import { computed, ref } from 'vue'
import type { BuiltinField, ContentEntry } from '@/lib/contentTypes'
import type { MediaMap, MediaSummary } from '@/lib/mediaField'
import {
	carriesDefault,
	firstIssueKey,
	initialImages,
	initialValues,
	valuesDiffer,
	type EntryIssues,
	type EntryValues,
	type FieldIssue,
} from '@/lib/entryForm'

export function useEntryForm(fields: () => BuiltinField[], creating: () => boolean) {
	const values = ref<EntryValues>({})
	const saved = ref<EntryValues>({})
	const images = ref<MediaMap>({})
	const issues = ref<EntryIssues>({})
	const rejected = ref(false)

	const dirty = computed(() => valuesDiffer(fields(), values.value, saved.value))
	const firstIssue = computed(() => firstIssueKey(fields(), issues.value))
	const hasIssues = computed(() => Object.keys(issues.value).length > 0)

	function reset(entry: ContentEntry | null) {
		const next = initialValues(fields(), entry)
		values.value = { ...next }
		saved.value = { ...next }
		images.value = initialImages(fields(), entry)
		issues.value = {}
		rejected.value = false
	}

	function setImage(key: string, image: MediaSummary | null | undefined) {
		if (image === undefined) {
			return
		}
		const next = { ...images.value }
		if (image === null) {
			delete next[key]
		} else {
			next[key] = image
		}
		images.value = next
	}

	function setValue(key: string, value: unknown, image?: MediaSummary | null) {
		values.value = { ...values.value, [key]: value }
		setImage(key, image)
		rejected.value = false
		if (issues.value[key]) {
			const rest = { ...issues.value }
			delete rest[key]
			issues.value = rest
		}
	}

	function reject(next: EntryIssues) {
		issues.value = next
		rejected.value = true
	}

	function rejectField(key: string, issue: FieldIssue) {
		reject({ [key]: issue })
	}

	function isDefault(field: BuiltinField) {
		return creating() && carriesDefault(field, values.value[field.key])
	}

	return {
		values,
		images,
		issues,
		rejected,
		dirty,
		firstIssue,
		hasIssues,
		reset,
		setValue,
		reject,
		rejectField,
		isDefault,
	}
}

export type EntryForm = ReturnType<typeof useEntryForm>