package main

import (
	"context"
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
)

func fakeChat(t *testing.T, status int, reply string) (*ChatBrain, *http.Request) {
	t.Helper()
	var got http.Request
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		got = *r
		var body map[string]any
		if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
			t.Errorf("request body is not JSON: %v", err)
		}
		if body["model"] != "openrouter/free" {
			t.Errorf("model = %v", body["model"])
		}
		w.WriteHeader(status)
		w.Write([]byte(reply))
	}))
	t.Cleanup(srv.Close)
	return &ChatBrain{provider: "OpenRouter", url: srv.URL, key: "k", model: "openrouter/free", client: srv.Client(),
		headers: map[string]string{"X-OpenRouter-Title": "So Many Crows"}}, &got
}

func TestChatBrainReply(t *testing.T) {
	b, req := fakeChat(t, 200, `{"model":"some/model:free","choices":[{"message":{"content":"caw"}}],"usage":{"prompt_tokens":10,"completion_tokens":5}}`)
	var model string
	text, tokens, err := b.Ask(withModelSlot(context.Background(), &model), "sys", "hi")
	if err != nil || text != "caw" || tokens != 15 || model != "some/model:free" {
		t.Fatalf("got %q %d %q %v", text, tokens, model, err)
	}
	if req.Header.Get("Authorization") != "Bearer k" || req.Header.Get("X-OpenRouter-Title") != "So Many Crows" {
		t.Fatalf("headers: %v", req.Header)
	}
}

func TestChatBrainEstimatesTokensWhenUsageMissing(t *testing.T) {
	b, _ := fakeChat(t, 200, `{"choices":[{"message":{"content":"`+strings.Repeat("a", 400)+`"}}]}`)
	_, tokens, err := b.Ask(context.Background(), "", "")
	if err != nil || tokens != 100 {
		t.Fatalf("tokens = %d, err %v; want the 4-chars-per-token estimate so budgets still bite", tokens, err)
	}
}

func TestChatBrainErrors(t *testing.T) {
	for name, c := range map[string]struct {
		status int
		body   string
		want   string
	}{
		"rate limit": {429, `{"error":{"message":"Rate limit exceeded"}}`, "429"},
		"error body": {200, `{"error":{"message":"no free models"}}`, "no free models"},
		"empty":      {200, `{"choices":[{"message":{"content":"  "}}]}`, "empty reply"},
	} {
		b, _ := fakeChat(t, c.status, c.body)
		if _, _, err := b.Ask(context.Background(), "s", "p"); err == nil || !strings.Contains(err.Error(), c.want) {
			t.Errorf("%s: err = %v, want %q", name, err, c.want)
		}
	}
}

func TestNewBrainPicksProvider(t *testing.T) {
	t.Setenv("ANTHROPIC_API_KEY", "")
	t.Setenv("OPENROUTER_API_KEY", "or")
	t.Setenv("CROWS_PROVIDER", "")
	t.Setenv("CROWS_MODEL", "")
	if got := NewBrain().Name(); got != "OpenRouter (openrouter/free)" {
		t.Fatalf("got %q", got)
	}
	t.Setenv("CROWS_PROVIDER", "anthropic")
	if got := NewBrain().Name(); got != "offline mock" {
		t.Fatalf("anthropic with no key should fall back to mock, got %q", got)
	}
}