// A lead session's team at work (harness spec 3.2.0, team.md): the rules of team.ts driven by real
// turns. The lead is the session's own engine; each member is a subagent engine of its own (the job
// machinery, app.ts spawn), started when the team gives it a slot. What the rules decide happens
// through three effects: a turn starts (a member's brief, a woken agent's messages), a message reaches
// a working agent at its next step, an agent is stopped.
import type { Bus } from "../bus/index.ts"
import { TOOL_SPECS } from "../harness.ts"
import type { Engine } from "../session/engine.ts"
import type { Tool } from "../tool/tool.ts"
import { parallelFrom, Team, TEAM, type TeamAgent } from "./team.ts"

/** A member's engine, as the app made it. */
export interface MemberHandle {
  engine: Engine
  /** Its next turn, with this text as the prompt (its context intact). */
  run(text: string): void
  /** Stop it where it is; nothing more comes from it. */
  cancel(): void
}

export interface RuntimeOptions {
  team: Team
  /** The lead's bus: where the team's news is said (`team` events). */
  bus: Bus
  /** Make a member's engine (attached here with `attach`) and start its first turn with `text`. */
  spawnMember(member: TeamAgent, text: string): void
  /** The lead: a message at its next step (`note`), or — idle — a turn of its own (`wake`). */
  lead: { note(text: string): void; wake(text: string): void }
  /** An unknown agent or model, answered as task answers it; undefined when both are known. The
   *  model's ref as the session knows it. */
  resolve?(agent: string, model: string | undefined): { error: string } | { model: string }
}

export class TeamRuntime {
  team: Team
  private members = new Map<string, MemberHandle>()
  /** The lead's turn waiting for a slot: resolved when it is given one. */
  private leadWaiter: (() => void) | undefined

  constructor(private o: RuntimeOptions) {
    this.team = o.team
    this.wire()
  }

  private wire() {
    this.team.effects = {
      start: (name, text) => this.start(name, text),
      deliver: (name, text) => this.deliver(name, text),
      stop: (name) => this.stopped(name),
    }
  }

  /** Another session: its members are stopped, and the team starts again, empty. */
  reset(team: Team) {
    this.stopAll()
    this.leadWaiter = undefined
    this.team = team
    this.wire()
    this.changed()
  }

  private changed() {
    this.o.bus.emit({ type: "team" })
  }

  /** Something the tools did changed the team: said, for whoever shows it. */
  notify() {
    this.changed()
  }

  /** team_add for `as`: an unknown agent or model is answered as task answers it, after the
   *  team's own refusals (the name, the goal, the size), which come first. */
  add(as: string, a: { name: string; role: string; task: string; goal?: string; lead?: boolean; agent?: string; model?: string }): { text: string; added?: TeamAgent } {
    const agent = a.agent ?? "general"
    const r = this.o.resolve?.(agent, a.model) ?? { model: a.model ?? this.team.get(as)?.model ?? this.team.model }
    // The team's refusals first; an added member needs a known agent and model.
    const dry = this.team.wouldRefuse(as, a)
    if (dry) return { text: dry }
    if ("error" in r) return { text: r.error }
    const out = this.team.add(as, { ...a, agent, model: r.model })
    this.changed()
    return out
  }

  private start(name: string, text: string) {
    if (name === TEAM.names.lead) {
      const waiter = this.leadWaiter
      this.leadWaiter = undefined
      if (waiter) {
        // The person's turn was waiting: it goes now, and what woke it meanwhile goes in at its first step.
        if (text) this.o.lead.note(text)
        waiter()
      } else if (text) this.o.lead.wake(text)
      this.changed()
      return
    }
    const known = this.members.get(name)
    if (known) known.run(text)
    else {
      const m = this.team.get(name)
      if (m) this.o.spawnMember(m, text)
    }
    this.changed()
  }

  private deliver(name: string, text: string) {
    if (name === TEAM.names.lead) this.o.lead.note(text)
    else this.members.get(name)?.engine.note(text)
  }

  private stopped(name: string) {
    const h = this.members.get(name)
    this.members.delete(name)
    h?.cancel()
    this.changed()
  }

  /** The lead's turn is about to run: it holds a slot, or waits for one (the lead first). False
   *  when it was stopped while it waited. */
  async beforeLeadTurn(signal: AbortSignal): Promise<boolean> {
    const lead = this.team.get(TEAM.names.lead)!
    if (lead.state === "working") return true
    if (this.team.leadWants()) {
      this.changed()
      return true
    }
    this.o.bus.emit({ type: "notice", message: `waiting for a free slot: the model serves ${parallelFrom(this.team.capacityOf(this.team.model))} requests at once and the team's members hold them` })
    this.changed()
    return await new Promise<boolean>((resolve) => {
      const onAbort = () => {
        this.leadWaiter = undefined
        this.team.leadIdle()
        this.changed()
        resolve(false)
      }
      signal.addEventListener("abort", onAbort, { once: true })
      this.leadWaiter = () => {
        signal.removeEventListener("abort", onAbort)
        resolve(true)
      }
    })
  }

  /** The lead's turn ended. */
  leadDone() {
    this.team.finish(TEAM.names.lead)
    this.changed()
  }

  /** A member's turn ended: its reply is its report; messages it was given too late wake it again. */
  memberDone(name: string, reply: string, reason: string, leftover: string[]) {
    if (!this.team.get(name)) return
    this.team.finish(name, reply, reason)
    if (leftover.length) this.team.undelivered(name, leftover)
    this.changed()
  }

  /** What a call answers before its permission check, for the agent `as`. */
  refuse(as: string, tool: Tool, args: unknown): string | undefined {
    if (tool.name === "task" && as !== TEAM.names.lead) return undefined
    // A tool the spec does not have (an MCP server's) by the class its call carries: read when it
    // says readOnlyHint, interact for the server's memory, else execute.
    let risk: string | undefined
    if (!TOOL_SPECS[tool.name]) {
      try {
        risk = tool.permission(args as never, {} as never).class
      } catch {
        risk = "execute"
      }
    }
    return this.team.refusal(as, tool.name, args, risk)
  }

  /** The person stopped a member in the UI (/team stop). */
  personStop(name: string): string[] {
    const gone = this.team.personStop(name)
    this.changed()
    return gone
  }

  /** Stop every member: the lead's session ends or is left. */
  stopAll() {
    for (const m of this.team.membersOf(TEAM.names.lead)) this.team.personStop(m.name)
    this.team.forgetStopped()
    for (const h of this.members.values()) h.cancel()
    this.members.clear()
  }

  /** A member's engine, made. */
  attach(name: string, h: MemberHandle) {
    this.members.set(name, h)
  }

  handle(name: string): MemberHandle | undefined {
    return this.members.get(name)
  }
}