import type { InjectionKey, Ref } from 'vue'
import { inject, provide, watch } from 'vue'

export interface RegistryEntry {
	key: string
	value: string
	defaultMessage?: string
	timestamp: number
}

export interface I18nDebugContext {
	enabled: Ref<boolean>
	keyReveal: Ref<boolean>
	registry: Map<string, RegistryEntry>
	panelOpen: Ref<boolean>
}

export const I18N_DEBUG_KEY: InjectionKey<I18nDebugContext> = Symbol('i18n-debug')

export function provideI18nDebug(context: I18nDebugContext): void {
	provide(I18N_DEBUG_KEY, context)
}

export function injectI18nDebug(): I18nDebugContext | null {
	return inject(I18N_DEBUG_KEY, null)
}

export function buildCrowdinUrl(key: string, locale: string): string {
	return `https://crowdin.com/translate/modrinth-platform/all/en-${locale}?filter=basic&value=0&search_type=identifier&search=${encodeURIComponent(key)}`
}

export function initI18nDebugRuntime(context: I18nDebugContext): void {
	import('@modrinth/assets/styles/i18n-debug.css')
	document.body.classList.add('i18n-debug')
	startMutationObserver(context.registry, context.keyReveal)
	setupKeyTooltip()
	registerKeyboardShortcuts(context.panelOpen, context.keyReveal)
}

function startMutationObserver(registry: Map<string, RegistryEntry>, keyReveal: Ref<boolean>) {
	let pending = false

	const observer = new MutationObserver((mutations) => {
		if (pending || keyReveal.value) return
		pending = true
		requestAnimationFrame(() => {
			pending = false
			if (!keyReveal.value) {
				processMutations(mutations, registry)
			}
		})
	})

	observer.observe(document.body, {
		childList: true,
		subtree: true,
		characterData: true,
	})

	// Re-annotate whenever the registry grows (keys register after render)
	let annotateTimer: ReturnType<typeof setTimeout> | undefined
	let lastSize = 0
	watch(
		() => registry.size,
		(size) => {
			if (size <= lastSize || keyReveal.value) return
			lastSize = size
			clearTimeout(annotateTimer)
			annotateTimer = setTimeout(() => annotateFullDocument(registry), 200)
		},
		{ immediate: true },
	)
}

function processMutations(mutations: MutationRecord[], registry: Map<string, RegistryEntry>) {
	const reverseLookup = new Map<string, string>()
	for (const [, entry] of registry) {
		if (entry.value) {
			reverseLookup.set(entry.value, entry.key)
		}
	}

	if (reverseLookup.size === 0) return

	for (const mutation of mutations) {
		if (mutation.type === 'childList') {
			for (const node of mutation.addedNodes) {
				if (node.nodeType === Node.ELEMENT_NODE) {
					annotateTextNodes(node as Element, reverseLookup)
				} else if (node.nodeType === Node.TEXT_NODE) {
					annotateTextNode(node as Text, reverseLookup)
				}
			}
			for (const node of mutation.removedNodes) {
				if (node.nodeType === Node.ELEMENT_NODE) {
					clearStaleAttributes(node as Element)
				}
			}
		} else if (mutation.type === 'characterData') {
			if (mutation.target.nodeType === Node.TEXT_NODE) {
				annotateTextNode(mutation.target as Text, reverseLookup)
			}
		}
	}
}

function annotateTextNodes(element: Element, reverseLookup: Map<string, string>) {
	if (element.closest('.i18n-debug-panel')) return

	const walker = document.createTreeWalker(element, NodeFilter.SHOW_TEXT)
	let node: Text | null
	while ((node = walker.nextNode() as Text | null)) {
		annotateTextNode(node, reverseLookup)
	}
}

function annotateTextNode(node: Text, reverseLookup: Map<string, string>) {
	const parent = node.parentElement
	if (!parent || parent.closest('.i18n-debug-panel')) return

	const text = node.textContent?.trim()
	if (!text) return

	const key = reverseLookup.get(text)
	if (key) {
		parent.setAttribute('data-i18n-key', key)
	}
}

export function clearAllAnnotations() {
	document.querySelectorAll('[data-i18n-key]').forEach((el) => {
		el.removeAttribute('data-i18n-key')
	})
}

export function hideKeyTooltip() {
	const tooltip = document.querySelector('.i18n-key-tooltip') as HTMLElement | null
	if (tooltip) tooltip.style.display = 'none'
}

function clearStaleAttributes(element: Element) {
	if (element.hasAttribute?.('data-i18n-key')) {
		element.removeAttribute('data-i18n-key')
	}
	const children = element.querySelectorAll?.('[data-i18n-key]')
	if (children) {
		for (const child of children) {
			child.removeAttribute('data-i18n-key')
		}
	}
}

export function annotateFullDocument(registry: Map<string, RegistryEntry>) {
	const reverseLookup = new Map<string, string>()
	for (const [, entry] of registry) {
		if (entry.value) {
			reverseLookup.set(entry.value, entry.key)
		}
	}
	if (reverseLookup.size === 0) return
	annotateTextNodes(document.body, reverseLookup)
}

function setupKeyTooltip() {
	const tooltip = document.createElement('div')
	tooltip.className = 'i18n-key-tooltip'
	tooltip.style.display = 'none'
	document.body.appendChild(tooltip)

	let activeTarget: Element | null = null

	function positionTooltip() {
		if (!activeTarget) return
		const rect = activeTarget.getBoundingClientRect()
		const tooltipRect = tooltip.getBoundingClientRect()
		let top = rect.top - tooltipRect.height - 6
		if (top < 4) top = rect.bottom + 6
		let left = rect.left
		if (left + tooltipRect.width > window.innerWidth - 4) {
			left = window.innerWidth - tooltipRect.width - 4
		}
		tooltip.style.top = `${top}px`
		tooltip.style.left = `${left}px`
	}

	document.body.addEventListener('mouseover', (e) => {
		const target = (e.target as Element).closest?.('[data-i18n-key]')
		if (!target) return
		const key = target.getAttribute('data-i18n-key')
		if (!key) return
		activeTarget = target
		tooltip.textContent = key
		tooltip.style.display = ''
		positionTooltip()
	})

	document.body.addEventListener('mouseout', (e) => {
		const target = (e.target as Element).closest?.('[data-i18n-key]')
		if (!target) return
		const related = (e as MouseEvent).relatedTarget as Element | null
		if (related?.closest?.('[data-i18n-key]') === target) return
		activeTarget = null
		tooltip.style.display = 'none'
	})

	document.addEventListener('scroll', () => positionTooltip(), { capture: true, passive: true })
}

function registerKeyboardShortcuts(panelOpen: Ref<boolean>, keyReveal: Ref<boolean>) {
	document.addEventListener('keydown', (e: KeyboardEvent) => {
		// Use Cmd on macOS, Ctrl on other platforms
		const mod = e.metaKey || e.ctrlKey
		if (!mod || !e.shiftKey) return

		if (e.code === 'Period') {
			e.preventDefault()
			panelOpen.value = !panelOpen.value
		} else if (e.code === 'KeyK') {
			e.preventDefault()
			keyReveal.value = !keyReveal.value
		}
	})
}