import { readdirSync, readFileSync, statSync } from 'node:fs'
import { join } from 'node:path'
import { icons } from '@iconify-json/lucide'
import { getIcons } from '@iconify/utils'
import type { Plugin } from 'vite'

const virtualId = 'virtual:lucide-subset'
const resolvedId = `\0${virtualId}`
const iconPattern = /i-lucide-([a-z0-9]+(?:-[a-z0-9]+)*)/g
const sourceExtensions = /\.(vue|ts|js|mjs)$/

function walk(dir: string, found: Set<string>) {
	for (const entry of readdirSync(dir)) {
		const full = join(dir, entry)
		const stat = statSync(full)
		if (stat.isDirectory()) {
			if (entry !== '__tests__') walk(full, found)
			continue
		}
		if (!sourceExtensions.test(entry)) continue
		for (const match of readFileSync(full, 'utf8').matchAll(iconPattern)) {
			found.add(match[1]!)
		}
	}
}

export function lucideSubset(roots: string[]): Plugin {
	return {
		name: 'lucide-subset',
		resolveId(id) {
			return id === virtualId ? resolvedId : null
		},
		load(id) {
			if (id !== resolvedId) return null
			const found = new Set<string>()
			for (const root of roots) walk(root, found)
			const subset = getIcons(icons, [...found].sort())
			return `export default ${JSON.stringify(subset)}`
		},
	}
}