package shared

import (
	"fmt"

	"git.flytoex.net/yuanwei/flyto-agent/pkg/flyto"
)

// CheckNoImageBlocks rejects requests whose messages contain flyto.BlockImage
// anywhere (top-level blocks OR nested inside BlockToolResult.ResultBlocks)
// with an explicit error instead of silently dropping the image block. Used
// by providers that have not yet wired vision support -- vision path routes
// through Anthropic for now; other providers call this at Stream entry to
// surface "your image never reached the model" loudly.
//
// Recursion note: when path B (tool returns image via Result.Data) wraps
// image blocks inside tool_result.ResultBlocks, a naive top-level-only scan
// would miss them and let the provider silently drop the nested image.
// This function recurses one level into ResultBlocks to catch that path.
// Deeper nesting (blocks containing blocks containing blocks) is not expected
// in the current Block model, so we stop at one level.
//
// providerName goes into the error message so the caller can tell which
// provider rejected the image.
//
// CheckNoImageBlocks 扫描请求消息, 顶层 block 或 BlockToolResult.ResultBlocks
// 嵌套层一旦出现 flyto.BlockImage 即返 error, 不做 silent drop. 未接 vision
// 的 provider 在 Stream 入口调用, 让调用方立刻知道"这张图没送到模型", 而
// 不是静默通过后纳闷为什么模型视若无睹. 当前 vision 路径只走 Anthropic, 其他
// provider 待 per-provider 启用.
//
// 递归说明: 路径 B (工具经 Result.Data 返图) 会把 image block 包在
// tool_result.ResultBlocks 里, 只扫顶层会漏, 让 provider 静默丢嵌套图.
// 本函数递归一层扫 ResultBlocks. 当前 Block 模型无更深嵌套预期, 一层即止.
//
// providerName 会写进 error message, 调用方可据此定位是谁拒的图.
func CheckNoImageBlocks(msgs []flyto.Message, providerName string) error {
	for _, msg := range msgs {
		for _, b := range msg.Blocks {
			if blockHasImage(b) {
				return fmt.Errorf("%s: BlockImage not yet supported by this provider (vision path currently routes through anthropic)", providerName)
			}
		}
	}
	return nil
}

// blockHasImage returns true for BlockImage directly or a BlockToolResult
// whose ResultBlocks contains a nested image. Centralizes recursion so
// CheckNoImageBlocks and future guards share the traversal.
//
// blockHasImage 对直接 BlockImage 或 BlockToolResult 内 ResultBlocks 嵌套
// image 返 true. 递归集中于此, 让 CheckNoImageBlocks 和未来其他 guard 共享
// 同一遍历.
func blockHasImage(b flyto.Block) bool {
	if b.Type == flyto.BlockImage {
		return true
	}
	if b.Type == flyto.BlockToolResult {
		for _, nested := range b.ResultBlocks {
			if nested.Type == flyto.BlockImage {
				return true
			}
		}
	}
	return false
}