import Foundation

struct DocumentWordCounts {
    let words: Int
    let characters: Int
    let charactersNoSpaces: Int
    let paragraphs: Int
    let selectedWords: Int?

    init(projection: CRDTProjection, content: NSAttributedString, selection: NSRange) {
        var whole = ""
        func visit(_ node: CRDTNode) {
            if node.type == "text" { whole += node.plainText }
            else {
                if !["image", "hard_break"].contains(node.type), !whole.isEmpty { whole += " " }
                for child in node.children ?? [] { visit(child) }
            }
        }
        for node in projection.children { visit(node) }
        words = Self.countWords(whole)
        characters = whole.utf16.count
        charactersNoSpaces = whole.unicodeScalars.filter { !CharacterSet.whitespacesAndNewlines.contains($0) }.reduce(0) { $0 + $1.utf16.count }
        paragraphs = projection.children.filter {
            ["paragraph", "heading", "code_block", "bullet_list", "ordered_list", "blockquote"].contains($0.type)
        }.count
        let valid = NSIntersectionRange(selection, NSRange(location: 0, length: content.length))
        if valid.length == 0 { selectedWords = nil }
        else {
            var selected = ""
            content.enumerateAttributes(in: valid) { attributes, range, _ in
                if attributes[.docsMarks] is Data {
                    selected += (content.string as NSString).substring(with: range)
                } else if attributes[.docsBlock] != nil {
                    // Only the paragraph terminator separates words. Inline
                    // images and hard breaks contribute no text in web counts.
                    for scalar in (content.string as NSString).substring(with: range).unicodeScalars where scalar == "\n" { selected += " " }
                }
            }
            selectedWords = Self.countWords(selected)
        }
    }

    static func countWords(_ text: String) -> Int {
        var count = 0
        text.enumerateSubstrings(in: text.startIndex..<text.endIndex, options: [.byWords, .substringNotRequired]) { _, _, _, _ in count += 1 }
        return count
    }
}