// SPDX-License-Identifier: LicenseRef-ConusAI-Template-1.0
// The Convex profile's half of `POST /api/v1/orgs/{org}/live` (live.ts): the CLP/1 stream is served by
// @conusai-kit/live-server in this process, over the deployment's own functions (convex/live.ts):
//
//   - the log: `live:head` and `live:changes` (internal queries) read with the admin key, and the wake-up
//     is a reactive subscription to `live:head` per organization a stream reads (`convexLiveLog`
//     refcounts it), over one websocket client opened by the first stream
//   - who may stream what: `live:open`, a public query run under the caller's identity (the same claims
//     every procedure call carries, convex-caller.ts), decides with the kernel's tenancy over the
//     deployment's rows (`decideLiveGrants`); its refusal comes back as the live problem the Postgres
//     profile answers (401 signed out, 404 not reached), and each heartbeat asks `live:recheck`
//
// The admin key stays in this process; the browser holds no Convex credential.

import {
  type ConvexLiveHead,
  type ConvexLiveRow,
  type ConvexLiveSource,
  type LiveAuthorization,
  type LiveRecheck,
  type OpenRequest,
  problems,
  type ResolvedTopic,
} from "@conusai-kit/live-server"
import { ConvexClient } from "convex/browser"
import { makeFunctionReference, type UserIdentityAttributes } from "convex/server"
import { ConvexError } from "convex/values"
import { asProblem, convexAdminClient } from "./convex-caller"

const OPEN = makeFunctionReference<"query">("live:open")
const RECHECK = makeFunctionReference<"query">("live:recheck")
const HEAD = makeFunctionReference<"query">("live:head")
const CHANGES = makeFunctionReference<"query">("live:changes")

/** What the source and the authorization ask of a one-shot client (`ConvexHttpClient`). */
export interface LiveQueryClient {
  query(reference: never, args: never): Promise<unknown>
}

/** What the source asks of a subscribing client (`ConvexClient`, a websocket). */
export interface LiveWatchClient {
  onUpdate(
    reference: never,
    args: never,
    callback: (value: unknown) => unknown,
    onError?: (error: Error) => unknown,
  ): () => void
  close(): Promise<void>
}

type AdminAuthWatchClient = ConvexClient & {
  /** Convex SDK 1.45.0 internal, as `ConvexHttpClient.setAdminAuth` (convex-caller.ts). */
  setAdminAuth(token: string, identity?: UserIdentityAttributes): void
}

/**
 * The log source over two clients: `admin` reads (it holds the admin key and no identity, so it may call
 * the internal `live:head` and `live:changes`), and `watcher` opens the subscribing client on the first
 * `watch`; `close` closes it.
 */
export function convexLiveSource(clients: {
  readonly admin: LiveQueryClient
  readonly watcher: () => LiveWatchClient
}): ConvexLiveSource {
  let watcher: LiveWatchClient | undefined
  return {
    head: async (orgId) => (await clients.admin.query(HEAD as never, { orgId } as never)) as ConvexLiveHead,
    changes: async (orgId, after, limit) =>
      (await clients.admin.query(
        CHANGES as never,
        { orgId, after: { txid: after.txid, seq: after.seq }, limit } as never,
      )) as {
        rows: readonly ConvexLiveRow[]
        head: ConvexLiveHead
        more: boolean
      },
    watch(orgId, onChange, onError) {
      watcher ??= clients.watcher()
      // Convex answers the current head first, then every new one: each is a wake-up, and a wake-up
      // with nothing new is one empty read.
      return watcher.onUpdate(HEAD as never, { orgId } as never, () => onChange(), onError)
    },
    async close() {
      const open = watcher
      watcher = undefined
      await open?.close()
    },
  }
}

/** The log source over the linked deployment, with its admin key (env.convex). */
export function deploymentLiveSource(convex: { readonly url: string; readonly adminKey: string }): ConvexLiveSource {
  return convexLiveSource({
    admin: convexAdminClient(convex) as unknown as LiveQueryClient,
    watcher: () => {
      const client = new ConvexClient(convex.url, { unsavedChangesWarning: false })
      ;(client as AdminAuthWatchClient).setAdminAuth(convex.adminKey)
      return client as unknown as LiveWatchClient
    },
  })
}

/** The verified caller of one stream, as live.ts resolves it from the request. */
export interface LiveCaller {
  readonly userId: string
  /** The session (or credential) key of the per-session stream limit. */
  readonly session: string
  /** The identity its Convex calls carry (convex-caller.ts `convexIdentity`). */
  readonly identity: UserIdentityAttributes
}

export interface ConvexLiveAuthorizeOptions {
  /** The request's caller: signed in (or the live 401) and its CSRF checked. */
  caller(request: Request): Promise<LiveCaller>
  /** A one-shot client that calls as `identity` (`convexAdminClient`). */
  clientFor(identity: UserIdentityAttributes): LiveQueryClient
  /** The org slug of `/api/v1/orgs/{org}/live`. */
  orgSlugOf(request: Request): string
  /** Where an unexpected re-check failure is reported (it does not end the stream). */
  warn(message: string): void
}

/** The status of a refusal: a live problem's own, or the problem a Convex function threw. */
function statusOf(error: unknown): number | undefined {
  if (error instanceof ConvexError) {
    const status = (error.data as { status?: unknown } | null)?.status
    return typeof status === "number" ? status : undefined
  }
  const status = (error as { status?: unknown } | null)?.status
  return typeof status === "number" ? status : undefined
}

/** A refusal of `live:open` as the Postgres profile answers it; another Convex problem as the kernel's. */
function refusalOf(error: unknown): unknown {
  if (!(error instanceof ConvexError)) return error
  const status = statusOf(error)
  if (status === 401) return problems.unauthenticated()
  if (status === 404) return problems.notFound()
  return asProblem(error)
}

interface OpenAnswer {
  readonly org: string
  readonly topics: readonly ResolvedTopic[]
  readonly entities: readonly string[]
  readonly denied: ReadonlyArray<{ readonly entity: string; readonly reason: string }>
}

/** The authorize function of `createLiveServer` on the Convex profile. */
export function convexLiveAuthorize(
  options: ConvexLiveAuthorizeOptions,
): (request: Request, open: OpenRequest) => Promise<LiveAuthorization> {
  return async (request, open) => {
    const caller = await options.caller(request)
    const slug = options.orgSlugOf(request)
    // The validator of `live:open` takes these fields only.
    const topics = open.topics.map((topic) => ({ ws: topic.ws, ...(topic.project ? { project: topic.project } : {}) }))
    let answer: OpenAnswer
    try {
      answer = (await options
        .clientFor(caller.identity)
        .query(OPEN as never, { org: slug, topics, entities: [...open.entities] } as never)) as OpenAnswer
    } catch (error) {
      throw refusalOf(error)
    }
    return {
      org: answer.org,
      session: caller.session,
      granted: { entities: answer.entities, topics: answer.topics },
      denied: answer.denied,
      // Every heartbeat and on a grant change: the credential is still valid, the caller still a member of
      // every scope, and still holds the read permission of every entity the stream was granted.
      recheck: async (): Promise<LiveRecheck> => {
        try {
          const again = await options.caller(new Request(request.url, { method: "GET", headers: request.headers }))
          if (again.userId !== caller.userId) return "session"
          return (await options
            .clientFor(again.identity)
            .query(RECHECK as never, { org: slug, topics, granted: [...answer.entities] } as never)) as LiveRecheck
        } catch (error) {
          const status = statusOf(error)
          if (status === 401) return "session"
          if (status === 403 || status === 404) return "membership"
          options.warn(`live: the re-check failed: ${error instanceof Error ? error.name : "failed"}`)
          return null
        }
      },
    }
  }
}