package loop

import (
	"context"

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

// ImageResolver is the loop's seam to the multimodal vision layer (design/06
// §0). It is called once at the start of Run for every message that carries an
// image content part, and may rewrite that message so the main model can reason
// over the image. The concrete resolver lives in the vision package and decides,
// via the vision Router, whether to keep the image for a vision-capable main
// model or fold it into a text description produced by the vision/OCR tool ("先
// 看图再对话"). Nil leaves the image content untouched so it flows straight to a
// vision-capable main model.
type ImageResolver interface {
	// Resolve rewrites msg, which carries at least one image content part. It
	// returns the (possibly rewritten) message. An error leaves the original
	// message in place so the turn still proceeds.
	Resolve(ctx context.Context, msg model.Message) (model.Message, error)
}

// ImageResolveFunc adapts a function to the ImageResolver interface.
type ImageResolveFunc func(ctx context.Context, msg model.Message) (model.Message, error)

// Resolve implements ImageResolver.
func (f ImageResolveFunc) Resolve(ctx context.Context, msg model.Message) (model.Message, error) {
	return f(ctx, msg)
}

// resolveImages rewrites every image-bearing message in messages using the
// injected resolver. It returns the input slice unchanged when no resolver is
// configured, no image is present, or a message fails to resolve (the failure is
// logged and the original message is kept so the turn still runs). A fresh slice
// is returned when any message changed.
func (l *Loop) resolveImages(ctx context.Context, messages []model.Message) []model.Message {
	if l.imageResolver == nil {
		return messages
	}
	out := make([]model.Message, len(messages))
	changed := false
	for i, m := range messages {
		if !messageHasImage(m) {
			out[i] = m
			continue
		}
		resolved, err := l.imageResolver.Resolve(ctx, m)
		if err != nil {
			l.log.Warn("image resolve", "error", err)
			out[i] = m
			continue
		}
		out[i] = resolved
		changed = true
	}
	if !changed {
		return messages
	}
	return out
}

// messageHasImage reports whether any content part of msg is an image part.
func messageHasImage(m model.Message) bool {
	for _, part := range m.Content {
		if part.Type == model.ContentTypeImage {
			return true
		}
	}
	return false
}