package errors

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

func TestNewNotFound(t *testing.T) {
	err := NewNotFound("user not found")

	if err.Code != "NOT_FOUND" {
		t.Errorf("expected code NOT_FOUND, got %s", err.Code)
	}
	if err.Message != "user not found" {
		t.Errorf("expected message 'user not found', got %s", err.Message)
	}
	if err.HTTPCode != http.StatusNotFound {
		t.Errorf("expected HTTP 404, got %d", err.HTTPCode)
	}
}

func TestNewUnauthorized(t *testing.T) {
	err := NewUnauthorized("invalid token")
	if err.Code != "UNAUTHORIZED" {
		t.Errorf("expected code UNAUTHORIZED, got %s", err.Code)
	}
	if err.HTTPCode != http.StatusUnauthorized {
		t.Errorf("expected HTTP 401, got %d", err.HTTPCode)
	}
}

func TestNewForbidden(t *testing.T) {
	err := NewForbidden("admin only")
	if err.HTTPCode != http.StatusForbidden {
		t.Errorf("expected HTTP 403, got %d", err.HTTPCode)
	}
}

func TestNewBadRequest(t *testing.T) {
	err := NewBadRequest("invalid input")
	if err.HTTPCode != http.StatusBadRequest {
		t.Errorf("expected HTTP 400, got %d", err.HTTPCode)
	}
}

func TestNewConflict(t *testing.T) {
	err := NewConflict("duplicate entry")
	if err.HTTPCode != http.StatusConflict {
		t.Errorf("expected HTTP 409, got %d", err.HTTPCode)
	}
}

func TestNewTooManyRequests(t *testing.T) {
	err := NewTooManyRequests("rate limit")
	if err.HTTPCode != http.StatusTooManyRequests {
		t.Errorf("expected HTTP 429, got %d", err.HTTPCode)
	}
}

func TestNewInternal(t *testing.T) {
	cause := fmt.Errorf("db connection refused")
	err := NewInternal("database error", cause)

	if err.Code != "INTERNAL" {
		t.Errorf("expected code INTERNAL, got %s", err.Code)
	}
	if err.HTTPCode != http.StatusInternalServerError {
		t.Errorf("expected HTTP 500, got %d", err.HTTPCode)
	}
	if err.Cause != cause {
		t.Errorf("expected cause to be preserved")
	}
	// Check that Error() includes the cause
	errStr := err.Error()
	if errStr[len(errStr)-1] == '.' {
		// just check it doesn't panic
	}
}

func TestNewValidation(t *testing.T) {
	err := NewValidation("field required: email")
	if err.Code != "VALIDATION" {
		t.Errorf("expected code VALIDATION, got %s", err.Code)
	}
	if err.HTTPCode != http.StatusBadRequest {
		t.Errorf("expected HTTP 400, got %d", err.HTTPCode)
	}
}

func TestWrap(t *testing.T) {
	cause := fmt.Errorf("raw error")
	err := Wrap(cause, "CUSTOM", "custom message", http.StatusTeapot)

	if err.Code != "CUSTOM" {
		t.Errorf("expected code CUSTOM, got %s", err.Code)
	}
	if err.Cause != cause {
		t.Errorf("expected cause to be preserved")
	}
	if err.HTTPCode != http.StatusTeapot {
		t.Errorf("expected HTTP 418, got %d", err.HTTPCode)
	}
}

func TestWrapConvenienceFuncs(t *testing.T) {
	cause := fmt.Errorf("raw error")

	tests := []struct {
		name     string
		err      *AppError
		code     string
		httpCode int
	}{
		{"WrapNotFound", WrapNotFound(cause, "not found"), "NOT_FOUND", 404},
		{"WrapBadRequest", WrapBadRequest(cause, "bad input"), "BAD_REQUEST", 400},
		{"WrapInternal", WrapInternal(cause, "oops"), "INTERNAL", 500},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			if tt.err.Code != tt.code {
				t.Errorf("expected code %s, got %s", tt.code, tt.err.Code)
			}
			if tt.err.HTTPCode != tt.httpCode {
				t.Errorf("expected HTTP %d, got %d", tt.httpCode, tt.err.HTTPCode)
			}
			if tt.err.Cause != cause {
				t.Errorf("expected cause to be preserved")
			}
		})
	}
}

func TestUnwrap(t *testing.T) {
	cause := fmt.Errorf("original")
	err := WrapInternal(cause, "wrapped")
	unwrapped := err.Unwrap()
	if unwrapped != cause {
		t.Errorf("Unwrap() = %v, want %v", unwrapped, cause)
	}
}

func TestIsAppError(t *testing.T) {
	ae := NewNotFound("test")
	_, ok := IsAppError(ae)
	if !ok {
		t.Error("expected AppError to be identified")
	}

	plain := fmt.Errorf("plain error")
	_, ok = IsAppError(plain)
	if ok {
		t.Error("plain error should not be AppError")
	}

	_, ok = IsAppError(nil)
	if ok {
		t.Error("nil should not be AppError")
	}
}

func TestStatusCode(t *testing.T) {
	if sc := StatusCode(NewNotFound("x")); sc != 404 {
		t.Errorf("expected 404, got %d", sc)
	}
	if sc := StatusCode(fmt.Errorf("plain")); sc != 500 {
		t.Errorf("expected 500 for plain error, got %d", sc)
	}
}

func TestMessage(t *testing.T) {
	if msg := Message(NewNotFound("user x not found")); msg != "user x not found" {
		t.Errorf("expected message preserved, got %s", msg)
	}
	if msg := Message(fmt.Errorf("raw")); msg != "Internal server error" {
		t.Errorf("expected generic message for unknown error, got %s", msg)
	}
}

func TestCode(t *testing.T) {
	if c := Code(NewForbidden("nope")); c != "FORBIDDEN" {
		t.Errorf("expected FORBIDDEN, got %s", c)
	}
	if c := Code(fmt.Errorf("raw")); c != "INTERNAL" {
		t.Errorf("expected INTERNAL for unknown error, got %s", c)
	}
}

func TestIsCode(t *testing.T) {
	err := NewNotFound("test")
	if !IsCode(err, "NOT_FOUND") {
		t.Error("expected IsCode true for NOT_FOUND")
	}
	if IsCode(err, "FORBIDDEN") {
		t.Error("expected IsCode false for wrong code")
	}
	if IsCode(nil, "NOT_FOUND") {
		t.Error("expected IsCode false for nil")
	}
}

func TestIsNotFound(t *testing.T) {
	if !IsNotFound(NewNotFound("x")) {
		t.Error("expected IsNotFound true")
	}
	if IsNotFound(NewBadRequest("x")) {
		t.Error("expected IsNotFound false for bad request")
	}
}

func TestSentinelErrors(t *testing.T) {
	if ErrUnauthorized.Code != "UNAUTHORIZED" {
		t.Errorf("expected UNAUTHORIZED sentinel")
	}
	if ErrForbidden.Code != "FORBIDDEN" {
		t.Errorf("expected FORBIDDEN sentinel")
	}
	if ErrInternal.Code != "INTERNAL" {
		t.Errorf("expected INTERNAL sentinel")
	}
}

func TestErrorFormatting(t *testing.T) {
	// Without cause
	err := NewNotFound("user not found")
	str := err.Error()
	if str != "[NOT_FOUND] user not found" {
		t.Errorf("unexpected format: %s", str)
	}

	// With cause
	cause := fmt.Errorf("sql: no rows")
	err2 := WrapInternal(cause, "database error")
	str2 := err2.Error()
	if str2[:len("[INTERNAL]")] != "[INTERNAL]" {
		t.Errorf("unexpected format: %s", str2)
	}
}