// SPDX-License-Identifier: AGPL-3.0-or-later

import {existsSync, mkdirSync, readdirSync, readFileSync, writeFileSync} from 'node:fs';
import {dirname, join, relative, resolve} from 'node:path';
import {SKELETON_SURFACE_TOKENS} from '@app/features/app/components/skeleton/SkeletonSurfaceContract';

type ThemeVariableKind = 'color' | 'font' | 'dimension' | 'number' | 'shadow' | 'transition' | 'other';

interface CssSource {
	file: string;
	label: string;
	generatedBy?: string;
}

interface VariableDefinition {
	name: string;
	kind: ThemeVariableKind;
	groupId: string;
	groupLabel: string;
	source: string;
}

const PRIORITY_CSS_SOURCES: ReadonlyArray<CssSource> = [
	{file: 'src/app/globals.css', label: 'globals'},
	{
		file: 'src/features/theme/styles/generated/color-system.css',
		label: 'color-system',
		generatedBy: 'pnpm generate:colors',
	},
	{
		file: 'src/features/theme/styles/generated/message-layout.css',
		label: 'message-layout',
		generatedBy: 'pnpm generate:message-layout',
	},
];
const PRIORITY_SOURCE_INDEX = new Map(PRIORITY_CSS_SOURCES.map((source, index) => [source.file, index]));
const IGNORED_SOURCE_PREFIXES = ['src/features/theme_studio/', 'src/theme/'];

const BUNDLED_FONT_VARIABLES_CSS = resolve(
	import.meta.dirname,
	'..',
	'..',
	'packages',
	'fonts',
	'css',
	'variables.css',
);

function bundledFontStack(name: string): string {
	const css = readFileSync(BUNDLED_FONT_VARIABLES_CSS, 'utf8');
	const declaration = new RegExp(`${name}:([^;]*);`).exec(css);
	if (!declaration) {
		throw new Error(`${name} is not declared in ${BUNDLED_FONT_VARIABLES_CSS}`);
	}
	return declaration[1].replace(/\s+/g, ' ').trim();
}

const EXTRA_GLOBAL_DEFAULTS: ReadonlyArray<{name: string; value: string; source: string}> = [
	{
		name: '--font-sans',
		value: bundledFontStack('--font-sans'),
		source: 'runtime-fonts',
	},
	{
		name: '--font-mono',
		value: bundledFontStack('--font-mono'),
		source: 'runtime-fonts',
	},
	{name: '--font-size', value: '1rem', source: 'runtime-accessibility'},
	{name: '--chat-horizontal-padding', value: '1rem', source: 'runtime-accessibility'},
	{name: '--message-group-spacing', value: '1rem', source: 'runtime-accessibility'},
	{name: '--link-decoration', value: 'none', source: 'runtime-accessibility'},
	{name: '--markup-strikethrough-color', value: 'currentColor', source: 'runtime-accessibility'},
];

const GROUP_LABELS: Record<string, string> = {
	typography: 'Typography',
	surfaces: 'Surfaces',
	headers: 'Headers',
	text: 'Text',
	brand: 'Brand & accents',
	status: 'Status indicators',
	borders: 'Borders & focus',
	alerts: 'Alerts & callouts',
	markup: 'Markup & mentions',
	buttons: 'Buttons',
	code: 'Code & terminal',
	tables: 'Tables',
	scrolling: 'Scrolling',
	layout: 'Layout',
	messages: 'Messages',
	emoji: 'Emoji',
	motion: 'Motion',
	layering: 'Layering',
	media: 'Media',
	forms: 'Forms',
	other: 'Other',
};

function stripAtRuleBlocks(css: string): string {
	let output = '';
	let index = 0;
	while (index < css.length) {
		if (css[index] !== '@') {
			output += css[index];
			index += 1;
			continue;
		}
		const nextSemicolon = css.indexOf(';', index);
		const nextBrace = css.indexOf('{', index);
		if (nextBrace === -1 || (nextSemicolon !== -1 && nextSemicolon < nextBrace)) {
			index = nextSemicolon === -1 ? css.length : nextSemicolon + 1;
			continue;
		}
		let depth = 0;
		let cursor = nextBrace;
		for (; cursor < css.length; cursor += 1) {
			if (css[cursor] === '{') depth += 1;
			if (css[cursor] === '}') {
				depth -= 1;
				if (depth === 0) {
					cursor += 1;
					break;
				}
			}
		}
		index = cursor;
	}
	return output;
}

function toPosixPath(path: string): string {
	return path.replaceAll('\\', '/');
}

function discoverCssSources(appDir: string): ReadonlyArray<CssSource> {
	const srcDir = join(appDir, 'src');
	const files: Array<string> = [];
	const visit = (directory: string) => {
		for (const entry of readdirSync(directory, {withFileTypes: true})) {
			const absolutePath = join(directory, entry.name);
			if (entry.isDirectory()) {
				visit(absolutePath);
				continue;
			}
			if (!entry.isFile() || !entry.name.endsWith('.css')) continue;
			const sourceFile = toPosixPath(relative(appDir, absolutePath));
			if (IGNORED_SOURCE_PREFIXES.some((prefix) => sourceFile.startsWith(prefix))) continue;
			files.push(sourceFile);
		}
	};
	visit(srcDir);
	const discovered = new Set(files);
	const missing = PRIORITY_CSS_SOURCES.filter((source) => !discovered.has(source.file));
	if (missing.length > 0) {
		const remedies = missing.map(
			(source) => `  ${source.file} is missing. Run \`${source.generatedBy ?? 'pnpm build'}\` first.`,
		);
		throw new Error(
			`Cannot generate the theme variable manifest from a partial input.\n${remedies.join('\n')}\n` +
				'Writing anyway would silently delete every variable those sources declare from a tracked file.',
		);
	}
	return files
		.sort((left, right) => {
			const leftPriority = PRIORITY_SOURCE_INDEX.get(left);
			const rightPriority = PRIORITY_SOURCE_INDEX.get(right);
			if (leftPriority !== undefined || rightPriority !== undefined) {
				return (leftPriority ?? Number.MAX_SAFE_INTEGER) - (rightPriority ?? Number.MAX_SAFE_INTEGER);
			}
			return left.localeCompare(right);
		})
		.map((file) => ({
			file,
			label: PRIORITY_CSS_SOURCES.find((source) => source.file === file)?.label ?? file.replace(/^src\//, ''),
		}));
}

function selectorHas(selector: string, target: string): boolean {
	return selector
		.split(',')
		.map((part) => part.trim())
		.includes(target);
}

function extractDeclarations(block: string): Array<[string, string]> {
	const declarations: Array<[string, string]> = [];
	const pattern = /(--[a-zA-Z0-9_-]+)\s*:\s*([^;]+);/g;
	let match: RegExpExecArray | null;
	while ((match = pattern.exec(block)) !== null) {
		const name = match[1] as string;
		const value = (match[2] as string).replace(/\s+/g, ' ').trim();
		declarations.push([name, value]);
	}
	return declarations;
}

function readSourceVariables(appDir: string): {
	darkDefaults: Map<string, string>;
	lightDefaults: Map<string, string>;
	sources: Map<string, string>;
} {
	const darkDefaults = new Map<string, string>();
	const lightOverrides = new Map<string, string>();
	const sources = new Map<string, string>();
	for (const source of discoverCssSources(appDir)) {
		const absolutePath = join(appDir, source.file);
		const css = stripAtRuleBlocks(readFileSync(absolutePath, 'utf8').replace(/\/\*[\s\S]*?\*\//g, ''));
		const blockPattern = /([^{}]+)\{([^{}]*)\}/g;
		let match: RegExpExecArray | null;
		while ((match = blockPattern.exec(css)) !== null) {
			const selector = (match[1] as string).trim();
			const block = match[2] as string;
			const isRoot = selectorHas(selector, ':root');
			const isLight = selectorHas(selector, '.theme-light');
			if (!isRoot && !isLight) continue;
			for (const [name, value] of extractDeclarations(block)) {
				if (isRoot) {
					darkDefaults.set(name, value);
					sources.set(name, source.label);
				}
				if (isLight) {
					lightOverrides.set(name, value);
					sources.set(name, source.label);
				}
			}
		}
	}
	for (const extra of EXTRA_GLOBAL_DEFAULTS) {
		if (!darkDefaults.has(extra.name)) {
			darkDefaults.set(extra.name, extra.value);
			sources.set(extra.name, extra.source);
		}
	}
	const lightDefaults = new Map(darkDefaults);
	for (const [name, value] of lightOverrides) {
		lightDefaults.set(name, value);
	}
	return {darkDefaults, lightDefaults, sources};
}

function findMatchingParen(text: string, openIndex: number): number {
	let depth = 0;
	for (let index = openIndex; index < text.length; index += 1) {
		const character = text[index];
		if (character === '(') depth += 1;
		if (character === ')') {
			depth -= 1;
			if (depth === 0) return index;
		}
	}
	return -1;
}

function splitVarArguments(inner: string): {dependency: string; fallback: string | null} {
	let depth = 0;
	for (let index = 0; index < inner.length; index += 1) {
		const character = inner[index];
		if (character === '(') depth += 1;
		if (character === ')') depth -= 1;
		if (character === ',' && depth === 0) {
			return {dependency: inner.slice(0, index).trim(), fallback: inner.slice(index + 1).trim()};
		}
	}
	return {dependency: inner.trim(), fallback: null};
}

function resolveVariableValue(name: string, values: ReadonlyMap<string, string>, stack = new Set<string>()): string {
	const value = values.get(name);
	if (!value) return '';
	let result = '';
	let cursor = 0;
	while (cursor < value.length) {
		const start = value.indexOf('var(', cursor);
		if (start === -1) {
			result += value.slice(cursor);
			return result;
		}
		const close = findMatchingParen(value, start + 3);
		if (close === -1) {
			result += value.slice(cursor);
			return result;
		}
		result += value.slice(cursor, start);
		const full = value.slice(start, close + 1);
		const {dependency, fallback} = splitVarArguments(value.slice(start + 4, close));
		if (dependency === '--saturation-factor') {
			result += full;
		} else if (stack.has(dependency) || !values.get(dependency)) {
			result += fallback ?? full;
		} else {
			const nextStack = new Set(stack);
			nextStack.add(name);
			result += resolveVariableValue(dependency, values, nextStack);
		}
		cursor = close + 1;
	}
	return result;
}

function getGroupId(name: string): string {
	if (name.startsWith('--font')) return 'typography';
	if (name.startsWith('--z-index')) return 'layering';
	if (name.startsWith('--transition')) return 'motion';
	if (name.startsWith('--shadow')) return 'borders';
	if (name.includes('scrollbar')) return 'scrolling';
	if (name.startsWith('--message')) return 'messages';
	if (name.includes('typing')) return 'messages';
	if (name.includes('emoji')) return 'emoji';
	if (name.includes('textarea') || name.includes('input') || name.includes('form')) return 'forms';
	if (name.includes('button') || name.includes('control-button')) return 'buttons';
	if (name.startsWith('--code') || name.startsWith('--ansi') || name === '--text-code') return 'code';
	if (name.includes('table')) return 'tables';
	if (name.startsWith('--markup') || name.includes('spoiler')) return 'markup';
	if (name.startsWith('--alert')) return 'alerts';
	if (name.startsWith('--status')) return 'status';
	if (name.startsWith('--brand') || name.startsWith('--accent') || name.startsWith('--plutonium')) return 'brand';
	if (name.startsWith('--text')) return 'text';
	if (name.includes('border') || name.includes('focus') || name.includes('radius')) return 'borders';
	if (name.includes('layout') || name.includes('spacing') || name.includes('padding') || name.includes('gap'))
		return 'layout';
	if (name.includes('width') || name.includes('height') || name.includes('size') || name.includes('gutter'))
		return 'layout';
	if (name.includes('media') || name.includes('avatar') || name.includes('guild-icon')) return 'media';
	if (name.includes('bg') || name.includes('background') || name.includes('surface') || name.includes('guild-list')) {
		return 'surfaces';
	}
	return 'other';
}

function getKind(name: string, value: string): ThemeVariableKind {
	const lowerName = name.toLowerCase();
	const lowerValue = value.toLowerCase();
	if (name === '--font-sans' || name === '--font-mono') return 'font';
	if (name.startsWith('--shadow')) return 'shadow';
	if (name.startsWith('--transition') || /\b\d+(?:\.\d+)?m?s\b/.test(lowerValue)) return 'transition';
	if (/^-?\d+(?:\.\d+)?$/.test(value)) return 'number';
	if (lowerName.includes('opacity')) return 'number';
	if (lowerValue.includes(' solid ')) return 'other';
	if (
		lowerValue === 'transparent' ||
		lowerValue === 'currentcolor' ||
		lowerValue.startsWith('#') ||
		lowerValue.startsWith('hsl') ||
		lowerValue.startsWith('rgb') ||
		lowerValue.startsWith('color-mix')
	) {
		return 'color';
	}
	if (
		/(?:^|\s)-?\d*\.?\d+(?:px|rem|em|%|vh|vw|dvh|svh|cqi)\b/.test(lowerValue) ||
		lowerValue.includes('calc(') ||
		lowerValue.includes('clamp(') ||
		lowerValue.includes('min(') ||
		lowerValue.includes('max(')
	) {
		return 'dimension';
	}
	if (
		lowerName.startsWith('--ansi') ||
		lowerName.includes('color') ||
		lowerName.startsWith('--text-') ||
		lowerName.endsWith('-text') ||
		lowerName.includes('-text-') ||
		lowerName.includes('bg') ||
		lowerName.includes('background') ||
		lowerName.includes('fill') ||
		lowerName.includes('accent') ||
		lowerName.includes('brand') ||
		lowerName.includes('status') ||
		lowerName.includes('alert') ||
		lowerName.includes('selection')
	) {
		return 'color';
	}
	return 'other';
}

function buildDefinitions(
	darkDefaults: ReadonlyMap<string, string>,
	sources: ReadonlyMap<string, string>,
): Array<VariableDefinition> {
	return [...darkDefaults.keys()]
		.sort((left, right) => left.localeCompare(right))
		.map((name) => {
			const value = resolveVariableValue(name, darkDefaults);
			const groupId = getGroupId(name);
			return {
				name,
				kind: getKind(name, value),
				groupId,
				groupLabel: GROUP_LABELS[groupId] ?? GROUP_LABELS.other,
				source: sources.get(name) ?? 'unknown',
			};
		});
}

function renderStringArray(name: string, values: ReadonlyArray<string>): string {
	const body = values.map((value) => `\t${JSON.stringify(value)},`).join('\n');
	return `export const ${name}: ReadonlyArray<string> = [\n${body}\n];`;
}

function renderValueMap(name: string, values: ReadonlyMap<string, string>): string {
	const body = [...values.keys()]
		.sort((left, right) => left.localeCompare(right))
		.map((key) => `\t${JSON.stringify(key)}: ${JSON.stringify(resolveVariableValue(key, values))},`)
		.join('\n');
	return `export const ${name}: Readonly<Record<string, string>> = {\n${body}\n};`;
}

function renderNameUnion(definitions: ReadonlyArray<VariableDefinition>): string {
	const body = definitions.map((definition) => `\t| ${JSON.stringify(definition.name)}`).join('\n');
	return `export type ThemeVariableName =\n${body};`;
}

function renderDefinitions(definitions: ReadonlyArray<VariableDefinition>): string {
	const body = definitions
		.map(
			(definition) =>
				`\t{name: ${JSON.stringify(definition.name)}, kind: ${JSON.stringify(definition.kind)}, groupId: ${JSON.stringify(definition.groupId)}, groupLabel: ${JSON.stringify(definition.groupLabel)}, source: ${JSON.stringify(definition.source)}},`,
		)
		.join('\n');
	return `export const THEME_VARIABLES: ReadonlyArray<ThemeVariableDefinition> = [\n${body}\n];`;
}

function render(appDir: string): string {
	const {darkDefaults, lightDefaults, sources} = readSourceVariables(appDir);
	const definitions = buildDefinitions(darkDefaults, sources);
	const colorVariables = definitions
		.filter((definition) => definition.kind === 'color')
		.map((definition) => definition.name);
	const fontVariables = definitions
		.filter((definition) => definition.kind === 'font')
		.map((definition) => definition.name);
	return `// SPDX-License-Identifier: AGPL-3.0-or-later
// Generated by scripts/GenerateThemeVariables.ts. Do not edit by hand.

export type ThemeVariableKind = 'color' | 'font' | 'dimension' | 'number' | 'shadow' | 'transition' | 'other';

export interface ThemeVariableDefinition {
\tname: string;
\tkind: ThemeVariableKind;
\tgroupId: string;
\tgroupLabel: string;
\tsource: string;
}

${renderNameUnion(definitions)}

${renderDefinitions(definitions)}

${renderStringArray(
	'THEME_VARIABLE_NAMES',
	definitions.map((definition) => definition.name),
)}

${renderStringArray('THEME_COLOR_VARIABLES', colorVariables)}

${renderStringArray('THEME_FONT_VARIABLES', fontVariables)}

${renderValueMap('THEME_STUDIO_DARK_DEFAULT_VARIABLE_VALUES', darkDefaults)}

${renderValueMap('THEME_STUDIO_LIGHT_DEFAULT_VARIABLE_VALUES', lightDefaults)}
`;
}

interface SkeletonSurfaceInvariant {
	file: string;
	requires?: ReadonlyArray<string>;
	requiresPattern?: ReadonlyArray<string>;
	forbids?: ReadonlyArray<string>;
	forbidsPattern?: ReadonlyArray<string>;
	counts?: Readonly<Record<string, number>>;
	minimums?: Readonly<Record<string, number>>;
}

const SKELETON_CHROME_BORDER_TOKEN = 'var(--skeleton-chrome-border)';

const SKELETON_SURFACE_INVARIANTS: ReadonlyArray<SkeletonSurfaceInvariant> = [
	{
		file: 'src/app/globals.css',
		counts: {
			'--skeleton-chrome-border-color': 2,
			'--skeleton-chrome-border-color: color-mix(in srgb, var(--background-modifier-accent) 25%, transparent);': 1,
			'--skeleton-chrome-border: 0.0625rem solid var(--skeleton-chrome-border-color);': 1,
			'--chat-horizontal-padding-default: 1rem;': 1,
			'--guild-members-columns-selectable: var(--guild-members-select-column-width) var(--guild-members-columns);': 1,
			'--guilds-layout-item-bg: color-mix(in srgb, var(--guild-list-foreground) 72%, var(--background-primary) 28%);': 1,
		},
	},
	{
		file: 'src/features/app/components/skeleton/ChatSkeleton.module.css',
		minimums: {[SKELETON_CHROME_BORDER_TOKEN]: 1},
		forbidsPattern: ['border[a-z-]*:\\s*[^;]*var\\(--background-modifier-accent\\)'],
		forbids: ['scopeBadge', 'scope-badge'],
	},
	{
		file: 'src/features/app/components/skeleton/ChatSkeleton.tsx',
		requires: [
			"import composerWrapperStyles from '@app/features/channel/components/textarea/InputWrapper.module.css';",
			'composerWrapperStyles.composerRoot',
			"'--chat-horizontal-padding': remFromPx(messagePresentation.messageGutterPx),",
			"'--font-size': remFromPx(messagePresentation.fontSizePx),",
			"'--message-group-spacing': remFromPx(messagePresentation.groupSpacingPx),",
			"'--message-compact-timestamp-width': remFromPx(messagePresentation.compactTimestampWidthPx),",
		],
		forbids: ['scopeBadge', 'scope-badge', '@tanstack/react-virtual'],
	},
	{
		file: 'src/features/app/components/skeleton/DiscoverySkeleton.module.css',
		minimums: {[SKELETON_CHROME_BORDER_TOKEN]: 2},
		forbidsPattern: ['border[a-z-]*:\\s*[^;]*var\\(--background-modifier-accent\\)'],
	},
	{
		file: 'src/features/app/components/skeleton/FriendsSkeleton.module.css',
		minimums: {[SKELETON_CHROME_BORDER_TOKEN]: 4},
		forbidsPattern: ['border[a-z-]*:\\s*[^;]*var\\(--background-modifier-accent\\)'],
		forbids: ['.activeNowPreview'],
	},
	{
		file: 'src/features/app/components/skeleton/FriendsSkeleton.tsx',
		forbids: ['LIVE_BADGE', 'CONTEXT_CHEVRON', 'ACTIVE_NOW_CONTEXT_ICON_SIZE'],
		requires: ['function resolveFriendsListSections('],
	},
	{
		file: 'src/features/app/components/skeleton/GuildRailSkeleton.module.css',
		requires: [
			'.outageSlot {\n\tmin-height: var(--guild-list-item-box-size);\n}',
			'.sectionTrailingGap {\n\tpadding-bottom: var(--guild-list-item-gap);\n}',
			'.itemsTrailingGapCancel {\n\tmargin-bottom: calc(-1 * var(--guild-list-item-gap));\n}',
			'background-color: var(--guilds-layout-item-bg);',
			".item[data-selected='true'] .fluxerIcon",
			'clip-path: inset(0);',
			'\ttransform: translateY(0rem);',
		],
		forbids: ['--guild-list-indicator-', '::before'],
		counts: {'z-index: 0;': 3, 'z-index: 1;': 3},
	},
	{
		file: 'src/features/app/components/skeleton/GuildRailSkeleton.tsx',
		requires: [
			"import guildStyles from '@app/features/app/components/layout/GuildsLayout.module.css';",
			'guildStyles.guildIndicator',
			'guildStyles.guildIndicatorBar',
			'resolveGuildListIndicatorBarTarget(',
			'const InlineDMPlaceholder = ',
		],
		requiresPattern: ['<ChatCircleIcon[^>]*weight="fill"[^>]*className=\\{styles\\.fluxerIconGlyph\\}'],
		forbids: ['data-indicator', 'GUILD_RAIL_INDICATOR_METRICS', 'Math.round'],
		counts: {'styles.sectionTrailingGap': 2, 'styles.itemsTrailingGapCancel': 1},
	},
	{
		file: 'src/features/ui/components/Scroller.module.css',
		counts: {'clip-path: inset(0);': 1},
	},
	{
		file: 'src/features/channel/components/MemberListSkeleton.tsx',
		counts: {'style={MEMBER_LIST_METRICS_STYLE}': 2},
	},
	{
		file: 'src/features/app/components/layout/GuildsLayout.module.css',
		requires: [
			'.guildListScrollContainer.guildListScrollContainer {\n\toverflow-anchor: auto;\n}',
			'--layout-user-area-overlay-height',
			'\tpadding-bottom: calc(\n\t\tvar(--layout-user-area-overlay-height, var(--layout-user-area-reserved-height, 0px)) +\n\t\tvar(--spacing-2)\n\t);',
			'.messageBubbleIcon {\n\theight: 1.75rem;\n\twidth: 1.75rem;',
			'.guildIndicator {',
			'.guildIndicatorBar {',
		],
		forbids: ['.fluxerSymbolIcon'],
	},
	{
		file: 'src/features/app/components/layout/GuildsLayout.tsx',
		forbids: ['useListScrollAnchor', 'usePersistentScrollAnchor', '@tanstack/react-virtual'],
		counts: {'scrollNode.scrollTop = ': 2},
	},
	{
		file: 'src/features/discovery/discovery/DiscoveryPage.tsx',
		counts: {"import {useVirtualizer} from '@tanstack/react-virtual';": 1},
	},
	{
		file: 'src/features/app/components/LongPressable.ts',
		forbids: ['useImperativeHandle'],
		requires: ['useMergeRefs'],
	},
	{
		file: 'src/features/app/components/layout/sidebar_nav/GuildListIndicator.ts',
		requires: ['height: remFromPx(resolveGuildListIndicatorHeight(request))'],
		forbids: ['transform', 'scale', 'getAppZoomFactor', 'getAppRemScale'],
		counts: {
			'function resolveGuildListIndicatorHeight': 1,
			'export function resolveGuildListIndicatorBarTarget': 1,
			'export ': 3,
		},
	},
	{
		file: 'src/features/app/components/layout/sidebar_nav/FluxerButton.tsx',
		requires: [
			'const shouldShowHoverState = isHovering || contextMenuOpen;',
			'ChatCircleIcon',
			'styles.messageBubbleIcon',
			'styles.contextMenuHover',
			'resolveGuildListIndicatorBarTarget(',
		],
		forbids: ['scale', 'getAppZoomFactor'],
	},
	{
		file: 'src/features/app/components/layout/sidebar_nav/FavoritesButton.tsx',
		requires: ['resolveGuildListIndicatorBarTarget('],
		forbids: ['scale', 'getAppZoomFactor'],
	},
	{
		file: 'src/features/app/components/layout/sidebar_nav/GuildListDMItem.tsx',
		requires: [
			'const shouldShowHoverState = isHovering || contextMenuOpen;',
			'guildStyles.contextMenuHover',
			'resolveGuildListIndicatorBarTarget(',
		],
		forbids: ['@tanstack/react-virtual', 'scale', 'getAppZoomFactor'],
	},
	{
		file: 'src/features/app/components/layout/sidebar_nav/GuildFolderItem.tsx',
		requires: [
			'const shouldShowHoverState = isHovering || contextMenuOpen;',
			'const FOLDER_BACKGROUND_FADE_TARGET = Object.freeze({opacity: 0});',
			"const FOLDER_GUILDS_COLLAPSE_TARGET = Object.freeze({opacity: 0, translateY: '-0.5rem'});",
			"to={{opacity: 1, translateY: '0rem'}}",
			'resolveGuildListIndicatorBarTarget(',
			'guildStyles.guildIndicatorBar',
		],
		forbids: ['@tanstack/react-virtual', 'scale', 'getAppZoomFactor'],
	},
	{
		file: 'src/features/app/components/layout/sidebar_nav/GuildFolderItem.module.css',
		forbids: ['.folderIndicator'],
	},
	{
		file: 'src/features/app/components/layout/sidebar_nav/GuildListItemContent.tsx',
		requires: [
			'const selectedFromThisRow = peekDirectSelection(DirectSelectionSurface.GUILD_RAIL);',
			'if (isInitialMount || selectedFromThisRow || !props.isSelected) return;',
		],
		forbids: ['preserveInitialScrollPosition', '@tanstack/react-virtual', 'scale', 'getAppZoomFactor'],
	},
	{
		file: 'src/features/app/components/layout/sidebar_nav/GuildListItemPresentation.tsx',
		forbids: ['@tanstack/react-virtual', 'scale', 'getAppZoomFactor'],
	},
	{
		file: 'src/features/channel/components/ChannelMembers.tsx',
		forbids: ['@tanstack/react-virtual'],
		requires: ['styles.virtualRow'],
	},
];

const SKELETON_STYLESHEET_DIRECTORIES: ReadonlyArray<string> = [
	'src/features/app/components/skeleton',
	'src/features/channel/components',
	'src/features/user/components/profile',
];
const SKELETON_STYLESHEET_SUFFIX = 'Skeleton.module.css';
const BORDER_DECLARATION_PATTERN =
	/(?<![\w-])border(?:-(?:top|right|bottom|left|block|inline|block-start|block-end|inline-start|inline-end))?\s*:\s*([^;}]+)/g;
const RAW_COLOR_PATTERN = /#[0-9a-fA-F]{3,8}\b|\b(?:rgba?|hsla?|hwb|lab|lch|oklab|oklch|color-mix)\(/;

function collectSkeletonStylesheets(appDir: string): ReadonlyArray<string> {
	const files: Array<string> = [];
	const visit = (directory: string) => {
		for (const entry of readdirSync(directory, {withFileTypes: true})) {
			const absolutePath = join(directory, entry.name);
			if (entry.isDirectory()) {
				visit(absolutePath);
				continue;
			}
			if (!entry.isFile() || !entry.name.endsWith(SKELETON_STYLESHEET_SUFFIX)) continue;
			files.push(toPosixPath(relative(appDir, absolutePath)));
		}
	};
	for (const directory of SKELETON_STYLESHEET_DIRECTORIES) {
		visit(join(appDir, directory));
	}
	return files.sort();
}

interface SkeletonSharedRuleSource {
	readonly file: string;
	readonly selectors: ReadonlyArray<string>;
}

const SKELETON_SHARED_RULE_SOURCES: ReadonlyArray<SkeletonSharedRuleSource> = [
	{
		file: 'src/features/app/components/layout/GuildsLayout.module.css',
		selectors: ['.guildIndicator', '.guildIndicatorBar'],
	},
];
const CUSTOM_PROPERTY_REFERENCE_PATTERN = /var\(\s*(--[a-zA-Z0-9-]+)/g;

function assertSkeletonSharedRuleTokens(appDir: string): void {
	const violations: Array<string> = [];
	const declaredTokens = new Set<string>(SKELETON_SURFACE_TOKENS);
	for (const source of SKELETON_SHARED_RULE_SOURCES) {
		const contents = readFileSync(join(appDir, source.file), 'utf8');
		for (const selector of source.selectors) {
			const rule = new RegExp(`^${selector.replace('.', '\\.')}\\s*\\{([^}]*)\\}`, 'mu').exec(contents);
			if (rule == null) {
				violations.push(`${source.file} must declare ${selector}; skeleton markup renders through that rule.`);
				continue;
			}
			for (const match of rule[1].matchAll(CUSTOM_PROPERTY_REFERENCE_PATTERN)) {
				const token = match[1];
				if (declaredTokens.has(token)) continue;
				violations.push(
					`${source.file} ${selector} reads ${token}, which skeleton markup also renders through; ` +
						'list it in SKELETON_SURFACE_TOKENS.',
				);
			}
		}
	}
	if (violations.length > 0) {
		throw new Error(`Skeleton surface invariants violated:\n${violations.map((line) => `  - ${line}`).join('\n')}`);
	}
}

const SKELETON_CHROME_BORDER_COLOR_DECLARATION = /--skeleton-chrome-border-color\s*:\s*([^;}]+)/g;

function assertSkeletonChromeBorderColourIsSoftened(appDir: string, violations: Array<string>): void {
	const file = 'src/app/globals.css';
	const contents = readFileSync(join(appDir, file), 'utf8');
	for (const match of contents.matchAll(SKELETON_CHROME_BORDER_COLOR_DECLARATION)) {
		const value = match[1].trim();
		if (value.startsWith('var(--background-modifier-accent')) {
			violations.push(
				`${file} declares --skeleton-chrome-border-color as ${JSON.stringify(value)}; ` +
					'skeleton chrome must use the softened colour, never the raw accent.',
			);
		}
	}
}

function assertSkeletonBorderTokens(appDir: string): void {
	const violations: Array<string> = [];
	assertSkeletonChromeBorderColourIsSoftened(appDir, violations);
	for (const file of collectSkeletonStylesheets(appDir)) {
		const contents = readFileSync(join(appDir, file), 'utf8');
		if (contents.includes('--skeleton-chrome-border-color')) {
			violations.push(
				`${file} names --skeleton-chrome-border-color directly; skeleton chrome must use ${SKELETON_CHROME_BORDER_TOKEN}.`,
			);
		}
		for (const match of contents.matchAll(BORDER_DECLARATION_PATTERN)) {
			const value = match[1].trim();
			if (RAW_COLOR_PATTERN.test(value) || value.includes('--background-modifier-accent')) {
				violations.push(
					`${file} writes a literal border colour in ${JSON.stringify(`border: ${value}`)}; ` +
						'skeleton borders must reference a shared token.',
				);
			}
		}
	}
	if (violations.length > 0) {
		throw new Error(`Skeleton surface invariants violated:\n${violations.map((line) => `  - ${line}`).join('\n')}`);
	}
}

function assertSkeletonSurfaceInvariants(appDir: string): void {
	const violations: Array<string> = [];
	for (const invariant of SKELETON_SURFACE_INVARIANTS) {
		const path = join(appDir, invariant.file);
		if (!existsSync(path)) {
			violations.push(`${invariant.file} is missing; a skeleton surface invariant depends on it.`);
			continue;
		}
		const contents = readFileSync(path, 'utf8');
		for (const required of invariant.requires ?? []) {
			if (!contents.includes(required)) {
				violations.push(`${invariant.file} must contain ${JSON.stringify(required)}.`);
			}
		}
		for (const forbidden of invariant.forbids ?? []) {
			if (contents.includes(forbidden)) {
				violations.push(`${invariant.file} must not contain ${JSON.stringify(forbidden)}.`);
			}
		}
		for (const source of invariant.requiresPattern ?? []) {
			if (!new RegExp(source, 'u').test(contents)) {
				violations.push(`${invariant.file} must match /${source}/.`);
			}
		}
		for (const source of invariant.forbidsPattern ?? []) {
			if (new RegExp(source, 'u').test(contents)) {
				violations.push(`${invariant.file} must not match /${source}/.`);
			}
		}
		for (const [needle, expected] of Object.entries(invariant.counts ?? {})) {
			const actual = contents.split(needle).length - 1;
			if (actual !== expected) {
				violations.push(`${invariant.file} must contain ${needle} exactly ${expected} time(s); found ${actual}.`);
			}
		}
		for (const [needle, minimum] of Object.entries(invariant.minimums ?? {})) {
			const actual = contents.split(needle).length - 1;
			if (actual < minimum) {
				violations.push(`${invariant.file} must contain ${needle} at least ${minimum} time(s); found ${actual}.`);
			}
		}
	}
	if (violations.length > 0) {
		throw new Error(`Skeleton surface invariants violated:\n${violations.map((line) => `  - ${line}`).join('\n')}`);
	}
}

function main(): void {
	const scriptDir = import.meta.dirname;
	const appDir = resolve(scriptDir, '..');
	assertSkeletonSurfaceInvariants(appDir);
	assertSkeletonSharedRuleTokens(appDir);
	assertSkeletonBorderTokens(appDir);
	const outputPath = join(appDir, 'src', 'features', 'theme', 'variables', 'ThemeVariableManifest.ts');
	const contents = render(appDir);
	if (process.argv.includes('--check')) {
		if (!existsSync(outputPath) || readFileSync(outputPath, 'utf8') !== contents) {
			throw new Error(`${relative(appDir, outputPath)} is stale. Run pnpm generate:theme-variables.`);
		}
		console.log(`Checked ${relative(appDir, outputPath)}`);
		return;
	}
	mkdirSync(dirname(outputPath), {recursive: true});
	writeFileSync(outputPath, contents);
	console.log(`Wrote ${relative(appDir, outputPath)}`);
}

main();