package orchestration

import (
	"context"
	"sync"
	"time"

	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/loop"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/memory"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/model"
)

// SubAgent is a single spawned sub-agent instance. The identity fields (ID, Goal,
// RoleID, Mode, AttachInfo, Data, Context, WorkingMemory) are set once at Spawn
// and never mutated. The lifecycle fields (Status, Summary, Result, Err) are
// written by the sub-agent's background goroutine and read through the
// synchronized accessors below, so reading them before the sub-agent finishes is
// safe. A sub-agent is terminal exactly once its Done reports true; Join returns
// once every sub-agent is terminal.
//
// SubAgent is created by (*Scheduler).Spawn; it should not be built directly.
type SubAgent struct {
	// ID uniquely identifies the sub-agent within its scheduler.
	ID string
	// Goal is the objective the sub-agent pursues.
	Goal string
	// RoleID is the bound role/persona.
	RoleID string
	// Mode is the bound behavior mode.
	Mode string
	// AttachInfo is the free-form attachment text supplied at spawn.
	AttachInfo string
	// Data is the optional structured payload supplied at spawn.
	Data any
	// Context is the isolated conversation context. It is a deep copy of the
	// AgentSpec.Context and is never shared with the front session.
	Context []model.Message
	// WorkingMemory is the sub-agent's own working-memory window, created fresh
	// at Spawn so it never overlaps another sub-agent or the front session.
	WorkingMemory *memory.WorkingMemory

	mu       sync.RWMutex
	status   Status
	summary  string
	result   *loop.Result
	runErr   error
	started  time.Time
	finished time.Time

	done       chan struct{}
	cancel     context.CancelFunc
	abortReq   bool
	doneClosed bool

	launchOnce sync.Once
	finishOnce sync.Once
}

// Status returns the sub-agent's current lifecycle status.
func (s *SubAgent) Status() Status {
	s.mu.RLock()
	defer s.mu.RUnlock()
	return s.status
}

// Summary returns the execution summary written when the sub-agent finalized:
// a completion summary on success, or a failure/abort reason otherwise. It is
// empty until the sub-agent is terminal.
func (s *SubAgent) Summary() string {
	s.mu.RLock()
	defer s.mu.RUnlock()
	return s.summary
}

// Result returns the loop result on a successful run, or nil when the run failed
// or was aborted.
func (s *SubAgent) Result() *loop.Result {
	s.mu.RLock()
	defer s.mu.RUnlock()
	return s.result
}

// Err returns the error that ended a failed or aborted run (nil on success).
func (s *SubAgent) Err() error {
	s.mu.RLock()
	defer s.mu.RUnlock()
	return s.runErr
}

// StartedAt returns when the sub-agent transitioned to running (zero if it never
// started).
func (s *SubAgent) StartedAt() time.Time {
	s.mu.RLock()
	defer s.mu.RUnlock()
	return s.started
}

// FinishedAt returns when the sub-agent reached a terminal state (zero if not
// terminal yet).
func (s *SubAgent) FinishedAt() time.Time {
	s.mu.RLock()
	defer s.mu.RUnlock()
	return s.finished
}

// Done reports whether the sub-agent reached a terminal state.
func (s *SubAgent) Done() bool { return s.Status().Terminal() }

// Snapshot returns a point-in-time copy of the sub-agent's state, safe to read
// while the sub-agent is still running.
func (s *SubAgent) Snapshot() SubAgentResult {
	s.mu.RLock()
	defer s.mu.RUnlock()
	snap := SubAgentResult{
		ID:         s.ID,
		Goal:       s.Goal,
		RoleID:     s.RoleID,
		Mode:       s.Mode,
		AttachInfo: s.AttachInfo,
		Status:     s.status,
		Summary:    s.summary,
		Err:        s.runErr,
		StartedAt:  s.started,
		FinishedAt: s.finished,
	}
	if s.result != nil {
		snap.Text = s.result.Text
		snap.Steps = s.result.Steps
	}
	return snap
}

// transitionRunning moves a pending sub-agent to running. It returns false when
// the sub-agent was already aborted (so it must not run) or is not pending.
func (s *SubAgent) transitionRunning() bool {
	s.mu.Lock()
	defer s.mu.Unlock()
	if s.abortReq || s.status != StatusPending {
		return false
	}
	s.status = StatusRunning
	s.started = time.Now()
	return true
}

// progress returns the current status snapshot for a progress event.
func (s *SubAgent) progress() Progress {
	s.mu.RLock()
	defer s.mu.RUnlock()
	return Progress{
		AgentID: s.ID,
		Goal:    s.Goal,
		RoleID:  s.RoleID,
		Mode:    s.Mode,
		Status:  s.status,
	}
}

// setOutcome records the terminal status, summary and error after the run ends.
// It is called at most once per sub-agent, guarded by finishOnce.
func (s *SubAgent) setOutcome(status Status, summary string, err error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.status = status
	s.summary = summary
	s.runErr = err
	s.finished = time.Now()
}

// setResult records the successful loop result.
func (s *SubAgent) setResult(res *loop.Result) {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.result = res
}

// setCancel stores the run context's cancel function so Abort can interrupt the
// loop. If the sub-agent was already aborted (cancelRun raced ahead), the stored
// cancel is invoked immediately.
func (s *SubAgent) setCancel(c context.CancelFunc) {
	s.mu.Lock()
	s.cancel = c
	aborted := s.abortReq
	s.mu.Unlock()
	if aborted {
		c()
	}
}

// cancelRun requests cancellation of the sub-agent. It is idempotent and safe for
// concurrent use: the done channel is closed once and the stored cancel (when set)
// is invoked once. A pending sub-agent unblocks from its parallel slot via done; a
// running sub-agent is interrupted via the cancel func.
func (s *SubAgent) cancelRun() {
	s.mu.Lock()
	s.abortReq = true
	c := s.cancel
	first := !s.doneClosed
	s.doneClosed = true
	s.mu.Unlock()
	if first {
		close(s.done)
	}
	if c != nil {
		c()
	}
}

// aborted reports whether a cancellation was requested for the sub-agent.
func (s *SubAgent) aborted() bool {
	s.mu.RLock()
	defer s.mu.RUnlock()
	return s.abortReq
}