/* ==========================================================================
   Expense & Budget Visualizer — css/style.css
   ==========================================================================
   Sections:
     1. Custom Properties & Base Reset        (task 2.1)
     2. Layout & Header                       (task 2.2)
     3. Summary Cards, Form & Spending Limit  (task 2.3)
     4. Chart Section & Transaction List      (task 2.4)
     5. Responsive, Focus & Sort Control      (task 2.5)
   ========================================================================== */


/* ==========================================================================
   1. CUSTOM PROPERTIES & BASE RESET
   ========================================================================== */

:root {
    /* Backgrounds */
    --color-background: #f4f6f9;
    --color-surface:    #ffffff;
    --color-surface-alt: #f0f2f5;

    /* Text */
    --color-text:         #1a1f36;
    --color-text-muted:   #6b7280;
    --color-text-inverse: #ffffff;

    /* Brand / accent */
    --color-accent:       #4f46e5;
    --color-accent-hover: #4338ca;

    /* Semantic */
    --color-danger:       #dc2626;
    --color-danger-light: #fef2f2;
    --color-warning:      #d97706;
    --color-warning-bg:   #fffbeb;
    --color-warning-border: #fcd34d;
    --color-success:      #059669;

    /* Borders */
    --color-border: #e5e7eb;

    /* Category badge colours */
    --color-food:      #e76f51;
    --color-transport: #2a9d8f;
    --color-fun:       #e9c46a;

    /* Progress bar */
    --color-progress-track: #e5e7eb;
    --color-progress-fill:  #4f46e5;

    /* Typography */
    --font-family: "Inter", "Segoe UI", system-ui, -apple-system, sans-serif;
    --font-size-base: 1rem;

    /* Spacing */
    --space-xs:  0.25rem;
    --space-sm:  0.5rem;
    --space-md:  1rem;
    --space-lg:  1.5rem;
    --space-xl:  2rem;
    --space-2xl: 3rem;

    /* Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.625rem;
    --radius-lg: 1rem;

    /* Shadows */
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.07), 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07), 0 2px 4px rgba(0, 0, 0, 0.05);

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
}

/* Dark theme overrides */
body[data-theme="dark"] {
    --color-background:    #0f1117;
    --color-surface:       #1e2130;
    --color-surface-alt:   #252840;

    --color-text:          #f1f5f9;
    --color-text-muted:    #94a3b8;
    --color-text-inverse:  #0f1117;

    --color-accent:        #818cf8;
    --color-accent-hover:  #a5b4fc;

    --color-danger:        #f87171;
    --color-danger-light:  #2d1414;
    --color-warning:       #fbbf24;
    --color-warning-bg:    #292014;
    --color-warning-border:#92400e;
    --color-success:       #34d399;

    --color-border:        #2e3347;

    --color-progress-track: #2e3347;
    --color-progress-fill:  #818cf8;

    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.4), 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.4), 0 2px 4px rgba(0, 0, 0, 0.3);
}

/* Minimal box-sizing reset */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    background-color: var(--color-background);
    color: var(--color-text);
    line-height: 1.6;
    min-height: 100vh;
    transition: background-color var(--transition-base),
                color var(--transition-base);
}

img,
canvas {
    display: block;
    max-width: 100%;
}

ul {
    list-style: none;
}

button {
    cursor: pointer;
    font-family: inherit;
}

input,
select,
button {
    font-size: inherit;
}


/* ==========================================================================
   2. LAYOUT & HEADER
   ========================================================================== */

/* Centred container with fluid padding */
.app-container {
    width: min(100% - 2rem, 1100px);
    margin-inline: auto;
}

/* ---- Header ---- */
.app-header {
    background-color: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
    padding: var(--space-lg) var(--space-md);
    box-shadow: var(--shadow-sm);

    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: var(--space-md);

    /* Respect the same max-width as main content */
    width: 100%;
}

/* Inner wrapper so the header content respects max-width */
.app-header > div:first-child {
    flex: 1 1 auto;
}

.app-header .eyebrow {
    font-size: 0.75rem;
    font-weight: 600;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--color-accent);
    margin-bottom: var(--space-xs);
}

.app-header h1 {
    font-size: clamp(1.25rem, 3vw, 1.75rem);
    font-weight: 700;
    color: var(--color-text);
    line-height: 1.2;
}

.app-header > div > p:last-child {
    font-size: 0.9rem;
    color: var(--color-text-muted);
    margin-top: var(--space-xs);
}

/* Theme toggle */
#theme-toggle {
    background-color: var(--color-surface-alt);
    color: var(--color-text);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
    font-weight: 500;
    min-height: 44px;
    white-space: nowrap;
    transition: background-color var(--transition-fast),
                border-color var(--transition-fast),
                color var(--transition-fast);
}

#theme-toggle:hover {
    background-color: var(--color-accent);
    border-color: var(--color-accent);
    color: var(--color-text-inverse);
}

/* ---- Main ---- */
.app-main {
    width: min(100% - 2rem, 1100px);
    margin-inline: auto;
    padding-block: var(--space-xl);
    display: flex;
    flex-direction: column;
    gap: var(--space-xl);
}

/* ---- Footer ---- */
.app-footer {
    background-color: var(--color-surface);
    border-top: 1px solid var(--color-border);
    text-align: center;
    padding: var(--space-lg) var(--space-md);
    color: var(--color-text-muted);
    font-size: 0.85rem;
}


/* ==========================================================================
   3. SUMMARY CARDS, FORM & SPENDING LIMIT
   ========================================================================== */

/* ---- Generic card ---- */
.card {
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-lg);
    box-shadow: var(--shadow-sm);
}

.card h2 {
    font-size: 0.8rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.07em;
    color: var(--color-text-muted);
    margin-bottom: var(--space-sm);
}

/* ---- Summary section (two cards side-by-side on larger screens) ---- */
.summary-section {
    display: flex;
    flex-direction: column;
    gap: var(--space-lg);
}

/* ---- Total expenses card ---- */
.total-card {
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
}

#total-display {
    font-size: clamp(1.75rem, 5vw, 2.5rem);
    font-weight: 800;
    color: var(--color-accent);
    line-height: 1.1;
    letter-spacing: -0.02em;
}

/* ---- Spending limit card ---- */
.spending-limit-section {
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
}

.spending-limit-section label {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--color-text-muted);
}

.limit-form-row {
    display: flex;
    gap: var(--space-sm);
    flex-wrap: wrap;
}

.limit-form-row input {
    flex: 1 1 140px;
}

#save-limit-btn {
    background-color: var(--color-accent);
    color: var(--color-text-inverse);
    border: none;
    border-radius: var(--radius-sm);
    padding: 0 var(--space-md);
    min-height: 44px;
    font-weight: 500;
    transition: background-color var(--transition-fast);
    white-space: nowrap;
}

#save-limit-btn:hover {
    background-color: var(--color-accent-hover);
}

/* Limit display area */
#limit-display {
    display: flex;
    flex-direction: column;
    gap: var(--space-xs);
    margin-top: var(--space-xs);
}

#limit-summary {
    font-size: 0.875rem;
    color: var(--color-text-muted);
}

#limit-percentage {
    font-size: 0.8rem;
    color: var(--color-text-muted);
}

/* Progress track */
.progress-track {
    width: 100%;
    height: 10px;
    background-color: var(--color-progress-track);
    border-radius: 999px;
    overflow: hidden;
}

#limit-progress-bar {
    height: 100%;
    width: 0;
    max-width: 100%;
    background-color: var(--color-progress-fill);
    border-radius: 999px;
    transition: width var(--transition-base), background-color var(--transition-base);
}

/* Warning state — applied by JS */
#limit-warning {
    font-size: 0.825rem;
    font-weight: 500;
    color: var(--color-warning);
    min-height: 1.2em; /* reserve space so layout doesn't jump */
}

/* When limit is exceeded, shift progress bar to danger colour */
.spending-limit-section.is-warning #limit-progress-bar {
    background-color: var(--color-danger);
}

.spending-limit-section.is-warning .progress-track {
    background-color: var(--color-danger-light);
}

/* ---- Transaction form section ---- */
.form-section {
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-lg);
    box-shadow: var(--shadow-sm);
}

.form-section h2 {
    font-size: 0.8rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.07em;
    color: var(--color-text-muted);
    margin-bottom: var(--space-md);
}

#transaction-form {
    display: flex;
    flex-direction: column;
    gap: var(--space-md);
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: var(--space-xs);
}

.form-group label {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--color-text);
}

/* Common input / select styles */
input[type="text"],
input[type="number"],
select {
    width: 100%;
    min-height: 44px;
    padding: 0.5rem 0.75rem;
    background-color: var(--color-surface-alt);
    color: var(--color-text);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    appearance: none;
    -webkit-appearance: none;
    transition: border-color var(--transition-fast),
                box-shadow var(--transition-fast);
}

input[type="text"]:hover,
input[type="number"]:hover,
select:hover {
    border-color: var(--color-accent);
}

input[type="text"]:focus,
input[type="number"]:focus,
select:focus {
    outline: none;
    border-color: var(--color-accent);
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.15);
}

/* Arrow indicator for selects */
select {
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%236b7280' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 0.75rem center;
    padding-right: 2rem;
}

/* Input error state */
input.is-invalid,
select.is-invalid {
    border-color: var(--color-danger);
    box-shadow: 0 0 0 3px rgba(220, 38, 38, 0.12);
}

/* Inline error messages */
.error-message {
    font-size: 0.8rem;
    color: var(--color-danger);
    min-height: 1.1em;
}

/* Submit button */
#add-btn {
    min-height: 44px;
    padding: 0 var(--space-lg);
    background-color: var(--color-accent);
    color: var(--color-text-inverse);
    border: none;
    border-radius: var(--radius-sm);
    font-weight: 600;
    font-size: 0.95rem;
    transition: background-color var(--transition-fast),
                transform var(--transition-fast);
    align-self: flex-start;
}

#add-btn:hover {
    background-color: var(--color-accent-hover);
}

#add-btn:active {
    transform: translateY(1px);
}


/* ==========================================================================
   4. CHART SECTION & TRANSACTION LIST
   ========================================================================== */

/* ---- Chart section ---- */
.chart-section {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-md);
}

.chart-section h2 {
    align-self: flex-start;
}

.chart-canvas-wrapper {
    width: 100%;
    max-width: 340px;
    margin-inline: auto;
    position: relative;
}

#spending-chart {
    width: 100% !important;
    height: auto !important;
}

#chart-empty-state {
    font-size: 0.9rem;
    color: var(--color-text-muted);
    text-align: center;
    padding: var(--space-xl);
    background-color: var(--color-surface-alt);
    border-radius: var(--radius-md);
    border: 1px dashed var(--color-border);
    width: 100%;
}

/* ---- Transaction history section ---- */
.history-section {
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-lg);
    box-shadow: var(--shadow-sm);
    display: flex;
    flex-direction: column;
    gap: var(--space-md);
}

.history-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: var(--space-sm);
}

.history-header h2 {
    font-size: 1rem;
    font-weight: 700;
    text-transform: none;
    letter-spacing: 0;
    color: var(--color-text);
    margin-bottom: 0;
}

/* ---- Sort control ---- */
.sort-control-wrapper {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    flex-wrap: nowrap;
}

.sort-control-wrapper label {
    font-size: 0.85rem;
    color: var(--color-text-muted);
    white-space: nowrap;
}

#sort-control {
    width: auto;
    min-height: 36px;
    padding: 0.3rem 2rem 0.3rem 0.6rem;
    font-size: 0.85rem;
    border-radius: var(--radius-sm);
    border: 1px solid var(--color-border);
    background-color: var(--color-surface-alt);
    color: var(--color-text);
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%236b7280' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 0.5rem center;
    appearance: none;
    -webkit-appearance: none;
}

/* ---- Transaction list ---- */
.transaction-list {
    max-height: 420px;
    overflow-y: auto;
    overscroll-behavior: contain;
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
}

/* Scrollbar styling (Webkit) */
.transaction-list::-webkit-scrollbar {
    width: 6px;
}

.transaction-list::-webkit-scrollbar-track {
    background: var(--color-surface-alt);
    border-radius: 999px;
}

.transaction-list::-webkit-scrollbar-thumb {
    background: var(--color-border);
    border-radius: 999px;
}

/* ---- Transaction item ---- */
.transaction-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-sm);
    padding: var(--space-sm) var(--space-md);
    background-color: var(--color-surface-alt);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    transition: border-color var(--transition-fast);
}

.transaction-item:hover {
    border-color: var(--color-accent);
}

/* Left side: name + category */
.transaction-info {
    display: flex;
    flex-direction: column;
    gap: var(--space-xs);
    min-width: 0; /* allow text truncation */
}

.transaction-name {
    font-weight: 600;
    font-size: 0.95rem;
    color: var(--color-text);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

/* Category badge */
.transaction-category {
    display: inline-flex;
    align-items: center;
    font-size: 0.72rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    padding: 0.15rem 0.5rem;
    border-radius: 999px;
    color: #ffffff;
    width: fit-content;
}

.transaction-category[data-category="Food"] {
    background-color: var(--color-food);
}

.transaction-category[data-category="Transport"] {
    background-color: var(--color-transport);
}

.transaction-category[data-category="Fun"] {
    background-color: var(--color-fun);
    color: #1a1f36; /* dark text on light yellow */
}

/* Right side: amount + delete */
.transaction-actions {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    flex-shrink: 0;
}

.transaction-amount {
    font-size: 0.9rem;
    font-weight: 700;
    color: var(--color-text);
    white-space: nowrap;
}

/* Delete button */
.delete-btn {
    background-color: transparent;
    color: var(--color-danger);
    border: 1px solid var(--color-danger);
    border-radius: var(--radius-sm);
    padding: 0.25rem 0.6rem;
    font-size: 0.78rem;
    font-weight: 500;
    min-height: 30px;
    transition: background-color var(--transition-fast),
                color var(--transition-fast);
}

.delete-btn:hover {
    background-color: var(--color-danger);
    color: #ffffff;
}

/* ---- Empty state ---- */
.transaction-empty-state {
    text-align: center;
    padding: var(--space-xl);
    color: var(--color-text-muted);
    font-size: 0.9rem;
    border: 1px dashed var(--color-border);
    border-radius: var(--radius-md);
    background-color: var(--color-surface-alt);
}


/* ==========================================================================
   5. RESPONSIVE BREAKPOINTS, FOCUS STYLES & SORT CONTROL
   ========================================================================== */

/* Base: form and chart sections stack with a gap on mobile */
.form-chart-row {
    display: flex;
    flex-direction: column;
    gap: var(--space-xl);
}

/* ---- Visible keyboard focus styles (WCAG 2.4.7) ---- */
button:focus-visible,
input:focus-visible,
select:focus-visible {
    outline: 3px solid var(--color-accent);
    outline-offset: 2px;
}

/* ---- Tablet and up (≥768 px) ---- */
@media (min-width: 768px) {

    /* Two-column layout for summary cards */
    .summary-section {
        display: grid;
        grid-template-columns: 1fr 1fr;
        align-items: start;
    }

    /* Two-column layout for form + chart */
    .form-chart-row {
        display: grid;
        grid-template-columns: 1fr 1fr;
        gap: var(--space-xl);
        align-items: start;
    }

    /* Wider transaction form submit button */
    #add-btn {
        width: auto;
    }
}

/* ---- Desktop and up (≥1024 px) ---- */
@media (min-width: 1024px) {

    /* Give total card a highlighted left border accent */
    .total-card {
        border-left: 4px solid var(--color-accent);
    }

    /* Larger total display */
    #total-display {
        font-size: 2.5rem;
    }
}

/* ---- Reduced motion preference ---- */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        transition-duration: 0.01ms !important;
        animation-duration: 0.01ms !important;
    }
}