// Copyright (c) 2022, Přemysl Eric Janouch <p@janouch.name>
// SPDX-License-Identifier: 0BSD
'use strict'

// ---- RPC --------------------------------------------------------------------

class RelayRpc extends EventTarget {
	constructor(url) {
		super()
		this.url = url
		this.commandSeq = 0
	}

	connect() {
		// We can't close the connection immediately, as that queues a task.
		if (this.ws !== undefined)
			throw "Already connecting or connected"

		return new Promise((resolve, reject) => {
			let ws = this.ws = new WebSocket(this.url)
			ws.onopen = event => {
				this._initialize()
				resolve()
			}
			// It's going to be code 1006 with no further info.
			ws.onclose = event => {
				reject()
				this.ws = undefined
			}
		})
	}

	_initialize() {
		this.ws.onopen = undefined
		this.ws.onmessage = event => {
			this._process(event.data)
		}
		this.ws.onerror = event => {
			this.dispatchEvent(new CustomEvent('error'))
		}
		this.ws.onclose = event => {
			let message = "Connection closed: " +
				event.code + " (" + event.reason + ")"
			for (const seq in this.promised)
				this.promised[seq].reject(message)

			this.ws = undefined
			this.dispatchEvent(new CustomEvent('close', {
				detail: {message, code: event.code, reason: event.reason},
			}))

			// Now connect() can be called again.
		}

		this.promised = {}
	}

	_process(data) {
		console.log(data)

		if (typeof data !== 'string')
			throw "Binary messages not supported"

		let message = JSON.parse(data)
		if (typeof message !== 'object')
			throw "Invalid message"
		let e = message.data
		if (typeof e !== 'object')
			throw "Invalid message"

		switch (e.event) {
		case 'Error':
			if (this.promised[e.commandSeq] !== undefined)
				this.promised[e.commandSeq].reject(e.error)
			else
				console.error("Unawaited error")
			break
		case 'Response':
			if (this.promised[e.commandSeq] !== undefined)
				this.promised[e.commandSeq].resolve(e.data)
			else
				console.error("Unawaited response")
			break
		default:
			if (typeof e.event !== 'string')
				throw "Invalid event tag"

			this.dispatchEvent(new CustomEvent(e.event, {detail: e}))

			// Minor abstraction layering violation.
			m.redraw()
			return
		}

		delete this.promised[e.commandSeq]
		for (const seq in this.promised) {
			// We don't particularly care about wraparound issues.
			if (seq >= e.commandSeq)
				continue

			this.promised[seq].reject("No response")
			delete this.promised[seq]
		}
	}

	send(params) {
		if (this.ws === undefined)
			throw "Not connected"
		if (typeof params !== 'object')
			throw "Method parameters must be an object"

		let seq = ++this.commandSeq
		if (seq >= 1 << 32)
			seq = this.commandSeq = 0

		this.ws.send(JSON.stringify({commandSeq: seq, data: params}))
		return new Promise((resolve, reject) => {
			this.promised[seq] = {resolve, reject}
		})
	}
}

// ---- Event processing -------------------------------------------------------

// TODO: Probably reset state on disconnect, and indicate to user.
let rpc = new RelayRpc(proxy)
rpc.connect()
	.then(result => {
		rpc.send({command: 'Hello', version: 1})
	})

let buffers = new Map()
let bufferCurrent = undefined

rpc.addEventListener('BufferUpdate', event => {
	let e = event.detail, b = buffers.get(e.bufferName)
	if (b === undefined) {
		b = {lines: []}
		buffers.set(e.bufferName, b)
	}
	// TODO: Update any buffer properties.
})

rpc.addEventListener('BufferRename', event => {
	let e = event.detail
	buffers.set(e.new, buffers.get(e.bufferName))
	buffers.delete(e.bufferName)
})

rpc.addEventListener('BufferRemove', event => {
	let e = event.detail
	buffers.delete(e.bufferName)
})

rpc.addEventListener('BufferActivate', event => {
	let e = event.detail
	bufferCurrent = e.bufferName
	// TODO: Somehow scroll to the end of it immediately.
	// TODO: Focus the textarea.
})

rpc.addEventListener('BufferLine', event => {
	let e = event.detail, b = buffers.get(e.bufferName)
	if (b !== undefined)
		b.lines.push({when: e.when, rendition: e.rendition, items: e.items})
})

rpc.addEventListener('BufferClear', event => {
	let e = event.detail, b = buffers.get(e.bufferName)
	if (b !== undefined)
		b.lines.length = 0
})

// --- Colours -----------------------------------------------------------------

let palette = [
	'#000', '#800', '#080', '#880', '#008', '#808', '#088', '#ccc',
	'#888', '#f00', '#0f0', '#ff0', '#00f', '#f0f', '#0ff', '#fff',
]
palette.length = 256
for (let i = 0; i < 216; i++) {
	let r = i / 36 >> 0, g = (i / 6 >> 0) % 6, b = i % 6
	r = !r ? '00' : (55 + 40 * r).toString(16)
	g = !g ? '00' : (55 + 40 * g).toString(16)
	b = !b ? '00' : (55 + 40 * b).toString(16)
	palette[16 + i] = `#${r}${g}${b}`
}
for (let i = 0; i < 24; i++) {
	let g = ('0' + (8 + i * 10).toString(16)).slice(-2)
	palette[232 + i] = `#${g}${g}${g}`
}

function applyColor(fg, bg, inverse) {
	if (inverse)
		[fg, bg] = [bg >= 0 ? bg : 15, fg >= 0 ? fg : 0]

	let style = ''
	if (fg >= 0)
		style += `color: ${palette[fg]};`
	if (bg >= 0)
		style += `background-color: ${palette[bg]};`
	if (style)
		return style
}

// ---- UI ---------------------------------------------------------------------

let BufferList = {
	view: vnode => {
		let items = []
		buffers.forEach((b, name) => {
			let attrs = {
				onclick: event => {
					rpc.send({command: 'BufferActivate', bufferName: name})
				},
			}
			if (name == bufferCurrent)
				attrs.class = 'active'
			items.push(m('.item', attrs, name))
		})
		return m('.list', {}, items)
	},
}

function linkify(text, attrs, a) {
	let re = new RegExp([
		/https?:\/\//,
		/([^\[\](){}<>"'\s]|\([^\[\](){}<>"'\s]*\))+/,
		/[^\[\](){}<>"'\s,.:]/,
	].map(r => r.source).join(''), 'g')

	let end = 0, match
	while ((match = re.exec(text)) !== null) {
		if (end < match.index)
			a.push(m('span', attrs, text.substring(end, match.index)))
		a.push(m('a', {href: match[0], ...attrs}, match[0]))
		end = re.lastIndex
	}
	if (end < text.length)
		a.push(m('span', attrs, text.substring(end)))
}

let Content = {
	view: vnode => {
		let line = vnode.children[0]
		let content = []
		switch (line.rendition) {
		case 'Indent': content.push(m('span.mark',        {}, ''));  break
		case 'Status': content.push(m('span.mark',        {}, '–')); break
		case 'Error':  content.push(m('span.mark.error',  {}, '⚠')); break
		case 'Join':   content.push(m('span.mark.join',   {}, '→')); break
		case 'Part':   content.push(m('span.mark.part',   {}, '←')); break
		case 'Action': content.push(m('span.mark.action', {}, '✶')); break
		}

		let classes = new Set()
		let flip = c => {
			if (classes.has(c))
				classes.delete(c)
			else
				classes.add(c)
		}
		let fg = -1, bg = -1, inverse = false
		line.items.forEach(item => {
			switch (item.kind) {
			case 'Text':
				linkify(item.text, {
					class: Array.from(classes.keys()).join(' '),
					style: applyColor(fg, bg, inverse),
				}, content)
				break
			case 'Reset':
				classes.clear()
				fg = bg = -1
				inverse = false
				break
			case 'FgColor':
				fg = item.color
				break
			case 'BgColor':
				bg = item.color
				break
			case 'FlipInverse':
				inverse = !inverse
				break
			case 'FlipBold':       flip('b'); break
			case 'FlipItalic':     flip('i'); break
			case 'FlipUnderline':  flip('u'); break
			case 'FlipCrossedOut': flip('s'); break
			case 'FlipMonospace':  flip('m'); break
			}
		})
		return m('.content', {}, content)
	},
}

let Buffer = {
	view: vnode => {
		let lines = []
		let b = buffers.get(bufferCurrent)
		if (b === undefined)
			return

		let lastDateMark = undefined
		b.lines.forEach(line => {
			let date = new Date(line.when)
			let dateMark = date.toLocaleDateString()
			if (dateMark !== lastDateMark) {
				lines.push(m('.date', {}, dateMark))
				lastDateMark = dateMark
			}

			lines.push(m('.time', {}, date.toLocaleTimeString()))
			lines.push(m(Content, {}, line))
		})
		return m('.buffer-container', {}, [
			m('.filler'),
			m('.buffer', {}, lines),
		])
	},
}

function onKeyDown(event) {
	// TODO: And perhaps on other actions, too.
	rpc.send({command: 'Active'})

	// TODO: Cancel any current autocomplete.

	let textarea = event.currentTarget
	switch (event.keyCode) {
	case 9:
		if (textarea.selectionStart !== textarea.selectionEnd)
			return
		rpc.send({
			command: 'BufferComplete',
			bufferName: bufferCurrent,
			text: textarea.value,
			position: textarea.selectionEnd,
		}).then(response => {
			// TODO: Somehow display remaining options, or cycle through.
			if (response.completions.length)
				textarea.setRangeText(response.completions[0],
					response.start, textarea.selectionEnd, 'end')
			if (response.completions.length === 1)
				textarea.setRangeText(' ',
					textarea.selectionStart, textarea.selectionEnd, 'end')
		})
		break;
	case 13:
		rpc.send({
			command: 'BufferInput',
			bufferName: bufferCurrent,
			text: textarea.value,
		})
		textarea.value = ''
		break;
	default:
		return
	}

	event.preventDefault()
}

// TODO: This should be remembered across buffer switches,
// and we'll probably have to intercept /all/ key presses.
let Input = {
	view: vnode => {
		return m('textarea', {
			rows: 1,
			onkeydown: onKeyDown,
		})
	},
}

let Main = {
	view: vnode => {
		return m('.xP', {}, [
			m('.title', {}, "xP"),
			m('.middle', {}, [m(BufferList), m(Buffer)]),
			m('.status', {}, bufferCurrent),
			m(Input),
		])
	},
}

// TODO: Buffer names should work as routes.
window.addEventListener('load', () => {
	m.route(document.body, '/', {
		'/': Main,
	})
})