import Foundation

struct DenoteNote: Identifiable, Hashable {
    let id: String
    let filename: String
    let path: String
    let title: String
    let keywords: [String]
    let fileExtension: String
    let modifiedDate: Date?
    var content: String?

    var displayTitle: String {
        title.isEmpty ? filename : title
    }

    var formattedDate: String {
        guard let date = modifiedDate else { return "" }
        let f = DateFormatter()
        f.dateStyle = .medium
        f.timeStyle = .none
        return f.string(from: date)
    }

    // Parses a Denote filename from a WebDAV href.
    // Expected format: /notes/YYYYMMDDTHHMMSS(==SIGNATURE)?(--TITLE)?(__KW1_KW2)?.EXT
    static func parse(href: String, modifiedDate: Date?) -> DenoteNote? {
        let filename = href.split(separator: "/").last.map(String.init) ?? href

        guard filename.range(of: #"^\d{8}T\d{6}"#, options: .regularExpression) != nil else { return nil }
        guard !filename.hasSuffix(".organice-bak"),
              !filename.hasSuffix(".bak"),
              filename != "DavLock" else { return nil }

        let nameWithoutExt: String
        let ext: String
        if let dotIndex = filename.lastIndex(of: ".") {
            nameWithoutExt = String(filename[..<dotIndex])
            ext = String(filename[filename.index(after: dotIndex)...])
        } else {
            nameWithoutExt = filename
            ext = ""
        }

        var remaining = nameWithoutExt
        let identifier: String
        if let range = remaining.range(of: "--") {
            let rawId = String(remaining[..<range.lowerBound])
            identifier = rawId.components(separatedBy: "==").first ?? rawId
            remaining = String(remaining[range.upperBound...])
        } else {
            identifier = remaining.components(separatedBy: "==").first ?? remaining
            remaining = ""
        }

        let title: String
        let keywords: [String]
        if let kwRange = remaining.range(of: "__") {
            title = slugToTitle(String(remaining[..<kwRange.lowerBound]))
            keywords = String(remaining[kwRange.upperBound...]).split(separator: "_").map(String.init)
        } else {
            title = slugToTitle(remaining)
            keywords = []
        }

        return DenoteNote(
            id: identifier,
            filename: filename,
            path: href,
            title: title,
            keywords: keywords,
            fileExtension: ext,
            modifiedDate: modifiedDate,
            content: nil
        )
    }

    private static func slugToTitle(_ slug: String) -> String {
        slug.replacingOccurrences(of: "-", with: " ")
            .split(separator: " ")
            .map { $0.prefix(1).uppercased() + $0.dropFirst() }
            .joined(separator: " ")
    }

    func hash(into hasher: inout Hasher) { hasher.combine(id) }
    static func == (lhs: DenoteNote, rhs: DenoteNote) -> Bool { lhs.id == rhs.id }
}