import fetch from 'node-fetch'
import { ApiKeyModel } from '../models/apikey.model.ts'
import { AssignmentModel } from '../models/assignments.model.ts'
import { KanjiModel } from '../models/kanji.model.ts'
import { VocabularyModel } from '../models/vocabulary.model.ts'

import type { KanjiItem, VocabularyItem } from '../types/wanikani.ts'

const WANIKANI_API_BASE = 'https://api.wanikani.com/v2'

export interface WaniKaniSubject {
	id: number
	object: string
	data: {
		characters: string
		meanings: { meaning: string; primary: boolean; accepted_answers: boolean }[]
		readings: { type: string; primary: boolean; accepted_answer: boolean; reading: string }[]
		auxiliary_meanings: { meaning: string; type: string }[]
		pronunciation_audios?: {
			url: string
			content_type: string
			metadata: { gender: string; pronunciation: string }[]
		}[]
		level: number
		slug: string
		unlocked_at?: string
	}
}

const fetchAllPages = async (
	url: string,
	headers: Record<string, string>,
): Promise<WaniKaniSubject[]> => {
	let results: WaniKaniSubject[] = []
	let nextUrl: string | null = url

	while (nextUrl) {
		const res = await fetch(nextUrl, { headers })
		if (!res.ok) throw new Error(`Failed fetching ${url}: ${res.statusText}`)
		const json = (await res.json()) as { data: WaniKaniSubject[]; pages: { next_url: string | null } }
		results = results.concat(json.data)
		nextUrl = json.pages.next_url
	}

	return results
}

const fetchSubjects = async (
	ids: number[],
	headers: Record<string, string>,
): Promise<WaniKaniSubject[]> => {
	const chunkSize = 1000
	let results: WaniKaniSubject[] = []

	for (let i = 0; i < ids.length; i += chunkSize) {
		const chunk = ids.slice(i, i + chunkSize)
		const res = await fetch(`${WANIKANI_API_BASE}/subjects?ids=${chunk.join(',')}`, { headers })
		if (!res.ok) throw new Error(`Failed fetching subjects: ${res.statusText}`)
		const json = (await res.json()) as { data: WaniKaniSubject[] }
		results = results.concat(json.data)
	}

	return results
}

const mapKanji = (item: WaniKaniSubject): KanjiItem => ({
	characters: item.data.characters,
	meanings: item.data.meanings,
	readings: item.data.readings,
	auxiliary_meanings: item.data.auxiliary_meanings,
	level: item.data.level,
	slug: item.data.slug,
	srs_score: 0,
})

const mapVocab = (item: WaniKaniSubject): VocabularyItem => ({
	characters: item.data.characters,
	meanings: item.data.meanings,
	readings: item.data.readings ?? [],
	auxiliary_meanings: item.data.auxiliary_meanings,
	pronunciation_audios: item.data.pronunciation_audios ?? [],
	level: item.data.level,
	slug: item.data.slug,
	srs_score: 0,
})

export const syncWanikaniData = async (apiKey: string): Promise<void> => {
	const headers = { Authorization: `Bearer ${apiKey}` }

	try {
		await ApiKeyModel.updateOne(
			{},
			{ $set: { value: apiKey, lastUsed: new Date() } },
			{ upsert: true },
		)

		const assignments = await fetchAllPages(`${WANIKANI_API_BASE}/assignments`, headers)

		const unlockedKanjiSubjectIds: number[] = []
		const unlockedVocabSubjectIds: number[] = []

		for (const a of assignments) {
			const assignmentData = a.data as any

			if (!assignmentData.unlocked_at) continue

			if (assignmentData.subject_type === 'kanji') {
				unlockedKanjiSubjectIds.push(assignmentData.subject_id)
			} else if (['vocabulary', 'kana_vocabulary'].includes(assignmentData.subject_type)) {
				unlockedVocabSubjectIds.push(assignmentData.subject_id)
			}
		}

		await AssignmentModel.updateOne(
			{ subject_type: 'kanji' },
			{ $set: { subject_ids: unlockedKanjiSubjectIds } },
			{ upsert: true },
		)

		await AssignmentModel.updateOne(
			{ subject_type: 'vocabulary' },
			{ $set: { subject_ids: unlockedVocabSubjectIds } },
			{ upsert: true },
		)

		const existingKanjiSlugs = new Set((await KanjiModel.find({}, { slug: 1 })).map(k => k.slug))
		const kanjiSubjects = await fetchSubjects(unlockedKanjiSubjectIds, headers)
		const newKanji = kanjiSubjects.filter(s => !existingKanjiSlugs.has(s.data.slug))
		if (newKanji.length > 0) await KanjiModel.insertMany(newKanji.map(mapKanji))

		const existingVocabSlugs = new Set((await VocabularyModel.find({}, { slug: 1 })).map(v => v.slug))
		const vocabSubjects = await fetchSubjects(unlockedVocabSubjectIds, headers)
		const newVocab = vocabSubjects.filter(s => !existingVocabSlugs.has(s.data.slug))
		if (newVocab.length > 0) await VocabularyModel.insertMany(newVocab.map(mapVocab))

		console.log('✅ Sync complete')
	} catch (err) {
		console.error('❌ Error syncing WaniKani data:', err)
		throw err
	}
}