package coverart

import (
	"context"
	"errors"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
	"time"
)

func TestFetcher_Success(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if !strings.Contains(r.URL.Path, "/release/abc-123/front-500") {
			http.Error(w, "wrong path", http.StatusBadRequest)
			return
		}
		w.Header().Set("Content-Type", "image/jpeg")
		_, _ = w.Write([]byte("FAKE_JPEG"))
	}))
	defer srv.Close()

	f := NewFetcher(FetcherConfig{
		BaseURL:    srv.URL,
		UserAgent:  "Minstrel/test (https://example.com)",
		MinPeriod:  0,
		HTTPClient: srv.Client(),
	})

	body, err := f.Fetch(context.Background(), "abc-123")
	if err != nil {
		t.Fatalf("Fetch: %v", err)
	}
	if string(body) != "FAKE_JPEG" {
		t.Errorf("body = %q, want FAKE_JPEG", string(body))
	}
}

func TestFetcher_NotFound(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		http.Error(w, "not found", http.StatusNotFound)
	}))
	defer srv.Close()
	f := NewFetcher(FetcherConfig{BaseURL: srv.URL, UserAgent: "test", MinPeriod: 0, HTTPClient: srv.Client()})
	_, err := f.Fetch(context.Background(), "missing")
	if !errors.Is(err, ErrNotFound) {
		t.Errorf("err = %v, want ErrNotFound", err)
	}
}

func TestFetcher_5xxIsTransient(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		http.Error(w, "boom", http.StatusInternalServerError)
	}))
	defer srv.Close()
	f := NewFetcher(FetcherConfig{BaseURL: srv.URL, UserAgent: "test", MinPeriod: 0, HTTPClient: srv.Client()})
	_, err := f.Fetch(context.Background(), "any")
	if !errors.Is(err, ErrTransient) {
		t.Errorf("err = %v, want ErrTransient", err)
	}
}

func TestFetcher_SendsUserAgent(t *testing.T) {
	var seen string
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		seen = r.Header.Get("User-Agent")
		_, _ = w.Write([]byte("ok"))
	}))
	defer srv.Close()
	f := NewFetcher(FetcherConfig{
		BaseURL:    srv.URL,
		UserAgent:  "Minstrel/0.1 (https://example.org)",
		MinPeriod:  0,
		HTTPClient: srv.Client(),
	})
	_, _ = f.Fetch(context.Background(), "ua-test")
	if seen != "Minstrel/0.1 (https://example.org)" {
		t.Errorf("UA = %q", seen)
	}
}

func TestFetcher_RateLimitSpacesCalls(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		_, _ = w.Write([]byte("ok"))
	}))
	defer srv.Close()
	f := NewFetcher(FetcherConfig{
		BaseURL:    srv.URL,
		UserAgent:  "test",
		MinPeriod:  150 * time.Millisecond,
		HTTPClient: srv.Client(),
	})
	start := time.Now()
	_, _ = f.Fetch(context.Background(), "a")
	_, _ = f.Fetch(context.Background(), "b")
	elapsed := time.Since(start)
	if elapsed < 150*time.Millisecond {
		t.Errorf("two calls in %v — rate limiter not enforcing", elapsed)
	}
}

func TestFetcher_EmptyMBID(t *testing.T) {
	f := NewFetcher(FetcherConfig{UserAgent: "test", MinPeriod: 0})
	_, err := f.Fetch(context.Background(), "")
	if err == nil {
		t.Error("expected error for empty mbid")
	}
}