// Minimal opencode-server protocol stub used by the Maestro activation E2E flows
// (.maestro/flows/activation-*.yaml). It is NOT a real opencode server — it
// implements just enough of the REST + Server-Sent-Events surface that the
// mobile client (src/lib/sdk.ts) actually talks to, so the app can genuinely
// go through connect -> create session -> send message -> receive a streamed
// reply against something real instead of a live server.
//
// Protocol notes (read from src/lib/sdk.ts / src/stores/connections.ts /
// src/stores/events.ts — NOT guessed):
//   - There is no WebSocket anywhere in the client. "Connect" = one GET
//     /global/health call (src/stores/connections.ts testConnection()).
//   - Real-time updates (including the assistant's streamed reply) arrive via
//     a single long-lived SSE connection: GET /global/event, framed as
//     `data: <json>\n\n` lines (see src/lib/sse.ts SSEParser).
//   - Sending a message is fire-and-forget: POST /session/:id/prompt_async
//     returns immediately; the actual reply is delivered as
//     `message.updated` + `message.part.updated` + `session.status` (idle)
//     events on the SSE stream (src/stores/events.ts).
//
// Two modes:
//   - Normal mode: implements the endpoints above so the app can connect,
//     open a session, send a message, and render a canned assistant reply.
//   - `--fail-auth` mode: every request returns 401, simulating a
//     connect-time auth failure (GitHub issue #76's failure class). Used by
//     .maestro/flows/activation-negative-401.yaml to assert the app surfaces
//     a visible, actionable error instead of failing silently.
//
// Usage:
//   node tests/fixtures/mock-opencode-server.ts --port 4096
//   node tests/fixtures/mock-opencode-server.ts --port 4097 --fail-auth

import http from "node:http"
import { randomUUID } from "node:crypto"

export interface MockServerOptions {
  port: number
  /** When true, ALL requests return 401 (simulates issue #76's connect-time auth failure). */
  failAuth?: boolean
  /** Canned assistant reply text streamed back after a prompt is submitted. */
  replyText?: string
  /** Delay before the canned reply is pushed over SSE, in ms. */
  replyDelayMs?: number
}

interface StoredSession {
  id: string
  slug: string
  projectID: string
  directory: string
  title: string
  version: string
  time: { created: number; updated: number }
}

interface StoredPart {
  id: string
  sessionID: string
  messageID: string
  type: string
  text?: string
}

interface StoredMessageInfo {
  id: string
  sessionID: string
  role: "user" | "assistant"
  time: { created: number; completed?: number }
  modelID?: string
  providerID?: string
}

interface StoredMessage {
  info: StoredMessageInfo
  parts: StoredPart[]
}

export const DEFAULT_REPLY_TEXT = "Hello from the mock opencode server — activation e2e canned reply."

export function createMockOpencodeServer(opts: MockServerOptions) {
  const { port, failAuth = false, replyText = DEFAULT_REPLY_TEXT, replyDelayMs = 300 } = opts

  const sessions = new Map<string, StoredSession>()
  const messagesBySession = new Map<string, StoredMessage[]>()
  const sseClients = new Set<http.ServerResponse>()

  function broadcast(type: string, properties: Record<string, unknown>) {
    const line = `data: ${JSON.stringify({ type, properties })}\n\n`
    for (const res of sseClients) {
      try {
        res.write(line)
      } catch {
        sseClients.delete(res)
      }
    }
  }

  function json(res: http.ServerResponse, status: number, body: unknown) {
    const data = JSON.stringify(body)
    res.writeHead(status, {
      "Content-Type": "application/json",
      "Content-Length": Buffer.byteLength(data),
    })
    res.end(data)
  }

  function unauthorized(res: http.ServerResponse) {
    json(res, 401, {
      error: "Unauthorized",
      message: "mock-opencode-server: running in --fail-auth mode (simulates GitHub issue #76)",
    })
  }

  function scheduleReply(sessionID: string) {
    const list = messagesBySession.get(sessionID)
    if (!list) return

    setTimeout(() => {
      broadcast("session.status", { sessionID, status: { type: "busy" } })

      const now = Date.now()
      const messageID = randomUUID()
      const info: StoredMessageInfo = {
        id: messageID,
        sessionID,
        role: "assistant",
        time: { created: now },
        modelID: "mock-model",
        providerID: "mock",
      }
      broadcast("message.updated", { info })

      const part: StoredPart = {
        id: randomUUID(),
        sessionID,
        messageID,
        type: "text",
        text: replyText,
      }
      broadcast("message.part.updated", { part })

      list.push({ info: { ...info, time: { created: now, completed: Date.now() } }, parts: [part] })

      broadcast("session.status", { sessionID, status: { type: "idle" } })
    }, replyDelayMs)
  }

  const server = http.createServer((req, res) => {
    const url = new URL(req.url || "/", `http://localhost:${port}`)
    const path = url.pathname
    const method = req.method || "GET"

    if (failAuth) {
      unauthorized(res)
      return
    }

    if (method === "GET" && path === "/global/health") {
      return json(res, 200, { healthy: true, version: "0.0.0-mock" })
    }

    if (method === "GET" && path === "/project/current") {
      return json(res, 200, {
        id: "mock-project",
        name: "mock-project",
        path: { cwd: "/mock/project", root: "/mock/project", absolute: "/mock/project" },
      })
    }
    if (method === "GET" && path === "/project") {
      return json(res, 200, [])
    }
    if (method === "GET" && path === "/path") {
      return json(res, 200, {
        home: "/mock/home",
        state: "/mock/home/.local/state/opencode",
        config: "/mock/home/.config/opencode",
        worktree: "/mock/project",
        directory: "/mock/project",
      })
    }

    if (method === "GET" && path === "/agent") {
      return json(res, 200, [{ name: "build", mode: "primary", options: {} }])
    }
    if (method === "GET" && path === "/command") {
      return json(res, 200, [])
    }
    if (method === "GET" && path === "/provider") {
      return json(res, 200, {
        all: [
          {
            id: "mock",
            name: "Mock Provider",
            models: {
              "mock-model": {
                id: "mock-model",
                name: "Mock Model",
                attachment: false,
                reasoning: false,
                tool_call: false,
                limit: { context: 8000, output: 2000 },
                status: "active",
              },
            },
          },
        ],
        default: { mock: "mock-model" },
        connected: ["mock"],
      })
    }
    if (method === "GET" && path === "/permission") {
      return json(res, 200, [])
    }
    if (method === "GET" && path === "/question") {
      return json(res, 200, [])
    }

    // SSE event stream — kept open for the lifetime of the connection.
    if (method === "GET" && path === "/global/event") {
      res.writeHead(200, {
        "Content-Type": "text/event-stream",
        "Cache-Control": "no-cache",
        Connection: "keep-alive",
      })
      res.write(": connected\n\n")
      sseClients.add(res)
      req.on("close", () => sseClients.delete(res))
      return
    }

    if (method === "POST" && path === "/session") {
      const id = randomUUID()
      const now = Date.now()
      const session: StoredSession = {
        id,
        slug: id.slice(0, 8),
        projectID: "mock-project",
        directory: "/mock/project",
        title: "Mock Session",
        version: "0.0.0-mock",
        time: { created: now, updated: now },
      }
      sessions.set(id, session)
      messagesBySession.set(id, [])
      return json(res, 200, session)
    }
    if (method === "GET" && path === "/session") {
      return json(res, 200, Array.from(sessions.values()))
    }

    const sessionMessageMatch = path.match(/^\/session\/([^/]+)\/message$/)
    if (method === "GET" && sessionMessageMatch) {
      const sid = sessionMessageMatch[1]
      return json(res, 200, messagesBySession.get(sid) || [])
    }

    const promptMatch = path.match(/^\/session\/([^/]+)\/prompt_async$/)
    if (method === "POST" && promptMatch) {
      const sid = promptMatch[1]
      let body = ""
      req.on("data", (chunk) => (body += chunk))
      req.on("end", () => {
        if (!sessions.has(sid)) {
          return json(res, 404, { error: `unknown session ${sid}` })
        }
        json(res, 200, { ok: true })
        scheduleReply(sid)
      })
      return
    }

    const abortMatch = path.match(/^\/session\/([^/]+)\/abort$/)
    if (method === "POST" && abortMatch) {
      return json(res, 200, true)
    }

    json(res, 404, { error: `mock-opencode-server: no handler for ${method} ${path}` })
  })

  return {
    server,
    url: `http://localhost:${port}`,
    listen(): Promise<void> {
      return new Promise((resolve) => server.listen(port, "0.0.0.0", () => resolve()))
    },
    close(): Promise<void> {
      for (const res of sseClients) {
        try {
          res.end()
        } catch {
          // ignore
        }
      }
      sseClients.clear()
      return new Promise((resolve, reject) => {
        server.close((err) => (err ? reject(err) : resolve()))
      })
    },
  }
}

function parseArgs(argv: string[]): { port: number; failAuth: boolean } {
  const opts = { port: 4096, failAuth: false }
  for (let i = 0; i < argv.length; i++) {
    if (argv[i] === "--port") opts.port = Number(argv[++i])
    else if (argv[i] === "--fail-auth") opts.failAuth = true
  }
  return opts
}

const invokedDirectly =
  typeof process !== "undefined" && process.argv[1] && import.meta.url === `file://${process.argv[1]}`

if (invokedDirectly) {
  const opts = parseArgs(process.argv.slice(2))
  const mock = createMockOpencodeServer(opts)
  mock.listen().then(() => {
    console.log(`[mock-opencode-server] listening on ${mock.url} (failAuth=${opts.failAuth})`)
  })
  const shutdown = () => {
    mock.close().then(() => process.exit(0))
  }
  process.on("SIGINT", shutdown)
  process.on("SIGTERM", shutdown)
}