#pragma once

// The seam between the Scheduler and CORE's engine. Everything the Scheduler drives on the
// engine goes through this interface, so the Scheduler is unit-testable without a live
// engine and the daemon is not bound to the concrete `vdm::Engine`. The real
// implementation (engine_port_core, added when velox::core's stage-8 bodies reach main)
// wraps `vdm::Engine` + `vdm::segment::SegmentBudget`; FakeEnginePort records calls.
//
// Task ids here are `vdm::TaskId` — the engine assigns one from start() and the Scheduler
// keeps the wire-UUID <-> TaskId map (ADR 0013). Admission is the Scheduler's: it calls
// start() only for a task the governor admitted, and the engine begins probing at once
// (it does not queue). The min-1 fairness rule in SegmentBudget then guarantees each
// started task a slot; set_task_order pushes the priority.

#include <cstdint>
#include <functional>
#include <string>
#include <vector>

#include "vdm/ids.hpp"
#include "vdm/task/download.hpp"

namespace velox::daemon::sched {

class EnginePort {
public:
    virtual ~EnginePort() = default;

    virtual vdm::TaskId start(const vdm::task::DownloadSpec& spec,
                              vdm::task::DownloadCallbacks callbacks) = 0;

    virtual void pause(vdm::TaskId) = 0;
    virtual void resume(vdm::TaskId) = 0;
    virtual void cancel(vdm::TaskId, bool discard_partial) = 0;
    virtual void provide_auth(vdm::TaskId, const std::string& username,
                              const std::string& password, bool remember) = 0;
    virtual void decide(vdm::TaskId, vdm::task::Decision) = 0;
    virtual void refresh_url(vdm::TaskId, const std::string& url) = 0;

    // The daemon is done with this task (it went terminal). Drop the handle. Idempotent.
    virtual void release(vdm::TaskId) = 0;

    // ADR 0011 admission surface. Values are DAEMON's; enforcement is the engine's.
    virtual void set_task_order(const std::vector<vdm::TaskId>& order) = 0;
    virtual void set_max_active_segments(std::uint32_t n) = 0;
    virtual void set_host_segment_cap(const std::string& host, std::uint32_t cap) = 0;
};

}  // namespace velox::daemon::sched