package api

import (
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
)

func TestWriteError(t *testing.T) {
	rec := httptest.NewRecorder()
	WriteError(rec, http.StatusBadRequest, "nope")

	if rec.Code != http.StatusBadRequest {
		t.Fatalf("status = %d, want %d", rec.Code, http.StatusBadRequest)
	}

	contentType := rec.Header().Get("Content-Type")

	if !strings.HasPrefix(contentType, "application/json") {
		t.Fatalf("Content-Type = %q, want application/json", contentType)
	}

	var body map[string]string

	if err := json.Unmarshal(rec.Body.Bytes(), &body); err != nil {
		t.Fatalf("response is not valid JSON: %v", err)
	}

	if body["error"] != "nope" {
		t.Fatalf("error message = %q, want %q", body["error"], "nope")
	}
}

func TestWriteJSONNilPayload(t *testing.T) {
	rec := httptest.NewRecorder()
	WriteJSON(rec, http.StatusNoContent, nil)

	if rec.Code != http.StatusNoContent {
		t.Fatalf("status = %d, want %d", rec.Code, http.StatusNoContent)
	}

	if rec.Body.Len() != 0 {
		t.Fatalf("body = %q, want empty", rec.Body.String())
	}
}

func TestDecodeJSON(t *testing.T) {
	type userRequest struct {
		Email    string `json:"email"`
		Password string `json:"password"`
	}

	req := httptest.NewRequest(http.MethodPost, "/", strings.NewReader(`{"email":"alice@example.com","password":"hunter2"}`))

	got, err := DecodeJSON[userRequest](req)

	if err != nil {
		t.Fatalf("DecodeJSON returned error: %v", err)
	}

	if got == nil || got.Email != "alice@example.com" || got.Password != "hunter2" {
		t.Fatalf("DecodeJSON = %+v, want alice@example.com/hunter2", got)
	}
}

func TestDecodeJSONInvalid(t *testing.T) {
	req := httptest.NewRequest(http.MethodPost, "/", strings.NewReader("not json"))

	_, err := DecodeJSON[struct{}](req)

	if err == nil {
		t.Fatal("DecodeJSON returned nil error for invalid body")
	}

	if err.Error() != "Failed to deserialize request" {
		t.Fatalf("error = %q, want %q", err.Error(), "Failed to deserialize request")
	}
}

func TestErrorSerializesToJSON(t *testing.T) {
	rec := httptest.NewRecorder()
	WriteJSON(rec, http.StatusConflict, Error{Err: "boom"})

	if !strings.Contains(rec.Body.String(), `"boom"`) {
		t.Fatalf("body = %q, want it to contain the error message", rec.Body.String())
	}
}