package errors

import (
	"errors"
	"fmt"
	"net/http"
	"strings"
	"testing"
)

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

	e := New("not_found", "用户不存在")
	if e.Code != "not_found" {
		t.Fatalf("Code = %q, want %q", e.Code, "not_found")
	}
	if e.Message != "用户不存在" {
		t.Fatalf("Message = %q, want %q", e.Message, "用户不存在")
	}
	if e.Error() != "用户不存在" {
		t.Fatalf("Error() = %q, want Message", e.Error())
	}
	if e.Cause != nil {
		t.Fatalf("Cause = %v, want nil", e.Cause)
	}
	if e.HTTPCode != 0 {
		t.Fatalf("HTTPCode = %d, want 0 (unset)", e.HTTPCode)
	}
}

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

	if got := New("x", "y").Unwrap(); got != nil {
		t.Fatalf("Unwrap() = %v, want nil for New", got)
	}
}

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

	original := ErrNotFound
	wrapped := Wrap(original, "not_found", "找不到用户 %s", "alice")

	if wrapped.Cause != original {
		t.Fatalf("Cause = %v, want original ErrNotFound", wrapped.Cause)
	}
	if wrapped.Message != "找不到用户 alice" {
		t.Fatalf("Message = %q, want %q", wrapped.Message, "找不到用户 alice")
	}
	if wrapped.Unwrap() != original {
		t.Fatalf("Unwrap() != original cause")
	}
	if !errors.Is(wrapped, original) {
		t.Fatalf("errors.Is(err, original) = false, want true (%%w penetration)")
	}
	if !errors.Is(wrapped, ErrNotFound) {
		t.Fatalf("errors.Is(err, ErrNotFound) = false, want true")
	}
}

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

	// errors.Is must not match an unrelated sentinel solely because the wrapper
	// uses that code string.
	wrapped := Wrap(ErrNotFound, "conflict", "写入冲突")
	if errors.Is(wrapped, ErrConflict) {
		t.Fatalf("errors.Is(err, ErrConflict) = true, want false")
	}
}

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

	outer := Wrap(Wrap(ErrNotFound, "internal", "加载配置失败"), "conflict", "写入冲突")
	if !errors.Is(outer, ErrNotFound) {
		t.Fatalf("errors.Is(outer, ErrNotFound) = false, want true through nested wraps")
	}

	var appErr *AppError
	if !errors.As(outer, &appErr) {
		t.Fatalf("errors.As(outer) = false, want true")
	}
	if appErr.Code != "conflict" {
		t.Fatalf("extracted Code = %q, want outer %q", appErr.Code, "conflict")
	}
}

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

	cases := []struct {
		name string
		err  error
		want bool
	}{
		{"sentinel", ErrNotFound, true},
		{"wrapped", Wrap(ErrNotFound, "not_found", "missing"), true},
		{"nested_wrap", Wrap(Wrap(ErrNotFound, "internal", "x"), "bad_request", "y"), true},
		{"std_error", fmt.Errorf("boom"), false},
		{"nil", nil, false},
	}

	for _, c := range cases {
		c := c
		t.Run(c.name, func(t *testing.T) {
			t.Parallel()
			if got := IsAppError(c.err); got != c.want {
				t.Fatalf("IsAppError(%v) = %v, want %v", c.err, got, c.want)
			}
		})
	}
}

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

	outer := Wrap(Wrap(ErrNotFound, "internal", "加载失败"), "conflict", "写入冲突")
	appErr, ok := As(outer)
	if !ok {
		t.Fatalf("As(outer) ok = false, want true")
	}
	if appErr.Code != "conflict" {
		t.Fatalf("As code = %q, want outer %q", appErr.Code, "conflict")
	}

	_, ok = As(fmt.Errorf("boom"))
	if ok {
		t.Fatalf("As(std error) ok = true, want false")
	}

	// a bare wrapped AppError chain: As must extract the typed error
	inner := Wrap(ErrUnauthorized, "unauthorized", "请先登录")
	extracted, ok := As(inner)
	if !ok {
		t.Fatalf("As(inner) ok = false, want true")
	}
	if extracted != inner {
		t.Fatalf("As(inner) != inner")
	}
}

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

	cases := []struct {
		name string
		err  error
		want int
	}{
		{"internal", ErrInternal, http.StatusInternalServerError},
		{"not_found", ErrNotFound, http.StatusNotFound},
		{"conflict", ErrConflict, http.StatusConflict},
		{"unauthorized", ErrUnauthorized, http.StatusUnauthorized},
		{"forbidden", ErrForbidden, http.StatusForbidden},
		{"bad_request", ErrBadRequest, http.StatusBadRequest},
		{"rate_limited", ErrRateLimited, http.StatusTooManyRequests},
		{"timeout", ErrTimeout, http.StatusServiceUnavailable},
		{"std_error", fmt.Errorf("boom"), http.StatusInternalServerError},
		{"nil", nil, http.StatusInternalServerError},
		{"custom_no_http", New("custom", "x"), http.StatusInternalServerError},
		{"wrap_inherits_cause", Wrap(ErrNotFound, "not_found", "missing"), http.StatusNotFound},
		{"wrap_std_error", Wrap(fmt.Errorf("db down"), "internal", "查询失败"), http.StatusInternalServerError},
	}

	for _, c := range cases {
		c := c
		t.Run(c.name, func(t *testing.T) {
			t.Parallel()
			if got := HTTPStatus(c.err); got != c.want {
				t.Fatalf("HTTPStatus(%v) = %d, want %d", c.err, got, c.want)
			}
		})
	}
}

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

	e := Wrap(ErrNotFound, "not_found", "资源不存在")
	js := ToJSON(e)

	if len(js) != 1 {
		t.Fatalf("ToJSON keys = %d, want exactly 1 (error)", len(js))
	}
	obj, ok := js["error"].(map[string]any)
	if !ok {
		t.Fatalf("error field is not a map, got %T", js["error"])
	}
	if got := obj["code"]; got != "not_found" {
		t.Fatalf("code = %v, want %q", got, "not_found")
	}
	if got := obj["message"]; got != "资源不存在" {
		t.Fatalf("message = %v, want %q", got, "资源不存在")
	}
}

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

	js := ToJSON(ErrUnauthorized)
	obj := js["error"].(map[string]any)
	if obj["code"] != "unauthorized" {
		t.Fatalf("code = %v, want %q", obj["code"], "unauthorized")
	}
	if obj["message"] != "unauthorized" {
		t.Fatalf("message = %v, want %q", obj["message"], "unauthorized")
	}
	if _, exists := js["data"]; exists {
		t.Fatalf("ToJSON leaked a data key; contract is only {error:{code,message}}")
	}
}

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

	raw := fmt.Errorf("connection refused: host=db-internal password=secret")
	js := ToJSON(raw)

	obj := js["error"].(map[string]any)
	if obj["code"] != "internal" {
		t.Fatalf("code = %v, want %q", obj["code"], "internal")
	}
	if obj["message"] != "internal error" {
		t.Fatalf("message = %v, want %q", obj["message"], "internal error")
	}
	body := fmt.Sprintf("%v", js)
	if strings.Contains(body, "secret") || strings.Contains(body, "db-internal") {
		t.Fatalf("ToJSON leaked internal detail: %s", body)
	}
}

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

	raw := fmt.Errorf("insert failed: PRIMARY KEY violation")
	wrapped := Wrap(raw, "conflict", "资源已存在")

	obj := ToJSON(wrapped)["error"].(map[string]any)
	if obj["message"] != "资源已存在" {
		t.Fatalf("message = %v, want %q", obj["message"], "资源已存在")
	}
	if strings.Contains(obj["message"].(string), "PRIMARY KEY") {
		t.Fatalf("user-facing message leaked internal detail: %s", obj["message"])
	}
	// The raw cause is still preserved for logging/diagnostics.
	if wrapped.Cause != raw {
		t.Fatalf("Cause not preserved, got %v", wrapped.Cause)
	}
}