package modeladapter

import (
	"regexp"
	"strconv"
)

func maxAnthropicTokens(req StreamRequest) int {
	if req.AnthropicMaxTokens > 0 {
		return req.AnthropicMaxTokens
	}
	if req.MaxTokens > 0 {
		return req.MaxTokens
	}
	return 65536
}

// anthropicOutputLimitPattern 匹配 one-api/new-api 风格网关在 max_tokens 超限时的 400 错误：
// "Requested token count exceeds the configured maximum output length of 131072 tokens."
var anthropicOutputLimitPattern = regexp.MustCompile(`exceeds the configured maximum output length of (\d+) tokens`)

// anthropicOutputLimitFromError 从网关错误文本中提取其声明的最大输出上限；不匹配或解析失败返回 0。
func anthropicOutputLimitFromError(err error) int {
	if err == nil {
		return 0
	}
	matches := anthropicOutputLimitPattern.FindStringSubmatch(err.Error())
	if len(matches) < 2 {
		return 0
	}
	limit, parseErr := strconv.Atoi(matches[1])
	if parseErr != nil || limit <= 0 {
		return 0
	}
	return limit
}

// anthropicBodyMaxTokens 读取既有请求体中实际发送的 max_tokens；
// 常规构造为 int，RequestBodyOverride 反序列化产物为 float64，两者都兼容。
func anthropicBodyMaxTokens(body map[string]any) int {
	switch value := body["max_tokens"].(type) {
	case int:
		return value
	case int64:
		return int(value)
	case float64:
		return int(value)
	default:
		return 0
	}
}

func maxThinkingBudget(req StreamRequest) int {
	if req.ThinkingBudgetTokens > 0 {
		return req.ThinkingBudgetTokens
	}
	return anthropicThinkingBudget(maxAnthropicTokens(req))
}