package neoircapi_test

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net"
	"net/http"
	"net/http/httptest"
	"net/url"
	"reflect"
	"slices"
	"strconv"
	"strings"
	"testing"

	api "sneak.berlin/go/neoirc/internal/cli/api"
	"sneak.berlin/go/neoirc/internal/hashcash"
)

const (
	cookieValue = "opaque-value"
	testNick    = "alice"
	testChannel = "#general"
)

// newSessionServer starts a plain-HTTP server that, like
// neoircd, sets a Secure auth cookie when a session is
// created and answers GET /api/v1/state only when that
// cookie comes back.
func newSessionServer(t *testing.T) *httptest.Server {
	t.Helper()

	mux := http.NewServeMux()

	// Without hashcash the server sends no hashcash_bits.
	mux.HandleFunc("GET /api/v1/server", func(
		writer http.ResponseWriter, _ *http.Request,
	) {
		_, _ = io.WriteString(writer, `{
			"name": "My NeoIRC Server",
			"version": "0.1.0",
			"motd": "Welcome! Be nice.",
			"users": 42
		}`)
	})

	mux.HandleFunc("POST /api/v1/session", func(
		writer http.ResponseWriter, _ *http.Request,
	) {
		http.SetCookie(writer, &http.Cookie{
			Name:     "neoirc_auth",
			Value:    cookieValue,
			Path:     "/",
			HttpOnly: true,
			Secure:   true,
			SameSite: http.SameSiteStrictMode,
		})
		writer.WriteHeader(http.StatusCreated)

		_, _ = io.WriteString(writer, `{"id":1,"nick":"alice"}`)
	})

	mux.HandleFunc("GET /api/v1/state", func(
		writer http.ResponseWriter, request *http.Request,
	) {
		cookie, err := request.Cookie("neoirc_auth")
		if err != nil || cookie.Value != cookieValue {
			writer.WriteHeader(http.StatusUnauthorized)

			return
		}

		_, _ = io.WriteString(writer, `{
			"id": 1,
			"nick": "alice",
			"channels": [
				{"id": 1, "name": "#general", "topic": "Welcome!"},
				{"id": 2, "name": "#dev", "topic": ""}
			]
		}`)
	})

	server := httptest.NewServer(mux)
	t.Cleanup(server.Close)

	return server
}

// newClientForPath starts a server that answers GET path with
// body, and returns a client for it.
func newClientForPath(t *testing.T, path, body string) *api.Client {
	t.Helper()

	mux := http.NewServeMux()

	mux.HandleFunc("GET "+path, func(
		writer http.ResponseWriter, _ *http.Request,
	) {
		_, _ = io.WriteString(writer, body)
	})

	server := httptest.NewServer(mux)
	t.Cleanup(server.Close)

	return api.NewClient(server.URL)
}

func TestGetStateDecodesFields(t *testing.T) {
	t.Parallel()

	client := api.NewClient(newSessionServer(t).URL)

	_, err := client.CreateSession(testNick)
	if err != nil {
		t.Fatalf("create session: %v", err)
	}

	state, err := client.GetState()
	if err != nil {
		t.Fatalf("state: %v", err)
	}

	want := api.StateResponse{
		ID:   1,
		Nick: testNick,
		Channels: []api.Channel{
			{Name: testChannel, Topic: "Welcome!"},
			{Name: "#dev", Topic: ""},
		},
	}
	if !reflect.DeepEqual(*state, want) {
		t.Fatalf("state: got %+v, want %+v", *state, want)
	}
}

func TestGetServerInfoDecodesFields(t *testing.T) {
	t.Parallel()

	client := newClientForPath(t, "/api/v1/server", `{
		"name": "My NeoIRC Server",
		"version": "0.1.0",
		"motd": "Welcome! Be nice.",
		"users": 42,
		"hashcash_bits": 20
	}`)

	info, err := client.GetServerInfo()
	if err != nil {
		t.Fatalf("server info: %v", err)
	}

	want := api.ServerInfo{
		Name:         "My NeoIRC Server",
		MOTD:         "Welcome! Be nice.",
		Version:      "0.1.0",
		HashcashBits: 20,
	}
	if *info != want {
		t.Fatalf("server info: got %+v, want %+v", *info, want)
	}
}

// TestCreateSessionSendsNickAndStamp serves a server that, like
// neoircd with hashcash on, advertises hashcash_bits and creates
// the session only for a pow_token the server's validator in
// internal/hashcash accepts.
func TestCreateSessionSendsNickAndStamp(t *testing.T) {
	t.Parallel()

	const (
		serverName = "My NeoIRC Server"
		stampBits  = 8
		sessionID  = 7
	)

	mux := http.NewServeMux()

	mux.HandleFunc("GET /api/v1/server", func(
		writer http.ResponseWriter, _ *http.Request,
	) {
		_, _ = fmt.Fprintf(writer, `{
			"name": %q,
			"version": "0.1.0",
			"motd": "Welcome! Be nice.",
			"users": 42,
			"hashcash_bits": %d
		}`, serverName, stampBits)
	})

	validator := hashcash.NewValidator(serverName)

	mux.HandleFunc("POST /api/v1/session", func(
		writer http.ResponseWriter, request *http.Request,
	) {
		// Decoded with the field names handleCreateSession uses.
		var payload struct {
			Nick     string `json:"nick"`
			Hashcash string `json:"pow_token"` //nolint:tagliatelle
		}

		err := json.NewDecoder(request.Body).Decode(&payload)
		if err != nil {
			writer.WriteHeader(http.StatusBadRequest)

			return
		}

		err = validator.Validate(payload.Hashcash, stampBits)
		if err != nil {
			writer.WriteHeader(http.StatusPaymentRequired)

			return
		}

		writer.WriteHeader(http.StatusCreated)

		_ = json.NewEncoder(writer).Encode(map[string]any{
			"id":   sessionID,
			"nick": payload.Nick,
		})
	})

	server := httptest.NewServer(mux)
	t.Cleanup(server.Close)

	session, err := api.NewClient(server.URL).CreateSession(testNick)
	if err != nil {
		t.Fatalf("create session: %v", err)
	}

	want := api.SessionResponse{ID: sessionID, Nick: testNick}
	if *session != want {
		t.Fatalf("session: got %+v, want %+v", *session, want)
	}
}

func TestListChannelsDecodesNamesAndTopics(t *testing.T) {
	t.Parallel()

	client := newClientForPath(t, "/api/v1/channels", `[
		{"id": 1, "name": "#general", "topic": "Welcome!"},
		{"id": 2, "name": "#dev", "topic": "Development discussion"}
	]`)

	channels, err := client.ListChannels()
	if err != nil {
		t.Fatalf("list channels: %v", err)
	}

	want := []api.Channel{
		{Name: testChannel, Topic: "Welcome!"},
		{Name: "#dev", Topic: "Development discussion"},
	}
	if !slices.Equal(channels, want) {
		t.Fatalf("channels: got %+v, want %+v", channels, want)
	}
}

func TestGetMembersDecodesMemberObjects(t *testing.T) {
	t.Parallel()

	client := newClientForPath(t, "/api/v1/channels/general/members", `[
		{
			"id": 1, "nick": "alice", "username": "alice",
			"hostname": "host.example.com",
			"isOperator": true, "isVoiced": false,
			"lastSeen": "2026-02-10T20:00:00Z"
		},
		{
			"id": 2, "nick": "bob", "username": "bob",
			"hostname": "host.example.com",
			"isOperator": false, "isVoiced": true,
			"lastSeen": "2026-02-10T20:00:00Z"
		},
		{
			"id": 3, "nick": "Carol", "username": "carol",
			"hostname": "host.example.com",
			"isOperator": false, "isVoiced": false,
			"lastSeen": "2026-02-10T20:00:00Z"
		}
	]`)

	members, err := client.GetMembers(testChannel)
	if err != nil {
		t.Fatalf("get members: %v", err)
	}

	want := []api.Member{
		{Nick: testNick, IsOperator: true, IsVoiced: false},
		{Nick: "bob", IsOperator: false, IsVoiced: true},
		{Nick: "Carol", IsOperator: false, IsVoiced: false},
	}
	if !slices.Equal(members, want) {
		t.Fatalf("members: got %+v, want %+v", members, want)
	}
}

// TestPollMessagesAdvancesCursor serves the queue as the server
// does: entries after the cursor, and last_id as the new cursor.
func TestPollMessagesAdvancesCursor(t *testing.T) {
	t.Parallel()

	const lastQueueID = 42

	mux := http.NewServeMux()

	mux.HandleFunc("GET /api/v1/messages", func(
		writer http.ResponseWriter, request *http.Request,
	) {
		after := request.URL.Query().Get("after")
		if after == strconv.Itoa(lastQueueID) {
			_, _ = io.WriteString(
				writer, `{"messages": [], "last_id": 42}`,
			)

			return
		}

		_, _ = io.WriteString(writer, `{
			"messages": [{
				"id": "b7c8210f-849c-4b90-9ee8-d99c8889358e",
				"command": "PRIVMSG",
				"from": "alice",
				"to": "#general",
				"body": ["hello world"],
				"ts": "2026-02-10T20:00:01.234567891Z",
				"meta": {}
			}],
			"last_id": 42
		}`)
	})

	server := httptest.NewServer(mux)
	t.Cleanup(server.Close)

	client := api.NewClient(server.URL)

	first, err := client.PollMessages(0, 0)
	if err != nil {
		t.Fatalf("first poll: %v", err)
	}

	if first.LastID != lastQueueID || len(first.Messages) != 1 {
		t.Fatalf(
			"first poll: got last ID %d and %d messages, "+
				"want %d and 1",
			first.LastID, len(first.Messages), lastQueueID,
		)
	}

	second, err := client.PollMessages(first.LastID, 0)
	if err != nil {
		t.Fatalf("second poll: %v", err)
	}

	if len(second.Messages) != 0 {
		t.Fatalf(
			"second poll: got %d messages again, want none",
			len(second.Messages),
		)
	}
}

// TestPollMessagesDecodesMessageFields serves a relayed PRIVMSG
// with the sender's meta and a numeric, as the server queues
// them.
func TestPollMessagesDecodesMessageFields(t *testing.T) {
	t.Parallel()

	client := newClientForPath(t, "/api/v1/messages", `{
		"messages": [
			{
				"id": "b7c8210f-849c-4b90-9ee8-d99c8889358e",
				"command": "PRIVMSG",
				"from": "alice",
				"to": "#general",
				"body": ["signed message"],
				"ts": "2026-02-10T20:00:01.234567891Z",
				"meta": {"sig": "base64...", "alg": "ed25519"}
			},
			{
				"id": "7f5a04f8-eab4-4d2e-be55-f5cfcfaf43c5",
				"command": "RPL_LUSEROP",
				"code": 252,
				"from": "neoirc",
				"to": "alice",
				"params": ["0"],
				"body": ["operator(s) online"],
				"ts": "2026-02-10T20:00:02Z",
				"meta": {}
			}
		],
		"last_id": 42
	}`)

	result, err := client.PollMessages(0, 0)
	if err != nil {
		t.Fatalf("poll: %v", err)
	}

	want := []api.Message{
		{
			ID:      "b7c8210f-849c-4b90-9ee8-d99c8889358e",
			Command: "PRIVMSG",
			From:    testNick,
			To:      testChannel,
			Body:    []any{"signed message"},
			TS:      "2026-02-10T20:00:01.234567891Z",
			Meta:    map[string]any{"sig": "base64...", "alg": "ed25519"},
		},
		{
			ID:      "7f5a04f8-eab4-4d2e-be55-f5cfcfaf43c5",
			Command: "RPL_LUSEROP",
			From:    "neoirc",
			To:      testNick,
			Params:  []string{"0"},
			Body:    []any{"operator(s) online"},
			TS:      "2026-02-10T20:00:02Z",
			Meta:    map[string]any{},
		},
	}
	if !reflect.DeepEqual(result.Messages, want) {
		t.Fatalf("messages: got %+v, want %+v", result.Messages, want)
	}
}

func TestClientKeepsSessionOverPlainHTTPOnLocalhost(t *testing.T) {
	t.Parallel()

	server := newSessionServer(t)

	serverURL, err := url.Parse(server.URL)
	if err != nil {
		t.Fatalf("parse server URL: %v", err)
	}

	for _, host := range []string{"127.0.0.1", "localhost"} {
		t.Run(host, func(t *testing.T) {
			t.Parallel()

			client := api.NewClient(
				"http://" + net.JoinHostPort(host, serverURL.Port()),
			)

			_, err := client.CreateSession(testNick)
			if err != nil {
				t.Fatalf("create session: %v", err)
			}

			_, err = client.GetState()
			if err != nil {
				t.Fatalf("state after creating the session: %v", err)
			}
		})
	}
}

func TestClientWithholdsCookieOverPlainHTTPFromOtherHosts(t *testing.T) {
	t.Parallel()

	server := newSessionServer(t)

	// neoirc.example is not loopback. Every connection the client
	// opens to it goes to the test server instead.
	client := api.NewClient("http://neoirc.example")
	client.HTTPClient.Transport = &http.Transport{
		DialContext: func(
			ctx context.Context, network, _ string,
		) (net.Conn, error) {
			var dialer net.Dialer

			return dialer.DialContext(
				ctx, network, server.Listener.Addr().String(),
			)
		},
	}

	_, err := client.CreateSession(testNick)
	if err != nil {
		t.Fatalf("create session: %v", err)
	}

	// The server answers 401 when the auth cookie does not arrive.
	_, err = client.GetState()
	if err == nil || !strings.Contains(err.Error(), "401") {
		t.Fatalf("state: got %v, want 401: cookie sent over plain HTTP", err)
	}
}