package validate

import (
	"errors"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"

	"github.com/tegwick/fluid-core/internal/contract"
	"github.com/tegwick/fluid-core/internal/runtime"
)

const hallContract = `
openapi: "3.1.0"
paths:
  /v1/hall-entries:
    post:
      operationId: publishEntry
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              required: [id, title, body]
              additionalProperties: false
              properties:
                id: {type: string, minLength: 1}
                title: {type: string, maxLength: 120}
                body: {type: string, maxLength: 4096}
                format: {type: string, enum: [teaser, full]}
    get:
      operationId: listEntries
      parameters:
        - name: limit
          in: query
          schema: {type: integer, minimum: 1, maximum: 100}
  /v1/hall-entries/latest:
    get:
      operationId: latestEntry
  /v1/hall-entries/{id}:
    get:
      operationId: getEntry
      parameters:
        - name: id
          in: path
          required: true
          schema: {type: string, minLength: 1}
`

func testRevision() contract.Revision {
	return contract.Revision{
		ID:       "R-1",
		Contract: contract.RevisionContract{Digest: contract.Digest("sha256:" + strings.Repeat("1", 64))},
	}
}

func newValidator(t *testing.T) *OpenAPIValidator {
	t.Helper()
	v := NewOpenAPIValidator()
	if err := v.Register(testRevision().Contract.Digest, []byte(hallContract)); err != nil {
		t.Fatal(err)
	}
	return v
}

func request(method, target, body string) *http.Request {
	var r *http.Request
	if body == "" {
		r = httptest.NewRequest(method, target, nil)
	} else {
		r = httptest.NewRequest(method, target, strings.NewReader(body))
		r.Header.Set("Content-Type", "application/json")
	}
	return r
}

func TestValidRequestPasses(t *testing.T) {
	v := newValidator(t)
	body := `{"id":"e-1","title":"the river reached the forge","body":"...","format":"teaser"}`
	if err := v.Validate(testRevision(), request(http.MethodPost, "/v1/hall-entries", body), []byte(body)); err != nil {
		t.Fatalf("a conforming request was rejected: %v", err)
	}
}

func TestRequiredFieldsEnforced(t *testing.T) {
	v := newValidator(t)
	body := `{"id":"e-1"}`
	err := v.Validate(testRevision(), request(http.MethodPost, "/v1/hall-entries", body), []byte(body))
	if err == nil {
		t.Fatal("a request missing required fields was accepted")
	}
	for _, want := range []string{"title", "body"} {
		if !strings.Contains(err.Error(), want) {
			t.Errorf("error does not name missing %q: %v", want, err)
		}
	}
}

// TestLengthLimitIsCountedInRunes is the case this framework exists to publish:
// a hall entry with accented characters must not be rejected for a byte count
// it never exceeded.
func TestLengthLimitIsCountedInRunes(t *testing.T) {
	v := newValidator(t)

	// 3000 multi-byte runes: well under the 4096 rune limit, well over it in bytes.
	body := `{"id":"e-1","title":"t","body":"` + strings.Repeat("é", 3000) + `"}`
	if err := v.Validate(testRevision(), request(http.MethodPost, "/v1/hall-entries", body), []byte(body)); err != nil {
		t.Fatalf("a 3000-character entry was rejected against a 4096-character limit: %v", err)
	}

	over := `{"id":"e-1","title":"t","body":"` + strings.Repeat("a", 4097) + `"}`
	if err := v.Validate(testRevision(), request(http.MethodPost, "/v1/hall-entries", over), []byte(over)); err == nil {
		t.Error("a 4097-character entry passed a 4096-character limit")
	}
}

func TestUnknownFieldRejectedWhenClosed(t *testing.T) {
	v := newValidator(t)
	body := `{"id":"e-1","title":"t","body":"b","urgency":"high"}`
	err := v.Validate(testRevision(), request(http.MethodPost, "/v1/hall-entries", body), []byte(body))
	if err == nil {
		t.Fatal("an undeclared field was accepted")
	}
	if !strings.Contains(err.Error(), "urgency") {
		t.Errorf("error does not name the unknown field: %v", err)
	}
}

func TestEnumEnforced(t *testing.T) {
	v := newValidator(t)
	body := `{"id":"e-1","title":"t","body":"b","format":"interpretive-dance"}`
	if err := v.Validate(testRevision(), request(http.MethodPost, "/v1/hall-entries", body), []byte(body)); err == nil {
		t.Error("a value outside the enum was accepted")
	}
}

// TestLiteralRoutesBeatTemplates: /latest must not be swallowed by /{id}.
func TestLiteralRoutesBeatTemplates(t *testing.T) {
	c, err := ParseOpenAPI([]byte(hallContract))
	if err != nil {
		t.Fatal(err)
	}

	matched, _, ok := c.match("/v1/hall-entries/latest")
	if !ok {
		t.Fatal("no route matched /latest")
	}
	if matched.template != "/v1/hall-entries/latest" {
		t.Errorf("matched %q; the literal route must win over the template", matched.template)
	}

	matched, vars, ok := c.match("/v1/hall-entries/e-7")
	if !ok {
		t.Fatal("no route matched an id")
	}
	if matched.template != "/v1/hall-entries/{id}" || vars["id"] != "e-7" {
		t.Errorf("template match wrong: %q vars %v", matched.template, vars)
	}
}

func TestUnknownPathAndMethodRejected(t *testing.T) {
	v := newValidator(t)

	err := v.Validate(testRevision(), request(http.MethodGet, "/v1/nope", ""), nil)
	if err == nil {
		t.Error("an undeclared path was accepted")
	}

	err = v.Validate(testRevision(), request(http.MethodDelete, "/v1/hall-entries", ""), nil)
	if err == nil {
		t.Fatal("an undeclared method was accepted")
	}
	// The error should say what is allowed; a bare rejection teaches nothing.
	if !strings.Contains(err.Error(), "GET") || !strings.Contains(err.Error(), "POST") {
		t.Errorf("error does not name the allowed methods: %v", err)
	}
}

func TestQueryParametersAreCoercedAndBounded(t *testing.T) {
	v := newValidator(t)

	if err := v.Validate(testRevision(), request(http.MethodGet, "/v1/hall-entries?limit=10", ""), nil); err != nil {
		t.Errorf("a valid numeric query parameter was rejected: %v", err)
	}
	if err := v.Validate(testRevision(), request(http.MethodGet, "/v1/hall-entries?limit=500", ""), nil); err == nil {
		t.Error("a query parameter over its maximum was accepted")
	}
	if err := v.Validate(testRevision(), request(http.MethodGet, "/v1/hall-entries?limit=lots", ""), nil); err == nil {
		t.Error("a non-numeric value for an integer parameter was accepted")
	}
	// An absent optional parameter is fine.
	if err := v.Validate(testRevision(), request(http.MethodGet, "/v1/hall-entries", ""), nil); err != nil {
		t.Errorf("an absent optional parameter was rejected: %v", err)
	}
}

// TestUnregisteredContractIsRefused: serving a revision whose contract cannot
// be found would mean serving undeclared semantics.
func TestUnregisteredContractIsRefused(t *testing.T) {
	v := NewOpenAPIValidator()
	err := v.Validate(testRevision(), request(http.MethodGet, "/v1/hall-entries", ""), nil)
	if err == nil {
		t.Fatal("a revision with no registered contract was served")
	}
	var ve *runtime.ValidationError
	if !errors.As(err, &ve) {
		t.Errorf("got %T, want *runtime.ValidationError", err)
	}
}

func TestMalformedBodyReportedClearly(t *testing.T) {
	v := newValidator(t)
	body := `{"id": "e-1",`
	err := v.Validate(testRevision(), request(http.MethodPost, "/v1/hall-entries", body), []byte(body))
	if err == nil {
		t.Fatal("malformed JSON was accepted")
	}
	if !strings.Contains(err.Error(), "valid JSON") {
		t.Errorf("error is not clear about the cause: %v", err)
	}
}

func TestRemoteRefsAreRefused(t *testing.T) {
	// Resolving a remote reference would make validation depend on a network
	// fetch from the request path.
	c, err := ParseOpenAPI([]byte(hallContract))
	if err != nil {
		t.Fatal(err)
	}
	if _, err := c.Resolve("https://example.com/schema.json"); !errors.Is(err, ErrUnsupported) {
		t.Errorf("a remote $ref was accepted: %v", err)
	}
}

func TestLocalRefsResolve(t *testing.T) {
	doc := `
openapi: "3.1.0"
components:
  schemas:
    Entry:
      type: object
      required: [id]
      properties:
        id: {type: string}
paths:
  /v1/entries:
    post:
      requestBody:
        required: true
        content:
          application/json:
            schema: {$ref: "#/components/schemas/Entry"}
`
	v := NewOpenAPIValidator()
	digest := contract.Digest("sha256:" + strings.Repeat("2", 64))
	if err := v.Register(digest, []byte(doc)); err != nil {
		t.Fatal(err)
	}

	rev := testRevision()
	rev.Contract.Digest = digest

	if err := v.Validate(rev, request(http.MethodPost, "/v1/entries", `{"id":"e-1"}`), []byte(`{"id":"e-1"}`)); err != nil {
		t.Errorf("a valid referenced body was rejected: %v", err)
	}
	if err := v.Validate(rev, request(http.MethodPost, "/v1/entries", `{}`), []byte(`{}`)); err == nil {
		t.Error("a body missing a required referenced field was accepted")
	}
}

func TestOperationsListedForComplexityMeasurement(t *testing.T) {
	c, err := ParseOpenAPI([]byte(hallContract))
	if err != nil {
		t.Fatal(err)
	}
	ops := c.Operations()
	if len(ops) != 4 {
		t.Errorf("operations = %v, want 4", ops)
	}
}

func TestEmptyContractRefused(t *testing.T) {
	if _, err := ParseOpenAPI([]byte(`openapi: "3.1.0"`)); err == nil {
		t.Error("a contract declaring no paths was accepted")
	}
}