import { defineStore } from 'pinia'
import { ref, computed, onMounted, watch } from 'vue'

interface User {
	id: number
	username: string
	email?: string
}

export const useAuthStore = defineStore('auth', () => {
	const user = ref<User | null>(null)
	const loading = ref(false)
	const error = ref<string | null>(null)

	let refreshInterval: ReturnType<typeof setInterval> | null = null

	/**
	 * Fetch the current logged-in user from the server.
	 * Tries refresh if access token expired.
	 */
	async function fetchUser() {
		try {
			loading.value = true
			const res = await fetch('/api/v1/user/info', {
				method: 'GET',
				credentials: 'include',
			})

			if (res.ok) {
				const data = await res.json()
				user.value = data.user
				error.value = null
				startAutoRefresh()
				return true
			}

			if (res.status === 401) {
				const refreshed = await refreshToken()
				if (refreshed) return await fetchUser()
				user.value = null
			} else {
				throw new Error('Failed to fetch user')
			}
		} catch (err: any) {
			console.warn('fetchUser failed:', err)
			error.value = err.message
			user.value = null
		} finally {
			loading.value = false
		}
	}

	/**
	 * Perform login and set cookies.
	 */
	async function login(username: string, password: string, remember: boolean) {
		try {
			loading.value = true
			error.value = null

			const res = await fetch('/api/v1/auth/login', {
				method: 'POST',
				headers: { 'Content-Type': 'application/json' },
				credentials: 'include',
				body: JSON.stringify({ username, password, remember }),
			})

			if (!res.ok) throw new Error('Invalid credentials')
			const data = await res.json()

			if (data.ok && data.user) {
				user.value = data.user
				startAutoRefresh()
				return true
			}

			throw new Error('Login failed')
		} catch (err: any) {
			error.value = err.message
			return false
		} finally {
			loading.value = false
		}
	}

	/**
	 * Refresh the access token using refresh cookie.
	 */
	async function refreshToken() {
		if (!document.cookie.includes('refresh_token')) return false

		try {
			const res = await fetch('/api/v1/auth/refresh', {
				method: 'POST',
				credentials: 'include',
			})

			if (res.ok) {
				console.info('[Auth] Token refreshed')
				return true
			}

			console.warn('[Auth] Token refresh failed with status', res.status)
			return false
		} catch (err) {
			console.error('[Auth] Refresh error', err)
			return false
		}
	}

	/**
	 * Automatically refresh tokens before expiry.
	 */
	function startAutoRefresh() {
		if (refreshInterval) clearInterval(refreshInterval)

		refreshInterval = setInterval(async () => {
			if (!user.value) return
			const success = await refreshToken()
			if (!success) {
				console.warn('[Auth] Auto-refresh failed, trying fetchUser')
				const ok = await fetchUser()
				if (!ok) {
					console.warn('[Auth] Session expired, logging out')
					await logout()
				}
			}
		}, 7.5 * 60 * 1000)

		document.addEventListener('visibilitychange', async () => {
			if (document.visibilityState === 'visible' && user.value) {
				const success = await refreshToken()
				if (!success) await logout()
			}
		})
	}

	/**
	 * Stop the refresh timer and logout from backend.
	 */
	async function logout() {
		try {
			await fetch('/api/v1/auth/logout', {
				method: 'POST',
				credentials: 'include',
			})
		} catch (err) {
			console.warn('Logout error:', err)
		} finally {
			user.value = null
			if (refreshInterval) clearInterval(refreshInterval)
			refreshInterval = null
		}
	}

	const isAuthenticated = computed(() => !!user.value)

	return {
		user,
		loading,
		error,
		isAuthenticated,
		login,
		logout,
		fetchUser,
		refreshToken,
	}
})