package agent

import (
	"context"
	"encoding/json"
	"log/slog"
	"net/http"
	"net/http/httptest"
	"testing"

	"git.wntrmute.dev/mc/mcp/internal/config"
)

func TestNilDNSRegistrarIsNoop(t *testing.T) {
	var d *DNSRegistrar
	if err := d.EnsureRecord(context.Background(), "svc"); err != nil {
		t.Fatalf("EnsureRecord on nil: %v", err)
	}
	if err := d.RemoveRecord(context.Background(), "svc"); err != nil {
		t.Fatalf("RemoveRecord on nil: %v", err)
	}
}

func TestNewDNSRegistrarDisabledWhenUnconfigured(t *testing.T) {
	d, err := NewDNSRegistrar(config.MCNSConfig{}, slog.Default())
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if d != nil {
		t.Fatal("expected nil registrar for empty config")
	}
}

func TestEnsureRecordCreatesWhenMissing(t *testing.T) {
	var gotMethod, gotPath, gotAuth string
	var gotBody map[string]interface{}

	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.Method == http.MethodGet {
			// List returns empty — no existing records.
			w.Header().Set("Content-Type", "application/json")
			_, _ = w.Write([]byte(`{"records":[]}`))
			return
		}
		gotMethod = r.Method
		gotPath = r.URL.Path
		gotAuth = r.Header.Get("Authorization")
		_ = json.NewDecoder(r.Body).Decode(&gotBody)
		w.WriteHeader(http.StatusCreated)
		_, _ = w.Write([]byte(`{"id":1}`))
	}))
	defer srv.Close()

	d := &DNSRegistrar{
		serverURL:  srv.URL,
		token:      "test-token",
		zone:       "svc.mcp.metacircular.net",
		nodeAddr:   "192.168.88.181",
		httpClient: srv.Client(),
		logger:     slog.Default(),
	}

	if err := d.EnsureRecord(context.Background(), "myservice"); err != nil {
		t.Fatalf("EnsureRecord: %v", err)
	}

	if gotMethod != http.MethodPost {
		t.Fatalf("method: got %q, want POST", gotMethod)
	}
	if gotPath != "/v1/zones/svc.mcp.metacircular.net/records" {
		t.Fatalf("path: got %q", gotPath)
	}
	if gotAuth != "Bearer test-token" {
		t.Fatalf("auth: got %q", gotAuth)
	}
	if gotBody["name"] != "myservice" {
		t.Fatalf("name: got %v", gotBody["name"])
	}
	if gotBody["type"] != "A" {
		t.Fatalf("type: got %v", gotBody["type"])
	}
	if gotBody["value"] != "192.168.88.181" {
		t.Fatalf("value: got %v", gotBody["value"])
	}
}

func TestEnsureRecordSkipsWhenExists(t *testing.T) {
	createCalled := false

	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.Method == http.MethodGet {
			// Return an existing record with the correct value.
			resp := map[string][]dnsRecord{"records": {{ID: 1, Name: "myservice", Type: "A", Value: "192.168.88.181", TTL: 300}}}
			w.Header().Set("Content-Type", "application/json")
			_ = json.NewEncoder(w).Encode(resp)
			return
		}
		createCalled = true
		w.WriteHeader(http.StatusCreated)
	}))
	defer srv.Close()

	d := &DNSRegistrar{
		serverURL:  srv.URL,
		token:      "test-token",
		zone:       "svc.mcp.metacircular.net",
		nodeAddr:   "192.168.88.181",
		httpClient: srv.Client(),
		logger:     slog.Default(),
	}

	if err := d.EnsureRecord(context.Background(), "myservice"); err != nil {
		t.Fatalf("EnsureRecord: %v", err)
	}
	if createCalled {
		t.Fatal("should not create when record already exists with correct value")
	}
}

func TestEnsureRecordUpdatesWrongValue(t *testing.T) {
	var gotMethod string
	var gotPath string

	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.Method == http.MethodGet {
			// Return a record with a stale value.
			resp := map[string][]dnsRecord{"records": {{ID: 42, Name: "myservice", Type: "A", Value: "10.0.0.1", TTL: 300}}}
			w.Header().Set("Content-Type", "application/json")
			_ = json.NewEncoder(w).Encode(resp)
			return
		}
		gotMethod = r.Method
		gotPath = r.URL.Path
		w.WriteHeader(http.StatusOK)
	}))
	defer srv.Close()

	d := &DNSRegistrar{
		serverURL:  srv.URL,
		token:      "test-token",
		zone:       "svc.mcp.metacircular.net",
		nodeAddr:   "192.168.88.181",
		httpClient: srv.Client(),
		logger:     slog.Default(),
	}

	if err := d.EnsureRecord(context.Background(), "myservice"); err != nil {
		t.Fatalf("EnsureRecord: %v", err)
	}
	if gotMethod != http.MethodPut {
		t.Fatalf("method: got %q, want PUT", gotMethod)
	}
	if gotPath != "/v1/zones/svc.mcp.metacircular.net/records/42" {
		t.Fatalf("path: got %q", gotPath)
	}
}

func TestRemoveRecordDeletes(t *testing.T) {
	var gotMethod, gotPath string

	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.Method == http.MethodGet {
			resp := map[string][]dnsRecord{"records": {{ID: 7, Name: "myservice", Type: "A", Value: "192.168.88.181", TTL: 300}}}
			w.Header().Set("Content-Type", "application/json")
			_ = json.NewEncoder(w).Encode(resp)
			return
		}
		gotMethod = r.Method
		gotPath = r.URL.Path
		w.WriteHeader(http.StatusNoContent)
	}))
	defer srv.Close()

	d := &DNSRegistrar{
		serverURL:  srv.URL,
		token:      "test-token",
		zone:       "svc.mcp.metacircular.net",
		nodeAddr:   "192.168.88.181",
		httpClient: srv.Client(),
		logger:     slog.Default(),
	}

	if err := d.RemoveRecord(context.Background(), "myservice"); err != nil {
		t.Fatalf("RemoveRecord: %v", err)
	}
	if gotMethod != http.MethodDelete {
		t.Fatalf("method: got %q, want DELETE", gotMethod)
	}
	if gotPath != "/v1/zones/svc.mcp.metacircular.net/records/7" {
		t.Fatalf("path: got %q", gotPath)
	}
}

func TestRemoveRecordNoopWhenMissing(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// List returns empty.
		w.Header().Set("Content-Type", "application/json")
		_, _ = w.Write([]byte(`{"records":[]}`))
	}))
	defer srv.Close()

	d := &DNSRegistrar{
		serverURL:  srv.URL,
		token:      "test-token",
		zone:       "svc.mcp.metacircular.net",
		nodeAddr:   "192.168.88.181",
		httpClient: srv.Client(),
		logger:     slog.Default(),
	}

	if err := d.RemoveRecord(context.Background(), "myservice"); err != nil {
		t.Fatalf("RemoveRecord: %v", err)
	}
}