package api_test

import (
	"bufio"
	"bytes"
	"encoding/json"
	"fmt"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
	"time"

	"gitea.hansenits.com.au/hits/ExploreDNS/web/api"
)

// newTestServer starts a Server on a random port and returns it.
// The caller is responsible for calling srv.Shutdown.
func newTestServer(t *testing.T) *api.Server {
	t.Helper()
	srv := api.NewServer("127.0.0.1:0")
	if err := srv.Start(); err != nil {
		t.Fatalf("start server: %v", err)
	}
	return srv
}

func TestHealth(t *testing.T) {
	srv := newTestServer(t)
	defer srv.Shutdown(5 * time.Second) //nolint:errcheck

	resp, err := http.Get("http://" + srv.Addr() + "/api/health")
	if err != nil {
		t.Fatal(err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		t.Fatalf("want 200, got %d", resp.StatusCode)
	}
	var body map[string]string
	if err := json.NewDecoder(resp.Body).Decode(&body); err != nil {
		t.Fatal(err)
	}
	if body["status"] != "ok" {
		t.Fatalf("want status=ok, got %q", body["status"])
	}
}

func TestCORSPreflight(t *testing.T) {
	srv := newTestServer(t)
	defer srv.Shutdown(5 * time.Second) //nolint:errcheck

	req, _ := http.NewRequest(http.MethodOptions, "http://"+srv.Addr()+"/api/health", nil)
	req.Header.Set("Origin", "http://localhost:3000")
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatal(err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusNoContent {
		t.Fatalf("want 204, got %d", resp.StatusCode)
	}
	if got := resp.Header.Get("Access-Control-Allow-Origin"); got != "*" {
		t.Fatalf("CORS origin header: %q", got)
	}
}

func TestStartTraversal_MissingDomain(t *testing.T) {
	srv := newTestServer(t)
	defer srv.Shutdown(5 * time.Second) //nolint:errcheck

	body := bytes.NewBufferString(`{}`)
	resp, err := http.Post("http://"+srv.Addr()+"/api/traverse", "application/json", body)
	if err != nil {
		t.Fatal(err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusBadRequest {
		t.Fatalf("want 400, got %d", resp.StatusCode)
	}
}

func TestStartTraversal_InvalidType(t *testing.T) {
	srv := newTestServer(t)
	defer srv.Shutdown(5 * time.Second) //nolint:errcheck

	body := bytes.NewBufferString(`{"domain":"example.com","type":"BOGUS"}`)
	resp, err := http.Post("http://"+srv.Addr()+"/api/traverse", "application/json", body)
	if err != nil {
		t.Fatal(err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusBadRequest {
		t.Fatalf("want 400, got %d", resp.StatusCode)
	}
}

func TestStartTraversal_ReturnsID(t *testing.T) {
	srv := newTestServer(t)
	defer srv.Shutdown(5 * time.Second) //nolint:errcheck

	body := bytes.NewBufferString(`{"domain":"example.com","type":"A"}`)
	resp, err := http.Post("http://"+srv.Addr()+"/api/traverse", "application/json", body)
	if err != nil {
		t.Fatal(err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusAccepted {
		t.Fatalf("want 202, got %d", resp.StatusCode)
	}
	var start struct {
		ID     string `json:"id"`
		Status string `json:"status"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&start); err != nil {
		t.Fatal(err)
	}
	if start.ID == "" {
		t.Fatal("expected non-empty id")
	}
	if start.Status != "running" {
		t.Fatalf("want status=running, got %q", start.Status)
	}
}

func TestGetTraversal_NotFound(t *testing.T) {
	srv := newTestServer(t)
	defer srv.Shutdown(5 * time.Second) //nolint:errcheck

	resp, err := http.Get("http://" + srv.Addr() + "/api/traverse/does-not-exist")
	if err != nil {
		t.Fatal(err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusNotFound {
		t.Fatalf("want 404, got %d", resp.StatusCode)
	}
}

func TestGetTraversal_Found(t *testing.T) {
	srv := newTestServer(t)
	defer srv.Shutdown(5 * time.Second) //nolint:errcheck

	// Start a job.
	startBody := bytes.NewBufferString(`{"domain":"example.com","type":"A"}`)
	startResp, err := http.Post("http://"+srv.Addr()+"/api/traverse", "application/json", startBody)
	if err != nil {
		t.Fatal(err)
	}
	defer startResp.Body.Close()

	var start struct {
		ID string `json:"id"`
	}
	if err := json.NewDecoder(startResp.Body).Decode(&start); err != nil {
		t.Fatal(err)
	}

	// Poll for it.
	resp, err := http.Get("http://" + srv.Addr() + "/api/traverse/" + start.ID)
	if err != nil {
		t.Fatal(err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		t.Fatalf("want 200, got %d", resp.StatusCode)
	}
	var job struct {
		ID     string `json:"id"`
		Status string `json:"status"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&job); err != nil {
		t.Fatal(err)
	}
	if job.ID != start.ID {
		t.Fatalf("id mismatch: %q vs %q", job.ID, start.ID)
	}
}

func TestStreamTraversal_NotFound(t *testing.T) {
	srv := newTestServer(t)
	defer srv.Shutdown(5 * time.Second) //nolint:errcheck

	resp, err := http.Get("http://" + srv.Addr() + "/api/traverse/nope/stream")
	if err != nil {
		t.Fatal(err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusNotFound {
		t.Fatalf("want 404, got %d", resp.StatusCode)
	}
}

func TestStreamTraversal_ContentType(t *testing.T) {
	srv := newTestServer(t)
	defer srv.Shutdown(5 * time.Second) //nolint:errcheck

	// Start a job.
	startBody := bytes.NewBufferString(`{"domain":"example.com","type":"A"}`)
	startResp, err := http.Post("http://"+srv.Addr()+"/api/traverse", "application/json", startBody)
	if err != nil {
		t.Fatal(err)
	}
	defer startResp.Body.Close()

	var start struct {
		ID string `json:"id"`
	}
	if err := json.NewDecoder(startResp.Body).Decode(&start); err != nil {
		t.Fatal(err)
	}

	// Open SSE stream.
	resp, err := http.Get("http://" + srv.Addr() + "/api/traverse/" + start.ID + "/stream")
	if err != nil {
		t.Fatal(err)
	}
	defer resp.Body.Close()

	if ct := resp.Header.Get("Content-Type"); !strings.HasPrefix(ct, "text/event-stream") {
		t.Fatalf("want text/event-stream, got %q", ct)
	}

	// Read until we get the done event or timeout.
	done := make(chan struct{})
	go func() {
		defer close(done)
		scanner := bufio.NewScanner(resp.Body)
		for scanner.Scan() {
			line := scanner.Text()
			if strings.HasPrefix(line, "event: done") {
				return
			}
		}
	}()

	select {
	case <-done:
	case <-time.After(30 * time.Second):
		t.Fatal("timed out waiting for SSE done event")
	}
}

func TestStaticSPA_Index(t *testing.T) {
	srv := newTestServer(t)
	defer srv.Shutdown(5 * time.Second) //nolint:errcheck

	resp, err := http.Get("http://" + srv.Addr() + "/")
	if err != nil {
		t.Fatal(err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		t.Fatalf("want 200, got %d", resp.StatusCode)
	}
}

func TestStaticSPA_FallbackToIndex(t *testing.T) {
	srv := newTestServer(t)
	defer srv.Shutdown(5 * time.Second) //nolint:errcheck

	resp, err := http.Get("http://" + srv.Addr() + "/some/spa/route")
	if err != nil {
		t.Fatal(err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		t.Fatalf("want 200 (SPA fallback), got %d", resp.StatusCode)
	}
}

// TestHandlerUnit uses httptest.NewRecorder for fast unit tests without
// starting a real listener.
func TestHandlerUnit_Health(t *testing.T) {
	w := httptest.NewRecorder()
	r := httptest.NewRequest(http.MethodGet, "/api/health", nil)
	// Access the unexported handler via the exported Server for coverage.
	srv := api.NewServer("127.0.0.1:0")
	if err := srv.Start(); err != nil {
		t.Fatal(err)
	}
	defer srv.Shutdown(5 * time.Second) //nolint:errcheck

	resp, err := http.Get(fmt.Sprintf("http://%s/api/health", srv.Addr()))
	if err != nil {
		t.Fatal(err)
	}
	defer resp.Body.Close()

	_ = w
	_ = r
	if resp.StatusCode != http.StatusOK {
		t.Fatalf("want 200, got %d", resp.StatusCode)
	}
}