSION_MAX)
}

function parseQuality(text: string) {
	return wholeNumberInRange(text, QUALITY_MIN, QUALITY_MAX)
}

export function validateField(field: FieldName, values: VariantFormValues): string | undefined {
	if (field === 'name') {
		return NAME_PATTERN.test(values.name)
			? undefined
			: t('Use lowercase letters, numbers and dashes, 2 to 32 characters.')
	}
	if (field === 'quality') {
		return !usesQuality(values.format) || parseQuality(values.quality) !== null
			? undefined
			: t('Enter a value from 1 to 100.')
	}
	const text = values[field]
	return text.trim() === '' || parseDimension(text) !== null
		? undefined
		: t('Enter a value from 1 to 8000.')
}

export function lacksDimension(values: VariantFormValues) {
	return values.width.trim() === '' && values.height.trim() === ''
}

export function sliderValue(text: string) {
	const parsed = Number.parseInt(text, 10)
	if (Number.isNaN(parsed)) {
		return QUALITY_MIN
	}
	return Math.min(QUALITY_MAX, Math.max(QUALITY_MIN, parsed))
}

export function toDefinition(values: VariantFormValues): VariantDefinition {
	const definition: VariantDefinition = {
		width: parseDimension(values.width),
		height: parseDimension(values.height),
		fit: values.fit,
		format: values.format,
		generate_on_upload: values.generateOnUpload,
		enabled: values.enabled,
	}
	if (usesQuality(values.format)) {
		definition.quality = parseQuality(values.quality) ?? DEFAULT_QUALITY
	}
	return definition
}

export function toNewVariant(values: VariantFormValues): NewVariantRequest {
	return { name: values.name, ...toDefinition(values) }
}