package llm

import (
	"context"
	"errors"
	"fmt"
	"io"
	"testing"
	"time"
)

// TestIsTransientStream 钉住"该重发"与"重发也没用"的分界：前者是网关/传输层的偶发
// 坏流，后者是确定性失败——把后者卷进重试环就是白烧预算 + 把一次明确的错误拖成十分钟。
func TestIsTransientStream(t *testing.T) {
	cases := []struct {
		name string
		err  error
		want bool
	}{
		{"nil", nil, false},
		{"整轮空补全", fmt.Errorf("openai: %w", ErrEmptyCompletion), true},
		{"流被截断", fmt.Errorf("anthropic: %w", ErrTruncatedStream), true},
		{"流卡死到看门狗上限", &StalledError{Idle: 90 * time.Second}, true},
		{"包过一层的卡死", fmt.Errorf("stream: %w", &StalledError{Idle: time.Minute}), true},
		{"连接被掐", errors.New("read tcp 10.0.0.5:52314->1.2.3.4:443: connection reset by peer"), true},
		{"连接被拒", errors.New("dial tcp 1.2.3.4:443: connect: connection refused"), true},
		{"读超时", errors.New("read tcp: i/o timeout"), true},
		{"裸 EOF", io.EOF, true},
		{"网关过载", errors.New("openai: HTTP 503: upstream busy"), true},
		{"限流", errors.New("openai: HTTP 429 Too Many Requests"), true},
		// 以下都是"重发只会再撞一次同一堵墙"。
		{"请求不合法", errors.New(`openai: HTTP 400: {"error":{"message":"inference request is invalid","code":"400002"}}`), false},
		{"上游拒了这条请求", errors.New(`openai: HTTP 400: {"error":{"code":"upstream_request_rejected","message":"Bad Request","type":"invalid_request_error"}}`), false},
		{"没权限", errors.New("openai: HTTP 401: invalid api key"), false},
		{"余额不足", errors.New("anthropic: credit balance is too low"), false},
		{"上下文满", errors.New("openai: model_context_window_exceeded"), false},
		{"用户取消", context.Canceled, false},
		{"外部 deadline", context.DeadlineExceeded, false},
	}
	for _, c := range cases {
		t.Run(c.name, func(t *testing.T) {
			if got := IsTransientStream(c.err); got != c.want {
				t.Errorf("IsTransientStream(%v) = %v, want %v", c.err, got, c.want)
			}
		})
	}
}