import { hasAnsi, stripAnsi } from "./ansi"
import { charWidth, stringWidth } from "./east-asian-width"
import type { OverflowLine, TuiCheckResult } from "./types"

const BOX_DRAWING_START = 0x2500
const BOX_DRAWING_END = 0x257f
const MAX_WIDE_COLUMNS = 64

function splitLines(text: string): string[] {
	const lines = text.split(/\r?\n/)
	if (lines.length > 1 && lines[lines.length - 1] === "") lines.pop()
	return lines
}

function isFrameLine(plain: string): boolean {
	for (const char of plain) {
		const codePoint = char.codePointAt(0)
		if (codePoint !== undefined && codePoint >= BOX_DRAWING_START && codePoint <= BOX_DRAWING_END) {
			return true
		}
	}
	return false
}

function wideStartColumns(plain: string): number[] {
	const columns: number[] = []
	let column = 0
	for (const char of plain) {
		const codePoint = char.codePointAt(0)
		if (codePoint === undefined) continue
		const width = charWidth(codePoint)
		if (width === 2) columns.push(column)
		column += width
	}
	return columns
}

function summarize(
	lineCount: number,
	maxWidth: number,
	expectedColumns: number,
	overflowCount: number,
	borderMisaligned: boolean,
	containsAnsi: boolean,
): string {
	const parts = [`${lineCount} line(s)`, `max width ${maxWidth}/${expectedColumns}`]
	if (overflowCount > 0) parts.push(`${overflowCount} overflow line(s)`)
	if (borderMisaligned) parts.push("borders misaligned")
	if (containsAnsi) parts.push("contains ANSI")
	return `${parts.join("; ")}.`
}

export function checkTui(text: string, expectedColumns: number): TuiCheckResult {
	const lines = splitLines(text)
	const lineWidths: number[] = []
	const overflowLines: OverflowLine[] = []
	const wideColumns = new Set<number>()
	const frameWidths = new Set<number>()

	for (let index = 0; index < lines.length; index++) {
		const plain = stripAnsi(lines[index] ?? "")
		const width = stringWidth(plain)
		lineWidths.push(width)
		if (expectedColumns > 0 && width > expectedColumns) {
			overflowLines.push({ line: index + 1, width })
		}
		if (isFrameLine(plain)) frameWidths.add(width)
		for (const column of wideStartColumns(plain)) {
			if (wideColumns.size < MAX_WIDE_COLUMNS) wideColumns.add(column)
		}
	}

	const maxWidth = lineWidths.reduce((max, width) => (width > max ? width : max), 0)
	const borderMisaligned = frameWidths.size > 1
	const containsAnsi = hasAnsi(text)
	return {
		command: "tui-check",
		expectedColumns,
		lineCount: lines.length,
		lineWidths,
		maxWidth,
		overflowLines,
		borderMisaligned,
		wideCharColumns: [...wideColumns].sort((a, b) => a - b),
		hasAnsi: containsAnsi,
		summary: summarize(lines.length, maxWidth, expectedColumns, overflowLines.length, borderMisaligned, containsAnsi),
	}
}