import { Editor, EditorRange, EditorSelection } from 'obsidian'

// ============================================================
// Selection Utilities
// ============================================================

/**
 * Get the main (primary) selection from the editor
 */
export function getMainSelection(editor: Editor): EditorSelection {
	return {
		anchor: editor.getCursor('anchor'),
		head: editor.getCursor('head'),
	}
}

/**
 * Convert a selection to a range (from/to with sorted positions)
 */
export function selectionToRange(selection: EditorSelection): EditorRange {
	const sortedPositions = [selection.anchor, selection.head].sort((a, b) => {
		if (a.line !== b.line) return a.line - b.line
		return a.ch - b.ch
	})
	return {
		from: sortedPositions[0],
		to: sortedPositions[1],
	}
}

/**
 * Convert a selection to encompass full lines
 */
export function selectionToLine(editor: Editor, selection: EditorSelection): EditorSelection {
	const range = selectionToRange(selection)
	return {
		anchor: { line: range.from.line, ch: 0 },
		head: { line: range.to.line, ch: editor.getLine(range.to.line).length },
	}
}

// ============================================================
// Text Utilities
// ============================================================

/**
 * Get leading whitespace (indentation) from a line
 */
export function getLeadingWhitespace(lineContent: string): string {
	const indentation = lineContent.match(/^\s+/)
	return indentation ? indentation[0] : ''
}

/**
 * Check if a character is a letter or digit
 */
export function isLetterOrDigit(char: string): boolean {
	return /\p{L}\p{M}*/u.test(char) || /\d/.test(char)
}

/**
 * Get the word range at a given position
 */
export function wordRangeAtPos(
	pos: { line: number; ch: number },
	lineContent: string
): { anchor: { line: number; ch: number }; head: { line: number; ch: number } } {
	let start = pos.ch
	let end = pos.ch
	while (start > 0 && isLetterOrDigit(lineContent.charAt(start - 1))) start--
	while (end < lineContent.length && isLetterOrDigit(lineContent.charAt(end))) end++
	return { anchor: { line: pos.line, ch: start }, head: { line: pos.line, ch: end } }
}

// ============================================================
// Case Transformation Utilities
// ============================================================

const LOWERCASE_ARTICLES = ['the', 'a', 'an']

/**
 * Convert text to title case
 */
export function toTitleCase(text: string): string {
	return text
		.split(/(\s+)/)
		.map((w, i, all) => {
			if (i > 0 && i < all.length - 1 && LOWERCASE_ARTICLES.includes(w.toLowerCase())) {
				return w.toLowerCase()
			}
			return w.charAt(0).toUpperCase() + w.slice(1).toLowerCase()
		})
		.join(' ')
}