// Package eino 封装基于 CloudWeGo Eino 的 Agent 图编排引擎。
package eino

import (
	"context"
	"log"

	"github.com/sundynix/sundynix-dispatcher/internal/harness"
	"github.com/sundynix/sundynix-dispatcher/internal/llm"
	"github.com/sundynix/sundynix-shared/contract"
)

// TokenSink 是 Token 流回流出口（由 NATS bus 实现）。
type TokenSink interface {
	PublishToken(taskID string, token []byte) error
	CompleteStream(taskID string) error
}

// Orchestrator 将 DSL 图编译为 Eino Graph 并驱动执行。
type Orchestrator struct {
	pool    *llm.Pool
	breaker *harness.CircuitBreaker
	sink    TokenSink
}

func NewOrchestrator(pool *llm.Pool, breaker *harness.CircuitBreaker, sink TokenSink) *Orchestrator {
	return &Orchestrator{pool: pool, breaker: breaker, sink: sink}
}

// Handle 消费一个任务：编译图 → 流式推理 → 经 sink 把 Token 回流到 sundynix.streams.<id>。
func (o *Orchestrator) Handle(ctx context.Context, t *contract.Task) error {
	if !o.breaker.Allow() {
		log.Printf("[eino] circuit open, drop task %s", t.ID)
		return nil
	}
	log.Printf("[eino] task %s received (graph=%d bytes), streaming tokens...", t.ID, len(t.Graph))

	// TODO: compose.NewGraph(...) 编译 DSL；此处 prompt 占位为图原文。
	//       工具节点经 NATS 调用第 5 层 MCP（sundynix.tools.go.* / sundynix.tools.py.*）。
	prompt := string(t.Graph)

	n := 0
	err := o.pool.Stream(ctx, prompt, func(tok []byte) {
		if perr := o.sink.PublishToken(t.ID, tok); perr != nil {
			log.Printf("[eino] publish token failed: %v", perr)
			return
		}
		n++
	})
	if err != nil {
		log.Printf("[eino] task %s stream error: %v", t.ID, err)
	}

	if cerr := o.sink.CompleteStream(t.ID); cerr != nil {
		log.Printf("[eino] complete stream failed: %v", cerr)
	}
	log.Printf("[eino] task %s done, %d tokens streamed", t.ID, n)
	o.breaker.Report(err == nil)
	return err
}