package llm

import (
	"context"
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"sync/atomic"
	"testing"
	"time"
)

func TestEndpointNormalization(t *testing.T) {
	cases := map[string]string{
		"http://h:4001":       "http://h:4001/v1/chat/completions",
		"http://h:4001/":      "http://h:4001/v1/chat/completions",
		"http://h:4001/v1":    "http://h:4001/v1/chat/completions",
		"http://h:4001/v1/":   "http://h:4001/v1/chat/completions",
		"http://h/prefix":     "http://h/prefix/v1/chat/completions",
		"http://h/prefix/v1/": "http://h/prefix/v1/chat/completions",
	}
	for in, want := range cases {
		c := NewClient(in, "k", time.Second, 0)
		if c.endpoint != want {
			t.Errorf("NewClient(%q).endpoint = %q, want %q", in, c.endpoint, want)
		}
	}
}

func TestChatSendsAuthAndModel(t *testing.T) {
	var gotAuth, gotModel string
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		gotAuth = r.Header.Get("Authorization")
		var req ChatRequest
		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
			t.Errorf("decode request: %v", err)
		}
		gotModel = req.Model
		w.Write([]byte(`{"choices":[{"message":{"role":"assistant","content":"hi"},"finish_reason":"stop"}],"usage":{"prompt_tokens":1,"completion_tokens":2,"total_tokens":3}}`))
	}))
	defer srv.Close()
	c := NewClient(srv.URL, "sk-test", time.Second, 0)
	resp, err := c.Chat(context.Background(), ChatRequest{Model: "glm-5.3", Messages: []Message{{Role: "user", Content: "x"}}})
	if err != nil {
		t.Fatalf("Chat: %v", err)
	}
	if gotAuth != "Bearer sk-test" {
		t.Errorf("auth = %q", gotAuth)
	}
	if gotModel != "glm-5.3" {
		t.Errorf("model = %q", gotModel)
	}
	if resp.Choices[0].Message.Content != "hi" || resp.Usage.TotalTokens != 3 {
		t.Errorf("resp = %+v", resp)
	}
}

func TestChatRetriesOn5xxThenSucceeds(t *testing.T) {
	var calls atomic.Int32
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if calls.Add(1) == 1 {
			http.Error(w, "upstream lost", http.StatusBadGateway)
			return
		}
		w.Write([]byte(`{"choices":[{"message":{"role":"assistant","content":"ok"},"finish_reason":"stop"}]}`))
	}))
	defer srv.Close()
	c := NewClient(srv.URL, "k", time.Second, 2)
	resp, err := c.Chat(context.Background(), ChatRequest{Model: "m"})
	if err != nil {
		t.Fatalf("Chat: %v", err)
	}
	if resp.Choices[0].Message.Content != "ok" || calls.Load() != 2 {
		t.Errorf("resp=%v calls=%d", resp, calls.Load())
	}
}

func TestChatNoRetryOn4xx(t *testing.T) {
	var calls atomic.Int32
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		calls.Add(1)
		http.Error(w, `{"error":"bad model"}`, http.StatusBadRequest)
	}))
	defer srv.Close()
	c := NewClient(srv.URL, "k", time.Second, 3)
	_, err := c.Chat(context.Background(), ChatRequest{Model: "m"})
	if err == nil {
		t.Fatal("expected error")
	}
	if calls.Load() != 1 {
		t.Errorf("4xx must not retry, calls=%d", calls.Load())
	}
}

func TestChatEmptyChoicesIsError(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Write([]byte(`{"choices":[]}`))
	}))
	defer srv.Close()
	c := NewClient(srv.URL, "k", time.Second, 0)
	if _, err := c.Chat(context.Background(), ChatRequest{Model: "m"}); err == nil {
		t.Fatal("expected empty-choices error")
	}
}