/**
 * Button Component System
 * Standardized button styles using design system tokens
 *
 * Related: RW-43
 * Epic: RW-3 (UI Component Library)
 * Reference: docs/UI_UX_MIGRATION_GUIDE.md Section 4.1
 */

/* ============================================================================
   BASE BUTTON STYLES
   ============================================================================ */

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: var(--button-padding-y-base, 0.5rem) var(--button-padding-x-base, 1rem);
    font-family: var(--font-family-sans, sans-serif);
    font-size: var(--font-size-base, 1rem);
    font-weight: var(--font-weight-semibold, 600);
    line-height: 1.5;
    text-align: center;
    text-decoration: none;
    white-space: nowrap;
    vertical-align: middle;
    cursor: pointer;
    user-select: none;
    border: 2px solid transparent;
    border-radius: var(--radius-md, 0.5rem);
    transition: var(--transition-property-common, all) var(--transition-fast, 150ms);
    outline: none;
}

.btn:focus {
    outline: 2px solid var(--color-primary-500, #1ea79e);
    outline-offset: 2px;
}

.btn:disabled,
.btn.disabled {
    opacity: 0.5;
    cursor: not-allowed;
    pointer-events: none;
}

/* ============================================================================
   BUTTON SIZES
   ============================================================================ */

.btn-xs {
    padding: 0.25rem 0.5rem;
    font-size: var(--font-size-xs, 0.75rem);
    border-radius: var(--radius-sm, 0.25rem);
}

.btn-sm {
    padding: var(--button-padding-y-sm, 0.375rem) var(--button-padding-x-sm, 0.75rem);
    font-size: var(--font-size-sm, 0.875rem);
}

.btn-md {
    padding: var(--button-padding-y-base, 0.5rem) var(--button-padding-x-base, 1rem);
    font-size: var(--font-size-base, 1rem);
}

.btn-lg {
    padding: var(--button-padding-y-lg, 0.75rem) var(--button-padding-x-lg, 1.5rem);
    font-size: var(--font-size-lg, 1.125rem);
}

/* ============================================================================
   BUTTON VARIANTS
   ============================================================================ */

/* Primary Button */
.btn-primary {
    background: linear-gradient(135deg, var(--color-primary-600, #18968d) 0%, var(--color-primary-500, #1ea79e) 100%);
    color: var(--color-text-white, #fff);
    border-color: var(--color-primary-600, #18968d);
    box-shadow: var(--shadow-brand-sm, 0 2px 4px rgba(6, 55, 53, 0.3));
}

.btn-primary:hover {
    background: linear-gradient(135deg, var(--color-primary-700, #147a73) 0%, var(--color-primary-600, #18968d) 100%);
    border-color: var(--color-primary-700, #147a73);
    box-shadow: var(--shadow-brand-md, 0 4px 8px rgba(6, 55, 53, 0.4));
    transform: translateY(-1px);
}

.btn-primary:active {
    background: var(--color-primary-700, #147a73);
    transform: translateY(0);
}

/* Secondary Button */
.btn-secondary {
    background: var(--color-secondary-500, #325553);
    color: var(--color-text-white, #fff);
    border-color: var(--color-secondary-500, #325553);
}

.btn-secondary:hover {
    background: var(--color-secondary-600, #2c4d4b);
    border-color: var(--color-secondary-600, #2c4d4b);
    transform: translateY(-1px);
}

/* Outline Button */
.btn-outline {
    background: transparent;
    color: var(--color-primary-600, #18968d);
    border-color: var(--color-primary-500, #1ea79e);
}

.btn-outline:hover {
    background: var(--color-primary-500, #1ea79e);
    color: var(--color-text-white, #fff);
    border-color: var(--color-primary-600, #18968d);
}

/* Outline Secondary */
.btn-outline-secondary {
    background: transparent;
    color: var(--color-secondary-600, #2c4d4b);
    border-color: var(--color-secondary-500, #325553);
}

.btn-outline-secondary:hover {
    background: var(--color-secondary-500, #325553);
    color: var(--color-text-white, #fff);
}

/* Success Button */
.btn-success {
    background: var(--color-success, #28a745);
    color: var(--color-text-white, #fff);
    border-color: var(--color-success-dark, #155724);
}

.btn-success:hover {
    background: var(--color-success-dark, #155724);
    box-shadow: var(--shadow-sm);
}

/* Danger Button */
.btn-danger {
    background: var(--color-danger, #dc3545);
    color: var(--color-text-white, #fff);
    border-color: var(--color-danger-dark, #721c24);
}

.btn-danger:hover {
    background: var(--color-danger-dark, #721c24);
    box-shadow: var(--shadow-sm);
}

/* Warning Button */
.btn-warning {
    background: var(--color-warning, #ffc107);
    color: var(--color-text-primary, #212529);
    border-color: var(--color-warning-dark, #856404);
}

.btn-warning:hover {
    background: var(--color-warning-dark, #856404);
    color: var(--color-text-white, #fff);
}

/* Info Button */
.btn-info {
    background: var(--color-info, #17a2b8);
    color: var(--color-text-white, #fff);
    border-color: var(--color-info-dark, #0c5460);
}

.btn-info:hover {
    background: var(--color-info-dark, #0c5460);
}

/* Light Button */
.btn-light {
    background: var(--color-neutral-100, #f1f3f4);
    color: var(--color-text-primary, #212529);
    border-color: var(--color-neutral-300, #dee2e6);
}

.btn-light:hover {
    background: var(--color-neutral-200, #e9ecef);
    border-color: var(--color-neutral-400, #ced4da);
}

/* Dark Button */
.btn-dark {
    background: var(--color-neutral-800, #343a40);
    color: var(--color-text-white, #fff);
    border-color: var(--color-neutral-900, #212529);
}

.btn-dark:hover {
    background: var(--color-neutral-900, #212529);
}

/* ============================================================================
   BUTTON STATES
   ============================================================================ */

/* Loading State */
.btn-loading {
    position: relative;
    color: transparent;
    pointer-events: none;
}

.btn-loading::after {
    content: '';
    position: absolute;
    width: 1rem;
    height: 1rem;
    top: 50%;
    left: 50%;
    margin-left: -0.5rem;
    margin-top: -0.5rem;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top-color: #fff;
    animation: btn-spin 0.6s linear infinite;
}

@keyframes btn-spin {
    to { transform: rotate(360deg); }
}

/* Active State */
.btn:active:not(:disabled) {
    transform: scale(0.98);
    box-shadow: var(--shadow-xs);
}

/* ============================================================================
   BUTTON GROUPS
   ============================================================================ */

.btn-group {
    display: inline-flex;
    gap: 0.5rem;
}

.btn-group-attached {
    display: inline-flex;
    gap: 0;
}

.btn-group-attached .btn {
    border-radius: 0;
    margin-left: -1px;
}

.btn-group-attached .btn:first-child {
    border-top-left-radius: var(--radius-md);
    border-bottom-left-radius: var(--radius-md);
    margin-left: 0;
}

.btn-group-attached .btn:last-child {
    border-top-right-radius: var(--radius-md);
    border-bottom-right-radius: var(--radius-md);
}

/* ============================================================================
   ICON BUTTONS
   ============================================================================ */

.btn-icon {
    padding: 0.5rem;
    min-width: 2.5rem;
    min-height: 2.5rem;
}

.btn-icon-sm {
    padding: 0.375rem;
    min-width: 2rem;
    min-height: 2rem;
}

.btn-icon-lg {
    padding: 0.75rem;
    min-width: 3rem;
    min-height: 3rem;
}

/* ============================================================================
   BLOCK BUTTON
   ============================================================================ */

.btn-block {
    display: flex;
    width: 100%;
}

/* ============================================================================
   LINK BUTTON (looks like link, behaves like button)
   ============================================================================ */

.btn-link {
    background: transparent;
    color: var(--color-text-link, #1ea79e);
    border-color: transparent;
    text-decoration: underline;
    padding: 0;
    box-shadow: none;
}

.btn-link:hover {
    color: var(--color-primary-700, #147a73);
    text-decoration: underline;
    background: transparent;
    transform: none;
}

/* ============================================================================
   GHOST BUTTON (transparent with hover fill)
   ============================================================================ */

.btn-ghost {
    background: transparent;
    color: var(--color-primary-600, #18968d);
    border-color: transparent;
}

.btn-ghost:hover {
    background: var(--color-primary-50, #e6f7f6);
    color: var(--color-primary-700, #147a73);
}