import type { BuiltinField } from '@/lib/contentTypes'

export const COLUMN_CAP = 6
export const DEFAULT_COLUMN_COUNT = 4

const STORAGE_PREFIX = 'renewcms-content-columns-'

export function columnsStorageKey(typeKey: string) {
	return `${STORAGE_PREFIX}${typeKey}`
}

export function defaultColumnKeys(fields: BuiltinField[]) {
	return fields.slice(0, DEFAULT_COLUMN_COUNT).map((field) => field.key)
}

export function resolveColumnKeys(fields: BuiltinField[], stored: unknown) {
	if (!Array.isArray(stored)) {
		return defaultColumnKeys(fields)
	}
	const wanted = new Set(stored.filter((key): key is string => typeof key === 'string'))
	const kept = fields
		.map((field) => field.key)
		.filter((key) => wanted.has(key))
		.slice(0, COLUMN_CAP)
	return kept.length > 0 ? kept : defaultColumnKeys(fields)
}

export function readStoredColumns(typeKey: string): unknown {
	try {
		const raw = localStorage.getItem(columnsStorageKey(typeKey))
		return raw === null ? null : JSON.parse(raw)
	} catch {
		return null
	}
}

export function storeColumns(typeKey: string, keys: string[]) {
	try {
		localStorage.setItem(columnsStorageKey(typeKey), JSON.stringify(keys))
	} catch {
		return
	}
}

export function clearStoredColumns(typeKey: string) {
	try {
		localStorage.removeItem(columnsStorageKey(typeKey))
	} catch {
		return
	}
}

export function toggleColumnKeys(
	fields: BuiltinField[],
	current: string[],
	key: string,
	on: boolean,
) {
	const wanted = new Set(current)
	if (on) {
		if (wanted.size >= COLUMN_CAP) {
			return current
		}
		wanted.add(key)
	} else if (wanted.size > 1) {
		wanted.delete(key)
	}
	return fields.map((field) => field.key).filter((fieldKey) => wanted.has(fieldKey))
}