interface PublicKeyResponse {
    enabled: boolean
    scope: string
    algorithm: string
    key_version: string
    public_key: string
    encrypted_paths?: string[]
}

interface EncryptSession {
    aesKey: Uint8Array
    iv: Uint8Array
    keyVersion: string
    encryptedKey: string
    encryptedIv: string
}

interface EncryptRequestResult {
    body: string
    headers: Record<string, string>
    session: EncryptSession | null
}

const PUBLIC_KEY_PATH = '/system/security/api-encrypt/public-key'
let publicKeyCache: PublicKeyResponse | null = null
let publicKeyFailureAt = 0
const PUBLIC_KEY_RETRY_INTERVAL = 30000

const textEncoder = new TextEncoder()
const textDecoder = new TextDecoder()

function normalizeBaseUrl(baseURL: string): string {
    return baseURL.endsWith('/') ? baseURL.slice(0, -1) : baseURL
}

function normalizePath(path: string): string {
    return path.startsWith('/') ? path : `/${path}`
}

function resolveRequestPath(baseURL: string, path: string): string {
    const normalizedBaseUrl = normalizeBaseUrl(baseURL)
    const normalizedPath = normalizePath(path)

    if (/^https?:\/\//i.test(normalizedPath)) {
        const url = new URL(normalizedPath)
        return url.pathname
    }

    if (normalizedPath.startsWith('/api/') || normalizedPath.startsWith('/adminapi/')) {
        return normalizedPath
    }

    try {
        const url = new URL(`${normalizedBaseUrl}${normalizedPath}`, window.location.origin)
        return url.pathname
    } catch {
        return normalizedPath
    }
}

function shouldSkipEncrypt(path: string): boolean {
    return path === '/api/auth/refresh'
        || path === '/adminapi/auth/refresh'
        || path === '/api/system/security/api-encrypt/public-key'
        || path === '/adminapi/system/security/api-encrypt/public-key'
}

function matchesEncryptedPath(path: string, encryptedPaths: string[] = []): boolean {
    const normalizedPath = normalizePath(path)
    return encryptedPaths.some((encryptedPath) => {
        const normalizedEncryptedPath = normalizePath(encryptedPath)
        return normalizedEncryptedPath === normalizedPath || normalizedPath.startsWith(`${normalizedEncryptedPath}/`)
    })
}

function toBase64(buffer: ArrayBuffer | Uint8Array): string {
    const bytes = buffer instanceof Uint8Array ? buffer : new Uint8Array(buffer)
    let binary = ''
    bytes.forEach((byte) => {
        binary += String.fromCharCode(byte)
    })
    return btoa(binary)
}

function toArrayBuffer(bytes: Uint8Array): ArrayBuffer {
    return bytes.buffer.slice(bytes.byteOffset, bytes.byteOffset + bytes.byteLength) as ArrayBuffer
}

function fromPem(pem: string): ArrayBuffer {
    const clean = pem.replace(/-----BEGIN PUBLIC KEY-----/g, '')
        .replace(/-----END PUBLIC KEY-----/g, '')
        .replace(/\s+/g, '')
    const binary = atob(clean)
    const bytes = new Uint8Array(binary.length)
    for (let i = 0; i < binary.length; i += 1) {
        bytes[i] = binary.charCodeAt(i)
    }
    return bytes.buffer
}

async function importPublicKey(publicKeyPem: string): Promise<CryptoKey> {
    return crypto.subtle.importKey(
        'spki',
        fromPem(publicKeyPem),
        {
            name: 'RSA-OAEP',
            hash: 'SHA-256'
        },
        true,
        ['encrypt']
    )
}

async function rsaEncrypt(publicKeyPem: string, data: Uint8Array): Promise<string> {
    const publicKey = await importPublicKey(publicKeyPem)
    const encrypted = await crypto.subtle.encrypt({ name: 'RSA-OAEP' }, publicKey, data)
    return toBase64(encrypted)
}

async function aesEncrypt(plainText: string, aesKey: Uint8Array, iv: Uint8Array): Promise<string> {
    const cryptoKey = await crypto.subtle.importKey(
        'raw',
        toArrayBuffer(aesKey),
        { name: 'AES-CBC' },
        false,
        ['encrypt']
    )
    const encrypted = await crypto.subtle.encrypt({ name: 'AES-CBC', iv: toArrayBuffer(iv) }, cryptoKey, textEncoder.encode(plainText))
    return toBase64(encrypted)
}

async function aesDecrypt(cipherText: string, aesKey: Uint8Array, iv: Uint8Array): Promise<string> {
    const cryptoKey = await crypto.subtle.importKey(
        'raw',
        toArrayBuffer(aesKey),
        { name: 'AES-CBC' },
        false,
        ['decrypt']
    )
    const binary = atob(cipherText)
    const bytes = new Uint8Array(binary.length)
    for (let i = 0; i < binary.length; i += 1) {
        bytes[i] = binary.charCodeAt(i)
    }
    const decrypted = await crypto.subtle.decrypt({ name: 'AES-CBC', iv: toArrayBuffer(iv) }, cryptoKey, toArrayBuffer(bytes))
    return textDecoder.decode(decrypted)
}

async function fetchPublicKey(baseURL: string): Promise<PublicKeyResponse | null> {
    const requestUrl = `${normalizeBaseUrl(baseURL)}${PUBLIC_KEY_PATH}`
    const response = await fetch(requestUrl, {
        method: 'GET',
        headers: {
            'Content-Type': 'application/json'
        }
    })

    const result = await response.json()
    if (!result || result.code !== 0 || !result.data) {
        return null
    }

    return result.data as PublicKeyResponse
}

async function ensurePublicKey(baseURL: string): Promise<PublicKeyResponse | null> {
    if (publicKeyCache) {
        return publicKeyCache
    }

    if (publicKeyFailureAt > 0 && Date.now() - publicKeyFailureAt < PUBLIC_KEY_RETRY_INTERVAL) {
        return null
    }

    let data: PublicKeyResponse | null = null
    try {
        data = await fetchPublicKey(baseURL)
    } catch {
        publicKeyFailureAt = Date.now()
        return null
    }

    if (!data) {
        publicKeyFailureAt = Date.now()
        return null
    }

    publicKeyFailureAt = 0
    publicKeyCache = data
    return publicKeyCache
}

export function clearApiEncryptPublicKeyCache() {
    publicKeyCache = null
    publicKeyFailureAt = 0
}

export async function prepareEncryptedRequest(baseURL: string, path: string, method: string, body?: unknown): Promise<EncryptRequestResult> {
    const resolvedPath = resolveRequestPath(baseURL, path)

    if (!resolvedPath.startsWith('/api/') && !resolvedPath.startsWith('/adminapi/')) {
        return {
            body: body ? JSON.stringify(body) : '',
            headers: {},
            session: null
        }
    }

    if (shouldSkipEncrypt(resolvedPath)) {
        return {
            body: body ? JSON.stringify(body) : '',
            headers: {},
            session: null
        }
    }

    const publicKeyData = await ensurePublicKey(baseURL)
    if (!publicKeyData || !publicKeyData.enabled || publicKeyData.scope === 'off') {
        return {
            body: body ? JSON.stringify(body) : '',
            headers: {},
            session: null
        }
    }

    if (publicKeyData.scope === 'partial' && !matchesEncryptedPath(resolvedPath, publicKeyData.encrypted_paths || [])) {
        return {
            body: body ? JSON.stringify(body) : '',
            headers: {},
            session: null
        }
    }

    const aesKey = crypto.getRandomValues(new Uint8Array(32))
    const iv = crypto.getRandomValues(new Uint8Array(16))
    const encryptedKey = await rsaEncrypt(publicKeyData.public_key, aesKey)
    const encryptedIv = await rsaEncrypt(publicKeyData.public_key, iv)

    let encryptedBody = ''
    if (body !== undefined && !['GET', 'HEAD'].includes(method.toUpperCase())) {
        const payload = JSON.stringify(body)
        encryptedBody = await aesEncrypt(payload, aesKey, iv)
    }

    return {
        body: encryptedBody === '' ? '' : JSON.stringify({
            encrypted: true,
            algorithm: publicKeyData.algorithm,
            key_version: publicKeyData.key_version,
            data: encryptedBody,
            method
        }),
        headers: {
            'X-Api-Encrypt': '1',
            'X-Api-Encrypt-Version': publicKeyData.key_version,
            'X-Api-Encrypt-Key': encryptedKey,
            'X-Api-Encrypt-Iv': encryptedIv
        },
        session: {
            aesKey,
            iv,
            keyVersion: publicKeyData.key_version,
            encryptedKey,
            encryptedIv
        }
    }
}

export async function decryptEncryptedResponse(data: any, session: EncryptSession | null): Promise<any> {
    if (!data || data.encrypted !== true || !session) {
        return data
    }

    const plainText = await aesDecrypt(String(data.data || ''), session.aesKey, session.iv)
    return JSON.parse(plainText)
}