import {
	ASPECT_RATIO_KEYS,
	BORDER_STYLE_KEYS,
	BORDER_WIDTH_KEYS,
	COLOR_ROLES,
	COLOR_SCALE_STEPS,
	CONTAINER_WIDTH_KEYS,
	CONTENT_WIDTH_KEYS,
	OPACITY_KEYS,
	SHADOW_KEYS,
	SIZE_PRIMITIVE_KEYS,
	TEXT_SIZES,
	Z_INDEX_KEYS,
	type BorderPrimitiveSet,
	type ColorRole,
	type ColorRoleDefinition,
	type ColorScale,
	type EidosCssContract,
	type EidosValidationIssue,
	type EidosValidationReport,
	type EidosConfig,
	type EidosConfigSnapshot,
	type SizePrimitive,
	type TextMetric,
	type ThemeDefinition,
	type TypographyPrimitiveSet
} from './config-types'
import { createEidosCssContract } from './contract'
import {
	createEidosConfigDocument as createEidosConfigDocumentEnvelope,
	parseEidosConfigDocument as parseEidosConfigDocumentEnvelope,
	readEidosConfigDocument as readEidosConfigDocumentEnvelope,
	serializeEidosConfigDocument as serializeEidosConfigDocumentEnvelope,
	type EidosConfigDocument
} from './persistence'
import { EidosConfigValidationError } from '../errors'

const COLOR_ROLE_SET = new Set<string>(COLOR_ROLES)
const ASPECT_RATIO_KEY_SET = new Set<string>(ASPECT_RATIO_KEYS)
const BORDER_WIDTH_KEY_SET = new Set<string>(BORDER_WIDTH_KEYS)
const BORDER_STYLE_KEY_SET = new Set<string>(BORDER_STYLE_KEYS)
const CONTAINER_WIDTH_KEY_SET = new Set<string>(CONTAINER_WIDTH_KEYS)
const CONTENT_WIDTH_KEY_SET = new Set<string>(CONTENT_WIDTH_KEYS)
const OPACITY_KEY_SET = new Set<string>(OPACITY_KEYS)
const SHADOW_KEY_SET = new Set<string>(SHADOW_KEYS)
const SIZE_PRIMITIVE_KEY_SET = new Set<string>(SIZE_PRIMITIVE_KEYS)
const TEXT_SIZE_SET = new Set<string>(TEXT_SIZES)
const Z_INDEX_KEY_SET = new Set<string>(Z_INDEX_KEYS)
const RESPONSIVE_KEY_SET = new Set(['base', 'sm', 'md', 'lg', 'xl', 'xxl'])

export function snapshotEidosConfig(options: EidosConfig): EidosConfigSnapshot {
	return clonePlain(options)
}

export function readEidosConfigFromDocument(document: unknown): EidosConfig {
	return snapshotEidosConfig(readEidosConfigDocumentEnvelope(document).options)
}

export function parseEidosConfigFromJson(json: string): EidosConfig {
	return snapshotEidosConfig(parseEidosConfigDocumentEnvelope(json).options)
}

export function createEidosConfigDocumentFromConfig(options: EidosConfig): EidosConfigDocument {
	assertValidEidosConfig(options)

	return createEidosConfigDocumentEnvelope(options)
}

export function serializeEidosConfig(options: EidosConfig): string {
	return serializeEidosConfigDocumentEnvelope(createEidosConfigDocumentFromConfig(options))
}

export function validateEidosConfig(options: EidosConfig): EidosValidationReport {
	const issues: EidosValidationIssue[] = []

	validateColorScales(options, issues)
	validateColorRoles(options, issues)
	validateTypography(options, issues)
	validateSizePrimitives(options, issues)
	validateBorderPrimitives(options, issues)
	validateLayoutPrimitives(options, issues)
	validateRecordPrimitive(
		'primitives.opacity',
		options.primitives.opacity,
		OPACITY_KEYS,
		OPACITY_KEY_SET,
		issues
	)
	validateRecordPrimitive(
		'primitives.zIndex',
		options.primitives.zIndex,
		Z_INDEX_KEYS,
		Z_INDEX_KEY_SET,
		issues
	)
	validateThemeShadows(options, issues)

	return {
		ok: issues.length === 0,
		issues
	}
}

export function assertValidEidosConfig(options: EidosConfig): void {
	const report = validateEidosConfig(options)
	if (report.ok) return
	throw new EidosConfigValidationError(report.issues)
}

export function listEidosColorScales(options: EidosConfig): readonly string[] {
	return Object.keys(options.primitives.color?.scales ?? {})
}

export function listEidosThemes(options: EidosConfig): readonly string[] {
	return Object.keys(options.themes ?? {})
}

export function getEidosTheme(options: EidosConfig, id: string): ThemeDefinition | undefined {
	const theme = options.themes?.[id]
	return theme ? clonePlain(theme) : undefined
}

export function listEidosColorRoles(): readonly ColorRole[] {
	return [...COLOR_ROLES]
}

export function getEidosColorScale(options: EidosConfig, name: string): ColorScale | undefined {
	const scale = options.primitives.color?.scales?.[name]
	return scale ? clonePlain(scale) : undefined
}

export function getEidosColorRoleScale(
	options: EidosConfig,
	role: ColorRole,
	themeId?: string
): ColorScale | undefined {
	const theme = themeId ? options.themes?.[themeId] : undefined
	const roleDef = theme?.color?.roles?.[role] ?? options.semantics.color.roles[role]
	const scaleName = resolveRoleScaleName(roleDef)
	if (!scaleName) return undefined

	const themeScale = theme?.color?.scales?.[scaleName]
	if (themeScale) return clonePlain(themeScale)

	return getEidosColorScale(options, scaleName)
}

export function getEidosCssContract(options: EidosConfig): EidosCssContract {
	assertValidEidosConfig(options)

	return createEidosCssContract(options)
}

function validateColorScales(options: EidosConfig, issues: EidosValidationIssue[]): void {
	const scales = options.primitives.color?.scales ?? {}

	for (const [name, scale] of Object.entries(scales)) {
		validateColorScale(`primitives.color.scales.${name}`, name, scale, issues)
	}

	for (const [themeId, theme] of Object.entries(options.themes ?? {})) {
		for (const [name, scale] of Object.entries(theme.color?.scales ?? {})) {
			validateColorScale(`themes.${themeId}.color.scales.${name}`, name, scale, issues)
		}
		for (const [name, scale] of Object.entries(theme.color?.alphaScales ?? {})) {
			validateColorScale(`themes.${themeId}.color.alphaScales.${name}`, name, scale, issues)
			if (
				!hasOwn(options.primitives.color?.scales ?? {}, name) &&
				!hasOwn(theme.color?.scales ?? {}, name)
			) {
				issues.push({
					path: `themes.${themeId}.color.alphaScales.${name}`,
					message: `alpha scale "${name}" must match a configured color scale`
				})
			}
		}
	}
}

function validateColorRoles(options: EidosConfig, issues: EidosValidationIssue[]): void {
	const roles = options.semantics.color.roles
	const globalScales = options.primitives.color?.scales ?? {}
	const themes = options.themes ?? {}

	for (const role of COLOR_ROLES) {
		if (!hasOwn(roles, role)) {
			issues.push({
				path: `semantics.color.roles.${role}`,
				message: 'every canonical color role must be mapped to a primitive scale'
			})
		}
	}

	for (const [role, roleDef] of Object.entries(roles)) {
		validateColorRole(`semantics.color.roles.${role}`, role, roleDef, globalScales, themes, issues)
	}

	for (const [themeId, theme] of Object.entries(themes)) {
		for (const [role, roleDef] of Object.entries(theme.color?.roles ?? {})) {
			validateColorRole(
				`themes.${themeId}.color.roles.${role}`,
				role,
				roleDef,
				globalScales,
				{ [themeId]: theme },
				issues
			)
		}
	}
}

function validateColorScale(
	path: string,
	name: string,
	scale: ColorScale,
	issues: EidosValidationIssue[]
): void {
	for (const step of COLOR_SCALE_STEPS) {
		if (!hasOwn(scale, step) || scale[step] === '') {
			issues.push({
				path: `${path}.${step}`,
				message: 'color scales must define every step from 1 to 12'
			})
		}
	}
}

function validateColorRole(
	path: string,
	role: string,
	roleDef: string | ColorRoleDefinition | undefined,
	globalScales: Record<string, ColorScale>,
	themes: Record<string, ThemeDefinition>,
	issues: EidosValidationIssue[]
): void {
	if (!COLOR_ROLE_SET.has(role)) {
		issues.push({
			path,
			message: 'unknown color role'
		})
		return
	}

	const scaleName = resolveRoleScaleName(roleDef)
	if (!scaleName) {
		issues.push({
			path,
			message: 'color role must point to a primitive scale'
		})
		return
	}

	const themeEntries = Object.entries(themes)
	if (themeEntries.length === 0) {
		if (!hasOwn(globalScales, scaleName)) {
			issues.push({
				path,
				message: `color role points to missing primitive scale "${scaleName}"`
			})
		}
		return
	}

	for (const [themeId, theme] of themeEntries) {
		if (!hasOwn(globalScales, scaleName) && !hasOwn(theme.color?.scales ?? {}, scaleName)) {
			issues.push({
				path: `themes.${themeId}.color.scales.${scaleName}`,
				message: `color role "${role}" points to a scale missing in this theme`
			})
		}
	}
}

function validateTypography(options: EidosConfig, issues: EidosValidationIssue[]): void {
	const typography = options.primitives.typography
	if (!typography) return

	for (const size of TEXT_SIZES) {
		const metric = typography.sizes[size]
		if (!metric) {
			issues.push({
				path: `primitives.typography.sizes.${size}`,
				message: 'every canonical text size must be defined'
			})
			continue
		}
		validateTextMetric(`primitives.typography.sizes.${size}`, metric, issues)
	}

	for (const [name, family] of Object.entries(typography.families)) {
		if (family.family.trim() === '') {
			issues.push({
				path: `primitives.typography.families.${name}.family`,
				message: 'font family name cannot be empty'
			})
		}
	}

	for (const [name, style] of Object.entries(typography.styles)) {
		const path = `primitives.typography.styles.${name}`

		if (style.family !== undefined && !hasOwn(typography.families, style.family)) {
			issues.push({
				path: `${path}.family`,
				message: `typography style points to missing family "${style.family}"`
			})
		}

		if (
			typeof style.weight === 'string' &&
			style.weight.trim() !== '' &&
			!hasOwn(typography.weights, style.weight)
		) {
			issues.push({
				path: `${path}.weight`,
				message: `typography style points to missing weight "${style.weight}"`
			})
		}

		validateTypographySizeValue(`${path}.size`, style.size, typography, issues)
	}
}

function validateSizePrimitives(options: EidosConfig, issues: EidosValidationIssue[]): void {
	const sizes = options.primitives.size
	if (!sizes) return

	for (const size of SIZE_PRIMITIVE_KEYS) {
		if (!hasOwn(sizes, size)) {
			issues.push({
				path: `primitives.size.${size}`,
				message: 'every canonical physical size must be defined'
			})
		}
	}

	for (const [name, size] of Object.entries(sizes)) {
		const path = `primitives.size.${name}`

		if (!SIZE_PRIMITIVE_KEY_SET.has(name)) {
			issues.push({
				path,
				message: 'unknown size primitive key'
			})
			continue
		}

		validateSizePrimitive(path, size, options, issues)
	}
}

function validateSizePrimitive(
	path: string,
	size: SizePrimitive,
	options: EidosConfig,
	issues: EidosValidationIssue[]
): void {
	if (!hasOwn(options.primitives.controlHeight ?? {}, size.controlHeight)) {
		issues.push({
			path: `${path}.controlHeight`,
			message: `size primitive points to missing control height "${size.controlHeight}"`
		})
	}

	const typography = options.primitives.typography
	if (!TEXT_SIZE_SET.has(size.fontSize) || !hasOwn(typography?.sizes ?? {}, size.fontSize)) {
		issues.push({
			path: `${path}.fontSize`,
			message: `size primitive points to missing font size "${size.fontSize}"`
		})
	}

	if (!hasOwn(options.primitives.icon?.size ?? {}, size.iconSize)) {
		issues.push({
			path: `${path}.iconSize`,
			message: `size primitive points to missing icon size "${size.iconSize}"`
		})
	}

	if (!hasOwn(options.primitives.radius ?? {}, size.radius)) {
		issues.push({
			path: `${path}.radius`,
			message: `size primitive points to missing radius "${size.radius}"`
		})
	}

	validateNonEmptyCssValue(`${path}.paddingInline`, size.paddingInline, issues)
	validateNonEmptyCssValue(`${path}.paddingBlock`, size.paddingBlock, issues)
	validateNonEmptyCssValue(`${path}.gap`, size.gap, issues)
}

function validateBorderPrimitives(options: EidosConfig, issues: EidosValidationIssue[]): void {
	const border = options.primitives.border
	if (!border) return

	validateRecordPrimitive(
		'primitives.border.width',
		border.width,
		BORDER_WIDTH_KEYS,
		BORDER_WIDTH_KEY_SET,
		issues
	)
	validateRecordPrimitive(
		'primitives.border.style',
		border.style,
		BORDER_STYLE_KEYS,
		BORDER_STYLE_KEY_SET,
		issues
	)

	validateBorderDefault(
		'primitives.border.defaultWidth',
		border.defaultWidth,
		border,
		'width',
		issues
	)
	validateBorderDefault(
		'primitives.border.defaultStyle',
		border.defaultStyle,
		border,
		'style',
		issues
	)
}

function validateBorderDefault(
	path: string,
	value: string,
	border: BorderPrimitiveSet,
	field: 'width' | 'style',
	issues: EidosValidationIssue[]
): void {
	if (hasOwn(border[field], value)) return
	issues.push({
		path,
		message: `border default points to missing ${field} "${value}"`
	})
}

function validateLayoutPrimitives(options: EidosConfig, issues: EidosValidationIssue[]): void {
	const layout = options.primitives.layout
	if (!layout) return

	validateRecordPrimitive(
		'primitives.layout.containerWidth',
		layout.containerWidth,
		CONTAINER_WIDTH_KEYS,
		CONTAINER_WIDTH_KEY_SET,
		issues
	)
	validateRecordPrimitive(
		'primitives.layout.contentWidth',
		layout.contentWidth,
		CONTENT_WIDTH_KEYS,
		CONTENT_WIDTH_KEY_SET,
		issues
	)
	validateRecordPrimitive(
		'primitives.layout.aspectRatio',
		layout.aspectRatio,
		ASPECT_RATIO_KEYS,
		ASPECT_RATIO_KEY_SET,
		issues
	)
	validateNonEmptyCssValue(
		'primitives.layout.containerPaddingInline',
		layout.containerPaddingInline,
		issues
	)
}

function validateThemeShadows(options: EidosConfig, issues: EidosValidationIssue[]): void {
	for (const [themeId, theme] of Object.entries(options.themes ?? {})) {
		validateRecordPrimitive(
			`themes.${themeId}.shadow`,
			theme.shadow,
			SHADOW_KEYS,
			SHADOW_KEY_SET,
			issues
		)
	}
}

function validateRecordPrimitive(
	path: string,
	record: Record<string, string | number> | undefined,
	keys: readonly string[],
	keySet: Set<string>,
	issues: EidosValidationIssue[]
): void {
	if (!record) return

	for (const key of keys) {
		if (!hasOwn(record, key)) {
			issues.push({
				path: `${path}.${key}`,
				message: 'every canonical token key must be defined'
			})
		}
	}

	for (const [key, value] of Object.entries(record)) {
		if (!keySet.has(key)) {
			issues.push({
				path: `${path}.${key}`,
				message: 'unknown token key'
			})
			continue
		}
		validateNonEmptyCssValue(`${path}.${key}`, String(value), issues)
	}
}

function validateTypographySizeValue(
	path: string,
	value: unknown,
	typography: TypographyPrimitiveSet,
	issues: EidosValidationIssue[]
): void {
	if (value === undefined) return

	if (typeof value === 'string') {
		if (!TEXT_SIZE_SET.has(value) || !hasOwn(typography.sizes, value)) {
			issues.push({
				path,
				message: `typography style points to missing text size "${value}"`
			})
		}
		return
	}

	if (isTextMetric(value)) {
		validateTextMetric(path, value, issues)
		return
	}

	if (isPlainRecord(value)) {
		for (const [key, item] of Object.entries(value)) {
			if (!RESPONSIVE_KEY_SET.has(key)) {
				issues.push({
					path: `${path}.${key}`,
					message: `unknown responsive breakpoint "${key}"`
				})
			}
			validateTypographySizeValue(`${path}.${key}`, item, typography, issues)
		}
		return
	}

	issues.push({
		path,
		message: 'typography size must be a canonical size, metric, or responsive map'
	})
}

function validateNonEmptyCssValue(
	path: string,
	value: string,
	issues: EidosValidationIssue[]
): void {
	if (value.trim() !== '') return
	issues.push({
		path,
		message: 'CSS value cannot be empty'
	})
}

function validateTextMetric(
	path: string,
	metric: TextMetric,
	issues: EidosValidationIssue[]
): void {
	if (metric.size.trim() === '') {
		issues.push({
			path: `${path}.size`,
			message: 'text metric size cannot be empty'
		})
	}
	if (metric.lineHeight.trim() === '') {
		issues.push({
			path: `${path}.lineHeight`,
			message: 'text metric lineHeight cannot be empty'
		})
	}
	if (metric.letterSpacing.trim() === '') {
		issues.push({
			path: `${path}.letterSpacing`,
			message: 'text metric letterSpacing cannot be empty'
		})
	}
}

function isTextMetric(value: unknown): value is TextMetric {
	return (
		isPlainRecord(value) &&
		typeof value.size === 'string' &&
		typeof value.lineHeight === 'string' &&
		typeof value.letterSpacing === 'string'
	)
}

function isPlainRecord(value: unknown): value is Record<string, unknown> {
	return typeof value === 'object' && value !== null && !Array.isArray(value)
}

function resolveRoleScaleName(
	roleDef: string | ColorRoleDefinition | undefined
): string | undefined {
	if (typeof roleDef === 'string') return roleDef
	return roleDef?.scale
}

function hasOwn<T extends object>(value: T, key: PropertyKey): boolean {
	return Object.prototype.hasOwnProperty.call(value, key)
}

function clonePlain<T>(value: T): T {
	if (typeof structuredClone === 'function') return structuredClone(value)
	return JSON.parse(JSON.stringify(value)) as T
}