/**
 * Button Component - Design System
 * BEM Methodology: .btn--{variant}
 */

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

.btn {
    padding: var(--spacing-3) var(--spacing-4);
    border-radius: var(--radius-sm);
    font-weight: var(--font-weight-semibold);
    font-size: var(--font-size-sm);
    border: 1px solid transparent;
    cursor: pointer;
    transition: all var(--transition-base);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-2);
    text-decoration: none;
    line-height: var(--line-height-tight);
    white-space: nowrap;
}

.btn:disabled,
.btn[aria-disabled="true"] {
    opacity: 0.5;
    cursor: not-allowed;
    pointer-events: none;
}

.btn:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

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

/* Primary Button */
.btn--primary {
    background: var(--color-primary);
    color: white;
    border-color: var(--color-primary);
}

.btn--primary:hover:not(:disabled) {
    background: var(--color-primary-dark);
    border-color: var(--color-primary-dark);
    box-shadow: var(--shadow-primary);
    transform: translateY(-1px);
}

.btn--primary:active:not(:disabled) {
    transform: translateY(0);
    box-shadow: var(--shadow-sm);
}

/* Secondary Button */
.btn--secondary {
    background: transparent;
    color: var(--color-primary);
    border-color: var(--color-primary);
}

.btn--secondary:hover:not(:disabled) {
    background: rgba(59, 89, 152, 0.08);
    border-color: var(--color-primary-dark);
    color: var(--color-primary-dark);
}

.btn--secondary:active:not(:disabled) {
    background: rgba(59, 89, 152, 0.12);
}

/* Ghost Button */
.btn--ghost {
    background: transparent;
    color: var(--color-text-secondary);
    border-color: var(--color-border-medium);
}

.btn--ghost:hover:not(:disabled) {
    background: var(--color-bg-tertiary);
    border-color: var(--color-border-dark);
    color: var(--color-text-primary);
}

.btn--ghost:active:not(:disabled) {
    background: var(--color-bg-secondary);
}

/* Success Button */
.btn--success {
    background: var(--color-success);
    color: white;
    border-color: var(--color-success);
}

.btn--success:hover:not(:disabled) {
    background: #059669;
    border-color: #059669;
    box-shadow: 0 4px 12px rgba(16, 185, 129, 0.3);
    transform: translateY(-1px);
}

/* Warning Button */
.btn--warning {
    background: var(--color-warning);
    color: white;
    border-color: var(--color-warning);
}

.btn--warning:hover:not(:disabled) {
    background: #d97706;
    border-color: #d97706;
    box-shadow: 0 4px 12px rgba(245, 158, 11, 0.3);
    transform: translateY(-1px);
}

/* Danger Button */
.btn--danger {
    background: var(--color-danger);
    color: white;
    border-color: var(--color-danger);
}

.btn--danger:hover:not(:disabled) {
    background: #dc2626;
    border-color: #dc2626;
    box-shadow: 0 4px 12px rgba(239, 68, 68, 0.3);
    transform: translateY(-1px);
}

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

.btn--sm {
    padding: var(--spacing-2) var(--spacing-3);
    font-size: var(--font-size-xs);
    gap: var(--spacing-1);
}

.btn--lg {
    padding: var(--spacing-4) var(--spacing-6);
    font-size: var(--font-size-base);
    gap: var(--spacing-3);
}

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

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

.btn--loading::after {
    content: "";
    position: absolute;
    width: 16px;
    height: 16px;
    top: 50%;
    left: 50%;
    margin-left: -8px;
    margin-top: -8px;
    border: 2px solid transparent;
    border-top-color: currentColor;
    border-radius: 50%;
    animation: btn-spin 0.6s linear infinite;
}

.btn--primary.btn--loading::after,
.btn--success.btn--loading::after,
.btn--warning.btn--loading::after,
.btn--danger.btn--loading::after {
    border-top-color: white;
}

.btn--secondary.btn--loading::after,
.btn--ghost.btn--loading::after {
    border-top-color: var(--color-primary);
}

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

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

.btn-group {
    display: inline-flex;
    gap: var(--spacing-2);
}

.btn-group--attached {
    gap: 0;
}

.btn-group--attached .btn:not(:first-child) {
    border-top-left-radius: 0;
    border-bottom-left-radius: 0;
    margin-left: -1px;
}

.btn-group--attached .btn:not(:last-child) {
    border-top-right-radius: 0;
    border-bottom-right-radius: 0;
}

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

.btn--icon-only {
    padding: var(--spacing-3);
    width: 40px;
    height: 40px;
}

.btn--icon-only.btn--sm {
    padding: var(--spacing-2);
    width: 32px;
    height: 32px;
}

.btn--icon-only.btn--lg {
    padding: var(--spacing-4);
    width: 48px;
    height: 48px;
}

/* ==========================================================================
   FULL WIDTH
   ========================================================================== */

.btn--full {
    width: 100%;
}