package loop

import (
	"context"
	"fmt"

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

// streamStep drives a streaming model call. It is the streaming counterpart of
// agent.RunStep: it builds the request from the agent's public surface, runs the
// loop's input guardrail, streams deltas through OnStream, runs the output
// guardrail and decodes any tool calls. Because RunStep does not expose a stream
// path, this method is owned by the loop; it mirrors the agent's semantics so the
// two behave identically apart from the delta callback.
func (l *Loop) streamStep(ctx context.Context, messages []model.Message) (*stepOutcome, error) {
	adapter := l.agent.Adapter()
	if adapter == nil {
		return nil, fmt.Errorf("loop: stream step: %w", ErrNoAdapter)
	}
	req := l.buildRequest(ctx, messages)

	if l.guards != nil {
		verdict, err := l.guards.CheckInput(ctx, &req)
		if err != nil {
			return nil, fmt.Errorf("loop: check input: %w", err)
		}
		if verdict != nil && !verdict.Allow {
			return &stepOutcome{final: true, text: verdict.Reason, stopReason: agent.StopReasonGuardrailInput}, nil
		}
	}

	resp, err := adapter.ChatStream(ctx, req, func(ev model.StreamEvent) {
		// Suppress UI broadcast for internal autonomous passes (backthink),
		// whose intermediate reasoning must not leak into the chat stream.
		if l.onStream != nil && !isMutedBroadcast(ctx) {
			l.onStream(ev)
		}
	})
	if err != nil {
		return nil, fmt.Errorf("loop: chat stream: %w", err)
	}

	if l.guards != nil {
		verdict, err := l.guards.CheckOutput(ctx, &resp)
		if err != nil {
			return nil, fmt.Errorf("loop: check output: %w", err)
		}
		if verdict != nil && !verdict.Allow {
			return &stepOutcome{final: true, text: verdict.Reason, stopReason: agent.StopReasonGuardrailOutput}, nil
		}
	}

	if calls, ok := decodeToolCalls(resp); ok {
		return &stepOutcome{final: false, toolCalls: calls, stopReason: agent.StopReasonToolCalls}, nil
	}
	return &stepOutcome{final: true, text: resp.Content, stopReason: agent.StopReasonStop}, nil
}