package httputil

import (
	"context"
	"encoding/json"
	"errors"
	"io"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"

	"code.nochebuena.dev/go/xerrors"
)

// --- mock validator ---

type mockValidator struct{ err error }

func (m *mockValidator) Struct(v any) error { return m.err }

var okValidator = &mockValidator{}

// --- helpers ---

func body(s string) io.Reader { return strings.NewReader(s) }

func decodeMap(t *testing.T, rec *httptest.ResponseRecorder) map[string]any {
	t.Helper()
	var m map[string]any
	if err := json.NewDecoder(rec.Body).Decode(&m); err != nil {
		t.Fatalf("decode: %v", err)
	}
	return m
}

// --- Handle ---

type req struct{ Value string }
type res struct{ Echo string }

func TestHandle_Success(t *testing.T) {
	fn := func(ctx context.Context, r req) (res, error) { return res{Echo: r.Value}, nil }
	h := Handle(okValidator, fn)
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, httptest.NewRequest(http.MethodPost, "/", body(`{"Value":"hello"}`)))
	if rec.Code != http.StatusOK {
		t.Errorf("want 200, got %d", rec.Code)
	}
	m := decodeMap(t, rec)
	if m["Echo"] != "hello" {
		t.Errorf("want Echo=hello, got %v", m["Echo"])
	}
}

func TestHandle_InvalidJSON(t *testing.T) {
	fn := func(ctx context.Context, r req) (res, error) { return res{}, nil }
	h := Handle(okValidator, fn)
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, httptest.NewRequest(http.MethodPost, "/", body(`not json`)))
	if rec.Code != http.StatusBadRequest {
		t.Errorf("want 400, got %d", rec.Code)
	}
}

func TestHandle_ValidationFails(t *testing.T) {
	v := &mockValidator{err: xerrors.InvalidInput("field required")}
	fn := func(ctx context.Context, r req) (res, error) { return res{}, nil }
	h := Handle(v, fn)
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, httptest.NewRequest(http.MethodPost, "/", body(`{}`)))
	if rec.Code != http.StatusBadRequest {
		t.Errorf("want 400, got %d", rec.Code)
	}
}

func TestHandle_FnError(t *testing.T) {
	fn := func(ctx context.Context, r req) (res, error) {
		return res{}, xerrors.New(xerrors.ErrNotFound, "not found")
	}
	h := Handle(okValidator, fn)
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, httptest.NewRequest(http.MethodPost, "/", body(`{}`)))
	if rec.Code != http.StatusNotFound {
		t.Errorf("want 404, got %d", rec.Code)
	}
}

// --- HandleNoBody ---

func TestHandleNoBody_Success(t *testing.T) {
	fn := func(ctx context.Context) (res, error) { return res{Echo: "ok"}, nil }
	h := HandleNoBody(fn)
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/", nil))
	if rec.Code != http.StatusOK {
		t.Errorf("want 200, got %d", rec.Code)
	}
}

func TestHandleNoBody_FnError(t *testing.T) {
	fn := func(ctx context.Context) (res, error) {
		return res{}, xerrors.New(xerrors.ErrUnavailable, "service down")
	}
	h := HandleNoBody(fn)
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/", nil))
	if rec.Code != http.StatusServiceUnavailable {
		t.Errorf("want 503, got %d", rec.Code)
	}
}

// --- HandleEmpty ---

func TestHandleEmpty_Success(t *testing.T) {
	fn := func(ctx context.Context, r req) error { return nil }
	h := HandleEmpty(okValidator, fn)
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, httptest.NewRequest(http.MethodDelete, "/", body(`{}`)))
	if rec.Code != http.StatusNoContent {
		t.Errorf("want 204, got %d", rec.Code)
	}
}

func TestHandleEmpty_ValidationFails(t *testing.T) {
	v := &mockValidator{err: xerrors.InvalidInput("required")}
	fn := func(ctx context.Context, r req) error { return nil }
	h := HandleEmpty(v, fn)
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, httptest.NewRequest(http.MethodDelete, "/", body(`{}`)))
	if rec.Code != http.StatusBadRequest {
		t.Errorf("want 400, got %d", rec.Code)
	}
}

func TestHandleEmpty_FnError(t *testing.T) {
	fn := func(ctx context.Context, r req) error {
		return xerrors.New(xerrors.ErrPermissionDenied, "forbidden")
	}
	h := HandleEmpty(okValidator, fn)
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, httptest.NewRequest(http.MethodDelete, "/", body(`{}`)))
	if rec.Code != http.StatusForbidden {
		t.Errorf("want 403, got %d", rec.Code)
	}
}

// --- HandlerFunc ---

func TestHandlerFunc_NoError(t *testing.T) {
	h := HandlerFunc(func(w http.ResponseWriter, r *http.Request) error {
		w.WriteHeader(http.StatusOK)
		return nil
	})
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/", nil))
	if rec.Code != http.StatusOK {
		t.Errorf("want 200, got %d", rec.Code)
	}
}

func TestHandlerFunc_WithError(t *testing.T) {
	h := HandlerFunc(func(w http.ResponseWriter, r *http.Request) error {
		return xerrors.New(xerrors.ErrUnauthorized, "unauthorized")
	})
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/", nil))
	if rec.Code != http.StatusUnauthorized {
		t.Errorf("want 401, got %d", rec.Code)
	}
}

// --- JSON / Error / NoContent ---

func TestJSON_SetsContentType(t *testing.T) {
	rec := httptest.NewRecorder()
	JSON(rec, http.StatusOK, map[string]string{"k": "v"})
	if ct := rec.Header().Get("Content-Type"); ct != "application/json" {
		t.Errorf("Content-Type: want application/json, got %s", ct)
	}
}

func TestJSON_EncodesBody(t *testing.T) {
	rec := httptest.NewRecorder()
	JSON(rec, http.StatusOK, map[string]string{"hello": "world"})
	m := decodeMap(t, rec)
	if m["hello"] != "world" {
		t.Errorf("want hello=world, got %v", m)
	}
}

func TestNoContent_Status(t *testing.T) {
	rec := httptest.NewRecorder()
	NoContent(rec)
	if rec.Code != http.StatusNoContent {
		t.Errorf("want 204, got %d", rec.Code)
	}
	if rec.Body.Len() != 0 {
		t.Errorf("want empty body, got %q", rec.Body.String())
	}
}

func TestError_XerrorsMapping(t *testing.T) {
	cases := []struct {
		code   xerrors.Code
		status int
	}{
		{xerrors.ErrInvalidInput, 400},
		{xerrors.ErrUnauthorized, 401},
		{xerrors.ErrPermissionDenied, 403},
		{xerrors.ErrNotFound, 404},
		{xerrors.ErrAlreadyExists, 409},
		{xerrors.ErrInternal, 500},
		{xerrors.ErrNotImplemented, 501},
		{xerrors.ErrUnavailable, 503},
		{xerrors.ErrDeadlineExceeded, 504},
	}
	for _, tc := range cases {
		rec := httptest.NewRecorder()
		Error(rec, xerrors.New(tc.code, "msg"))
		if rec.Code != tc.status {
			t.Errorf("code %s: want %d, got %d", tc.code, tc.status, rec.Code)
		}
	}
}

func TestError_UnknownError(t *testing.T) {
	rec := httptest.NewRecorder()
	Error(rec, errors.New("oops"))
	if rec.Code != http.StatusInternalServerError {
		t.Errorf("want 500, got %d", rec.Code)
	}
}

func TestError_NilError(t *testing.T) {
	rec := httptest.NewRecorder()
	Error(rec, nil)
	if rec.Code != http.StatusInternalServerError {
		t.Errorf("want 500, got %d", rec.Code)
	}
}

func TestErrorCodeToStatus_AllCodes(t *testing.T) {
	cases := []struct {
		code   xerrors.Code
		status int
	}{
		{xerrors.ErrInvalidInput, 400},
		{xerrors.ErrUnauthorized, 401},
		{xerrors.ErrPermissionDenied, 403},
		{xerrors.ErrNotFound, 404},
		{xerrors.ErrAlreadyExists, 409},
		{xerrors.ErrGone, 410},
		{xerrors.ErrPreconditionFailed, 412},
		{xerrors.ErrRateLimited, 429},
		{xerrors.ErrInternal, 500},
		{xerrors.ErrNotImplemented, 501},
		{xerrors.ErrUnavailable, 503},
		{xerrors.ErrDeadlineExceeded, 504},
		{"UNKNOWN_CODE", 500},
	}
	for _, tc := range cases {
		got := errorCodeToStatus(tc.code)
		if got != tc.status {
			t.Errorf("errorCodeToStatus(%s): want %d, got %d", tc.code, tc.status, got)
		}
	}
}