export const TEXT_FORMATS = ['bold', 'italic', 'underlined', 'strikethrough', 'obfuscated'] as const

export type TextFormat = (typeof TEXT_FORMATS)[number]

export type GradientTextRun = {
	text: string
	formats: TextFormat[]
}

export type GradientTextDocument = {
	lines: GradientTextRun[][]
}

export type GradientFormatId =
	| 'vanilla'
	| 'vanilla-compatible'
	| 'standard'
	| 'cmi'
	| 'minimessage'
	| 'minimessage-gradient'
	| 'minedown'
	| 'snbt'
	| 'trchat'
	| 'taboolib'
	| 'taboolib-gradient'
	| 'rosegarden-gradient'
	| 'chat-colors'
	| 'motd'
	| 'bbcode'
	| 'json'
	| 'html'
	| 'csv'
	| 'terraria'

export type GradientFormatAdapter = {
	id: GradientFormatId
	label: string
	sample: string
	mimeType: string
	extension: string
	supportsVanillaCharacter?: boolean
	supportsSimplify?: boolean
}

export type GradientOutputOptions = {
	vanillaCharacter: '&' | '§'
	simplifyGradients: boolean
}

type GradientCharacter = {
	character: string
	color: string | null
	formats: TextFormat[]
	newline?: boolean
}

type Color = {
	red: number
	green: number
	blue: number
}

export const DEFAULT_GRADIENT_COLORS = ['#A855F7', '#22C55E']

export const DEFAULT_GRADIENT_DOCUMENT: GradientTextDocument = {
	lines: [[{ text: 'Starlight', formats: [] }]],
}

export const gradientFormatAdapters: readonly GradientFormatAdapter[] = [
	{
		id: 'vanilla',
		label: 'Vanilla',
		sample: '&#RRGGBB',
		mimeType: 'text/plain',
		extension: 'txt',
		supportsVanillaCharacter: true,
	},
	{
		id: 'vanilla-compatible',
		label: 'Vanilla compatible',
		sample: '&x&R&R&G&G&B&B',
		mimeType: 'text/plain',
		extension: 'txt',
		supportsVanillaCharacter: true,
	},
	{
		id: 'standard',
		label: 'Standard HEX',
		sample: '#RRGGBB',
		mimeType: 'text/plain',
		extension: 'txt',
	},
	{ id: 'cmi', label: 'CMI', sample: '{#RRGGBB}', mimeType: 'text/plain', extension: 'txt' },
	{
		id: 'minimessage',
		label: 'MiniMessage',
		sample: '<#RRGGBB>',
		mimeType: 'text/plain',
		extension: 'txt',
	},
	{
		id: 'minimessage-gradient',
		label: 'MiniMessage gradient',
		sample: '<gradient:#RRGGBB:#RRGGBB>',
		mimeType: 'text/plain',
		extension: 'txt',
		supportsSimplify: true,
	},
	{
		id: 'minedown',
		label: 'MineDown',
		sample: '&#RRGGBB&',
		mimeType: 'text/plain',
		extension: 'txt',
	},
	{
		id: 'snbt',
		label: 'Stringified NBT',
		sample: "{text:'T',color:'#RRGGBB'}",
		mimeType: 'application/json',
		extension: 'snbt',
	},
	{ id: 'trchat', label: 'TrChat', sample: '&{#RRGGBB}', mimeType: 'text/plain', extension: 'txt' },
	{
		id: 'taboolib',
		label: 'TabooLib',
		sample: '&{#RRGGBB}',
		mimeType: 'text/plain',
		extension: 'txt',
	},
	{
		id: 'taboolib-gradient',
		label: 'TabooLib gradient',
		sample: '[Text](gradient=#RRGGBB,#RRGGBB)',
		mimeType: 'text/plain',
		extension: 'txt',
		supportsSimplify: true,
	},
	{
		id: 'rosegarden-gradient',
		label: 'RoseGarden gradient',
		sample: '<g:#RRGGBB:#RRGGBB>Text',
		mimeType: 'text/plain',
		extension: 'txt',
		supportsSimplify: true,
	},
	{
		id: 'chat-colors',
		label: 'Chat Colors',
		sample: '[#RRGGBB]',
		mimeType: 'text/plain',
		extension: 'txt',
	},
	{ id: 'motd', label: 'MOTD', sample: '\\u00A7x', mimeType: 'text/plain', extension: 'txt' },
	{
		id: 'bbcode',
		label: 'BBCode',
		sample: '[color=#RRGGBB]Text[/color]',
		mimeType: 'text/plain',
		extension: 'txt',
	},
	{
		id: 'json',
		label: 'JSON text component',
		sample: '{"text":"T","color":"#RRGGBB"}',
		mimeType: 'application/json',
		extension: 'json',
	},
	{
		id: 'html',
		label: 'HTML',
		sample: '<span style="color: #RRGGBB">Text</span>',
		mimeType: 'text/html',
		extension: 'html',
	},
	{ id: 'csv', label: 'CSV', sample: '#RRGGBB,T', mimeType: 'text/csv', extension: 'csv' },
	{
		id: 'terraria',
		label: 'Terraria',
		sample: '[c/RRGGBB:T]',
		mimeType: 'text/plain',
		extension: 'txt',
	},
]

export function cloneGradientDocument(document: GradientTextDocument): GradientTextDocument {
	return {
		lines: document.lines.map((line) =>
			line.map((run) => ({ text: run.text, formats: [...run.formats] })),
		),
	}
}

export function createDocumentFromPlainText(text: string): GradientTextDocument {
	return {
		lines: text.split('\n').map((line) => [{ text: line, formats: [] }]),
	}
}

export function plainTextFromDocument(document: GradientTextDocument): string {
	return document.lines.map((line) => line.map((run) => run.text).join('')).join('\n')
}

export function normalizeHexColor(value: string): string | null {
	const match = value.trim().match(/^#?([0-9a-f]{3}|[0-9a-f]{6})$/i)
	if (!match) return null
	const normalized =
		match[1].length === 3
			? match[1]
					.split('')
					.map((part) => `${part}${part}`)
					.join('')
			: match[1]
	return `#${normalized.toUpperCase()}`
}

export function parseGradientColors(value: string): string[] {
	const colors: string[] = []
	const hexMatches = value.match(/#(?:[0-9a-f]{3}|[0-9a-f]{6})\b/gi) ?? []
	for (const match of hexMatches) {
		const color = normalizeHexColor(match)
		if (color) colors.push(color)
	}

	const rgbExpression = /rgba?\(\s*(\d{1,3})\s*,\s*(\d{1,3})\s*,\s*(\d{1,3})/gi
	for (const match of value.matchAll(rgbExpression)) {
		const components = match.slice(1, 4).map(Number)
		if (components.every((component) => component >= 0 && component <= 255)) {
			colors.push(colorToHex({ red: components[0], green: components[1], blue: components[2] }))
		}
	}

	return [...new Set(colors)]
}

export function randomGradientColor(random = Math.random): string {
	return colorToHex({
		red: Math.floor(random() * 256),
		green: Math.floor(random() * 256),
		blue: Math.floor(random() * 256),
	})
}

export function getMinecraftTextShadow(color: string | null): string {
	const normalized = color ? normalizeHexColor(color) : null
	if (!normalized) return '#000000'

	const source = hexToColor(normalized)
	const red = source.red / 255
	const green = source.green / 255
	const blue = source.blue / 255
	const maximum = Math.max(red, green, blue)
	const minimum = Math.min(red, green, blue)
	const delta = maximum - minimum
	const saturation = maximum === 0 ? 0 : delta / maximum
	let hue = 0

	if (delta) {
		if (maximum === red) hue = ((green - blue) / delta) % 6
		else if (maximum === green) hue = (blue - red) / delta + 2
		else hue = (red - green) / delta + 4
		hue = ((hue * 60 + 360) % 360) / 360
	}

	const lightness = maximum / 4
	const chroma = (1 - Math.abs(2 * lightness - 1)) * saturation
	const segment = hue * 6
	const secondary = chroma * (1 - Math.abs((segment % 2) - 1))
	const match = lightness - chroma / 2
	const [shadowRed, shadowGreen, shadowBlue] =
		segment < 1
			? [chroma, secondary, 0]
			: segment < 2
				? [secondary, chroma, 0]
				: segment < 3
					? [0, chroma, secondary]
					: segment < 4
						? [0, secondary, chroma]
						: segment < 5
							? [secondary, 0, chroma]
							: [chroma, 0, secondary]

	return colorToHex({
		red: Math.round((shadowRed + match) * 255),
		green: Math.round((shadowGreen + match) * 255),
		blue: Math.round((shadowBlue + match) * 255),
	})
}

export function interpolateGradient(colors: string[], count: number): string[] {
	const normalized = colors
		.map(normalizeHexColor)
		.filter((color): color is string => color !== null)
	if (count <= 0 || normalized.length === 0) return []
	if (normalized.length === 1 || count === 1)
		return Array.from({ length: count }, () => normalized[0])

	const source = normalized.map(hexToColor)
	return Array.from({ length: count }, (_, index) => {
		const position = index / (count - 1)
		const scaled = position * (source.length - 1)
		const startIndex = Math.floor(scaled)
		const endIndex = Math.min(source.length - 1, startIndex + 1)
		const progress = scaled - startIndex
		const start = source[startIndex]
		const end = source[endIndex]
		return colorToHex({
			red: Math.round(start.red + (end.red - start.red) * progress),
			green: Math.round(start.green + (end.green - start.green) * progress),
			blue: Math.round(start.blue + (end.blue - start.blue) * progress),
		})
	})
}

export function buildGradientCharacters(
	document: GradientTextDocument,
	colors: string[],
): GradientCharacter[] {
	const safeDocument = normalizeGradientDocument(document)
	const uncoloredCharacterCount = safeDocument.lines.reduce(
		(total, line) =>
			total +
			line.reduce(
				(lineTotal, run) =>
					lineTotal + Array.from(run.text).filter((character) => !/\s/u.test(character)).length,
				0,
			),
		0,
	)
	const gradient = interpolateGradient(colors, uncoloredCharacterCount)
	let colorIndex = 0
	const characters: GradientCharacter[] = []

	safeDocument.lines.forEach((line, lineIndex) => {
		line.forEach((run) => {
			for (const character of Array.from(run.text)) {
				const color = /\s/u.test(character) ? null : (gradient[colorIndex++] ?? null)
				characters.push({ character, color, formats: run.formats })
			}
		})
		if (lineIndex < safeDocument.lines.length - 1) {
			characters.push({ character: '\n', color: null, formats: [], newline: true })
		}
	})

	return characters
}

export function generateGradientOutput(
	document: GradientTextDocument,
	colors: string[],
	adapterId: GradientFormatId,
	options: GradientOutputOptions,
): string {
	const characters = buildGradientCharacters(document, colors)
	switch (adapterId) {
		case 'vanilla':
			return formatVanillaCharacters(characters, options.vanillaCharacter)
		case 'vanilla-compatible':
			return formatVanillaCompatibleCharacters(characters, options.vanillaCharacter)
		case 'standard':
			return formatEachCharacter(characters, (character) =>
				character.color ? `${character.color}${character.character}` : character.character,
			)
		case 'cmi':
			return formatEachCharacter(
				characters,
				(character) =>
					character.color ? `{${character.color}}${character.character}` : character.character,
				ampersandFormats,
			)
		case 'minimessage':
			return formatEachCharacter(
				characters,
				(character) =>
					character.color ? `<${character.color}>${character.character}` : character.character,
				minimessageFormats,
			)
		case 'minimessage-gradient':
			return formatGradientRuns(
				characters,
				colors,
				options.simplifyGradients,
				(text, runColors, formats) =>
					wrapFormats(
						`<gradient:${runColors.join(':')}>${text}</gradient>`,
						formats,
						minimessageFormats,
					),
			)
		case 'minedown':
			return formatEachCharacter(
				characters,
				(character) =>
					character.color ? `&${character.color}&${character.character}` : character.character,
				minedownFormats,
			)
		case 'snbt':
			return toSnbt(characters)
		case 'trchat':
		case 'taboolib':
			return formatEachCharacter(
				characters,
				(character) =>
					character.color ? `&{${character.color}}${character.character}` : character.character,
				ampersandFormats,
			)
		case 'taboolib-gradient':
			return formatGradientRuns(
				characters,
				colors,
				options.simplifyGradients,
				(text, runColors, formats) => {
					const modifiers = formats.map((format) => taboolibFormats[format]).filter(Boolean)
					return `[${text}](gradient=${runColors.join(',')}${modifiers.length ? `;${modifiers.join(';')}` : ''})`
				},
			)
		case 'rosegarden-gradient':
			return formatGradientRuns(
				characters,
				colors,
				options.simplifyGradients,
				(text, runColors, formats) =>
					wrapFormats(`<g:${runColors.join(':')}>${text}`, formats, minimessageFormats),
			)
		case 'chat-colors':
			return formatEachCharacter(
				characters,
				(character) =>
					character.color ? `[${character.color}]${character.character}` : character.character,
				chatColorsFormats,
			)
		case 'motd':
			return formatMotdCharacters(characters)
		case 'bbcode':
			return formatEachCharacter(
				characters,
				(character) =>
					character.color
						? `[color=${character.color}]${character.character}[/color]`
						: character.character,
				bbcodeFormats,
			)
		case 'json':
			return JSON.stringify(toTextComponents(characters))
		case 'html':
			return toHtml(characters)
		case 'csv':
			return toCsv(characters)
		case 'terraria':
			return formatEachCharacter(characters, (character) =>
				character.color
					? `[c/${character.color.slice(1)}:${character.character}]`
					: character.character,
			)
	}
}

export function normalizeGradientDocument(value: GradientTextDocument): GradientTextDocument {
	const lines = Array.isArray(value?.lines) ? value.lines : []
	const normalizedLines = lines.map((line) => {
		if (!Array.isArray(line)) return []
		return line
			.filter((run): run is GradientTextRun => typeof run?.text === 'string')
			.map((run) => ({
				text: run.text,
				formats: TEXT_FORMATS.filter(
					(format) => Array.isArray(run.formats) && run.formats.includes(format),
				),
			}))
	})
	return { lines: normalizedLines.length ? normalizedLines : [[{ text: '', formats: [] }]] }
}

const minimessageFormats: Record<TextFormat, readonly [string, string]> = {
	bold: ['<b>', '</b>'],
	italic: ['<i>', '</i>'],
	underlined: ['<u>', '</u>'],
	strikethrough: ['<st>', '</st>'],
	obfuscated: ['<obf>', '</obf>'],
}

const ampersandFormats: Record<TextFormat, readonly [string, string]> = {
	bold: ['&l', ''],
	italic: ['&o', ''],
	underlined: ['&n', ''],
	strikethrough: ['&m', ''],
	obfuscated: ['&k', ''],
}

const minedownFormats: Record<TextFormat, readonly [string, string]> = {
	bold: ['**', '**'],
	italic: ['##', '##'],
	underlined: ['__', '__'],
	strikethrough: ['~~', '~~'],
	obfuscated: ['??', '??'],
}

const chatColorsFormats: Record<TextFormat, readonly [string, string]> = {
	bold: ['**', '**'],
	italic: ['*', '*'],
	underlined: ['__', '__'],
	strikethrough: ['~~', '~~'],
	obfuscated: ['', ''],
}

const bbcodeFormats: Record<TextFormat, readonly [string, string]> = {
	bold: ['[b]', '[/b]'],
	italic: ['[i]', '[/i]'],
	underlined: ['[u]', '[/u]'],
	strikethrough: ['[s]', '[/s]'],
	obfuscated: ['', ''],
}

const taboolibFormats: Record<TextFormat, string> = {
	bold: 'b',
	italic: 'i',
	underlined: 'u',
	strikethrough: 's',
	obfuscated: 'o',
}

function formatEachCharacter(
	characters: GradientCharacter[],
	formatter: (character: GradientCharacter) => string,
	formatMap?: Record<TextFormat, readonly [string, string]>,
): string {
	return characters
		.map((character) => {
			if (character.newline) return '\n'
			const formatted = formatter(character)
			return formatMap ? wrapFormats(formatted, character.formats, formatMap) : formatted
		})
		.join('')
}

function formatLegacyCharacters(
	characters: GradientCharacter[],
	formatter: (character: GradientCharacter) => string,
): string {
	return characters
		.map((character) => {
			if (character.newline) return '\n'
			return formatter(character)
		})
		.join('')
}

function formatVanillaCharacters(
	characters: GradientCharacter[],
	characterCode: '&' | '§',
): string {
	return formatLegacyCharacters(characters, (character) => {
		if (!character.color) return character.character
		return `${characterCode}${character.color}${legacyFormatCodes(character.formats, characterCode)}${character.character}`
	})
}

function formatVanillaCompatibleCharacters(
	characters: GradientCharacter[],
	characterCode: '&' | '§',
): string {
	return formatLegacyCharacters(characters, (character) => {
		if (!character.color) return character.character
		const hexadecimal = character.color
			.slice(1)
			.split('')
			.map((part) => `${characterCode}${part}`)
			.join('')
		return `${characterCode}x${hexadecimal}${legacyFormatCodes(character.formats, characterCode)}${character.character}`
	})
}

function formatMotdCharacters(characters: GradientCharacter[]): string {
	const characterCode = '\\u00A7'
	return formatLegacyCharacters(characters, (character) => {
		if (!character.color) return character.character
		const hexadecimal = character.color
			.slice(1)
			.split('')
			.map((part) => `${characterCode}${part}`)
			.join('')
		return `${characterCode}x${hexadecimal}${legacyFormatCodes(character.formats, characterCode)}${character.character}`
	})
}

function legacyFormatCodes(formats: TextFormat[], characterCode: string): string {
	return formats
		.map((format) => {
			switch (format) {
				case 'bold':
					return `${characterCode}l`
				case 'italic':
					return `${characterCode}o`
				case 'underlined':
					return `${characterCode}n`
				case 'strikethrough':
					return `${characterCode}m`
				case 'obfuscated':
					return `${characterCode}k`
			}
		})
		.join('')
}

function formatGradientRuns(
	characters: GradientCharacter[],
	baseColors: string[],
	simplify: boolean,
	formatter: (text: string, colors: string[], formats: TextFormat[]) => string,
): string {
	const output: string[] = []
	let run: GradientCharacter[] = []

	const flush = () => {
		if (!run.length) return
		const text = run.map((character) => character.character).join('')
		const runColors = run
			.map((character) => character.color)
			.filter((color): color is string => color !== null)
		const colors =
			simplify && runColors.length > 1 ? [runColors[0], runColors[runColors.length - 1]] : runColors
		output.push(formatter(text, colors.length ? colors : baseColors, run[0].formats))
		run = []
	}

	for (const character of characters) {
		if (character.newline) {
			flush()
			output.push('\n')
			continue
		}
		if (
			run.length &&
			(run[0].formats.join(',') !== character.formats.join(',') || character.color === null)
		) {
			flush()
		}
		run.push(character)
	}
	flush()
	return output.join('')
}

function wrapFormats(
	text: string,
	formats: TextFormat[],
	formatMap: Record<TextFormat, readonly [string, string]>,
): string {
	return formats.reduce((result, format) => {
		const [start, end] = formatMap[format]
		return `${start}${result}${end}`
	}, text)
}

function toTextComponents(characters: GradientCharacter[]) {
	return characters.map((character) => {
		const component: Record<string, string | boolean> = { text: character.character }
		if (character.color) component.color = character.color
		for (const format of character.formats) component[format] = true
		return component
	})
}

function toSnbt(characters: GradientCharacter[]): string {
	return `[${characters
		.map((character) => {
			const entries = [`text:${quoteSnbt(character.character)}`]
			if (character.color) entries.push(`color:${quoteSnbt(character.color)}`)
			for (const format of character.formats) entries.push(`${format}:true`)
			return `{${entries.join(',')}}`
		})
		.join(',')}]`
}

function toHtml(characters: GradientCharacter[]): string {
	const lines: string[] = ['']
	for (const character of characters) {
		if (character.newline) {
			lines.push('')
			continue
		}
		const content = character.character === ' ' ? '&nbsp;' : escapeHtml(character.character)
		const colored = character.color
			? `<span style="color: ${character.color};">${content}</span>`
			: content
		lines[lines.length - 1] += wrapFormats(colored, character.formats, htmlFormats)
	}
	return lines.map((line) => `<p>${line}</p>`).join('')
}

const htmlFormats: Record<TextFormat, readonly [string, string]> = {
	bold: ['<b>', '</b>'],
	italic: ['<i>', '</i>'],
	underlined: ['<u>', '</u>'],
	strikethrough: ['<s>', '</s>'],
	obfuscated: ['', ''],
}

function toCsv(characters: GradientCharacter[]): string {
	const header = 'color,char,bold,italic,underlined,strikethrough,obfuscated'
	const rows = characters.map((character) =>
		[
			character.color ?? '',
			character.newline ? '\\n' : character.character,
			...TEXT_FORMATS.map((format) => character.formats.includes(format)),
		]
			.map(csvCell)
			.join(','),
	)
	return [header, ...rows].join('\n')
}

function csvCell(value: string | boolean): string {
	const text = String(value)
	return /[",\n]/.test(text) ? `"${text.replaceAll('"', '""')}"` : text
}

function quoteSnbt(value: string): string {
	return `'${value.replaceAll('\\', '\\\\').replaceAll("'", "\\'")}'`
}

function escapeHtml(value: string): string {
	return value
		.replaceAll('&', '&amp;')
		.replaceAll('<', '&lt;')
		.replaceAll('>', '&gt;')
		.replaceAll('"', '&quot;')
		.replaceAll("'", '&#39;')
}

function hexToColor(hex: string): Color {
	const value = hex.slice(1)
	return {
		red: Number.parseInt(value.slice(0, 2), 16),
		green: Number.parseInt(value.slice(2, 4), 16),
		blue: Number.parseInt(value.slice(4, 6), 16),
	}
}

function colorToHex(color: Color): string {
	return `#${[color.red, color.green, color.blue]
		.map((component) => Math.max(0, Math.min(255, component)).toString(16).padStart(2, '0'))
		.join('')
		.toUpperCase()}`
}