import assert from "node:assert/strict"
import { readFileSync } from "node:fs"
import test from "node:test"
import vm from "node:vm"
import ts from "typescript"

const storage = () => {
  const values = new Map()
  return { getItem: (key) => values.get(key) ?? null, setItem: (key, value) => values.set(key, value), removeItem: (key) => values.delete(key) }
}
const deferred = () => {
  let resolve, reject
  const promise = new Promise((yes, no) => { resolve = yes; reject = no })
  return { promise, resolve, reject }
}
const token = (identityKey, channelCode = "support", mode = "guest", extra = {}) =>
  `test.${Buffer.from(JSON.stringify({ identityKey, channelCode, identityScope: `v1:${mode}:test-channel-scope`, ...extra })).toString("base64url")}.not-a-real-signature`
const exchange = (identityKey = "guest:server-assigned", channelCode = "support", mode = "guest") => ({
  identityKey, customerSessionToken: token(identityKey, channelCode, mode),
  expiresAt: "2099-01-01T00:00:00Z", customer: { id: 1, name: "Visitor" },
})

function harness(request) {
  let config = { baseUrl: "https://support.example", channelId: "support", externalId: "client-guest" }
  const localStorage = storage(), sessionStorage = storage()
  const source = readFileSync(new URL("./im.ts", import.meta.url), "utf8")
  const compiled = ts.transpileModule(source, { compilerOptions: { target: ts.ScriptTarget.ES2022, module: ts.ModuleKind.CommonJS } })
  const module = { exports: {} }
  const mocks = {
    "@/lib/api/client": { request },
    "@/i18n/messages": { translateCurrentMessage: (key) => key },
    "@/lib/sdk/runtime-config": { readSupportChatRuntimeConfig: () => config },
    "@/lib/utils": { generateUUID: () => "browser-local-guest", parseApiTimestamp: Date.parse },
  }
  vm.runInNewContext(compiled.outputText, { module, exports: module.exports,
    require: (name) => { if (!mocks[name]) throw new Error(`Unexpected import ${name}`); return mocks[name] },
    process: { env: {} }, window: { localStorage, sessionStorage }, atob, TextDecoder, URLSearchParams })
  return { api: module.exports, sessionStorage, setConfig: (next) => { config = { ...config, ...next } } }
}

test("concurrent session ensures share one guest exchange and cache server-owned identity", async () => {
  const pending = deferred()
  let calls = 0
  const h = harness(() => { calls++; return pending.promise })
  const first = h.api.ensureCustomerSession(), second = h.api.ensureCustomerSession()
  assert.equal(calls, 1)
  pending.resolve(exchange())
  const [left, right] = await Promise.all([first, second])
  assert.equal(left.identityKey, "guest:server-assigned")
  assert.equal(right.identityKey, left.identityKey)
  assert.equal(left.guestContext, "client-guest")
  await h.api.ensureCustomerSession()
  assert.equal(calls, 1)
})

test("guest token cannot be reused under a different initiating visitor context", async () => {
  let calls = 0
  const h = harness(async () => exchange(`guest:server-${++calls}`))
  await h.api.ensureCustomerSession()
  h.setConfig({ externalId: "someone-else" })
  assert.equal(h.api.getCustomerSessionToken(), "")
  const next = await h.api.ensureCustomerSession()
  assert.equal(calls, 2)
  assert.equal(next.identityKey, "guest:server-2")
})

test("legacy unscoped tokens are re-exchanged instead of sent to protected endpoints", async () => {
  let calls = 0
  const h = harness(async () => { calls++; return exchange() })
  h.sessionStorage.setItem("cs_ai_agent_customer_session", JSON.stringify({ ...exchange("guest:client-guest"),
    customerSessionToken: token("guest:client-guest", "support", "guest", { identityScope: undefined }),
    baseUrl: "https://support.example", channelId: "support", guestContext: "client-guest" }))
  assert.equal(h.api.getCustomerSessionToken(), "")
  await h.api.ensureCustomerSession()
  assert.equal(calls, 1)
})

test("late session exchange from old identity cannot overwrite new session", async () => {
  const old = deferred()
  let calls = 0
  const h = harness(() => ++calls === 1 ? old.promise : Promise.resolve(exchange("guest:new-server")))
  const first = h.api.ensureCustomerSession()
  h.setConfig({ externalId: "new-visitor" })
  const next = await h.api.ensureCustomerSession()
  old.resolve(exchange("guest:old-server"))
  await assert.rejects(first, /supportAuthenticationRequired/)
  assert.equal(h.api.readCustomerSession().identityKey, next.identityKey)
})

test("A to B to A entry changes invalidate old same-value exchange", async () => {
  const old = deferred()
  let calls = 0
  const h = harness(() => ++calls === 1 ? old.promise : Promise.resolve(exchange("guest:new-A")))
  const first = h.api.ensureCustomerSession()
  h.setConfig({ externalId: "B" })
  h.api.getCustomerIdentityScope()
  h.setConfig({ externalId: "client-guest" })
  await h.api.ensureCustomerSession()
  old.resolve(exchange("guest:old-A"))
  await assert.rejects(first, /supportAuthenticationRequired/)
  assert.equal(h.api.readCustomerSession().identityKey, "guest:new-A")
})

test("customer token rotation preserves scope, but replacement guest identity changes it", async () => {
  let calls = 0
  const h = harness(async () => exchange(`guest:server-${++calls}`))
  await h.api.ensureCustomerSession()
  const scope = h.api.getCustomerIdentityScope()
  h.api.applyCustomerSessionRefresh({ customerSessionToken: token("guest:server-1", "support", "guest", { revision: 2 }), expiresAt: "2099-02-01T00:00:00Z" })
  assert.equal(h.api.getCustomerIdentityScope(), scope)
  await h.api.exchangeCustomerSession()
  assert.notEqual(h.api.getCustomerIdentityScope(), scope)
})

test("refresh with another auth mode or channel cannot poison cached session", async () => {
  const h = harness(async () => exchange())
  await h.api.ensureCustomerSession()
  const original = h.api.getCustomerSessionToken()
  h.api.applyCustomerSessionRefresh({ customerSessionToken: token("guest:server-assigned", "support", "jwt"), expiresAt: "2099-02-01T00:00:00Z" })
  assert.equal(h.api.getCustomerSessionToken(), original)
  h.api.applyCustomerSessionRefresh({ customerSessionToken: token("guest:server-assigned", "other"), expiresAt: "2099-02-01T00:00:00Z" })
  assert.equal(h.api.getCustomerSessionToken(), original)
})

test("signed identity still requires exact user ID and correct auth mode", async () => {
  const h = harness(async () => exchange("user:wrong", "support", "hmac"))
  h.setConfig({ externalId: "expected", externalIdSignature: "test-not-a-real-signature", externalIdSignedAt: 1 })
  await assert.rejects(h.api.ensureCustomerSession(), /supportAuthenticationRequired/)
  assert.equal(h.api.getCustomerSessionToken(), "")
})

test("matching renewal arriving during old token expiry window keeps guest identity", async () => {
  const h = harness(async () => exchange())
  await h.api.ensureCustomerSession()
  const cached = h.api.readCustomerSession()
  h.sessionStorage.setItem("cs_ai_agent_customer_session", JSON.stringify({ ...cached, expiresAt: "2000-01-01T00:00:00Z" }))
  const renewed = token(cached.identityKey, "support", "guest", { revision: 2 })
  h.api.applyCustomerSessionRefresh({ customerSessionToken: renewed, expiresAt: "2099-02-01T00:00:00Z" })
  assert.equal(h.api.getCustomerSessionToken(), renewed)
})

test("near-expiry guest renews its existing identity instead of exchanging a fresh guest", async () => {
  const routes = []
  const h = harness(async (route, options) => {
    routes.push(route)
    if (route.endsWith("session_refresh")) {
      assert.equal(options.method, "POST")
      assert.ok(options.headers.Authorization.startsWith("Bearer "))
    }
    return exchange("guest:original")
  })
  await h.api.ensureCustomerSession()
  const cached = h.api.readCustomerSession()
  h.sessionStorage.setItem("cs_ai_agent_customer_session", JSON.stringify({ ...cached, expiresAt: new Date(Date.now() + 4000).toISOString() }))
  const resumed = await h.api.ensureCustomerSession()
  assert.equal(resumed.identityKey, cached.identityKey)
  assert.deepEqual(routes, ["/api/customer/session_exchange", "/api/customer/session_refresh"])
})

test("failed near-expiry refresh never falls back to a different anonymous guest", async () => {
  let calls = 0
  const h = harness(async (route) => {
    calls++
    if (route.endsWith("session_refresh")) throw new Error("offline")
    return exchange("guest:original")
  })
  await h.api.ensureCustomerSession()
  const cached = h.api.readCustomerSession()
  h.sessionStorage.setItem("cs_ai_agent_customer_session", JSON.stringify({ ...cached, expiresAt: new Date(Date.now() + 4000).toISOString() }))
  await assert.rejects(h.api.ensureCustomerSession(), /offline/)
  assert.equal(calls, 2)
  assert.equal(h.api.readCustomerSession().identityKey, "guest:original")
})